Circular troughs in Tessera Terrains: preliminary results from a global survey on Venus

Abstract

Tesseras are highly deformed terrains characterized by two or more sets of tectonic structures crosscutting each other, which is indicative of a complex tectonic history [1]. Because these terrains mainly appear inside crustal plateaus, interpreting Tessera tectonic history can be related to their origin and evolution [2]. Detailed observations of radar images of Tessera terrains on Venus can be used to define a new tectonic structure characterized by a circular through that left inside a circular area with the average elevation of the surrounding tessera terrains.Concentric and radial tectonic lineaments appear associated to these structures. Often the circular troughs appear flooded by intra-tessera lavas, becoming more visible in radar images.These features are especially abundant in the internal areas of crustal plateaus characterized by basin and dome tectonic interference patterns,but also can be found at tessera inliers surrounded by volcanic plains. Since they can be found around Venus, these estructures are probably related to a geological process of planetary importance that needs to be studied. According to their main feature we propose to call them Circular Troughs (CT).