Aeromagnetic Constraints on Transantarctic Mountains Rift Flank Structure, Southern Victoria Land
Abstract
The Transantarctic Mountains (TAM) rift flank uplift has developed along the ancestral margin of the East Antarctic craton, rimming the thinned lithosphere of the West Antarctic rift system. The extensive ice cover hampers regional mapping of faults and other geologic boundaries, hence the large-scale configuration of structural boundaries remains poorly defined. TAMARA is a collaborative research program designed to document the regional structural and magmatic architecture of the TAM in southern Victoria Land (SVL). Aeromagnetic data have been acquired in a cooperative U.S.-German field campaign by a helicopter-borne semi-draped survey. As part of the TAMARA program a GIS database of satellite imagery and geological and geophysical data sets has been developed to support modeling and interpretation of the magnetic data and for long-term study of the evolution of the TAM. Regional structural maps from satellite imagery and aeromagnetic data are used to test models for the structural origin of prominent lineaments of TAM and to map the Jurassic Ferrar magmatic intrusive architecture. The Radian lineament is a W-NW trending transverse structure crossing the TAM and extending westward beneath the ice sheet. Because the path of the lineament is nearly entirely ice-filled, the nature and kinematics of this major crustal feature remain poorly known. Magnetic anomalies in the vicinity of the ice-covered, western portion of the lineament appear to show a pattern related to the lineament. The analysis of glaciological data reveals increased ice velocity, even possible streaming flow along the lineament, suggesting that the subglacial bed is soft, perhaps lubricated by meltwater or water-saturated till. Our modeling tests whether this structure marks a fault, whether it displaces Beacon Supergroup strata and Ferrar Dolerite, and whether there is any signature of basement offset associated with the lineament. Prominent linear to curvilinear anomalies to the north and south of the Radian lineament either correlate with outcrops of Jurassic Ferrar Dolerite or with subglacial bedrock highs that are also likely to be Ferrar. Modeling is used to evaluate whether the sill-like geometries that characterize outcrops of Ferrar Dolerite can cause the linear anomalies or, alternatively, whether dike-like roots are required. The latter model is significant because no feeder dikes for the vast Ferrar Large Igneous Province of the Transantarctic Mountains have been identified in outcrop.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2001
- Bibcode:
- 2001AGUSM..GP42A08C
- Keywords:
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- 1517 Magnetic anomaly modeling;
- 8015 Local crustal structure;
- 8040 Remote sensing;
- 8109 Continental tectonics--extensional (0905);
- 9310 Antarctica