1. Introduction

The geometry and kinematics of subduction beneath the west coast of South America and the consequent tectono-magmatic evolution of the Andes continue to be explored by field and laboratory studies, physical and numerical modeling, and plate-to-plate and plate-to-hotspots reconstructions. Low-angle subduction of the Nazca Plate (first recognized by Barazangi and Isacks, 1976), the role of hotspot traces, and consequent volcanic gaps and deflections within the Andes (Fig. 1) are of particular interest even after more than forty years since such a functional role was initially proposed (Cross and Pilger, 1978a). Subsequent work via global plate and hotspot trace reconstructions showed correspondence with apparent gaps in the then limited Cenozoic magmatic record from Peru, Chile, Bolivia, and Argentina (Pilger, 1981, 1984), by analogy with contemporary intersection of such traces with two (and possibly three) low-angle zones within the subducting Nazca plate. Pilger’s approach involved taking models of Pacific plate motion relative to hotspots (principally the Hawaiian-Emperor and Louisville hotspots) and extending them to the Nazca plate by relative plate reconstructions. The Nazca plate, including the modeled Easter-Nazca, Juan Fernández, and Galápagos-Carnegie hotspot traces, was then restored relative to the South American plate for several discrete times via global plate reconstructions. The 1981 global circuit was via Nazca-Pacific-Antarctic-Indian-African-South American plates; the 1984 circuit eliminated the connection through the Indian plate, replacing it with then newly published Antarctic to African plates reconstructions. Other workers subsequently calculated reconstructions of the Nazca to South American plates and Easter-Nazca and/or Juan Fernández hotspot traces relative to South America using a variety of approaches. Yáñez et al . (2001) utilized plate reconstructions relative to a fixed hotspot reference frame (rather than using a global plate circuit) as well as calculating the Juan Fernández hotspot trace in the same frame. Hampel (2002) reconstructed the projected Easter-Nazca trace relative to South America assuming mirror-imaging of the Tuamotu ridge on the Pacific plate (similar to Pilger, 1981), and updated relative plate motion parameters from Somoza (1998); however, Hampel did not calculate full relative reconstructions, but utilized Somoza’s finite difference rotations assuming constant rotation rates. Martinod and Husson (2010) followed a methodology like Pilger’s (1981, 1984), with updated reconstructions in a global circuit and a Pacific-hotspot model (along with other hotspot reference frames) for the Juan Fernández hotspot trace relative to South America. Bello-González et al. (2018) calculated the Juan Fernández trace relative to South America, using a software package that incorporates global circuits for relative motions assuming a global moving hotspot frame. In each of these cases, the observations of the positions of the two hotspot traces relative to South America are broadly consistent with those of Pilger (1981, 1984), but differ in calculated dates and precise positions for the encounter of the traces with the Andean subduction zone, possibly due to changes in geomagnetic timescales, resolution of relative plate reconstructions, and specific plate-hotspot models. In the current work, higher resolution relative plate reconstructions (largely similar to Martinod and Husson, 2010, but with revised South American-African-Antarctic reconstructions), and a combination of revised Pacific plate-hotspot models provide improved apparent correspondence with volcanic patterns in the Andes. (No other reconstruction study has addressed comparisons of modeled hotspot traces with documented Cenozoic magmatism patterns since the 1984 paper)  As a byproduct of this revisitation of the role of hotspot trace subduction, the fate of previously subducted traces after passage beneath the Andes may explain anomalous magmatism well to the east along coastal Brazil and extending into the western South Atlantic Ocean .

FIG. 1. Calculated traces of three hotspots, Juan Fernández (JF), Easter-Nazca (EN), and Galápagos-Carnegie (GC) relative to the contemporary Nazca plate with seismicity of the Andean subduction zone; the traces are not conformable to the inferred subduction zone. The calculations are based on a composite of several models of Pacific plate motion relative to hotspots, propagated to the Nazca plate by Pacific-Nazca plate motion, as discussed in the text. Parameters of Nazca/Farallon plate motion relative to the South American plate at 5 Myr increments are listed in table 1; parameters at 1 Myr increments are listed in Supplementary table 2.

1.1. Updated reconstructions across spreading centers

Plate-pair reconstructions in the ocean basins have greatly improved in resolution and confidence from denser magnetic and bathymetric coverage (especially over younger oceanic lithosphere) and satellite geoid measurements which constrain fracture zone locations. For example, Quiero et al. (2022) provide the most recent relative reconstructions of the Nazca and South American plates, although limited to ~30 Ma and younger, incorporating high resolution studies in the South Atlantic, Southwest Indian, and Southwest Pacific Oceans along with lower resolution studies in the East Pacific. While resolution over older portions of plates in the Atlantic and Indian oceans and East Pacific is reduced, largely due to less dense survey coverage, reconstructions extending to 80 Ma (for this study, reconstructions of the Pacific plate relative to the Atlantic-Indian Ocean plates are uncertain prior to ~84 Ma) are nevertheless improved relative to previous studies. Table A1 in the Appendix summarizes the source references for the plate-pair reconstructions used in this study (the source parameters are provided in Supplementary Table 1).

1.2. Plate-hotspot models

Beginning with Morgan (1972), numerous models of the motion of the Pacific plate relative to hotspots have been produced as more data have accumulated, especially with the replacement of potassium-argon by more accurate and precise argon-argon dating. Of particular relevance is the age of the Hawaiian-Emperor (HE) bend and its correlatives along other traces of the plate. Pacific-hotspot reconstruction parameters can be extrapolated to the Nazca plate by relative plate reconstructions, providing a means of distinguishing among the various Pacific-hotspot models by comparison with traces on the Nazca plate and patterns of subduction-related magmatism in the Andes. Figure 2 illustrates nine such models, applied to the Easter-Nazca, Juan Fernández, and Galápagos-Carnegie hotspots relative to the Nazca plate. As elaborated further below, a composite of several of the parameter sets over the last ~80 Myr (Fig. 3) appears to best correspond with the volcanic history of the Andes since ~30 Ma, while remaining conformable to Pacific and Nazca plate hotspot trace dates and patterns and global plate reconstructions. Table A2 in the Appendix summarizes the sources for the plate-hotspot reconstructions used in this study.

FIG. 2. A. Calculated loci of the Easter-Nazca (EN), Galápagos-Carnegie (GC), and Juan Fernández (JF) hotspot traces reconstructed relative to the Nazca Plate for eight Pacific-Hotspot models, plus composite model, modified to a Hawaiian-Emperor bend age of 50 Ma, propagated via Pacific-Nazca relative plate reconstructions (see text for details). B. Zoomed view of the JF trace as in A. Model key with sources: A06: Andrews et al. (2006; 10.9-80 Ma), G22: Gaastra et al. (2022; 1-80 Ma), H00: Harada and Hamano (2000; 2-70 Ma), N00: Norton (2000; 5-81 Ma), R00: Raymond et al. (2000 and personal communication, 2003; 5.81-78.78 Ma), W06: Wessel et al. (2006; 2.58-125 Ma), W08A and W08G: Wessel and Kroenke (2008; 2.58-140 and 3.36-140 Ma, respectively).

 

FIG. 3. A. Reconstruction of the Juan Fernández (JF) hotspot trace on the Nazca plate relative to the South American plate, 0-80 Ma, at 1 Myr increments; every fifth increment is colored gold. Parameters of Nazca/Farallon plate motion relative to the South American Plate are listed in table 1 at 5 Myr increments; the parameters at every 1 Myr are in Supplementary table 2. B. Reconstruction of the Easter-Nazca (EN) trace on the Nazca plate as in A. for 0-80 Ma.

For the plates of the Atlantic and Indian oceans, the younger part of the classic model of Müller et al. (1993; “M93”) for the hotspot traces corresponds well with the southward propagating wave of magmatism in east-central Africa from ~60 Ma to Present (Pilger, 2003) and with reconstructions of the Caribbean island arc over the same period of time (Müller et al., 1999), neither of which were used in derivation of M93. M93 is utilized in the last part of this study, after examining several alternative “moving hotspot” models, beginning with O’Neill et al. (2005) and modified by Doubrovine et al. (2012); Torsvik et al. (2019) and Müller et al. (2019).

1.3. Magmatic history of the Andes

The author updated and expanded the compilation of radiometric dates from Andean igneous rocks providing for comparison with plate-to-plate and plate-hotspot reconstructions. The dataset, which incorporates previous regional compilations as well as numerous original publications, is particularly focused on the Andean crest from northern Peru to southern Chile and along the foreland from Peru through Bolivia and Argentina. Maps at 10 Myr intervals, 0-80 Ma, are provided in the Supplementary Data, along with a Supplementary File for display in Google Earth. For this study, sections parallel with the oceanic trench display the radiometric data projected normal to the sections. Figure 4 portrays the dates in two stacked views, in age versus latitude, for 0-100 Ma and 10° N to 60° S. Figures 5 and 6 are graphs of age versus latitude for 1° longitude segments together with reconstructed loci intersections.

FIG. 4. Isotopic dates (Ma) from the Andes, versus latitude, along sections parallel with the oceanic trench. Distance from trench in longitudinal segments, by indicated symbol. A. “View” is from the east. B. “View” from the west. The data, from 0-100 Ma silicic and intermediate igneous rocks, are provided in the Supplementary File. The full compilation can be accessed via GEOROC (Pilger, 2022).

FIG. 5. Projection of isotopic dates ranging from 0 to 100 Ma and 10°N-60°S latitude from the Andes and adjacent foreland in arc segments at increments of 1° of arc separation from the contemporary Andean trench, from 0-1° (A) to 6-7° (G) of arc, with intersections of reconstructed hotspot locus at 1° increments. JF: Juan Fernández, EN: Easter-Nazca, PH: Pacific Hotspot model.

FIG. 6. Zoomed projections of isotopic dates and intersections of hotspot traces as in figure 5, for 0-40 Ma and 10° N-40° S latitude. Symbols as in figure 5.

2. Methodology

Global reconstructions of the motion of the subducting Nazca/Farallon plate (the Farallon plate fragmented into the Nazca and Cocos plates at ~23 Ma) relative to the upper, South American, plate follow the circuit Nazca/Farallon-Pacific-West Antarctic-East Antarctic-African-South American (plate-pair sources are indicated in the Table A1 in the Appendix, with parameter values in Supplementary Table 1), interpolated at 1 Myr increments from 0 to 80 Ma, using cubic-splined pseudovectors (converted from the original spherical coordinates) with magnitude equal to the total rotation rate (Pilger, 2003). The plate parameters are calibrated to the recent timescale of Ogg (2020), which is tied to the astronomically tuned timescale of Gradstein et al. (2020). Rotations are composed using quaternions transformed from the pseudovectors (Pilger, 2003), with further composition of the total reconstruction quaternions to rotate the (unit vector) points; the latter reconstructed vectors are inverted to spherical coordinates for display in Google Earth. Table 1 provides the calculated Nazca/Farallon-South America reconstruction parameters at 5 Myr increments (more detailed parameters at 1 Myr increments are provided in the Supplementary Data along with the source plate-pair reconstructions). Uncertainties are not provided because they cannot be legitimately calculated via interpolation (the rationale is provided in the Supplementary Data; see also discussion in Pilger, 2007). Instantaneous rotation rates are calculated at the same 1 Myr increments using the derivatives of the spline parameters (using the modified Smith, 1985, equation by Pilger, 2003) at several locations along the oceanic trench.

Three persistent hotspots appear to exist beneath the Nazca plate (Fig. 1), with traces extending to the east and northeast: the Juan Fernández (JF), Easter/Nazca (EN), and Galápagos/Carnegie (GC; this also appears to have an associated trace, the Cocos Ridge, on the Cocos plate). The motion of the Nazca (and its predecessor plate, the Farallon) relative to hotspots beneath the Pacific plate is calculated for eight Pacific-hotspot models (Table A2 in the Appendix), with dates for the parameters adjusted to an age of 50 Ma for the Hawaiian-Emperor (HE) bend (Pilger and Handschumacher, 1981; Sharp and Clague, 2006; O’Connor et al., 2013; Wright et al., 2015; Hu et al., 2022), extended by relative plate reconstructions from the Pacific to the Nazca plate from 0 to 140 Ma at 1 Myr increments (some models do not cover the full 140 Ma, so the older part of the Wessel and Kroenke, 2008, model A is appended to them as shown in figure 2). The calculated traces relative to the Nazca plate are then reconstructed at 1 Myr increments relative to the South American plate to 80 Ma (Fig. 2), utilizing the global reconstruction circuit parameters and assuming symmetrical spreading across the Pacific-Farallon boundary between 53 and 83.65 Ma. A composite model was constructed by selecting segments of several models which best visually fit the bathymetry of the JF and GC traces, the seismicity onshore of JF, and the earliest intersection of the JF trace with the Andean crest. The selected model components are taken from Gripp and Gordon (2002; 0 Ma), Gaastra et al. (2022; 1-16 Ma), Norton (2000; 25-50 Ma), Raymond et al. (2000; 50-80 Ma), and Wessel and Kroenke (2008; Model A, 83.5-144 Ma), assuming an age of 50 Ma for the HE bend, spline-interpolated as with the relative plate reconstruction parameters. The Pacific-hotspot models can be extended to the Nazca/Farallon plate to 140 Ma or even earlier, but the motion of the Pacific, and thus Farallon, plates relative to South America cannot be confidently determined prior to the younger edge of magnetic isochron 34, that is, 83.65 Ma, because of uncertainty in the position of the Pacific plate relative to both Antarctica and Australia prior to this time. A spreading center between the Pacific and West Antarctic plates, permitting reconstructions, only came into existence at approximately isochron 34 time (e.g., Wright et al., 2015).

From the composite model, the calculated JF and EN hotspot traces on the Nazca plate were again reconstructed relative to the South American plate back to 80 Ma, at 1 Myr increments(Fig. 3, with 5 Myr increments highlighted). The traces are not conformed to an inferred three-dimensional subduction zone configuration in either map views or graphical sections.

