The Search for Lunar Thrust Fault Scarps: Findings from LROC's First Year in Orbit

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Small-scale thrust faults on the Moon have major implications for lunar formation and thermal evolution. Lobate scarps with lengths of several kilometers or more have been typically observed in the highlands and are interpreted as thrust faults that accommodate small amounts (tens of meters) of displacement formed by late-stage global thermal contraction. Due to poor spatial coverage of high-resolution images with low lighting angles, the global distribution and other properties of lunar highland thrust faults are not well understood. The Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Cameras (NACs) are returning high resolution images ideal for the search of these small-scale scarps on the Moon. LROC NAC images collected during the first year in orbit have revealed more than a dozen previously-unknown lobate scarps distributed globally throughout the lunar highlands. Forty-six landforms found in an Apollo Metric Camera image search, most notably the Joy scarp, are imaged to determine their origins. Another 48 fault scarps identified in other searches are also imaged by LROC. Using the geospatial program FEATURE, lengths, orientations, etc. are measured for all scarps imaged by LROC. These data provide constraints for the global stress and thermal evolution of the Moon.