Noachian–Hesperian geologic history of the Echus Chasma and Kasei Valles system on Mars: New data and interpretations

Abstract

New high-resolution datasets have prompted a mapping-based study of the 2500-km-long Echus Chasma and Kasei Valles system that utilizes geomorphic details, stratigraphic relations, and cratering statistics derived from the new datasets. Our results suggest that between the Hesperian and Amazonian Epochs on Mars (3.7 Ga to Recent) the study areawas affected by at least 4 episodes of widespread volcanic activity and 4 periods of episodic fluvio-glacial activity. This paper discusses the Noachian to Hesperian (N2.6 Ga) history of the study area, during which time in the Hesperian three of the volcanic episodes took place along with the first two episodes of fluvioglacial activity. Highlights of our new findings and refinements from this time period include (1) two ancient western floods sourced from Tharsis that occurred around 3.61 and 3.4 Ga and carved the east-trending path of north Kasei Valles; (2) Uranius Dorsum with 58 aligned cones along its length that was emplaced in north Kasei around 3.6 Ga between these periods of early flooding; (3) possible ash deposits surrounding Echus Chasma, one of which contains narrow dendritic valley systems that may have been carved over a period of about 10,000 yr; and (4) evidence that suggests glaciers and near-surface ice may have contributed to erosion of local units.