Abstracts Geography

The role of volatiles in the evolution of north-central Arabia Terra, Mars

by Michael Zeilnhofer

The results from this study show that during the middle Amazonian period (2 Ga), Arabia Terra did exhibit glacial and fluvial activity as predicted by the Global Circulation Model. Arabia Terra is the largest expanse of ancient terrain north of the Martian equator. Arabia Terra extends across the Martian prime meridian from approximately 30°E (330°W) westward to 300°E in longitude and from the equator to 50°N. Glacial and fluvial activity during the Amazonian era in the north-central region (20°-40°N, 0°-30°E) of Arabia Terra was of high interest because of the Global Circulation Model (GCM) predictions of lower latitude precipitation during periods of high obliquity (> 35°) [Forget et al., 2006]. The Ejecta morphologies, interior morphologies, and preservational states of 3732 craters with diameters ranging from 1.0-161.7 km were analyzed during the study. The interior morphologies which displayed glacial and fluvial activity were analyzed in detail for this project but aeolian, tectonic, and complex features were also studied. Distribution maps of all the interior morphologies and size-frequency distribution plots were created to determine the location and ages of these activities. Younger craters which did not display glacial and fluvial morphologies were used to create a lower bound for the size-frequency distribution plots for the region. Older craters were used to create upper bounds to show older periods of glacial and fluvial activity. Glacial and fluvial morphologies were mainly concentrated north of 30° but there were some variations in concentration for the glacial morphologies.