New Geodetic and Gravimetric Maps to Infer Geodynamics of Antarctica with Insights on Victoria Land

Abstract

In order to make inferences on the geodynamics of Antarctica, geodetic and gravimetric maps derived from past and new observations can be used. This paper provides new insights into the geodynamics of Antarctica by integrating data at regional and continental scales. In particular, signatures of geodynamic activity at a regional extent have been investigated in Victoria Land (VL, Antarctica) by means of Global Navigation Satellite System (GNSS) permanent station observations, data from the VLNDEF (Victoria Land Network for Deformation control) discontinuous network, and gravity station measurements. At the continental scale, episodic GNSS observations on VLNDEF sites collected for 20 years, together with continuous data from the International GNSS Service (IGS) and Polar Earth Observing Network (POLENET) sites, were processed, and the Euler pole position assessed with the angular velocity of the Antarctic plate. Both the Bouguer and the free-air gravity anomaly maps were obtained by integrating the available open-access geophysics dataset, and a compilation of 180 gravity measurements collected in the VL within the Italian National Program for Antarctic Research (PNRA) activities. As a result, new evidence has been detected at regional and continental scale. The main absolute motion of VL is towards SE (Ve 9.9 ± 0.26 mm/yr, Vn −11.9 ± 0.27 mm/yr) with a pattern similar to the transforms of the Tasman and Balleny fracture zones produced as consequence of Southern Ocean spreading. Residual velocities of the GNSS stations located in VL confirm the active role of the two main tectonic lineaments of the region, the Rennick–Aviator and the Lillie–Tucker faults with right-lateral sense of shear. The resulting VL gravity anomalies show a NW region characterized by small sized Bouguer anomaly with high uplift rates associated and a SE region with low values of Bouguer anomaly and general subsidence phenomena. The East and West Antarctica are characterized by a different thickness of the Earth’s crust, and the relative velocities obtained by the observed GNSS data confirm that movements between the two regions are negligible. In East Antarctica, the roots of the main subglacial highlands, Gamburtsev Mts and Dronning Maud Land, are present. The Northern Victoria Land (NVL) is characterized by more scattered anomalies. These confirm the differences between the Glacial Isostatic Adjustment (GIA) modeled and observed uplift rates that could be related to deep-seated, regional scale structures.

Victoria Land, Antarctica: An Improved Geodynamic Interpretation Based on the Strain Rate Field of the Current Crustal Motion and Moho Depth Model

“…Some of the mentioned studies adopted a set of extra-Antarctic CGNSS stations to define a reference frame for further investigations of surface motions and geodynamics within the Antarctic plate. For instance, Zanutta et al [14] used a total of 235 GNSS stations worldwide (95 of which located in Antarctica, Figure 1A) for estimating the Eulerian pole of the Antarctic plate.…”

“…Figure 1B shows the locations of VLNDEF and TAMDEF GNSS stations distributed in VL. [14], 95 of which are in Antarctica. Victoria Land (VL), the object of this study, is represented in a black frame, bottom-right inset.…”

Recent local geodynamic processes in the Penola Strait_Lemaire Channel fault area (West Antarctica)

“…Recently, the results of GNSS observation have been frequently used for studies of geodynamic processes. Zanutta et al (2018) noted that in geosciences, GNSS and gravimetric observations are key methods to highlight geodynamic and geophysical phenomena of a geological region, and are a fundamental support in the formulation of deformation models at regional and continental scale, referring also to the interaction mechanisms of interaction between the solid Earth and the cryosphere. For instance, by Richter et al (2008Richter et al ( , 2013 the velocity magnitudes and azimuths of the ice flow at 50 surface markers in the Vostok Subglacial Lake region (East Antarctica) have been determined from repeated GNSS observations.…”

“…The flow direction diverges south east in the southern part and east north in the northern part of the subglacial lake. Zanutta et al (2017Zanutta et al ( , 2018 based on GNSS data collected over the past 20 years determined recent geodynamic parameters of Victoria Land (East Antarctica). Processing highlights a movement of Victoria Land towards the south east with a pathway nearly parallel to the transforms, which start from the Tasman and Balleny fracture zones and propagate on land in Antarctica.…”

Research of horizontal movements of the earth's crust in the Archipelago Argentine Islands (Antarctica) during period 2003-2018

“…Annual parameters of the tensor of inertia and momentum of Antarctic tectonic plate are determined. In [6], according to the results of repeated GNSS observations in the territory of Antarctica, the assessment and differentiation the earth's surface movements on the global (Antarctic Plate), the regional (Antarctic Peninsula) and the local (Argentine Islands archipelago) have been assessed. In [7], the geodynamic model of the Penola fault is detailed.…”