Unraveling the Tectonic History of the Tharsis Rise on Mars: Plume Migration and Critical Taper Dome

Abstract

Wrinkle ridges are widespread tectonic landforms that serve as paleo-strain and paleo-stress indicators of the compressional history and thermal evolution of Mars. To reconstruct the center of the Tharsis rise and its migration with time, we mapped wrinkle ridges in the periphery of the dome and analyzed 34,741 wrinkle ridge segments with a total length of 77,294 km. We determined the deviation of each wrinkle ridge segment from a concentric strike direction for systematically changing centers. A fitting procedure indicates that all wrinkle ridge segments can be allocated with good precision to five different stress centers (C1-5) within the Tharsis rise: the southern edge of the Alba Mons caldera (C1), Ceraunius Fossae (C2), between Ulysses Patera and Pavonis Chasma (C3), Phoenicis Lacus (C4), and Claritas Rupes (C5). We performed a morphometric analysis of each wrinkle ridge and calculated the amount of shortening and depth of detachment, making use of methods for constructing balanced cross-sections. The amount of horizontal shortening varies from 1.5 to 3.8 km and the range of the detachment depth was found to be between 2.9 and 8.8 km, with significant variance forming an acute wedge of 1.2°–2.2°. Based on the critical taper theory, we inferred a very low basal friction coefficient ranging from 0.077 to 0.093 across the detachments for the five centers (C1–C5). Our findings suggest that these detachments are either localized along salt or clay layers or occur where liquid water is dominant below an impermeable permafrost layer.