Analisis paleoambiental de los depositos detalud de la Formacion Kotick Point (Cretacico Inferior) en el area de Punta Stoneley, Isla James Ross, Antartica (64°S)

Abstract

ABSTRACT. Paleoenvironmental analysis of the slope deposits on the Kotick Point Formation (Lower Cretaceous) at 5toneley Point, James Ross Island, Antarctica (64°5). The Kotick Point Formation (Aptian•Albian), exposed at Stoneley Point, James Ross Island, Antarctica, is interpreted as having been deposited on a fault controlled slope. Eight lithofacies have been defined, forming three distinct depositional elements: slope foot wedge, open slope and sand lobes. Lithofacies A (breccias and conglomerates with projected clasts) and B (graded or massive sandstones) make up the slope foot wedge where sandy debris flows, fluidized f10ws and high•density turbidity currents were the dominant processes. A large Jurassic glide block is associated to this coarse grained wedge. Lithofacies e (medium•grained conglomerates to coarse sandstones) represents the development of a unique channelized turbidite system. Open slope is represented by lithofacies D (very fine sandstones with lag deposit); E (highly bioturbated medium to fine•grained sandstones); F (parallel stratified tabular sandstones) and G (non lithified mudstones). The latter is dominant, suggesting suspension sedimentation, whereas the former three represent deposition from esporadical turbidity currents and probable bottom currents reworking. Sand lobes are characterized by progradational cycles of lithofacies H (finegrained sandstones to mudstones).lntrabasinal tectonism and sea level changes played a major role in slope sedimentation. High sea level stand and tectonic quiescence are inferred for the deposition of hundreds of meters of mudstone packets. Formation of the slope foot wedge and the channelized turbidite system may have been related to fault reactivation.