Radial Variations in Lithospheric Properties in Northeast Tharsis: First Results

Introduction and Background: Radial grabens at Tharsis record crustal extension due to the load [1−3]. However their development and significance beyond 2-D strain estimates are largely unknown. For example, early Viking-based strain models required two separate phases of Tharsis loading to produce the “inner” and “outer” radial grabens [4,5]. In contrast, recent MGS-based stress models for Tharsis [6] imply synchronous development of radial graben sets over their entire length [7]. Important factors that can influence graben set development [8,9], such as lithospheric thickness and heat flow, are unconstrained at the small scales relevant to the observed external tectonic record.