Tectónica de piel fina en el Domo de Tharsis, Marte: pruebas de una neotectónica marciana

Abstract

A photogeological reconnaissance of Viking mosaics and images of the Tharsis dome, Mars, has been carried out. Fourteen new areas of transcurrent faulting have been located which, together with other structures previously detected, permit to support a model in which the Thaumasia Plateau, the southeastern part of the Tharsis dome, is proposed to be an independent lithospheric block that experienced buckling and thrust faulting in Late Noachian or Early Hesperian times as a result of an E-W-directed compression. Evidence is presented that this stress field, rather than the Tharsis uplift, was decisive in the inception of Valles Marineris, that we consider a transtensive, dextral accident. The buckling spacing permits moreover to tentatively reconstruct a Martian Hesperian lithosphere similar in thickness to the mean present terrestrial oceanic lithosphere, thus supporting the possibility of a restricted lithospheric mobility in that period. Tharsis lithosphere was again subjected to shear stresses in Amazonian times, a period in which important accidents, such as strike-slip faults, wrinkle ridges, and straight and sigmoidal graben were formed under a thin-skin tectonic regime. The possible causes of those stresses, and especially their relationships to a putative period of plate tectonics, are discussed.