High-resolution elastic thickness variation across Tharsis and Valles
Marineris: Results from a space-domain convolution method and the
implications for the structure and evolution of the lithosphere
Abstract
We derived high-resolution spatial variation of elastic thickness
(Te) and crustal thickness (Tc) models across the crustal
dichotomy in and around the Tharsis-Valles Marineris provinces on Mars
by using a space-domain convolution technique. In the Tharsis volcanic
province, large-Te (55-60 km) and Tc (66-73 km)
characteristics of the large volcanoes are consistent with the idea that
most of their volcanic loads were emplaced on an old-cold-thicker and
hence mechanically stronger lithosphere in a geologically later period
(i.e., Amazonian). A relatively small-Te and thinned crustal
structure in the central part of the Valles Marineris with the inferred
layered plutons, flood basalts, and mafic dikes are suggestive of a
rift-like evolution. However, rifting ultimately may have failed because
of the presence of mechanically stronger lithospheric segments in its
western and eastern extremities. The results mainly suggest that the
crustal dichotomy also reflects rheological differences between northern
lowlands and southern highlands such that the low-Te and thinned
crustal structure of the northern lowlands and large variations in
Te and Tc structure in the southern highlands correspond
to a simple-layered and complex/multi-layered lithospheric setting,
respectively. Also, variations and patterns of Te characterizes
unmodified, plume-affected, and impact affected lithosphere, which
substantiate the published geological and geophysical constraints on the
evolution and geodynamic setting of complex geological
structures/provinces in the study area.