Dextral Shear Deformation Belt on Southern Margin of Central Ovda Regio, Venus: Preliminary

Introduction: Crustal plateaus are a major class of tectonic features on Venus surface, and its study is essential in order to understand the geological evolution previous to the global resurfacing process. These regional units are flat topped highlands formed by tessera terrain, characterized by superposition of crosscutting structures [1-2], with complex tectonic patterns; also intratessera volcanic plains with diferent roughness appear flooding depressions. There are two principal and opposite hypothesis explaining the origin of crustal plateaus. One of them advocates a mantle downwelling process as the driving mechanism, producing thikening and shortening of the lower ductile crust above mantle downwelling flows [3], but some other authors point out that crustal plateau formation is controlled by plumes in a thin crust geodinamic regime where crustal thikening is produced by flood volcanism [4]. The greatest crustal plateau is Ovda Regio (western Aphrodite Terra), with three major groups of structures, folds, ribbons and grabens, and a history of contractional and extensional tectonic stages which understanding is highly significant for getting a genetic model. Strike-Slip tectonism has not been described in Ovda Regio, though it has been found in other areas of Aphrodite Terra [5,6]. In this paper we describe a zone with brittle strike-slip faults at Ovda Regio southern margin and discuss its implications in crustal plateaus tectonic evolution.