Morphometric analysis of fluvial channels over Thaumasia highland, Mars: Implications for the Martian aqueous history

Ubiquitous fluvial valley networks on the Martian surface document the existence of liquid water on Mars. In this study, we delineate and study the morphometry and patterns of fluvial channels in Noachian (Nb, Nphl, Nf, Nfc, Nfd, Npld, Npl_2; Dohm et al., 2001) and Hesperian (HNt, HNpld, HNplt, Hpld, and Hr; Dohm et al., 2001) terrains of the Thaumasia highland (67⁰W-17⁰S to 55⁰W-32⁰S), using orbital remote sensing and laser altimeter data (MOLA, HRSC, THEMIS, CTX and MCC) in order to get insights into the aqueous history of Mars. The mean channels densities for the Noachian terrains Nb, Nphl, Nf, Nfc, Nfd, Npld, Npl₂ are 0.064, 0.058, 0.059, 0.152, 0.083, 0.073, and 0.026 respectively; and for the Hesperian terrains HNt, HNpld, HNplt, Hpld, and Hr are 0.005, 0.078, 0.056, 0.038, and 0.003 respectively, indicating a decline in aqueous activity from the Noachian to Hesperian. Terrain-wise bifurcation ratios also show a linear decreasing trend from Noachian to Hesperian. The shape of these channels is mostly parallel with a few being radial. At different places, channels are found to follow the existing structural pathways. This study also shows that morphometric parameters are strongly influenced by the resolution of the datasets. The use of high-resolution datasets (viz., CTX) results in higher values of channel density as compared to previous studies.