In figure 4, all isotopic dates <80 Ma are projected onto a graph of age versus latitude arranged by longitudinal distance from the trench. The dates farthest from the trench are progressively “on top” of dates closer to the trench in figure 4A, and viceversa in figure 4B.

The isotopic dates are further analyzed in comparison with the reconstructed hotspot traces using projected sections of width one degree of arc from and parallel with the trench (Figs. 5 and 6; Google Earth map views of the dates in 10 Myr intervals are provided in the Supplementary File). Most of the dates are concentrated along the crest of the Andes, approximately two to three degrees of arc from the contemporary trench. Some dates are observed along the east and west flanks of the range, extending into the respective foreland and hinterland.

3. Results

3.1. Reconstructions of the Nazca/Farallon and South American plates and the hotspot traces

As previously inferred from sparse radiometric dates (e.g., Pilger, 1981, 1984), in Peru (5°  to 18° S) there is a northwest-to-southeast, time-transgressive, narrowing gap in young igneous dates along the Andean crest, implying cessation of volcanism from ~13 Ma to the Present (Figs. 5C and 6C). The cessation pattern is parallel with and slightly younger than the calculated intersection of the reconstructed EN trace (Figs. 5C and 6C), and consistent with the progressive onset of low-angle subduction from northwest to southeast.

The patterns of magmatism farther south beginning at 20°S indicate near continuous activity since 80 Ma, although varying in longitudinal position, to 32° S (Figs. 4-6). Along the Andean crest, a gap in volcanism is apparent between 32 and 33° S especially over the last 10 Myr, widening at younger ages (Fig. 6C), again strengthening the inferences of Pilger (1981, 1984). The gap corresponds well with the calculated intersections of the JF hotspot trace, beginning at about 13 Ma, and with the Pampean low-angle subduction segment (e.g., Ramos et al., 2002).

What is the significance of the correlation of isotopic dates and loci intersections of hotspot traces? It is inferred that after passage of the JF trace to the south, magmatism increased and spread farther to the east (e.g., Kay and Coira, 2009). In other words, a southward-shifting, short-lived period of low-angle subduction (depending on the width of the segment, perhaps 2 to 4 Myr in duration between 25 and 15 Ma) interrupted normal subduction and was quickly followed by resumption of, perhaps even increase in magmatism, after passage of the trace (e.g., de Silva and Kay, 2018). Note that the older (>50 Ma) parts of the JF locus intersections lack obvious correspondence with observed isotopic dates (Fig. 5); this is also the least certain part of the Pacific-hotspot motion (Wessel and Kroenke, 2008) due to the scarcity of dates from the Pacific traces older than 80 Ma, although Gaastra et al. (2022) have shown that a fixed hotspot model can fit available data for the past 80 Myr. For the younger parts of both hotspot traces, especially <40 Ma, the projected dates are a bit older than the calculated intersections; because of the two-dimensionality of the graphs, the differences are uncertain. This may be a function of errors in the Pacific-Nazca reconstructions, especially between 10 and 25 Ma, for which magnetic survey coverage is sorely lacking. It is possible that the JF trace encountered the trench several million years earlier than calculated here. Given the sparse magnetic surveys over the Nazca and east-central Pacific plates, and reliance upon assumptions of symmetric spreading based on one-sided reconstructions of the Farallon-Pacific spreading center, there is room for significant variation in the calculated reconstructions (for example, compare the parameters from Rowan and Rowley, 2014, used in this study, with those from Wright et al., 2015). Also, given the oblique encounter of the JF trace with the subduction zone from 25 to 15 Ma, the cessation of trace subduction, as the ridge-subduction intersection migrates southbound, would produce a propagating window with possible “leakage” into the overlying South American plate ahead of the actual deeper trace intersection; that is, possible propagating tears or gaps in the subducting slab accompanying both flanks of the low-angle segment (cf. Báez et al., 2023).

Figure 7 is a sketch of the postulated sequence of events involved with the change from normal subduction (Time 0) to the encounter with the hotspot trace (Time 1) and return to normal subduction (Time 2). The replacement of normal by low-angle subduction would likely result in a transient reduction, if not extinguishment, of magmatism (e.g., Kay and Coira, 2009). With the resumption of normal subduction, a “window” develops, resulting in widening of the magmatic arc, perhaps enhanced by delamination of the mantle portion of the South American plate (e.g., Kay and Kay, 1993; Risse et al., 2013) above the window. Time 3 represents a later period in which normal subduction has continued while the remnant of the trace is eventually under the thinner eastern edge of the South American plate (for the current traces, this is far into the future; long subducted, older traces could have been responsible for observed anomalous magmatism along the east coast of Brazil - see below).

FIG. 7. Schematic illustration of the transitory interaction of a hotspot trace with the Andean subduction zone. Volcanic zone is indicated by triangles (filled: active, empty: inactive). Time 0: Subduction of normal oceanic plate. Time 1: Subduction of part of a hotspot trace. Time 2: Resumption of normal subduction after trace migration. Time 3: Prolonged normal subduction, with trace remnant under thinner upper plate, producing anomalous volcanism. At Time 1, supply of magma to the volcanic arc is suppressed, so that remaining volcanism is from previous magma chambers. Note development of a “window” during Time 2 as the trace segment is overridden by the upper plate, allowing for widening of the volcanic arc. Interruption of normal subduction produces the detached lower oceanic plate, resulting in separation of seismic zones within the subduction zone.

Juan Fernández ridge subduction has also been inferred to produce rotation of the region of the Andes north and south of ~15° S, (i.e., oroclinal bending; Isacks, 1988), as proposed by a number of workers (e.g., Yáñez et al., 2001; McQuarrie, 2002; Martinod et al., 2010; Arriagada et al., 2013; Schepers et al., 2017). The correspondence of the reconstruction timing with the geological observations, as they noted, is supported by paleomagnetic evidence as well (e.g., Dupont-Nivet et al., 1996; Arriagada et al., 2008; Puigdomenech et al., 2021).

3.2. Convergence rate and direction

Figure 8 illustrates instantaneous Nazca to South American convergence rates and directions calculated at 1 Myr increments at locations along the Andean trench, via spline interpolation of rotation pseudovectors. The angles are measured clockwise from the trench. Resolution of source data is denser over the past 25 Myr, because of the greater resolution of source plate pairs in the South Atlantic, Southwest Indian, and Southwest Pacific oceans.

FIG. 8. Incremental average rates and angles. A. Instantaneous Nazca/Farallon to South American plate convergence rates calculated at indicated locations along the Andean Trench, as described in the text. B. Instantaneous angle between convergence direction and Andean trench, measured clockwise at same points as A.

Comparison of the convergence rates (Fig. 8A) with the isotopic date sections shown in figures 5 and 6 is not easily characterized. However, there does appear to be a correlation of the greater density of dates between 45 to 30 Ma and 25 to 15 Ma in parts of the Andes with the observed higher convergence rates (e.g., Figs. 5C and 6C). In addition, gaps in magmatism in the Peruvian Andes prior to 45 Ma appear to correlate with highly oblique subduction. A short pulse of oblique convergence between 30 and 25 Ma may also correlate with reduced density of dates over much of the Andes. The variations in the convergence angle and rate over time may have implications for the tectonics of the Andes, as shown recently in some studies (e.g., Bello-González et al., 2018; Quiero et al., 2022). The principal variations in rate and direction, now quantifiable at higher resolution were, nevertheless, implicit in the earliest studies, (e.g., Pilger, 1983; Cande, 1985; and Pardo-Casas and Molnar, 1987), although apparent errors in the early geomagnetic time scales used then may have resulted in artificial variations in the calculated convergence rates. It is worth mentioning that the Pacific-Nazca plate pair is still poorly documented due to low density of magnetic surveys (e.g., Wilder, 2003; Seton et al., 2014), so it is likely that further improvement in the rate/angle calculations could result from future, higher density coverage of the region.

3.3. Complications and alternative models

A spectrum of models to explain the Peruvian and Pampean low-angle subduction zones have been advanced since these zones were first recognized. In addition to subduction of hotspot traces, these models have included the absolute motion of the upper (continental) plate, convergence rate, cycles of upper plate thickening due to crustal shortening, trench erosion, and/or magmatism. In support of such models, physical and numerical modeling as well as empirical observations have been utilized. As background to such investigations, a comprehensive study of subduction zone configuration, updating Jarrard’s (1986) original study, by Lallemand et al. (2005) showed that increased absolute motion rate of the upper plate toward the trench may be an important factor in systematically reducing the subduction dip angle. However, they did not consider the effect of hotspot trace subduction in their global synthesis.

Martinod et al. (2005, 2013) applied analog modeling to testing the role of aseismic ridge subduction without success in producing low-angle inclination of the descending slab. Numerical modeling by van Hunen et al. (2004) supported the absolute motion effect, as Cross and Pilger (1978a, b) had earlier proposed. Physical analog modeling by Espurt et al. (2008) suggested that low-angle subduction of a thickened oceanic feature like the Nazca Ridge would require ~7 Myr to develop, assuming the thickened portion retains continuity with previously subducted normal, denser oceanic lithosphere. They also supported the inferred absolute motion effect but did not test the subduction of thickened oceanic plate detached from previously subducted normal oceanic plate. DeCelles et al. (2009) advanced a grand model which emphasize inferred cyclicity in Andean-type subduction relative to tectonic effects within and along the magmatic arc, while incorporating the role of subducting hotspot traces as rare factors independent of the cyclicity, producing not only low-angle subduction but also internal deformation of the foreland of the mountain belt, such as the central Chile-Argentina low-angle subduction segment and the Laramide Rocky Mountains of the United States.

Gerya et al. (2009) interpreted their numerical modeling to imply the aseismic ridge effect on subduction was transient and unstable. However, they did not consider the absolute motion of the upper plate. Skinner and Clayton (2010, 2013) argued against the hotspot trace subduction effect based on an interpreted seamount chain on the Nazca plate, unlike the Easter/Nazca or Juan Fernández traces, whose extension into the subduction zone has no apparent effect on the inclined seismic zone (in the 2010 paper they also cited examples of similar subducting traces in the western Pacific, but did not consider the role of absolute motion as an additional factor). Their 2013 study is discussed further, below.

Rodríguez‐González et al. (2012) suggested the thermal state of the upper plate is an important factor in low-angle subduction, through numerical modeling and comparisons of subduction zones beneath Mexico and southern Central America; however, they did not consider the contrasting absolute motions of the upper plates in either environment (e.g., Cross and Pilger, 1982). Manea et al. (2012, 2017) applied numerical modeling with results supporting trenchward absolute motion and thickness of the upper plate as important factors in low-angle subduction, while ruling out hotspot traces based on Skinner and Clayton’s (2010) evidence. Antonijevic et al. (2015), in studying the configuration of the low-angle subduction segment beneath Peru, supported a combination of the subducting Nazca Ridge, trenchward movement of the upper plate, and suction. Huangfu et al. (2016) applied numerical modeling to subducting oceanic plate and produced lower angle subduction with thickened lithosphere; absolute motion of the upper plate toward the trench also could contribute to low-angle subduction in their work. Hu et al. (2016) were able also to produce low-angle subduction from the aseismic ridge effect and increased thickness of the upper plate without taking trenchward motion of the upper plate into account.

Schepers et al. (2017) emphasized absolute motion of the upper plate (in a moving hotspot reference frame) as a primary factor in low-angle subduction beneath Peru, excluding a Nazca ridge effect, based on Skinner and Clayton’s (2013) inferences. Flórez‐Rodríguez et al. (2019), from analog modeling, inferred that aseismic ridges can produce low-angle subduction in some circumstances; they also contrasted their modeling with that of Martinod et al. (2005, 2013) to explain their differing results. Bishop et al. (2017), from seismicity and velocity modeling, detected an apparent low-velocity layer beneath the crustal part of the subducting Nazca ridge which they infer may represent serpentinized lower oceanic lithosphere, which would contribute to the buoyancy of the ridge, a factor which dynamic modelers may want to incorporate in future work (Kopp et al., 2004 previously inferred possible serpentinization of the lithosphere beneath the Juan Fernández seamount chain). Yan et al. (2020), from numerical modeling, inferred that subduction of an oceanic plateau in combination with trenchward displacement of the upper plate leads to low-angle subduction (they did not deal with the origin of such a plateau). Schellart (2020), based on numerical and analog modeling and a global synthesis, argued against the roles of subducting ridges and/or trenchward migration of the upper plate, and ruled out their role in combination by one example, Mexico, where no aseismic ridge is observed.

For the most part a combination of subduction of aseismic ridges and trenchward motion of the upper plate appear to be the most consistent mechanisms the numerical and analog modeling studies have inferred. With few exceptions, most of the studies did not consider the evidence from plate reconstructions (e.g., Pilger, 1981, 1984; Yáñez et al., 2001; Bello-González et al., 2018) that show correspondences with Andean tectonism and volcanic patterns.

