Morphometric analysis of small-scale lobate scarps on the Moon using data from the Lunar Reconnaissance Orbiter

Abstract

Prior to Lunar Reconnaissance Orbiter (LRO), the morphology and dimensions of only a limited number of lobate scarps, all located near the equator (within 21°), had been characterized. Topography derived from LRO Camera stereo images and Lunar Orbiter Laser Altimeter (LOLA) ranging is used to measure the relief and analyze the morphology of previously known and newly detected low and high latitude lobate scarps. The asymmetric profiles and maximum slopes on scarp faces (∼5° to 29°) of lunar lobate scarps are similar to those of lobate scarps observed on Mars and Mercury. Scarp lengths range from ∼0.6 to 21.6km (mean = ∼6.0 km, median = ∼4.4 km, n = 79), and measured relief ranges from ∼5 to 150 m (mean = ∼35 m, median = ∼20 m, n = 26). Assuming a range of 20° to 40° for the fault plane dip, estimated lower limits for the horizontal shortening (S) expressed by the lobate scarp thrust faults range from ∼10 to 410 m. The range in S estimated for the lunar scarps is roughly an order of magnitude lower than estimates of S for lobate scarp thrust faults on Mars and Mercury. The relatively small range of S estimated for the growing number of well-characterized lunar scarps is consistent with a small amount of global contraction. Copyright 2012 by the American Geophysical Union.