Mapping the Tesserae Highlands of Venus – Insights into Tectonic Deformation and Plateau Genesis

Abstract

Tesserae terrains on Venus are characterized by intersecting sets of tectonic fabrics, signifying pervasive, complex, and multi-stage deformation. The locally stratigraphically oldest tesserae units, which cover around 8% of Venus’s surface, are primarily exposed within regions of high topography, flat-topped, quasi-circular crustal plateaus. This association suggests that the highly deformed tesserae units are intrinsic to the formation of crustal plateaus, and that the tesserae units encapsulate a significant record of Venus’ early geologic history. The origin of crustal plateaus remains debated. Various models have been put forward to explain their formation, each considering the complex deformation evidenced by the tesserae unit and the thickened crust, which is supported by data on small gravity anomalies and low gravity to topography ratios. These models include (1) mantle upwelling, (2) mantle downwelling, (3) pulsating continent with subduction, (4) heat-pipe volcanism, and (5) lava pond and bolide impact hypothesis. Testing these models involves identifying the boundary relationship of tesserae units and surrounding units, as well as the types and sequences of deformation in the tectonic lineaments. In this study, we present a focused examination of the following selected tesserae highlands, ranging from the well-studied and previously mapped Ishtar terra to Western Ovda Regio, Ovda Regio, Thetis Regio, Tellus Regio, and Alpha Regio. Magellan synthetic aperture radar (SAR) full-resolution map (FMAP) and digital elevation model (DEM) are used to map the interior deformation patterns, as well as the stratigraphic and tectonic relationships at the highland boundaries. Preliminary results mostly do not support a bolide impact model yet are unable to falsify the remaining models. The current spatial resolution of the dataset limits our ability to identify the structural type of tectonic lineaments. Our work aims to advance our understanding of Venusian tectonics and highlight the importance of the acquisition of higher-resolution data to unravel Venus’ geological evolution.