Some other observations involving aseismic ridge models also can be addressed. For example, subduction of a Manihiki Plateau (MP) fragment in the late Paleocene-early Eocene may have formed the Bolivian orocline at  ~18-22° S (O’Driscoll et al., 2012; Saylor et al., 2023). Interestingly, calculated loci for three models of the JF hotspot relative to the Pacific plate for 140-80 Ma (Fig. 9, calculated from the parameters of Wessel and Kroenke, 2006, and 2008, their models A and B) intersect the region to the west of the MP where O’Driscoll et al. (2012) postulated a Farallon plate complement existed at approximately 125 Ma. Given the variations in the positions between the three modeled loci (Fig. 9), it seems plausible that the existing JF hotspot is a remnant of the plume that O’Driscoll et al. (2012) and others postulated produced the MP and the Ontong Java plateau. In contrast, the modeled loci from the parameters of Torsvik et al. (2019) place the calculated JF locus well to the east of the MP (Fig. 9), which is inconsistent with the association of the MP and the JF. Also, the calculated locus of the Foundation (FN) hotspot relative to the Pacific plate, calculated from the composite Wessel and Kroenke (2008) Model A utilized here, falls just north of the MP at about 100 Ma. The composite Torsvik et al. (2019) model intersects the northern flank of the MP (Fig. 9). Ages as young as the locus predicts (~100 Ma) have not been reported, but this part of the plateau may be yet unsampled. In sum, the proposal of O’Driscoll et al. (2012) is consistent only in part with the results presented here. The Manihiki Plateau may have been produced by the same hotspot (or plume) that produced the Juan Fernández trace; however, the reconstructed portion of the trace that intersected the Peru-Chile trench offshore southern Peru and northern Chile (responsible for the Bolivian orocline), is younger than the Plateau (Fig. 3A). The complement to the Plateau on the Nazca plate, if it indeed existed, would have encountered the trench earlier (i.e., >40 Ma) than the formation of the orocline. Alternatively, the complement to the Manihiki Plateau may have been displaced onto the now subducted Phoenix plate (beneath Antarctica; Hochmuth and Gohl, 2017), rather than becoming part of the Nazca plate, but this does not obviate a common origin of the Plateau, its complement, and the Juan Fernández hotspot.

FIG. 9. Region around Manihiki Plateau with loci from proposed Juan Fernández (JF) and Foundation (FN) hotspots, relative to a Pacific hotspot frame, based on three composite model with various parameters for 80-140 Ma as indicated. CT19: Torsvik   et al. (2019). CW06: Wessel et al. (2006). CW08A and CW08B: Wessel and Kroenke (2008).

As noted above, Skinner and Clayton (2013) suggested another subducting aseismic ridge exists offshore southern Peru and northern Chile (17° to 19° S), previously interpreted as a propagating spreading center (Cande and Haxby, 1991). Where the inferred ridge encounters the trench there is no obvious effect on the subduction configuration, which argues against the hypothetical correlation of hotspot traces with low-angle subduction; this observation has been cited by several workers as an argument for other mechanisms for low-angle subduction (as mentioned above). A candidate for this ridge’s hotspot is the same melting center assumed to have produced the Foundation seamount chain on the young Pacific plate (Bello-González et al., 2018, see also Contreras-Reyes et al., 2021). Utilizing the composite Pacific-hotspot model of Pacific and Nazca/Farallon plate motion, loci of the Foundation hotspot on each plate are calculated (Fig. 10) and come close to observed ridge segments on each plate, including that which Skinner and Clayton (2013) recognized, as well as that by Cande and Haxby (1991) on the Pacific plate. When the age of the hypothetical hotspot trace on the Pacific plate is compared to the age of the underlying plate, the portion of the locus >50 Ma is younger than the plate (Fig. 10A). Conversely the corresponding part of the locus on the Nazca/Farallon plate is older than the underlying plate (Fig. 10B). This implies that, prior to ~50 Ma the Foundation hotspot was beneath the Pacific plate, not the Farallon plate. Only after ~50 Ma until ~25 Ma was the hotspot beneath the Farallon plate (Bello-González et al., 2018). Then it began forming the younger Foundation seamount chain on the Pacific plate. If this model is approximately correct, a limited section of the Foundation hotspot trace formed on the Nazca plate (Fig. 10B). This implies that an aseismic ridge within this segment of the Andean subduction zone, as postulated by the model of Skinner and Clayton (2013), is not present.

FIG. 10. Foundation hotspot loci (Composite model) compared with the Global Seafloor Fabric and Magnetic Lineation (GSFML) magnetic isochron identification ages (Seton et al., 2014). A. Locus over Pacific plate. B. Locus over Nazca plate. Inversion: Transition of younging locus age from younger to older than plate age. Reversion: Transition of younging locus age from older to younger than plate age.

Báez et al. (2023), using Bello-González et al.’s (2018) reconstructions and extensive field data, proposed that the late Cenozoic volcanic history of the Southern Puna region (~24-27° S) reflected fracturing of the subducting plate along flexures controlled by subducting aseismic ridges (two lesser Nazca plate features as well as the Juan Fernández trace). They did not attempt to reconstruct these features beyond projections into the subduction zone. Whether they represent small hotspots or alternative features of the Nazca plate is uncertain.

4. Discussion

4.1. Implications for low-angle subduction

This empirical study shows that one reconstructed hotspot trace (Juan Fernández) undergoing subduction is consistent with magmatic patterns in the Andes since at least ~50 Ma, and a second trace (Easter-Nazca) since ~15 Ma. Physical and numerical models discussed above, which involve non-hotspot trace explanations for the two contemporary low-angle subduction segments beneath the Andes, have not been tested against Cenozoic magmatic patterns and/or are inconsistent with plate reconstructions. As also noted, variations in the Nazca/Farallon convergence rate over the last 80 Myr do not indicate a clear correspondence with the formation of the low-angle subduction segments. Insofar as upper (e.g., South American) plate-to-hotspot motion is concerned, displacement of the upper plate toward the trench (and relative to the underlying asthenosphere) appears to be necessary, if not sufficient, for the existence of a volcanic arc on the upper plate and the absence of significant back-arc extension (e.g., Cross and Pilger, 1982; Jurdy, 1983; Jarrard, 1986). There may be a dynamic effect on the angle of normal subduction observed beneath the Andes (e.g., Lallemand et al., 2005; Schellart, 2017), typically a maximum of 45° to a depth of 300 km, in contrast with near vertical subduction observed beneath some island arcs of the western Pacific which are experiencing back-arc extension. Where motion relative to hotspots is calculable, the upper plate appears to be stationary or moving away from the trench (e.g., Jurdy, 1983; Jarrard, 1986). Other factors may contribute to low-angle subduction without aseismic ridge subduction: e.g., young age of the subducting plate, convergence rate, and motion of the upper plate toward the trench (Cross and Pilger, 1982). The latter two such controls are relevant to an entire subduction system and/or for long periods of time, and do not necessarily explain short-duration, anomalous low-angle subduction such as that observed in this study.

4.2. Implications for the fixed hotspot hypothesis

In addition to strengthening the proposal that hotspot traces may contribute to low-angle subduction, this study also provides support for an expanded distinct Pacific hotspot reference frame. This domain extends from Hawaii in the northwest to Juan Fernández in the southeast and includes Louisville to the southwest and the Gulf of Alaska and Yellowstone to the northeast. Figure 11 illustrates the reconstructed Yellowstone trace beneath the northwestern United States, including the Basin and Range Province (after McQuarrie and Wernicke, 2005), in the Hawaiian reference frame (using the composite model), and a reconstructed trace relative to the M93 Atlantic-Indian Ocean frame model. Isotopic dates along the reconstructed trace in figure 11 correspond relatively well with the trace in the Hawaiian frame (volcanism began after the arrival of the trace for a given longitude). The Hawaiian and Tristan (Atlantic-Indian Oceans) frames appear to deviate from one another (e.g., Duncan, 1981; Norton, 1995; Raymond et al., 2000). The moving-hotspot reference frames (e.g., O’Neill et al., 2005; Doubrovine et al., 2012) are rooted in a mantle convection model based on seismic tomography, with velocity converted to density, and radial, but not spherical, viscosity variations. The hotspots deviation from the convection model is then globally averaged over the last 80 Myr with dates from four traces to produce final models. Gaastra et al. (2022) showed that two of the traces, the Hawaiian-Emperor and Louisville, from the Pacific plate, do not require significant motion between their source hotspots over the same period based on more recent dating, modeling incorporating data from other Pacific plate traces, and treating the hotspot locations as variables. Similarly, the two hotspot traces from the Atlantic and Indian oceans are consistent with a separate reference frame as Müller et al. (1993) defined (modifying Duncan, 1981; see also Maher et al., 2015). Perhaps, instead of globally moving hotspots (such as in the Atlantic-Indian frame), there are the two geographically restricted reference frames: Hawaiian (beneath the plates of the Pacific Ocean and western North America) and Tristan (beneath the Indian and the South and central North Atlantic oceans and bordering continents), with perhaps a third, Iceland, which includes most of Eurasia (Pilger, 2003).

FIG. 11. Basalt isotopic dates between 42° and 43°N latitude, western North America, with points along the calculated locus of the Yellowstone hotspot trace. The calculated locus incorporates the composite Pacific-hotspot model with the crustal extension model of McQuarrie and Wernicke (2005) for the Basin and Range Province relative to the North American plate. A. Google Earth view - red triangles: isotopic date locations (dates in white); green circles: restored Yellowstone hotspot trace locations (ages in orange). Curves: calculated loci relative to stable North American plate (Hawaiian hotspot frame, green; Tristan hotspot frame, blue). B. Plot of isotopic ages (Ma) versus longitude for basalts (red triangles) with restored locations of the Yellowstone hotspot trace (green circles) in the Hawaiian reference frame. Isotopic data from Hillenbrand et al. (2023).

4.3. Byproduct of hotspot trace subduction: post-rifting magmatism in Paraguay and Eastern Brazil?

The distribution of volcanism from the Andean crest to the east, and its relationship to inferred hotspot traces within the underlying Nazca/Farallon plate, prompts a question regarding the fate of subducted hotspot traces beneath the South American plate (Fig. 7). Does a subducted trace segment, perhaps detached from the subducted plate, itself sink into the deeper mantle? Or, alternatively, might it be incorporated into the shallow asthenosphere, especially if the trace lithosphere is extensively serpentinized?

In Paraguay and northeast and southeast Brazil there are two seemingly anomalous magmatic zones significantly younger than volcanics associated with rifting and initial spreading of the South Atlantic Ocean (e.g., Gomes et al., 1990, 2013; Gibson et al., 1995; Mizusaki et al., 2002; Perlingeiro et al., 2013; Souza et al., 2013). Two hotspots (perhaps underlain by plumes) have been suggested to be responsible for the Fernando de Noronha and Martin Vaz archipelagos. However, the age patterns onshore do not provide an obvious age progression, especially for Fernando de Noronha (e.g., Knesel et al., 2011). One explanation for the younger volcanism is that it represents edge-effect convection in the asthenosphere along the zone of progressive thinning of the lithosphere from the Amazonian craton to the oceanic lithosphere of the South Atlantic, like what has been observed on the African margin to the east (e.g., Knesel et al., 2011; Belay et al., 2019). Other explanations invoke deviated plumes from the presumed Tristan da Cunha plume in the South Atlantic or extensional stresses propagating through the lithosphere, tapping hot asthenosphere at depth (e.g., Geraldes et al., 2022). Guimarães et al. (2020) propose a complex model, involving pre-South Atlantic rifting asthenosphere, having experienced extended heating, which slowly flows into rifted or thinned lithosphere for a prolonged period after the South Atlantic Ocean began to open. This model requires decompression melting as the asthenospheric material reaches shallower depths, either through previous crustal-scale structures or induced by intraplate extension. Stanton et al. (2022) also invoke decompression melting above a postulated thermal anomaly.

It is proposed here that the anomalous zones involve older, shallowly subducted hotspot traces (originally from the Farallon or other Pacific oceanic plate; that is, from the west) in the upper asthenosphere. As they initially pass beneath the progressively thickened South American lithosphere of the Amazon craton, melting ceases. Further passage to the east, where the lithosphere is thinner, may allow for decompression and resumed partial melting of the subducted remnant blocks to produce the eastern Brazil/Paraguay magmatism. Two or more hotspot traces on the Farallon (or another Pacific) plate, older than the existing Easter-Nazca and Juan Fernández traces, are required in this model to explain the anomalous magmatism observed in Paraguay and eastern Brazil.   

There are two tests for the hypothesis outlined above. In the first, the distribution of Paraguayan and east Brazilian age dates (see Appendix for age references) is plotted on a map of calculated lithospheric thicknesses beneath continental South America (Fig. 12; see Supplementary File for the geospatial data). The isotopic ages utilized in this study occur along boundaries between thick and thin lithosphere (subjectively inferred at ~150 km), consistent with the depressurization hypothesis, that is, magmatism does not occur within the thickest parts of the South American plate (decompression melting is also part of some the alternative models as noted above). Second, the various date sample locations are restored back in time relative to the Müller et al. (1993) African hotspot reference frame (Fig. 13) extended to South America. Many of the restored loci extending as early as 130 Ma are proximal to the Andean foreland front where igneous bodies of that age and older are present. Were one to further transform the loci into a Pacific plate frame (from earlier subduction of the postulated older Pacific plate and the included older hotspot traces), the loci would be restored further to the west into the paleo-Pacific Ocean. These reconstructions indicate the plausibility of the plate kinematics required, despite uncertainty in the South Atlantic plate-hotspot model used, as well as in the proposed hotspot sources for the inferred subducted traces.

FIG. 12. Calculated thickness in km of the South American continental lithosphere after Artemieva (2006; data provided by author) with dated sample points (blue squares; geospatial data provided in Supplementary File). Note how most onshore samples in east Brazil and Paraguay occur along boundaries between thin (<150 km) and thick (>150 km) lithosphere. Oceanic plate lithosphere thickness is on the order of 90 km (e.g., Niu, 2021).

FIG. 13. Full loci of isotopic dates from eastern Brazil and Paraguay (blue squares) backtracked with respect to the Tristan hotspot reference frame using (spline interpolated) parameters of Müller et al. (1993) for 0-130 Ma and Maher et al. (2015) for 130-150 Ma. Also shown are Jurassic and Cretaceous dates (red diamonds) in Colombia, Peru, Bolivia, Argentina, and Chile. (Note how many back-tracked loci come close to the data points in the Andes.) Data points and loci provided in Supplementary File.

