Formation of the double rift system in the Thaumasia Highlands, Mars

Abstract

The Thaumasia Highland Rifts are two complex graben structures in the Thaumasia Highland belt, located in the southern Thaumasia region, Mars. The rifts are arranged 90-130 km apart in a nearly subparallel setting and represent a very unusual style of crustal deformation. We have investigated the mechanism responsible for this peculiar style of rifting and found strain localization by volcanic weak zones to be a major factor for fault-pattern formation, indicating widespread prerift and synrift volcanic activity in the region. This result is consistent with the high heat flow during rift emplacement as estimated from rift flank uplift. Our results indicate that the onset of volcanism predates the rift formation process and that magmatism and the associated lithospheric weak zones control the rift locations. The simulations performed here are in good agreement with the observations for extension in the NW-SE to NNW-SSE direction, and we favor a formation scenario involving passive rifting in a magmatectonically active environment. Copyright 2007 by the American Geophysical Union.