Geological and topographical analysis of Anshar Sulcus, Ganymede: Implications for grooved terrain formation

Abstract

The formation of grooved terrains on the icy surface of Ganymede is still debated and it could involve extensive rifting or spreading, strike-slip tectonics, and minor cryovolcanic resurfacing. Anshar Sulcus is a terminal portion of a groove network imaged at high resolution by the Galileo Solid State Imaging subsystem (SSI). To investigate the origin and evolution of the grooved terrains, we performed a geomorphological and structural analysis of Anshar Sulcus producing a geomorphological map of the study area in 1:500,000 scale, and we conducted a topographical analysis producing a Digital Elevation Model (DEM) of this region. We found several indicators that the formation of Anshar Sulcus' grooved terrain is the result of two tectonic events, the first being a right lateral strike-slip type and the second a crustal spreading. We found that the right lateral strike-slip movement that divided the dark terrain of this area into two distinct regions represents the precursor of the formation of the sulcus, and that the crustal spreading subsequently occurred through transtensional movement of the regions. We also found that the grooves were formed within the solid-state raised material by brittle fracturing and tilting of the newly formed crust.