Simulated degradation of lunar impact craters and a new method for age dating farside mare deposits
Article first published online: 21 SEP 2012
Copyright 2000 by the American Geophysical Union.
Journal of Geophysical Research: Planets (1991–2012)
Volume 105, Issue E8, pages 20387–20401, 25 August 2000
How to Cite
2000), Simulated degradation of lunar impact craters and a new method for age dating farside mare deposits, J. Geophys. Res., 105(E8), 20387–20401, doi:10.1029/1999JE001099., and (
- Issue published online: 21 SEP 2012
- Article first published online: 21 SEP 2012
- Manuscript Accepted: 5 OCT 1999
- Manuscript Received: 1 JUN 1999
With the advent of Clementine data it is now possible to determine the lithology and extent of geologic materials on the Moon, particularly the farside mare deposits. However, traditional crater counting techniques do not provide reliable age estimates of these materials owing to their small surface areas. To support such studies, we present a model for estimating their age by analyzing the morphometry of degraded craters 1–3 km in diameter. A photoclinometric model was adapted for use with monoscopic 0.750-μm ultraviolet-visible and high-resolution images where we extracted the topography of fresh craters. A two-dimensional computer model simulating linear diffusional creep was applied to fresh craters at a variety of diameters. The resulting profiles were then compared to photoclinometric profiles of degraded craters of known ages for calibration. Application of the resulting model to degraded craters in the mare deposit of the central Apollo basin (∼36.5° latitude, 208.0° longitude) indicates that this material was emplaced during the early Imbrian period (∼3.85 Ga). By calculating the amount of material eroded from each of the degraded craters observed in this unit, the average erosion rate is estimated to be 2.0±0.1 × 10−7 mm/yr on the Moon since the Imbrian. The estimated amount of material eroded during any given period suggests that the erosion rate has decreased with time, implying that the flux of larger impactors has as well.