GEOLOGIC STUDY OF THE NILI PATERA AREA, SYRTIS MAJOR, MARS (MTM 10292): MORPHOLOGY, STRUCTURE, AND COMPOSITION OF A MARTIAN VOLCANIC REGION

Syrtis Major Planum is a low albedo region on Mars previously identified as a large, Hesperian-aged volcanic province. Within Syrtis Major are Nili and Meroe Paterae, which are part of a larger caldera complex distinguished by a large topographic depression in the center of Syrtis Major. This is an important area to study because the presence of volcanic features, potentially including evolved compositions, and absence of surface dust allows for detailed chemical and morphological studies that can help elucidate the thermal and chemical evolution of the planet. The objective of this study is to analyze and map Nili Patera and the surrounding area to gain a better understanding of the volcanic history and subsequent modification of the region. The study area displays diverse lava flow morphologies, complex lava flow stratigraphy, and many different terrain types. To characterize this diverse landscape, a 1:500,000 scale geologic map of MTM 10292 is being compiled in a Geographic Information Systems framework based primarily on Mars Orbiter Camera (MOC), Mars Orbiter Laser Altimeter (MOLA), Thermal Emission Imaging System (THEMIS), and High Resolution Imaging Science Experiment (HiRISE) data. Preliminary mapping includes delineating lava flows, distinguishing and analyzing volcanic and impact structures, and interpreting other surface morphologies. Many overlapping lava flows are distributed within, and radially from, the caldera complex. Lava flows are distinguished by identifying flow fronts, flow direction, and surface composition. Levees and channels within these flows are used to further characterize the flows. Within the volcanic complex are distinct differences in infrared emissivity that previously have been interpreted to indicate evolved lava flow compositions. Nili Patera is surrounded by a series of concentric faults associated with magmatic withdrawal and caldera collapse. Depositional features such as barchan dunes and dunes associated with channelized wind are present within and around the volcanic complex and show evidence of wind direction and possible alteration of the surface morphology. Given the potential for evolved lava compositions, understanding the geologic history of the Syrtis Major volcanic complex is critical to understanding the thermal and chemical history of Mars.