The possible role of shallow subduction of hotspot traces in sourcing magmatism to the far east, in Brazil and Paraguay (1,500-3,000 km from the current oceanic trench), is not inconsistent with the analysis of Speziale et al. (2020a, b), or with the model of Ferreira et al. (2022, and references therein), in which crustal extension, shallow convection, and variations in lithospheric thickness are invoked as contributors to that anomalous igneous activity. The proposal advanced herein provides potentially predictable heterogeneities in the shallow asthenosphere (for example, introducing eclogite which originated as oceanic hotspot trace crust as well as serpentinite) that melted and mixed with shallower continental lithospheric sources. Additional magmatic studies might provide a potential record of passage of South American lithosphere over older subducted hotspot traces like that of ridges undergoing contemporary subduction. Such a model may also be pertinent to other zones of anomalous magmatism which do not clearly fit hotspot trace models (cf. Gianni et al., 2023), including those beneath the African plate, which may represent previously subducted traces formed on the Tethys plate.

4.4. Additional considerations

Three recent contributions, Gianni and Navarrete (2022); Gianni et al. (2023) and Mather et al. (2023) invoke low-angle subduction or its remnants, in some cases produced by anomalous thick lithosphere, as responsible for distinctive igneous events in the geologic record. Such possible features are compatible with the hypotheses put forward in this contribution. Gianni et al. (2023) and Mather et al. (2023) propose that asthenosphere remnants of low-angle subduction persist for long and would be responsible for some peculiar geochemical magmatic patterns. Gianni and Navarrete (2022) suggest that slab loss by detachment of normal lithosphere from newly subducted, thickened oceanic lithosphere produced a gap in the igneous record of part of southwestern Pangea, by a mechanism distinct from those proposed here.

As with any scientific study, more data are desirable, not only for improved understanding of hotspots and their products and the tectono-magmatic evolution of the Andes, but their global implications for plate reconstructions for the Mesozoic and Cenozoic. Perhaps new technology, such as multiple solar-powered magnetometers in GPS-guided drones could obtain more detailed surveys of the east-central Pacific, at much lower cost than conventional marine surveying. From such surveys, significant improvement in characterization of the kinematics of the Pacific-Nazca/Farallon plate boundary since ~84 Ma, including microplates, could be accomplished.

Significant progress in the study of island-seamount chains and aseismic ridges of the world oceans has been made. However, many such features have not been dated or have had only potassium-argon measurements made. The composite plate-hotspot model constructed in this work can be improved upon by additional dating, especially adding the traces on the Nazca and Cocos plates to those on the Pacific plate in future modeling.

Insofar as on-land studies are concerned, it is quite possible that additional relevant published dates have been overlooked in this study. Dating of known volcanics and intrusive bodies which have not been analyzed here, particularly where apparent gaps exist, would be most valuable. Like several hotspot studies, this work has not incorporated geochemical implications for the origin and evolution of volcanic arc and intraplate magmas, so the context of hotspot trace subduction could be enhanced by incorporating ages with petrological models.

5. Conclusions

This study strengthens the inferences that (1) the Pacific hotspots form a relatively fixed reference frame beneath the Pacific, Nazca, and Cocos plates, and (2) traces formed from the hotspots beneath the Nazca plate, especially those produced by the Juan Fernández and Easter-Nazca hotspots, produce low-angle subduction segments and profoundly influence subduction-related magmatism in and adjacent to the Andes. In addition, it is inferred that remnants of long-subducted hotspot traces may be responsible for anomalous magmatism in Paraguay, eastern Brazil, and offshore in the western South Atlantic Ocean. Uncertainties in the details of these correlations and inferences persist, especially because of sparse magnetic surveys of the eastern Pacific Ocean, far-from-complete studies of the seamounts of the Pacific and Atlantic, and the derivative plate-hotspot models. Some of the most rapid seafloor spreading in the world ocean occur along perhaps the least surveyed young ocean floor, that of the east-central Pacific, so future studies are recommended in that direction.

Acknowledgements
Comments by an anonymous reviewer and the editor were very helpful in suggesting areas for clarification and are appreciated.

References

Andrews, D.L.; Gordon, R.G.; Horner-Johnson, B.C. 2006. Uncertainties in plate reconstructions relative to the hotspots; Pacific-hotspot rotations and uncertainties for the past 68 million years. Geophysical Journal International 166: 939-951. doi: https://doi.org/10.1111/j.1365-246X.2006.03029.x

Antonijevic, S.K.; Wagner, L.S.; Kumar, A.; Beck, S.L.; Long, M.D.; Zandt, G.; Tavera, H.; Condori, C. 2015. The role of ridges in the formation and longevity of flat slabs. Nature 524: 212-215.

Arriagada, C.; Roperch, P.; Mpodozis, C.; Cobbold, P.R. 2008. Paleogene building of the Bolivian Orocline: Tectonic restoration of the central Andes in 2-D map view. Tectonics 27: TC6014. doi: https://doi.org/ 10.1029/2008TC002269

Arriagada, C.; Ferrando, R.; Córdova, L.; Morata, D.; Roperch, P. 2013. Andean Geology, The Maipo Orocline: A first scale structural feature in the Miocene to Recent geodynamic evolution in the central Chilean Andes. Andean Geology 40 (3): 419-437. doi: http://dx.doi.org/10.5027/andgeoV40n3-a02

Artemieva, I.M. 2006. Global 1° x 1° thermal model TC1 for the continental lithosphere: implications for lithosphere secular evolution. Tectonophysics 416 (1-4): 245-277. doi: https://doi.org/10.1016/j.tecto.2005.11.022

Báez, W.; Bustos, E.; Chiodi, A.; García, H.P.A.; Álvarez, O.; Simón, V.; Folguera, A. 2023. Reviewing the geodynamic impact of aseismic ridges subduction on the tectonic-magmatic evolution of the Southern Puna plateau. Journal of South American Earth Sciences 129: 104520. doi: https://doi.org/10.1016/j.jsames.2023.104520.

Barazangi, M.; Isacks, B.L. 1976. Spatial distribution of earthquakes and subduction of the Nazca plate beneath South America. Geology 4: 686-692. doi: https://doi.org/10.1130/0091-7613(1976)4%3C686:SDOEAS%3E2.0.CO;2

Belay, I.G.; Tanaka, R.; Kitagawa, H.; Kobayashi, K.; Nakamura, E. 2019. Origin of ocean island basalts in the West African passive margin without mantle plume involvement. Nature Communications 10: 1-12. doi: https://doi.org/10.1038/s41467-019-10832-7.

Bello-González, J.P.; Contreras-Reyes, E.; Arriagada, C. 2018. Predicted path for hotspot tracks off South America since Paleocene times: Tectonic implications of ridge-trench collision along the Andean margin. Gondwana Research 64: 216-234. doi: https://doi.org/10.1016/j.gr.2018.07.008

Bishop, B.T.; Beck, S.L.; Zandt, G.; Wagner, L.; Long, M.D.; Antonijevic, S.K.; Kumar, A.; Tavera, H. 2017. Geosphere, Causes and consequences of flat-slab subduction in southern Peru. Geosphere 13: 1392-1407. doi: https://doi.org/10.1130/GES01440.1

Cande, S.C. 1985. Nazca-South America plate interactions since 50 My B.P. In Ocean Margin Drilling Program, (Hussong, D.M.; Dang, S.P.; Kulm, L.D.; Couch, R.W.; Hilde, T.W.C.; editors). Regional Atlas Series, Atlas 9, Peru-Chile Trench off Peru.

Cande, S.C.; Haxby, W.F. 1991. Eocene propagating rifts in the southwest Pacific and their conjugate features on the Nazca Plate. Journal of Geophysical Research 96 (B12): 19609-19622. doi: https://doi.org/10.1029/91JB01991

Contreras-Reyes, E.; Obando-Orrego, S.; Geersen, J.; Bello-González, J.P. 2021. Density structure, flexure, and tectonics of the Iquique Ridge, northern Chile. Journal of South American Earth Sciences 111: 103423. doi: https://doi.org/10.1016/j.jsames.2021.103423

Cross, T.A.; Pilger, R.H.Jr. 1978a. Tectonic controls of Late Cretaceous sedimentation, western interior, U.S.A. Nature 274: 653-657. doi: https://doi.org/10.1038/274653a0

Cross, T.A.; Pilger, R.H.Jr. 1978b. Constraints on absolute motion and plate interactions inferred from Cenozoic igneous activity in the western United States. American Journal of Science 278: 865-902. doi: https://doi.org/10.2475/ajs.278.7.865

Cross, T.A.; Pilger, R.H.Jr. 1982. Geological Society of America Bulletin, Controls of subduction geometry, location of magmatic arcs, and tectonics of arc and back-arc regions. Geological Society of America Bulletin 93 (6): 545-562. doi: https://doi.org/10.1130/0016-7606(1982)93%3C545:COSGLO%3E2.0.CO;2

de Silva, S.; Kay, S.M. 2018. Turning up the Heat: High-Flux Magmatism in the Central Andes. Elements 14 (4): 245-250. doi: https://doi.org/10.2138/gselements.14.4.245

DeCelles, P.G.; Ducea, M.N.; Kapp, P.; Zandt, G. 2009. Cyclicity in Cordilleran orogenic systems. Nature Geoscience 2: 251-257. doi: https://doi.org/10.1038/ngeo469

Doubrovine, P.V.; Steinberger, B.; Torsvik, T.H. 2012. Absolute plate motions in a reference frame defined by moving hotspots in the Pacific, Atlantic and Indian Oceans. Journal of Geophysical Research 117: B09101. doi: https://doi.org/10.1029/2011JB009072

Duncan, R.A. 1981. Hotspots in the southern oceans; an absolute frame of reference for motion of the Gondwana continents. Tectonophysics 74 (1-2): 29-42. doi: https://doi.org/10.1016/0040-1951(81)90126-8

Dupont-Nivet, G.; Roperch, P.; Gautier, P.; Chauvin, A.; Gerard, M.; Carlier, G. 1996. Clockwise rotations in northern Chile: oroclinal bending and in situ tectonic rotations. Third International Symposium on Andean Geodynamics: 355-358. St. Malo.

Espurt, N.; Funiciello, F.; Martinod, J.; Guillaume, B.; Regard, V.; Faccenna, C.; Brusset, S. 2008. Flat subduction dynamics and deformation of the South American plate: Insights from analog modeling. Tectonics 27: TC3011. doi: https://doi.org/10.1029/2007TC002175

Ferreira, A.C.D.; Conceição, R.; Vieira, M.; Pimentel, A.M. 2022. Mesozoic to Cenozoic alkaline and tholeiitic magmatism related to West Gondwana break-up and dispersal. Gondwana Research 106: 15-33. doi: https://doi.org/10.1016/j.gr.2022.01.005

Flórez‐Rodríguez, A.G.; Schellart, W.P.; Strak, V. 2019. Impact of aseismic ridges on subduction systems: Insights from analog modeling. Journal of Geophysical Research: Solid Earth 124: 5951-5969. doi: https://doi.org/10.1029/2019JB017488

Gaastra, K.M.; Gordon, R.G.; Woodworth, D.T. 2022. Quantification of Pacific plate hotspot tracks since 80 Ma. Tectonics 41 (7): e2021TC006772. doi: https://doi.org/10.1029/2021TC006772

Geraldes, M.C.; Mohriak, W.U.; Bonifácio, J.F.; Cardoso, L.M.C.; Moura, S.C. 2022. The role of the Rio Grande Rise on the continental Meso-Cenozoic alkaline magmatism in southwest Brazil. In Meso-Cenozoic Brazilian Offshore Magmatism. Geochemistry, Petrology and Tectonics, Chapter 8: 257-292. doi: https://doi.org/10.1016/B978-0-12-823988-9.00005-8

Gerya, T.V.; Fossati, D.; Cantieni, C.; Seward, D. 2009. Dynamic effects of aseismic ridge subduction: numerical modelling. European Journal Mineralogy 21 (3): 649-661.

Gianni, G.M.; Navarrete, C.R. 2022. Catastrophic slab loss in southwestern Pangea preserved in the mantle and igneous record. Nature Communications 13: 698. doi: https://doi.org/10.1038/s41467-022-28290-z

Gianni, G.M.; Likerman, J.; Navarrete, C.R.; Gianni, C.R.; Zlotnik, S. 2023. Ghost-arc geochemical anomaly at a spreading ridge caused by supersized flat subduction. Nature Communications 14: 2023. doi: https://doi.org/10.1038/s41467-023-37799-w

Gibson, S.A.; Thompson, R.N.; Leonardos, O.H.; Dickin, A.P.; Mitchell, J.G. 1995. The Late Cretaceous impact of the Trindade mantle plume: Evidence from large-volume, mafic, potassic magmatism in SE Brazil. Journal of Petrology 36 (1): 189-229. doi: https://doi.org/10.1093/petrology/36.1.189

Gomes, C.B.; Ruberti, E.; Morbidelli, L. 1990. Carbonatite complexes from Brazil: a review. Journal of South American Earth Sciences 3: 51-63. doi: https://doi.org/10.1016/0895-9811(90)90017-U

Gomes, C.B.; Comin-Chiaramonti, P.; Velázquez, V.F. 2013. A synthesis on the alkaline magmatism of Eastern Paraguay. Brazilian Journal of Geology 43: 745-761. doi: https://doi.org/10.5327/Z2317-488920130004000012

Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M. 2020. Geologic Time Scale 2020. Elsevier BV. Amsterdam. doi: https://doi.org/10.1016/B978-0-12-824360-2.00032-2

Gripp, A.E.; Gordon, R.G. 2002. Young tracks of hotspots and current plate velocities. Geophysical Journal International 150 (2): 321-361. doi: https://doi.org/10.1046/j.1365-246X.2002.01627.x

Guimarães, A.R.; Fitton, J.G.; Kirstein, L.A.; Barfod, D.N. 2020. Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum. Earth and Planetary Science Letters 536: 116147. doi: https://doi.org/10.1016/j.epsl.2020.116147

Hampel, A. 2002. The migration history of the Nazca Ridge along the Peruvian active margin: a re-evaluation. Earth and Planetary Science Letters 203 (2): 665-679. doi: https://doi.org/10.1016/S0012-821X(02)00859-2.

