Amazonian 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 area was affected by at least 4 episodes of widespread volcanic activity and 4 periods of episodic fluvio-glacial activity. This paper discusses the Amazonian (b1.8 Ga) history of the study area, during which time the last of the four volcanic episodes occurred between the last two episodes of fluvio-glacial activity. Highlights of our new findings from this time period include (1) evidence that suggests glaciers and near-surface ice may have persisted through Amazonian time in local areas over the entire length of Kasei Valles; (2) a new widespread platy-flow surface material that is interpreted to be 2100-km-runout flood lavas sourced from Echus Chasma; and (3) a fracture in Echus Chasma, identified to have sourced at least one late-stage flood, that may have been the origin for the platy-flow material and young north-trending Kasei flood water.