Evolution of Pyrrhae Fossae, Mars: an explication from the age estimation using the Buffered Crater Counting technique

Pyrrhae Fossae (PyFo) on Mars is a palaeo-extensional tectonic feature preserved within a Noachian basement in the north-western Noachis Terra (NT). We have tried to understand the possible origin of the stress responsible for the evolution of these tectonic structures and to correlate their formation with other global Martian events. We estimated the absolute model age of PyFo, using the Buffered Crater Counting (BCC) technique, which indicates that these extensional structures were formed at ~3.79 Ga, after the basement formation at ~3.98 Ga. Considering the ages and geology of the terrains adjoining the PyFo region, we propose that the regional scale flexural bending was promoted either in response to Tharsis-related volcano-tectonic load or thinning of northern lowlands producing extension at the upper crustal level, generating these fossae at the early stage of Martian evolution.