Reconstructing the geological and geomorphological history of Morella Crater, Mars

Abstract

Ancient impact craters on Mars provide insights into the geological events and are time markers for studying global processes like colossal volcanism and fluvial activities. Among these craters, the 77 km diameter Morella Crater serves as a representative, capable of demonstrating diverse processes that acted on Martian terrain, and hence, the geological and geomorphological history of this crater is studied in detail. Despite its infilling, Morella hosts Ganges Cavus, a significant collapse structure, and Elaver Vallis, an outflow channel. We hypothesize the development of the crater through five stages, from its origin to its current denuded state, exhibiting diverse processes that determine the fate of Martian craters. Crater size-frequency distribution suggests a formation age of ${3.8}_{-0.03}^{+0.03}$ Ga for the plateau hosting Morella Crater and ${3.6}_{-0.01}^{+0.06}$Ga for Morella Plains, the vast expansive plains within the crater. The occurrence of pyroxene and olivine in Morella Plains, identified through hyperspectral data, indicates impact-induced volcanism. The heat source associated with faulting and dike intrusion in the adjoining Ophir Catenae Structural Complex might have ruptured the confined cryosphere, resulting in the formation of Ganges Cavus and eventual filling of Morella with water, which subsequently breached to form Elaver Vallis at${3.4}_{-0.10}^{+0.07}$ Ga. Hydraulic modelling reveals a floodwater volume of 3.27 × 10¹² m³ and an estimated peak discharge of 3 × 10⁷ m s⁻¹ associated with this event. Morella witnessed additional fluvial activity at ${3.3}_{-0.4}^{+0.1}$ Ga that created the dark-toned channels. The extensive range of geological and geomorphological processes makes Morella Crater a promising location for future Mars missions.