Decompensative Gravity Anomalies Reveal the Structure of the Upper Crust of Antarctica

• Published in: Pure and Applied Geophysics
• Main Authors: Haeger, C., Kaban, M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2019
• Subjects: Antarctic; The Antarctic; East Antarctica; Dronning Maud Land; Transantarctic Mountains; Ronne Ice Shelf; Wilkes Subglacial Basin; Antarc*; Antarctica; Enderby Land; Filchner Ronne Ice Shelf; Filchner-Ronne Ice Shelf; Ice Shelf
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_4459891

As Antarctica is almost entirely covered by thick ice shields impeding in situ measurements, information about upper crustal structures and sedimentary basins is still sparse and the analysis of the gravity anomalies offers new insights. Isostatic gravity anomalies are often used to investigate upper crust structures. However, compensating masses significantly reduce the gravity effect of unknown sedimentary and upper crustal structures. To separate these effects, we apply so-called decompensative corrections to the isostatic anomalies for the Antarctic continent, which reach values of up to ± 70 mGal. The obtained decompensative anomalies well correspond to the known sedimentary basins, such as in the areas of the Filchner-Ronne Ice Shelf and Lambert Graben, and also suggest the existence of other large sedimentary deposits both in West and East Antarctica, which are not or only sparsely mapped by existing seismic surveys, e.g. in coastal Dronning Maud Land and Enderby Land. A dipole-like structure exists at the Transantarctic Mountains and the Wilkes Subglacial Basin, suggesting the presence of isostatic disturbances linked to the dynamic uplift of the Transantarctic Mountains and thick sedimentary accumulations in the east. Extended positive anomalies in East Antarctica are likely related to the old and dense cratonic crust as well as to isostatic disturbances caused by the transition from local to regional compensation around the Lambert Graben.