Paleomagnetism of probably remagnetized late Mesozoic volcanic rocks near Lago Verde, Aisén, Southern Chile

Abstract

Paleomagnetic data were obtained for 12 sites in gently dipping, fresh to slightly altered volcanic and volcaniclastic rocks near Lago Verde, Aisén Province, Southern Chile. Similar directions found in high and low stability magnetite and pyrrhotite, plus increase in dispersion upon correcting for tilt, suggest that the remanence is a post-tilting secondary magnetization. It is uncertain whether the rocks sampled are correlative with nearby exposures of the Ibáñez Group (Jurassic), or the Divisadero Group (early to middle Cretaceous). However, intrusion of rocks of the Patagonian batholith, a likely cause of remagnetization, is well dated at about 90 Ma. Compared to a new 90 Ma reference pole, the Lago Verde result indicates that the area has been rotated about 17º clockwise, with no significant latitudinal displacement. This result is similar to results of other nearby paleomagnetic investigations east of the Liquiñe-Ofqui Fault.