P055-0015
Pre-Tharsis tectonics and the geological and structural history of Bathys Planum, Mars

Monday, 14 December 2020
Poster
John Adrian, Jet Propulsion Laboratory, Geosciences Group, Pasadena, CA, United States; California Polytechnic State University San Luis Obispo, STEM Teacher and Researcher Program (STAR), San Luis Obispo, CA, United States, Andrew Siwabessy, California State University Long Beach, Geography, Long Beach, CA, United States, James matthew Dohm, University of Tokyo, Bunkyo-ku, Japan and Robert C Anderson, JPL, Pasadena, CA, United States
Abstract:
Preliminary geologic and paleotectonic mapping has been completed at a 1:1M scale of the Bathys region of Mars (240°-250° E, 29°-40° S) in Esri’s ArcGIS Pro. On a THEMIS daytime IR mosaic basemap, CTX and HRSC data are overlaid and co-registered for context. We discuss several observations that have been made from this mapping investigation.

One of the major observations of this map region is the ancient E-W basement structures that appear to control the formation of younger, Tharsis-associated graben. Some of the Tharsis-associated graben, for example, take a zig-zagged pattern as they intersect with the more ancient basement structural fabric. These cross-cutting patterns suggest that these ancient structures control early Tharsis-driven tectonics. There is a high density of these ancient structures, some of which exhibit a curvilinear pattern. This pattern may mark a magmatic-driven uplift stemming from the emplacement of an igneous intrusion. Therefore, it is possible that a Bathys tectonic center preceded Tharsis-driven tectonism.

Other ancient geologic activity, possibly pre-Tharsis, is the formation of large promontories scattered throughout the region. These distinct mountains have been interpreted to be volcanic in origin. The largest of these promontories has an area of roughly 37,000 Km2 which is about ⅔ the area of the Idaho batholith. Associated with this large promontory are several large and deep collapse pits, possibly calderas. Some of these are relatively pristine with very little infill, suggesting relatively recent geologic activity (Hesperian/Amazonian).

The far-reaching geologic history of this region includes landscapes that record terrain softening, differential erosion, and possibly volcanic constructs that formed beneath ice sheets (e.g. tuyas) and/or ablating ice-cores relating to ancient ice sheets or frozen lakes. A candidate Martian tuya (38°36'17.29"S, 119°16'58.43"W) compares with an Icelandic tuya, Herðubreið (65°10′44.06″ N, 16°20′50.36″ W).

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