Harada, Y.; Hamano, Y. 2000. Recent progress on plate motions relative to hot spots. In The History and Dynamics of Global Plate Motions, Geophysical Monograph Series, 121 (Richards, M.A.; Gordon, R.G.; van der Hilst, R.D.; editors). American Geophysical Union: 327-338, Washington, D.C.

Hillenbrand, I.W.; Thomson, K.D.; Morgan, L.E.; Gilmer, A.K.; Dombrowski, A.D.; Warrell, K.F.; Malone, J.R.; Souders, A.K.; Hudson, A.M.; Cosca, M.A.; Paces, J.B.; Thompson, R.A.; Park, A.J. 2023. USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data. United States Geological Survey data release. doi: https://doi.org/10.5066/P9RZNPIF

Hochmuth, K.; Gohl, K. 2017. Collision of Manihiki Plateau fragments to accretional margins of northern Andes and Antarctic Peninsula. Tectonics 36 (2): 229-240. doi: https://doi.org/10.1002/2016TC004333

Hu, J.; Liu, L.; Hermosillo, A.; Zhou, Q. 2016. Simulation of late Cenozoic South American flat-slab subduction using geodynamic models with data assimilation. Earth and Planetary Science Letters, 438: 1-13. doi: https://doi.org/10.1016/j.epsl.2016.01.011

Hu, J.; Gurnis, M.; Rudi, J.; Stadler, G.; Müller, R.D. 2022. Dynamics of the abrupt change in Pacific Plate motion around 50 million years ago. Nature Geoscience 15: 74-78. doi: https://www.nature.com/articles/s41561-021-00862-6

Huangfu, P.; Wang, Y.; Cawood, P.A.; Li, Z.-H.; Fan, W.; Gerya, T.V. 2016. Thermo-mechanical controls of flat subduction: Insights from numerical modeling. Gondwana Research. doi: https://doi.org/10.1016/j.gr.2016.08.012

Isacks, B.L. 1988. Uplift of the Central Andean Plateau and Bending of the Bolivian Orocline. Journal of Geophysical Research: Solid Earth 93 (B4): 3211-3231. doi: https://doi.org/10.1029/JB093iB04p03211.

Jarrard, R.D. 1986. Relations among subduction parameters. Reviews of Geophysics 24 (2): 217-284. doi: https://doi.org/10.1029/RG024i002p00217

Jurdy, D.M. 1983. Early Tertiary subduction zones and hot spots. Journal of Geophysical Research-Solid Earth 88 (B8): 6395-6402. doi: https://doi.org/10.1029/JB088iB08p06395

Kay, S.M.; Coira, B.L. 2009. Shallowing and steepening subduction zones, continental lithospheric loss, magmatism, and crustal flow under the Central Andean Altiplano-Puna Plateau. In Backbone of the Americas: Shallow Subduction, Plateau Uplift, and Ridge and Terrane Collision (Kay, S.M.; Ramos, V.A.; Dickinson, W.R.; editors). Memoir of the Geological Society of America 204: 229-259. doi: https://doi.org/10.1130/2009.1204(11)

Kay, R.W.; Kay, S.M. 1993. Delamination and delamination magmatism. Tectonophysics 219 (1-3): 177-189. doi: https://doi.org/10.1016/0040-1951(93)90295-U

Knesel, K.M.; Souza, Z.S.; Vasconcelos, P.M.; Cohen, B.E.; Silveira, F.V. 2011. Young volcanism in the Borborema Province, NE Brazil, shows no evidence for a trace of the Fernando de Noronha plume on the continent. Earth and Planetary Science Letters 302 (1-2): 38-50. doi: https://doi.org/10.1016/j.epsl.2010.11.036

Kopp, H.; Flueh, E.R.; Papenberg, C.; Klaeschen, D. 2004. Seismic investigations of the O’Higgins Seamount Group and Juan Fernández Ridge: Aseismic ridge emplacement and lithosphere hydration. Tectonics 23: 21 p. doi: https://doi.org/10.1029/2003TC001590

Lallemand, S.; Heuret, A.; Boutelier, D. 2005. On the relationships between slab dip, back-arc stress, upper plate absolute motion, and crustal nature in subduction zones. Geochemistry, Geophysics, Geosystems 6 (9): Q09006. doi: https://doi.org/10.1029/2005GC000917

Maher, S.M.; Wessel, P.; Müller, R.D.; Williams, S.E.; Harada, Y. 2015. Absolute plate motion of Africa around Hawaii-Emperor bend time. Geophysical Journal International 201 (3): 1743-1764. doi: https://doi.org/10.1093/gji/ggv104

Manea, V.C.; Pérez-Gussinyé, M.; Manea, M. 2012. Chilean flat slab subduction controlled by overriding plate thickness and trench rollback. Geology 40: 35-38. doi: https://doi.org/10.1130/G32543.1

Manea, V.C.; Manea, M.; Ferrari, L.; Orozco-Esquivel, T.; Valenzuela, R.W.; Husker, A.; Kostoglodov, V. 2017. A review of the geodynamic evolution of flat slab subduction in Mexico, Peru, and Chile. Tectonophysics 695: 27-5.

Martinod, J.; Husson, N. 2010. Horizontal subduction zones, convergence velocity and the building of the Andes. Earth and Planetary Science Letters 299 (3-4): 299-309. doi: https://doi.org/10.1016/j.epsl.2010.09.010

Martinod, J.; Funiciello, F.; Faccenna, C.; Labanieh, S.; Regard, V. 2005. Dynamical effects of subducting ridges: Insights from 3-D laboratory models. Geophysical Journal International 163 (3): 1137-1150. doi: https://doi.org/10.1111/j.1365-246X.2005.02797.x

Mather, B.R.; Müller, R.D.; Alfonso, C.P.; Seton, M.; Wright, N.M. 2023. Kimberlite eruptions driven by slab flux and subduction angle. Scientific Report 13: 9216. doi: https://doi.org/10.1038/s41598-023-36250-w

McQuarrie, N. 2002. Initial plate geometry, shortening variations, and evolution of the Bolivian orocline. Geology 30 (10): 867-870. doi: https://doi.org/10.1130/0091-7613(2002)030%3C0867:IPGSVA%3E2.0.CO;2

McQuarrie, N.; Wernicke, B.P. 2005. An animated tectonic reconstruction of southwestern North America since 36 Ma. Geosphere 1 (3): 147-172. doi: https://doi.org/10.1130/GES00016.1

Mizusaki, A.M.P.; Thomaz-Filho, A.; Milani, E.J.; de Cesero, P. 2002. Mesozoic and Cenozoic igneous activity and its tectonic control in northeastern Brazil. Journal of South American Earth Sciences 15 (2) 183-198. doi: https://doi.org/10.1016/S0895-9811(02)00014-7

Morgan, W.J. 1972. Plate motions and deep mantle convection. Geological Society of America Memoir 132: 7-22.

Müller, R.D.; Royer, J.-Y.; Lawver, L.A. 1993. Revised plate motions relative to the hotspots from combined Atlantic and Indian Ocean hotspot tracks. Geology 21 (3): 275-278. doi: https://doi.org/10.1130/0091-7613(1993)021%3C0275:RPMRTT%3E2.3.CO;2

Müller, R.D.; Cande, S.C.; Royer, J.-Y.; Roest, W.R.; Maschenkov, S. 1999. New constraints on the Late Cretaceous/Tertiary plate tectonic evolution of the Caribbean. In Caribbean Basins (Mann, P.; editor). Elsevier: 39-55. Amsterdam.

Müller, R.D.; Zahirovic, S.; Williams, S.E.; Cannon, J.; Seton, M.; Bower, D.J.; Tetley, M.G.; Heine1, C.; Le Breton, E.; Liu, S.; Russell, S.H.J.; Yang, T.; Leonard, J.; Gurnis, M. 2019. A global plate model including lithospheric deformation along major rifts and orogens since the Triassic. Tectonics 38 (6): 1884-1907. doi: https://doi.org/10.1029/2018TC005462

Niu, Y. 2021. Lithosphere thickness controls the extent of mantle melting, depth of melt extraction and basalt compositions in all tectonic settings on Earth-A review and new perspectives. Earth-Science Reviews 217: 103614. doi: https://doi.org/10.1016/j.earscirev.2021.103614

Norton, I.O. 1995. Plate motions in the North Pacific: the 43 Ma nonevent. Tectonics 14 (5): 1080-1094. doi: https://doi.org/10.1029/95TC01256

Norton, I.O. 2000. Global hotspot reference frames and plate motion. In The History and Dynamics of Global Plate Motions (Richards, M.A.; Gordon, R.G.; van der Hilst, R.D.; editors). American Geophysical Union, Geophysical Monograph Series 121: 339-357.

O’Connor, J.M.; Steinberger, B.; Regelous, M.; Koppers, A.A.P.; Wijbrans, J.R.; Haase, K.M.; Stoffers, P.; Jokat, W.; Garbe-Schönberg, D. 2013. Constraints on past plate and mantle motion from new ages for the Hawaiian-Emperor Seamount Chain. Geochemistry, Geophysics, Geosystems 14 (10): 4564-4584. doi: https://doi.org/10.1002/ggge.20267

O’Driscoll, L.J.; Richards, M.A.; Humphreys, E.D. 2012. Nazca-South America interactions and the late Eocene-late Oligocene flat-slab episode in the central Andes. Tectonics 31 (2): TC2013. doi: https://doi.org/10.1029/2011TC003036

O’Neill, C.; Müller, R.D.; Steinberger, B. 2005. On the uncertainties in hot spot reconstructions and the significance of moving hot spot reference frames. Geochemistry, Geophysics, Geosystems 6 (4). doi: https://doi.org/10.1029/2004GC000784

Ogg, J.G. 2020. Geomagnetic Polarity Time Scale. In Geologic Time Scale 2020 (Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M.; editors). Elsevier, Amsterdam 1: 159-192.

Pardo-Casas, F.; Molnar, P.; 1987. Relative motion of the Nazca (Farallon) and South American Plates since Late Cretaceous time. Tectonics 6 (3): 233-248. doi: https://doi.org/10.1029/TC006i003p00233

Perlingeiro, G.; Vasconcelos, P.M.; Knesel, K.M.; Thiede, D.S.; Cordani, U.G. 2013. ⁴⁰Ar/³⁹Ar geochronology of the Fernando de Noronha Archipelago and implications for the origin of alkaline volcanism in the NE Brazil. Journal of Volcanology and Geothermal Research 249: 140-154. doi: https://doi.org/10.1016/j.jvolgeores.2012.08.017

Pilger, R.H.Jr. 1981. Plate reconstructions, aseismic ridges, and low-angle subduction beneath the Andes. Geological Society of America Bulletin 92 (7): 448-456. doi: https://doi.org/10.1130/0016-7606(1981)92<448:PRARAL>2.0.CO;2

Pilger, R.H.Jr. 1983. Kinematics of the South American subduction zone from global plate reconstructions. In Geodynamics of the Eastern Pacific Region, Caribbean and Scotia Arcs Geodynamics of the Eastern Pacific Region, Caribbean and Scotia Arcs, 9 (Ramón-Cabré, S.J.; editor). doi: https://doi.org/10.1029/GD009p0113

Pilger, R.H.Jr. 1984. Cenozoic plate kinematics. subduction and magmatism: South American Andes. Journal of the Geological Society 141 (5): 793-802. doi: https://doi.org/10.1144/gsjgs.141.5.0793

Pilger, R.H.Jr. 2003. Geokinematics-Prelude to Geodynamics. Springer, New York. doi: https://doi.org/10.1007/978-3-662-07439-8

Pilger, R.H.Jr. 2007. The Bend: Origin and significance. Geological Society of America Bulletin 119 (3-4): 302-313. doi: https://doi.org/10.1130/B25713.1

Pilger, R.H.Jr. 2022. Radiometric ages from the South American Andes and adjacent areas: A compilation hosted by GEOROC. doi: http://dx.doi.org/10.25625/NGG0Q7

Pilger, R.H.Jr.; Handschumacher, D. 1981. The fixed-hotspot hypothesis and origin of the Easter-Sala y Gómez-Nazca trace. Geological Society of America Bulletin 92 (7): 437-446. doi: https://doi.org/10.1130/0016-7606(1981)92<437:TFHAOO>2.0.CO;2

Puigdomenech, C.; Alarcón, S.; Ruiz González, V.; Rossel, P.; Orts, D.; Zaffarana, C. 2021. Tectonic rotations in central Chile: New insights on the southern limit of the Maipo Orocline. Journal of South American Earth Sciences 106: 103012. doi: https://doi.org/10.1016/j.jsames.2020.103012

Quiero, F.; Tassara, A.; Iaffaldano, G.; Rabbia, O. 2022. Growth of Neogene Andes linked to changes in plate convergence using high-resolution kinematic models. Nature Communications 13: 1339. doi: https://doi.org/10.1038/s41467-022-29055-4

Ramos, V.A.; Cristallini, E.O.; Pérez, D.J. 2002. The Pampean flat-slab of the Central Andes. Journal of South American Earth Sciences 15 (1): 59-78. doi: https://doi.org/10.1016/S0895-9811(02)00006-8

Raymond, C.A.; Stock, J.M.; Cande, S.C. 2000. Fast Paleogene motion of the Pacific hotspots from revised global plate circuit constraints. In History and Dynamics of Plate Motions (Richards, M.A.; Gordon, R.G.; van der Hilst, R.D.; editors). American Geophysical Union, Geophysical Monograph Series 121: 359-375.

