Oblique rifting at Tempe Fossae, Mars

Abstract

This work shows the results of a structural study of the faults observed at the Tempe
Rift (northeastern Tharsis region), Mars. A new, detailed map of faults and fault systems
was used to geometrically characterize the fracture architecture of the Tempe Rift and
to measure fault length, displacement, and spacing data, to analyze the spatial distribution
of fault centroids, and to investigate the fractal nature of fault trace maps. A comparison
with analog models and the use of conventional techniques of fault population analysis
show that the Tempe Rift was most probably generated under sinistral oblique-rifting
processes, which highlights the importance of the presence of inherited fractures in the
tectonic evolution of the Noachian crust. The angle between the extension direction and
the rift axis varies along the Tempe Rift, ranging from 50º–60º at its central southern part
to 66º–88º to the southwest. Fault scaling relationships are similar to those found at midocean
ridges on Earth with exponential fault length-frequency distributions. Localized,
inhomogeneous deformation generated weakly interacting faults, spanning the entire
thickness of the mechanical layer. This thickness decreased from southwest to northeast
along the rift, along with distance from the central part of the Tharsis dome.