Crustal density structure of the Antarctic continent from constrained 3-D gravity inversion

Abstract

<p>Crustal density is a fundamental physical parameter that helps to reveal its composition and structure, and is also significantly related to the tectonic evolution and geodynamics. Based on the latest Bouguer gravity anomalies and the constrains of 3-D shear velocity model and surface heat flow data, the 3-D gravity inversion method, incorporating deep weight function, has been used to obtain the refined density structure over the Antarctic continent. Our results show that the density anomalies changes from -0.25 g/cm<sup>3</sup> to 0.20 g/cm<sup>3</sup>. Due to the multi-phase extensional tectonics in Mesozoic and Cenozoic, the low density anomalies dominates in the West Antarctica, while the East Antarctica is characterized by high values of density anomalies. By comparing with the variations of effective elastic thickness, the inverted density structure correlates well with the lithospheric integrated strength. According to the mechanical strength and inverted density structure in the West Antarctic Rift System (WARS), our analysis found that except for the local area affected by the Cenozoic extension and magmatic activity, the crustal thermal structure in the WARS tends to be normal under the effect of heat dissipation. Finally, the low density anomalies features in West Antarctica extend to beneath the Transantarcitc Mountains (TAMs), however, we hypothesize that a single rift mechanism seems not be used to explain the entire TAMs range.</p>