Risse, A.; Trumbull, R.B.; Kay, S.M.; Coira, B.; Romer, R.L. 2013. Multi-stage evolution of Late Neogene mantle-derived magmas from the Central Andes back-arc in the southern Puna Plateau of Argentina. Journal of Petrology 54 (10): 1963-1995. doi: https://doi.org/10.1093/petrology/egt038

Rodríguez‐González, J.; Negredo, A.M.; Billen, M.I. 2012. The role of the overriding plate thermal state on slab dip variability and on the occurrence of flat subduction. Geochemistry, Geophysics, Geosystems 13 (1): Q01002. doi: http://dx.doi.org/10.1029/2011GC003859

Rowan, C.J.; Rowley, D.B. 2014. Spreading behaviour of the Pacific-Farallon ridge system since 83 Ma. Geophysical Journal International 197 (3): 1273-1283. doi: https://doi.org/10.1093/gji/ggu056

Saylor, J.E.; Sundell, K.E.; Pérez, N.D.; Hensley, J.B.; McCain, P.; Runyon, B.; Álvarez, P.; Cárdenas, J.; Usnayo, W.P.; Valer, C.S. 2023. Basin formation, magmatism, and exhumation document southward migrating flat-slab subduction in the central Andes. Earth and Planetary Science Letters 606: 118050. doi: https://doi.org/10.1016/j.epsl.2023.118050

Schellart, W.P. 2017. Andean mountain building and magmatic arc migration driven by subduction-induced whole mantle flow. Nature Communications 8: 2010. doi: https://doi.org/10.1038/s41467-017-01847-z

Schellart, W.P. 2020. Frontiers in Earth Science, Control of subduction zone age and size on flat slab subduction. Frontiers in Earth Science 8 (26). doi: https://doi.org/10.3389/feart.2020.00026

Schepers, G.; van Hinsbergen, D.; Spakman, W.; Kosters, M.E.; Boschman, L.M.; McQuarrie, N. 2017. South-American plate advance and forced Andean trench retreat as drivers for transient flat subduction episodes. Nature Communications 8: 15249. doi: https://doi.org/10.1038/ncomms15249

Seton, M.; Whittaker, J.; Wessel, P.; Müller, R.D.; DeMets, C.; Merkouriev, S.; Cande, S.; Gaina, C.; Eagles, G.; Granot, R.; Stock, J.; Wright, N.; Williams, S. 2014. Community infrastructure and repository for marine magnetic identifications. Geochemistry, Geophysics, Geosystems 15 (4): 1629-1641. doi: https://doi.org/10.1002/2013GC005176

Sharp, W.D.; Clague, D.A. 2006. 50-Ma Initiation of Hawaiian-Emperor Bend records major change in Pacific plate motion. Science 313 (5791): 1281-1284. doi: https://doi.org/10.1126/science.1128489

Skinner, S.M.; Clayton, R.W. 2010. An evaluation of proposed mechanisms of slab flattening on central Mexico. Pure and Applied Geophysics 168: 1461-1474. doi: https://doi.org/10.1007/s00024-010-0200-3

Skinner, B.; Clayton, R.W. 2013. The lack of correlation between flat slabs and bathymetric impactors in South America. Earth and Planet Science Letters 371-372: 1-5. doi: 10.1016/j.epsl.2013.04.013

Smith, E.G.C. 1985. Calculations of poles of instantaneous rotation from poles of finite rotation. Geophysical Journal of the Royal Astronomical Society 65 (1): 223-227. doi: https://doi.org/10.1111/j.1365-246X.1981.tb02710.x

Somoza, R. 1998. Updated Nazca (Farallon)-South America relative motions during the last 40 My: implications for mountain building in the central Andean region. Journal of South American Earth Sciences 11 (3): 211-215. doi: https://doi.org/10.1016/S0895-9811(98)00012-1

Souza, Z.S.; Vasconcelos, P.M.; Knesel, K.M.; da Silveira Dias, L.G.; Roesner, E.H.; Cordeiro de Farias, P.R.; de Morais Neto, J.M. 2013. The tectonic evolution of Cenozoic extensional basins, northeast Brazil: Geochronological constraints from continental basalt ⁴⁰Ar/³⁹Ar ages. Journal of South American Earth Sciences 48: 159-172. doi: https://doi.org/10.1016/j.jsames.2013.09.008

Speziale, S.; Castorina, F.; Censi, P.; de Barros Gomes, C.; Marques, L.S.; Comin-Chiaramonti, P. 2020a. Carbonatites from the Southern Brazilian platform: I. Open Geosciences 12 (1): 452-478. doi: https://doi.org/10.1515/geo-2020-0050

Speziale, S.; Castorina, F.; Censi, P.; de Barros Gomes, C.; Marques, L.S.; Comin-Chiaramonti, P. 2020b. Carbonatites from the Southern Brazilian Platform: A review. II: Isotopic evidences. Open Geosciences 12 (1): 678-702. doi: https://doi.org/10.1515/geo-2020-0032

Stanton, N.; Gordon, A.C.; Valente, S.C.; Mohriak, W.U.; Maia, T.H.; Arena, M. 2022. The Abrolhos Magmatic Province, the largest post breakup magmatism of the Eastern Brazilian margin: a geological, geophysical, and geochemical review. In Meso-Cenozoic Brazilian Offshore Magmatism: Geochemistry, Petrology, and Tectonics (Costa dos Santos, A.; Hackspacher, P.C.; editors). Academic Press 6: 189-230. doi: https://doi.org/10.1016/B978-0-12-823988-9.00014-9

Torsvik, T.H.; Steinberger, B.; Shephard, G.E.; Doubrovine, P.V.; Gaina, C.; Domeier, M.; Conrad, C.P.; Sager, W.W. 2019. Pacific‐Panthalassic reconstructions: Overview, errata and the way forward. Geochemistry, Geophysics, Geosystems 20 (7): 3659-3689. doi: https://doi.org/10.1029/2019GC008402

van Hunen, J.; van der Berg, A.P.; Vlaar, N.J. 2004. Various mechanisms to induce present-day flat subduction and implications for the younger Earth: A numerical parameter study. Physics of the Earth and Planetary Interiors 146: 179-194. doi: https://doi.org/10.1016/j.pepi.2003.07.027

Wessel, P.; Kroenke, L.W. 2008. Pacific absolute plate motions since 145 Ma. Journal of Geophysical Research 113: B06101. doi: https://doi.org/10.1029/ 2007JB005499

Wessel, P.; Harada, Y.; Kroenke, L.W. 2006. Toward a self-consistent, high-resolution absolute plate motion model for the Pacific. Geochemistry, Geophysics, Geosystems 7: Q03L12. doi: https://doi.org/10.1029/ 2005GC001000.

Wilder, D.T. 2003. Relative motion history of the Pacific-Nazca (Farallon) plates since 30 million years ago. M.Sc. Thesis, University of South Florida.

Wright, N.; Müller, R.D.; Seton, M.; Williams, S. 2015. Revision of Paleogene plate motions in the Pacific and implications for the Hawaiian-Emperor bend. Geology 43 (5): 455-458. doi: https://doi.org/10.1130/G36303.1

Yan, Z.; Chen, L.; Xiong, X.; Wang, K.; Xie, R.; Hsu, H.T. 2020. Observations and modeling of flat subduction and its geological effects. Science China Earth Sciences 63: 1069-1091. doi: https://doi.org/10.1007/s11430-019-9575-2

Yáñez, G.A.; Ranero, C.R.; von Huene, R.; Díaz, J. 2001. Journal of Geophysical Research, Magnetic anomaly interpretation across the southern central Andes (32°-34°S): The role of the Juan Fernández Ridge in the late Tertiary evolution of the margin. Journal of Geophysical Research 106 (B4): 6325- 6345. doi: https://doi.org/10.1029/2000JB900337

 

Appendix

Table A1. Sources for plate-pair reconstruction models between the South American and Nazca plates.

Table A2. Sources for plate-hotspot reconstruction models.

References

Andrews, D.L.; Gordon, R.G.; Horner-Johnson, B.C. 2006. Uncertainties in plate reconstructions relative to the hotspots; Pacific-hotspot rotations and uncertainties for the past 68 million years. Geophysical Journal International 166: 939-951. doi: https://doi.org/10.1111/j.1365-246X.2006.03029.x

Bernard, A.; Munschy, M.; Rotstein, Y.; Sauter, D. 2005. Refined spreading history at the Southwest Indian Ridge for the last 96 Ma, with the aid of satellite gravity data. Geophysical Journal International 162: 765-778. doi: https://doi.org/10.1111/j.1365-246X.2005.02672.x

Bustamante, C.; Archanjo, C.J.; Cardona, A.; Vervoort, J.D. 2016. Late Jurassic to Early Cretaceous plutonism in the Colombian Andes: A record of long-term arc maturity. Geological Society of America Bulletin 128 (11-12): 1762-1779. doi: https://doi.org/10.1130/B31307.1

Cande, S.C.; Patriat, P. 2015. The anticorrelated velocities of Africa and India in the Late Cretaceous and early Cenozoic. Geophysical Journal International 200 (1): 227-243. doi: https://doi.org/10.1093/gji/ggu392

Cande, S.C.; Patriat, P.; Dyment, J. 2010. Motion between the Indian, Antarctic and African plates in the early Cenozoic. Geophysical Journal International 183: 127-149. doi: https://doi.org/10.1111/j.1365-246X.2010.04737.x

Coelho, M.H.P.; Martins, M.V.A.; Tavares, A.D.Jr.; Armando, D.; Muniz, L.; Romero, L.F.; Paiva, G.A.; Zan, W.G.; Weska, R.K.; Geraldes, M.C. 2022. U-Pb and Lu-Hf in zircon deciphering magmatic pulses of the Juína Kimberlite: Implications for the lithospheric mantle isotopic composition of the Amazonian Craton. Boletim Paranaense de Geociências 80 (2): 129-153. doi: http://dx.doi.org/10.5380/geo.v80i2.88628

Comin-Chiaramonti, P.; Civeta, L.; Petrini, R.; Piccirillo, E.M.; Bellieni, G.; Censi, P.; Bitschene, P.; Demarchi, G.; De Min, A.; Gomes, C.B.; Castilho, A.M.; Velázquez, J.C. 1991. Tertiary nephelinitic magmatism in Eastern Paraguay: petrology, Sr-Nd isotopes and genetic relationships. European Journal of Mineralogy 3: 507-525.

Conceição, F.T.; Vasconcelos, P.M.; Godoy, L.H.; Navarro, G.R.B. 2020. ⁴⁰Ar/³⁹Ar geochronological evidence for multiple magmatic events during the emplacement of Tapira alkaline-carbonatite complex, Minas Gerais, Brazil. Journal of South American Earth Sciences 97: 102416. doi: https://doi.org/10.1016/j.jsames.2019.102416

Costa dos Santos, A.; Hackspacher, P.C. 2020. Trindade Island Revisited: constraints based on Isotopes, ⁴⁰Ar/³⁹Ar dating, mineral and whole-rock chemistry of a metasomatized-CO2-garnet-lherzolite mantle: the role of a shallow secondary plume. Goldschmidt Abstracts. doi: https://doi.org/10.46427/gold2020.2277

Croon, M.B.; Cande, S.C.; Stock, J.M. 2008. Geochemistry Geophysics Geosystems, Revised Pacific-Antarctic plate motions and geophysics of the Menard Fracture Zone. Geochemistry, Geophysics, Geosystems 9 (7): Q07001. doi: https://doi.org/10.1029/2008GC002019

de Oliveira Amaral Quaresma, G.; Costa dos Santos, A.; Rocha-Júnior, E.R.V.; Bonifácio, J.; Queiroz R.; Caio A.; Mata, J.; de Morisson, V.C.; Jourdan, F.; Mattielli, N.; Geraldes, M.C. 2023. Isotopic Constraints on Davis Bank, Vitória-Trindade Ridge: A Revisited Petrogenetic Model. Journal of South American Earth Sciences 122: 104099. doi: https://doi.org/10.1016/j.jsames.2022.104099

DeMets, C.; Merkouriev, S. 2019. Geophysical Journal International, High-resolution reconstructions of Nubia, North America, and Antarctic plate motions relative to South America: 34 Ma to present. Geophysical Journal International 217 (3): 1821-1853. doi: https://doi.org/10.1093/gji/ggz087

DeMets, C.; Merkouriev, S.; Sauter, D. 2015. Geophysical Journal International, High-resolution estimates of Southwest Indian Ridge plate motions, 20 Ma to present. Geophysical Journal International 203 (3): 1495-1527. doi: https://doi.org/10.1093/gji/ggv366

Fodor, R.V.; McKee, E.H.; Asmus, H.E. 1983. K-Ar ages and the opening of the South Atlantic Ocean: basaltic rock from the Brazilian margin. Marine Geology 54 (1-2): M1-M8. doi: https://doi.org/10.1016/0025-3227(83)90002-6

Fodor, R.V.; Mukasa, S.B.; Sial, A.N. 1998. Isotopic and trace-element indications of lithospheric and asthenospheric components in Tertiary alkalic basalts, northeastern Brazil. Lithos 43 (4): 197-217. doi: https://doi.org/10.1016/S0024-4937(98)00012-7

Gaastra, K.M.; Gordon, R.G.; Woodworth, D.T.; 2022. Quantification of Pacific Plate Hotspot Tracks Since 80 Ma. Tectonics 41 (7): e2021TC006772. doi: https://doi.org/10.1029/2021TC006772

Geraldes, M.C.; Motoki, A.; Costa, A.; Mota, C.E.; Mohriak, W.U. 2013. Geochronology (Ar/Ar and K-Ar) of the South Atlantic post breakup magmatism, Conjugate Divergent Margins. Geological Society, London, Special Publications 369 (1): 41-74. doi: http://dx.doi.org/10.1144/SP369.21

