East Antarctica is a Precambrian craton where the thickness of the crust is about 35-40 km. The main geological structures are buried by the extensive continental ice sheet apart from sparse outcrops along the perimeter of the continent. Present understanding of the tectonic evolution of East Antarctica mainly derives from remotely sensed images and geophysical data. Bedrock physiography in Dome C-Vostok region is characterised by Vostok Lake, Aurora and Vincennes basins. A relief region includes the Vostok Subglacial Highlands, the Gamburtsev Subglacial Mountains and the Belgica Subglacial Highlands. Several model have been proposed to tectonically explain the presence of these depressions: the existence of an Early Paleozoic regional rifting, a Paleozoic compressional tectonic setting or else a glacial erosional origin. It is possible to frame the origin and evolution of Lake Vostok and Dome C structural depressions within a common geodynamic scenario: they form a set of elongated, roughly N-S to NNW-SSE structural depressions related to a NE-SW trending trans-extensional corridor. The relative young age of the Antarctic Ice Cap, about 38 Ma, compared to the old, Mesozoic age of the former, peneplanised landscape constrains the age of these structures in Late Cenozoic time. The presence of this subglacial morphology induces variations in the surface texture of the ice cap either due to the movements of the ice sheet on the roughness of the bedrock morphology, and/or to the interaction with active tectonic processes. A series of preferential orientations may relate also to exogenous processes. The analysis of the resulting textural anisotropy of the ice surface detected on the Radarsat mosaic of Antarctica proved a useful tool to investigate the active tectonic processes of the bedrock An original algorithm developed in SID software allowed to detect the main lineament domains of the surface ice cap in the investigated area. Gaussian analysis eventually made possible to understand the nature of the linear textural anisotropy by discriminating features produced by exogenous process and the tectonic induced linear features. SID analysis showed that the main lineament domains detected on the ice sheet surface are compatible with the principal N-S to NNW-SSE morpho-tectonic bedrock directions in Dome C-Vostok region (Aurora, Concordia and Vostok structural depression) and that morpho-tectonic directions control the ice-sheet dynamics in the investigated area.
Cianfarra, P., Salvini, F. (2004). Inferring bedrock Cenozoic tectonics from ice surface pattern in the Dome C area, East Antarctica.
Inferring bedrock Cenozoic tectonics from ice surface pattern in the Dome C area, East Antarctica
CIANFARRA, Paola;SALVINI, Francesco
2004-01-01
Abstract
East Antarctica is a Precambrian craton where the thickness of the crust is about 35-40 km. The main geological structures are buried by the extensive continental ice sheet apart from sparse outcrops along the perimeter of the continent. Present understanding of the tectonic evolution of East Antarctica mainly derives from remotely sensed images and geophysical data. Bedrock physiography in Dome C-Vostok region is characterised by Vostok Lake, Aurora and Vincennes basins. A relief region includes the Vostok Subglacial Highlands, the Gamburtsev Subglacial Mountains and the Belgica Subglacial Highlands. Several model have been proposed to tectonically explain the presence of these depressions: the existence of an Early Paleozoic regional rifting, a Paleozoic compressional tectonic setting or else a glacial erosional origin. It is possible to frame the origin and evolution of Lake Vostok and Dome C structural depressions within a common geodynamic scenario: they form a set of elongated, roughly N-S to NNW-SSE structural depressions related to a NE-SW trending trans-extensional corridor. The relative young age of the Antarctic Ice Cap, about 38 Ma, compared to the old, Mesozoic age of the former, peneplanised landscape constrains the age of these structures in Late Cenozoic time. The presence of this subglacial morphology induces variations in the surface texture of the ice cap either due to the movements of the ice sheet on the roughness of the bedrock morphology, and/or to the interaction with active tectonic processes. A series of preferential orientations may relate also to exogenous processes. The analysis of the resulting textural anisotropy of the ice surface detected on the Radarsat mosaic of Antarctica proved a useful tool to investigate the active tectonic processes of the bedrock An original algorithm developed in SID software allowed to detect the main lineament domains of the surface ice cap in the investigated area. Gaussian analysis eventually made possible to understand the nature of the linear textural anisotropy by discriminating features produced by exogenous process and the tectonic induced linear features. SID analysis showed that the main lineament domains detected on the ice sheet surface are compatible with the principal N-S to NNW-SSE morpho-tectonic bedrock directions in Dome C-Vostok region (Aurora, Concordia and Vostok structural depression) and that morpho-tectonic directions control the ice-sheet dynamics in the investigated area.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
