Abstract
In Antarctica, the severe climatic conditions and the thick ice sheet that covers the largest and most internal part of the continent make it particularly difficult to systematically carry out geophysical and geodetic observations on a continental scale. It prevents the comprehensive understanding of both the onshore and offshore geology as well as the relationship between the inner part of East Antarctica (EA) and the coastal sector of Victoria Land (VL). With the aim to reduce this gap, in this paper multiple geophysical dataset collected since the 1980s in Antarctica by Programma Nazionale di Ricerche in Antartide (PNRA) were integrated with geodetic observations. In particular, the analyzed data includes: (i) Geodetic time series from Trans Antarctic Mountains DEFormation (TAMDEF), and Victoria Land Network for DEFormation control (VLNDEF) GNSS stations installed in Victoria Land; (ii) the integration of on-shore (ground points data and airborne) gravity measurements in Victoria Land and marine gravity surveys performed in the Ross Sea and the narrow strip of Southern Ocean facing the coasts of northern Victoria Land. Gravity data modelling has improved the knowledge of the Moho depth of VL and surrounding the offshore areas. By the integration of geodetic and gravitational (or gravity) potential results it was possible to better constrain/identify four geodynamic blocks characterized by homogeneous geophysical signature: the Southern Ocean to the N, the Ross Sea to the E, the Wilkes Basin to the W, and VL in between. The last block is characterized by a small but significant clockwise rotation relative to East Antarctica. The presence of a N-S to NNW-SSE 1-km step in the Moho in correspondence of the Rennick Geodynamic Belt confirms the existence of this crustal scale discontinuity, possibly representing the tectonic boundary between East Antarctica and the northern part of VL block, as previously proposed by some geological studies.
Highlights
The geodynamic interpretation of the Antarctic continent and geological sub-regions is challenging because of the gaps and spatial heterogeneity of data
About a hundred of continuous Global Navigation Satellite Systems (CGNSS) stations have been installed in Antarctica in the last two decades by several research initiatives coordinated by the scientific committee on Antarctic research (SCAR)
We propose the presence of a clockwise rotation of Victoria Land (VL) with respect to the East Antarctica (EA), with larger relative motions along the Rennick Geodynamic Belt (RGB), [14]
Summary
The geodynamic interpretation of the Antarctic continent and geological sub-regions is challenging because of the gaps and spatial heterogeneity of data. Continuous Global Navigation Satellite Systems (CGNSS) and airborne or shipborne-based gravimetric surveys provided the fundamental data compilation to derive geodynamic and geophysical models of the Antarctic regions. Such geodetic and gravimetric signatures could reflect the complex interaction mechanisms between the solid earth and the cryosphere and provide insights about the structure of the upper mantle, crustal thicknesses, active tectonic, and geodynamic processes in Antarctica. We improved the geodynamic interpretation of VL using new surface strain rates estimates derived from GNSS observations and Moho depth computations derived from the inversion of new gravimetric data collected from both onshore and offshore in the frame of the Italian national program for Antarctic research, PNRA (see Figure 1B to locate gravimetric measurements from surface shipborne gravimetry). We conclude that the integration of high-density geophysical and geodetic data allows an improved geodynamic interpretation of VL by the delineation of sub-regions with different geodetic and gravimetric signatures
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