Gibson, S.A.; Thompson, R.N.; Leonardos, O.H.; Turner, S.E.; Mitchell, J.G.; Dickin, A.P. 1994. The Serra do Bueno Potassic Diatreme: A Possible Hypabyssal Equivalent of the Ultramafic Alkaline Volcanics in the Late Cretaceous Alto Paranaíba Igneous Province, SE Brazil. Mineralogical Magazine 58 (392): 357-373. doi: https://doi.org/10.1180/minmag.1994.058.392.02

Gibson, S.A.; Thompson, R.N.; Leonardos, O.H.; Dickin, A.P.; Mitchell, J.G. 1995. The Late Cretaceous impact of the Trindade mantle plume: Evidence from large-volume, mafic, potassic magmatism in SE Brazil. Journal of Petrology 36 (1): 189-229. doi: https://doi.org/10.1093/petrology/36.1.189

Granot, R.; Dyment, J. 2018. Late Cenozoic unification of East and West Antarctica. Nature Communications 9: 3189. doi: https://doi.org/10.1038/s41467-018-05270-w

Granot, R.; Cande, S.C.; Stock, J.M.; Damaske, D. 2013. Revised Eocene-Oligocene kinematics for the West Antarctic rift system. Geophysical Research Letters 40 (2): 279-284. doi: https://doi.org/10.1029/2012GL054181

Guedes, E.; Heilbron, M.; Vasconcelos, P.M.; de Morisson Valeriano, C.; Horta de Almeida, J.; Teixeira, W.; Thomaz Filho, A. 2005. K-Ar and ⁴⁰Ar/³⁹Ar ages of dikes emplaced in the onshore basement of the Santos Basin, Resende area, SE Brazil: implications for the south Atlantic opening and Tertiary reactivation. Journal of South American Earth Sciences 18 (3-4): 371-382. doi: https://doi.org/10.1016/j.jsames.2004.11.008

Guimarães, A.R.; Fitton, J.G.; Kirstein, L.A.; Barfod, D.N. 2020. Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum. Earth and Planetary Science Letters 536: 116147. doi: https://doi.org/10.1016/j.epsl.2020.116147

Hansen, M.A.F.; Viramonte, J.G.; Troian, F.L.; Mizusaki, A.M.P.; Becchio, R.; Fensterseifer, H.C. 1998. Nuevas edades para el volcanismo de las islas Trindade y Martín Vaz, Brasil. In International Meeting: Colima Volcano, Mexico, No. 6, Abstracts: p. 125.

Harada, Y.; Hamano, Y. 2000. Recent progress on plate motions relative to hot spots. In The History and Dynamics of Global Plate Motions. Geophysical Monograph Series, 121, (Richards, M.A.; Gordon, R.G.; van der Hilst, R.D.; editors). American Geophysical Union: 327-338. Washington, D.C.

Hartmann, L.A.; Baggio, S.B.; Brückmann, M.P.; Knijnik, D.B.; Lana, C.; Massonne, H.-J.; Opitz, J.; Pinto, V.M.; Sato, K.; Tassinari, C.C.G.; Arena, K.R. 2019. U-Pb geochronology of Paraná volcanics combined with trace element geochemistry of the zircon crystals and zircon Hf isotope data. Journal of South American Earth Sciences 89: 219-226. doi: https://doi.org/10.1016/j.jsames.2018.11.026

Knesel, K.M.; Souza, Z.S.; Vasconcelos, P.M.; Cohen, B.E.; Silveira, F.V. 2011. Young volcanism in the Borborema Province, NE Brazil, shows no evidence for a trace of the Fernando de Noronha plume on the continent. Earth and Planetary Science Letters 302 (1-2): 38-50. doi: https://doi.org/10.1016/j.epsl.2010.11.036

Maher, S.M.; Wessel, P.; Müller, R.D.; Williams, S.E.; Harada, Y. 2015. Absolute plate motion of Africa around Hawaii-Emperor bend time. Geophysical Journal International 201 (3): 1743-1764. doi: https://doi.org/10.1093/gji/ggv104

Matthews, K.J.; Williams, S.E.; Whittaker, J.M.; Müller, R.D.; Seton, M.; Clarke, G.L. 2015. Geologic and kinematic constraints on Late Cretaceous to mid Eocene plate boundaries in the southwest Pacific. Earth‐Science Reviews 140: 72-107. doi: https://doi.org/10.1016/j.Earscirev.2014.10.008

Mizusaki, A.M.P.; Thomaz-Filho, A.; Milani, E.J.; de Cesero, P. 2002. Mesozoic and Cenozoic igneous activity and its tectonic control in northeastern Brazil. Journal of South American Earth Sciences 15 (2) 183-198. doi: https://doi.org/10.1016/S0895-9811(02)00014-7

Motoki, A.; Motoki, K.; Costa dos Santos, A.; Cardoso Nogueira, C.; Holanda dos Santos, W.; Geraldes, M.C.; Sichel, S.; Vargas, T. 2018. Geology, Petrology and Magmatic Evolution of the Felsic Alkaline Rocks of the Vitória Island, São Paulo State, Brazil. Anuário do Instituto de Geociências-Federal University of Rio de Janeiro (UFRJ) 41: 125-136. doi: http://dx.doi.org/10.11137/2018_3_125_136

Müller, R.D.; Royer, J.-Y.; Lawver, L.A. 1993. Revised plate motions relative to the hotspots from combined Atlantic and Indian Ocean hotspot tracks. Geology 21 (3): 275-278. doi: https://doi.org/10.1130/0091-7613(1993)021%3C0275:RPMRTT%3E2.3.CO;2

Dietmar-Müller, R.; Royer, J.-Y.; Cande, S.C.; Roest, W.R.; Maschenkov, S. 1999. New constraints on the late cretaceous/tertiary plate tectonic evolution of the caribbean, Sedimentary Basins of the World (Mann, P.; editor), Elsevier, Chapter 2: 33-59. doi: https://doi.org/10.1016/S1874-5997(99)80036-7

Müller, R.D.; Zahirovic, S.; Williams, S.E.; Cannon, J.; Seton, M.; Bower, D.J.; Tetley, M.G.; Heine1, C.; Le Breton, E.; Liu, S.; Russell, S.H.J.; Yang, T.; Leonard, J.; Gurnis, M. 2019. A global plate model including lithospheric deformation along major rifts and orogens since the Triassic. Tectonics 38 (6): 1884-1907. doi: https://doi.org/10.1029/2018TC005462

Nankivell, A.P. 1997. Tectonic evolution of the southern ocean between Antarctica, South America and Africa over the last 84 Ma. PhD thesis, University of Oxford: 303 p. Oxford.

Norton, I.O. 2000. Global hotspot reference frames and plate motion. In The History and Dynamics of Global Plate Motions (Richards, M.A.; Gordon, R.G.; van der Hilst, R.D.; editors). American Geophysical Union, Geophysical Monograph Series 121: 339-357.

O’Neill, C.; Müller, R.D.; Steinberger, B. 2005. On the uncertainties in hot spot reconstructions and the significance of moving hot spot reference frames. Geochemistry, Geophysics, Geosystems 6 (4): Q04003. doi: https://doi.org/10.1029/2004GC000784.

Omarini, R.H.; Gasparon, M.; De Min, A.; Comin-Chiaramonti, P. 2016. An overview of the Mesozoic-Cenozoic magmatism and tectonics in Eastern Paraguay and central Andes (Western Gondwana): Implications for the composition of mantle sources. Journal of South American Earth Sciences 72: 302-314. doi: https://doi.org/10.1016/j.jsames.2016.10.002

Pérez-Díaz, L.; Eagles, G. 2014. Constraining South Atlantic growth with seafloor spreading data. Tectonics 33 (9): 1848-1873. doi: https://doi.org/10.1002/2014TC003644

Perlingeiro, G.; Vasconcelos, P.M.; Knesel, K.M.; Thiede, D.S.; Cordani, U.G. 2013. ⁴⁰Ar/³⁹Ar geochronology of the Fernando de Noronha Archipelago and implications for the origin of alkaline volcanism in the NE Brazil. Journal of Volcanology and Geothermal Research 249: 140-154. doi: https://doi.org/10.1016/j.jvolgeores.2012.08.017

Raymond, C.A.; Stock, J.M.; Cande, S.C. 2000. Fast Paleogene motion of the Pacific hotspots from revised global plate circuit constraints. In History and Dynamics of Plate Motions (Richards, M.A.; Gordon, R.G.; van der Hilst, R.D.; editors). American Geophysical Union, Geophysical Monograph 121: 359-375.

Riccomini, C.; Melo, M.S.; Coutinho, J.M.V. 1991. Late cretaceous-early tertiary ultrabasic magmatism in the western part of the state of Rio de Janeiro, II. Workshop on Mafic Dyke Swarms of Brazil, Brazil Boletim IG-USP. Publicação Especial 10: 77-84. doi: https://doi.org/10.11606/issn.2317-8078.v0i10p77-84

Rowan, C.J.; Rowley, D.B. 2014. Spreading behaviour of the Pacific-Farallon ridge system since 83 Ma. Geophysical Journal International 197 (3): 1273-1283. doi: https://doi.org/10.1093/gji/ggu056

Seton, M.; Müller, R.D.; Zahirovic, S.; Gaina, C.; Torsvik, T.; Shephard, G.; Talsma, A.; Gurnis, M.; Turner, Maus, S.; Chandler, M. 2012. Global continental and ocean basin reconstructions since 2000 Ma. Earth-Science Reviews 113 (3-4): 212-270. doi: https://doi.org/10.1016/j.earscirev.2012.03.002

Siebel, W.; Becchiob, R.; Volker, F.; Hansene, M.A.F.; Viramonte, J.; Trumbull, R.B.; Haase, G.; Zimmer, M. 2000. Trindade and Martin Vaz Islands, South Atlantic: Isotopic (Sr, Nd, Pb) and trace element constraints on plume related magmatism. Journal of South American Earth Sciences 13: 79-103. doi: https://doi.org/10.1016/S0895-9811(00)00015-8

Skolotnev, S.G.; Bylinskaya, M.E.; Golovina, L.A.; Ipat’eva, I.S. 2011. First data on the age of rocks from the central part of the Vitoria-Trindade Ridge (Brazil Basin, South Atlantic). Doklady Earth Sciences 437 (1): 316-322. doi: https://doi.org/10.1134/S1028334X11030093

Sonoki, I.K.; Garda, G.M. 1988. Idades K-Ar de rochas alcalinas do Brasil Meridional e Paraguai Oriental: compilação e adaptação às novas constantes de decaimento. Boletim IG-USP Série Científica 19: 63-85. doi: https://doi.org/10.11606/issn.2316-8986.v19i0p63-85

Souza, Z.S.; Vasconcelos, P.M.; Knesel, K.M.; da Silveira Dias, L.G.; Roesner, E.H.; Cordeiro de Farias, P.R.; de Morais Neto, J.M. 2013. The tectonic evolution of Cenozoic extensional basins, northeast Brazil: Geochronological constraints from continental basalt ⁴⁰Ar/³⁹Ar ages. Journal of South American Earth Sciences 48: 159-172. doi: https://doi.org/10.1016/j.jsames.2013.09.008

Tebbens, S.F.; Cande, S.C. 1997. Journal of Geophysical Research: Solid Earth, Southeast Pacific tectonic evolution from Early Oligocene to Present. Journal of Geophysical Research, Solid Earth 102 (B6): 12061-12084. doi: https://doi.org/10.1029/96JB02582

Torsvik, T.H.; Steinberger, B.; Shephard, G.E.; Doubrovine, P.V.; Gaina, C.; Domeier, M.; Carmen Gaina, C.; Domeier, M.; Conrad, C.P. 2019. Pacific‐Panthalassic reconstructions: Overview, errata and the way forward. Geochemistry, Geophysics, Geosystems 20. doi: https://doi.org/10.1029/2019GC008402

Wessel, P.; Kroenke, L.W. 2008. Journal of Geophysical Research, Pacific absolute plate motions since 145 Ma. Journal of Geophysical Research 113 (B6): B06101. doi: https://doi.org/10.1029/2007JB005499

Wessel, P.; Harada, Y.; Kroenke, L.W. 2006. Toward a self-consistent, high-resolution absolute plate motion model for the Pacific. Geochemistry, Geophysics, Geosystems 7: Q03L12. doi: https://doi.org/10.1029/2005GC001000

Wilder, D.T. 2003. Relative motion history of the Pacific-Nazca (Farallon) plates since 30 million years ago. MSc Thesis (Unpublished), University of South Florida: 94 p.

Wright, N.; Müller, R.D.; Seton, M.; Williams, S. 2015. Revision of Paleogene plate motions in the Pacific and implications for the Hawaiian-Emperor bend. Geology 43 (5): 455-458. doi: https://doi.org/10.1130/G36303.1

Wright, N.; Müller, R.D.; Seton, M.; Williams, S. 2016, The Late Cretaceous to recent tectonic history of the Pacific Ocean basin. Earth-Science Reviews 154: 138-173. doi: https://doi.org/10.1016/j.earscirev.2015.11.015

 

Supplementary figures and tables

Pilger (2023)-Tracing hotspot traces in the Andes: supplementary data

Supplementary figures and tables

Figure S1. Map view of isotopic dates of Andean igneous rocks, 0-100 Ma

Figure S2A-H. Map views of isotopic dates of Andean igneous rocks in 10 Myr increments, 0-80 Ma

Figure S3. Plate-Hotspot models and East Africa magmatism

Table S1. Source plate-pair reconstruction parameters, timescale of Ogg (2020)

Table S2. Calculated reconstruction parameters at 1 Myr increments

Uncertainties in Global Plate Reconstructions-An Unsolved Problem

 

Separate file for display in Google Earth: Andes_Tracing_Traces_Supporting.kmz - Includes:

• Pacific Hotspot Dates

• Andes 0-100 Ma Silicic-Intermediate Igneous Dates

• Hawaiian Hotspot-Nazca Loci

• Brazil-Paraguay Igneous Dates and Loci (post Parana)

• South American Lithospheric Thickness

• East African (EAFR) Igneous Dates (Cenozoic)

• Tristan Hotspot Loci

 

Fig. S1. Map view of isotopic dates of igneous rocks, South American Andes, and adjacent areas, 0-100 Ma. Data accessible via GEOROC (see main text for details).

Fig. S2A. 0-10 Ma.

Fig. S2B. 10-20 Ma.

Fig. S2C. 20-30 Ma.

Fig. S2D. 30-40 Ma.

Fig. S2E. 40-50 Ma.

Fig. S2F. 50-60 Ma.

Fig. S2G. 60-70 Ma.

Fig. S2H. 70-80 Ma. Fig. S2. Map views of isotopic dates of igneous rocks, 0-80 Ma, South American Andes, in 10 Myr Intervals. Data accessible via GEOROC (see main text for details). Data also included in the Google Earth file attached to this paper.

TABLE S1. SOURCE PLATE-PAIR RECONSTRUCTION PARAMETERS, TIMESCALE OF OGG (2020).

TABLE S2. CALCULATED RECONSTRUCTION PARAMETERS AT 1 MYR INCREMENTS.

Uncertainties in global plate reconstructions - an unsolved problem

The conventional method of derivation of relative plate reconstructions of corresponding magnetic isochrons and fracture zone offsets is that of Hellinger (1981; e.g., Kirkwood et al., 1999). Three unknown parameters are sought: the latitude and longitude of the finite pole of rotation, and the counterclockwise angle of rotation. However, additional parameters are required, defining great circle segments which fit separate clusters of magnetic isochron, and fracture zone offset identifications. Each segment requires two parameters, for example the latitude and longitude of the pole to its fitted great circle. Thus, the reconstruction produces three plus two times the number of great circle segments; a typical reconstruction might involve ten segments, thus requiring 23 parameters. (Each segment must have a minimum of three distinct identifications to produce a unique great circle fit.) The fitting criterion is minimization of the sum of the squared distance of each data point from its corresponding great circle segment as a function of the parameters. The problem includes non-linear components and, therefore, an iterative process of searching out the optimal solution.

If uncertainties in the location of each data point are available, the algorithm can incorporate the uncertainties as weights in the least-squares solution. Conventional applications produce “estimates” of the rotation parameters plus uncertainties, including variances and covariances, from which ellipsoids of uncertainty can be constructed for the three parameters. What are the sources of uncertainty in individual identifications? Navigation, modeling of isochrons, and width of fracture zones are most relevant, recognizing that the obliquity of the navigation to the linear feature contributes to the uncertainty. (Further, note that the uncertainty is measured in distance units, not age) The non-linearity of the problem means that the ellipsoid of uncertainty is itself an approximation of error. More importantly, however, note that the uncertainties in the great circle segment parameters are largely ignored and treated as nuisance factors.

The calculation of global reconstructions by composing plate-pair reconstructions, including uncertainties, is straightforward if the ages across each pair are all the same. However, should ages of reconstructions vary among the plate pairs, interpolation is required. Conventional interpolation assumes constant finite difference poles and rotation rates between finite rotations. Alternatively, spline interpolation of pseudovectors representing the rotation parameters (with magnitude equal to rotation rate) may be utilized. The latter may be more realistic in that the conventional approach forces changes in rotations to correspond with the finite reconstruction isochrons, which are usually most confidently identified for near-constant spreading directions, not times of significant rotation changes. In either case, interpolation of uncertainties is indeterminant, since the source uncertainties are measured in distance, not time; interpolation necessarily involves rates, therefore time, as well as distance.

Various studies which include interpolation may report uncertainties, but their meaning is itself uncertain. The finite rotation parameterization assumption is kinematic rigidity of plates, a tested keystone of the theory of plate tectonics. However, there is no geologically meaningful consensus on parameterizing motions between finite reconstructions. Consequently, there is no clear rationale for any uncertainty interpolation method. Further, neglecting uncertainties in great circle segment poles as “nuisance parameters” lacks any rationale, beyond convenience, as well.

Plate-Hotspot models and East Africa magmatism

Fig. S3. Plot of isotopic dates from igneous rocks, East Africa (compilation of Pilger, 2003) versus latitude, plus calculated loci of hypothetical hotspot, arbitrarily located at 33⁰E and -4.6⁰S. Loci are based on reconstruction models from Muller et al. (1993, 2019), O’Neill et al. (2005); Torsvik et al. (2010); Doubrovine et al. (2012); Maher et al. (2015); Gaastra et al. (2022).

Supplementary References

Cande, S.C.; Patriat, P. 2015. The anticorrelated velocities of Africa and India in the Late Cretaceous and early Cenozoic. Geophysical Journal International 200 (1): 227-243. doi: https://doi.org/10.1093/gji/ggu392

Croon, M.B.; Cande, S.C.; Stock, J.M. 2008. Revised Pacific-Antarctic plate motions and geophysics of the Menard Fracture Zone. Geochemistry, Geophysics, Geosystems 9 (7): Q07001. doi: https://doi.org/10.1029/2008GC002019

DeMets, C.; Merkouriev, S. 2019. High-resolution reconstructions of Nubia, North America, and Antarctic plate motions relative to South America: 34 Ma to present. Geophysical Journal International 217 (3): 1821-1853. doi: https://doi.org/10.1093/gji/ggz087

DeMets, C.; Gordon, R.G.; Argus, D.F. 2010. Geologically current plate motions. Geophysical Journal International 181 (1): 1-80. doi: https://doi.org/10.1111/j.1365-246X.2009.04491.x

DeMets, C.; Merkouriev, S.; Sauter, D. 2021. High resolution reconstructions of the Southwest Indian Ridge, 52 Ma to present: implications for the breakup and absolute motion of the Africa plate. Geophysical Journal International 226 (3): 1461-1497. doi: https://doi.org/10.1093/gji/ggab107

Doubrovine, P.V.; Steinberger, B.; Torsvik, T.H. 2012. Absolute plate motions in a reference frame defined by moving hotspots in the Pacific, Atlantic and Indian Oceans. Journal of Geophysical Research 117: B09101. doi. https://doi.org/10.1029/2011JB009072

Gaastra, K.M.; Gordon, R.G.; Woodworth, D.T. 2022. Quantification of Pacific Plate hotspot tracks since 80 Ma. Tectonics 41(7): e2021TC006772. doi: https://doi.org/10.1029/2021TC006772

Granot, R.; Dyment, J. 2018. Late Cenozoic unification of East and West Antarctica. Nature Communications 9: 3189. doi: https://doi.org/10.1038/s41467-018-05270-w

Granot, R.; Cande, S.C.; Stock, J.M.; Damaske, D. 2013. Revised Eocene-Oligocene kinematics for the West Antarctic rift system. Geophysical Research Letters 40 (2): 279-284. doi: https://doi.org/10.1029/2012GL054181

Gripp, A.E.; Gordon, R.G. 2002. Young tracks of hotspots and current plate velocities. Geophysical Journal International 150 (2): 321-361. doi: https://doi.org/10.1046/j.1365-246X.2002.01627.x

Hellinger, S.J. 1981. The uncertainties of finite rotations in plate tectonics, Journal of Geophysical Research 86 (B10): 9312-9318. doi: https://doi.org/10.1029/JB086iB10p09312

Kirkwood, B.H.; Royer, J.-Y.; Chang, T.C.; Gordon, R.G. 1999. Statistical tools for estimating and combining finite rotations and their uncertainties. Geophysical Journal International 137 (2): 408-428. doi: https://doi.org/10.1046/j.1365-246X.1999.00787.x

König, M.; Jokat, W. 2006. The Mesozoic breakup of the Weddell Sea. Journal of Geophysical Research 111: B12102, doi: https://doi.org/10.1029/2005JB004035

Lonsdale, P. 2005. Creation of the Cocos and Nazca plates by fission of the Farallon plate. Tectonophysics 404(3): 237-264. doi: https://doi.org/10.1016/j.tecto.2005.05.011

Maher, S.M.; Wessel, P.; Müller, R.D.; Williams, S.E.; Harada, Y. 2015. Absolute plate motion of Africa around Hawaii-Emperor bend time. Geophysical Journal International 201 (3): 1743-1764. doi: https://doi.org/10.1093/gji/ggv104

Marks, K.; Stock, J. 2001. Evolution of the Malvinas plate south of Africa. Marine Geophysical Researches 22: 289-302. doi: https://doi.org/10.1023/A:1014638325616

Matthews, K.J.; Williams, S.E.; Whittaker, J.M.; Müller, R.D.; Seton, M.; Clarke, G.L. 2015. Geologic and kinematic constraints on Late Cretaceous to mid Eocene plate boundaries in the southwest Pacific. Earth‐Science Reviews 140: 72-107. doi: https://doi.org/10.1016/j.Earscirev.2014.10.008

Müller, R.D.; Royer, J.-Y.; Lawver, L.A. 1993. Revised plate motions relative to the hotspots from combined Atlantic and Indian Ocean hotspot tracks. Geology 21 (3): 275-278. doi: https://doi.org/10.1130/0091-7613(1993)021%3C0275:RPMRTT%3E2.3.CO;2

Müller, R.D.; Sdrolias, M.; Gaina, C.; Roest, W.R. 2008. Age, spreading rates, and spreading asymmetry of the world’s ocean crust. Geochemistry, Geophysics, Geosystems 9 (4). doi: https://doi.org/10.1029/2007GC001743

Müller, R.D.; Zahirovic, S.; Williams, S.E.; Cannon, J.; Seton, M.; Bower, D.J.; Tetley, M.G.; Heine1, C.; Le Breton, E.; Liu, S.; Russell, S.H.J.; Yang, T.; Leonard, J.; Gurnis, M. 2019. A global plate model including lithospheric deformation along major rifts and orogens since the Triassic. Tectonics 38 (6): 1884-1907. doi: https://doi.org/10.1029/2018TC005462

Norton, I.O. 2000. Global hotspot reference frames and plate motion. In The history and dynamics of global plate motions (Richards, M.A; Gordon, R.G.; van der Hilst, R.D.; editors). American Geophysical Union, Geophysical Monograph 121: 339-357.

Ogg, J.G. 2020. Geomagnetic Polarity Time Scale. In Geologic Time Scale 2020 (Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M.; editors). Elsevier 1: 159-192. Amsterdam.

O’Neill, C.; Müller, R.D.; Steinberger, B. 2005. On the uncertainties in hot spot reconstructions and the significance of moving hot spot reference frames. Geochemistry, Geophysics, Geosystems 6 (4): Q04003. doi: https://doi.org/10.1029/2004GC000784

Pérez-Díaz, L.; Eagles, G. 2014. Constraining South Atlantic growth with seafloor spreading data. Tectonics 33 (9): 1848-1873. doi: https://doi.org/10.1002/2014TC003644

Pilger, R.H.Jr. 2003. Geokinematics - Prelude to Geodynamics. Springer, New York. doi: https://doi.org/10.1007/978-3-662-07439-8.

Raymond, C.A.; Stock, J.M.; Cande, S.C. 2000. Fast Paleogene motion of the Pacific hotspots from revised global plate circuit constraints. In the history and dynamics of global plate motions (Richards, M.A.; Gordon, R.G.; van der Hilst, R.D.; editors). American Geophysical Union, Geophysical Monograph 121: 359-375.

Rowan, C.J.; Rowley, D.B. 2014. Spreading behaviour of the Pacific-Farallon ridge system since 83 Ma. Geophysical Journal International 197 (3): 1273-1283. doi: https://doi.org/10.1093/gji/ggu056

Seton, M.; Müller, R.D.; Zahirovic, S.; Gaina, C.; Torsvik, T.; Shephard, G.; Talsma, A.; Gurnis, M.; Turner, M.; Maus, S.; Chandler, M. 2012. Global continental and ocean basin reconstructions since 2000 Ma. Earth-Science Reviews 113 (3-4): 212-270. doi: https://doi.org/10.1016/j.earscirev.2012.03.002

Tebbens, S.F.; Cande, S.C. 1997. Southeast Pacific tectonic evolution from Early Oligocene to Present. Journal of Geophysical Research, Solid Earth 102 (B6): 12061-12084. doi: https://doi.org/10.1029/96JB02582

Torsvik, T.H.; Steinberger, B.; Gurnis, M.; Gaina, C. 2010. Plate tectonics and net lithosphere rotation over the past 150 My. Earth and Planetary Science Letters 291: 106-112. doi: https://doi.org/10.1016/j.epsl.2009.12.055

Torsvik, T.H.; Steinberger, B.; Shephard, G.E.; Doubrovine, P.V.; Gaina, C.; Domeier, M.; Conrad, C.P.; Sager, W.W. 2019. Pacific‐Panthalassic reconstructions: Overview, errata and the way forward. Geochemistry, Geophysics, Geosystems 20 (7): 3659-3689. doi: https://doi.org/10.1029/2019GC008402

Wilder, D.T. 2003. Relative motion history of the Pacific-Nazca (Farallon) plates since 30 million years ago. M.Sc. Thesis (Unpublished), University of South Florida: 94 p.

Wilson, D.S. 1996. Fastest known spreading on the Miocene Cocos-Pacific Plate Boundary. Geophysical Research Letters 23 (21): 3003-3006. doi: https://doi.org/10.1029/96GL02893 Wright, N.; Müller, R.D.; Seton, M.; Williams, S. 2016. The Late Cretaceous to recent tectonic history of the Pacific Ocean basin. Earth-Science Reviews 154: 138-173. doi: https://doi.org/10.1016/j.earscirev.2015.11.015