Physics
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufm.p53c1542f&link_type=abstract
American Geophysical Union, Fall Meeting 2010, abstract #P53C-1542
Physics
[5420] Planetary Sciences: Solid Surface Planets / Impact Phenomena, Cratering, [6250] Planetary Sciences: Solar System Objects / Moon
Scientific paper
We have measured the thickness of ejecta in the surroundings of the Orientale basin using topographic information from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter (LRO). Understanding the radial decay of ejecta around large basins is important for a number of important problems in lunar science, including how basins (1) influence and modify lunar topography and surface geology, (2) form the megaregolith, (3) transport material across the lunar surface and incorporate it within the stratigraphic column, and (4) contribute material to our current and future sample collections. We use the new topography from LOLA to directly measure the fill / ejecta within the surroundings of Orientale, particularly focusing on pre-Orientale craters. We also use the erasure of pre-existing craters to establish the minimum amount of ejecta (plus incorporated pre-basin material), emplaced at a given radial range. We find an ejecta deposit thickness near the Cordillera ring of ~3.5 km, which decays to a thickness of ~1 km at a distance of 300 km from the ring (the decaying is modeled as a power function of range, with an exponent of -2.5±0.5). These measurements imply a volume of ejecta in the region within ~1000 km of the Cordillera Ring of ~4 x 106 km3. Beyond ~1000 km, approximately one basin diameter from the Cordillera, the ejecta becomes discontinuous, secondaries from Orientale become more prominent, and the distal ejecta thickness is hard to assess. Given the different processes that operate at large radial ranges, it is unlikely that an extrapolation of proximal measurements will accurately predict the thickness of distal ejecta. (A) Radial distribution of fill within craters near Orientale, based on their diminished relief when compared to fresh craters of the same size. Since this reduction in relief reflects the sum of pre-Orientale infill and Orientale ejecta, it is a strict overestimate of ejecta deposit thickness. For this reason, the lower envelope on the data is relied upon for fitting. (B) Estimates for the thickness of ejecta on the basis of the erasure of craters at a given radial range; for example, a pre-existing D=11 km crater survived the Orientale event at a distance of ~200 km from the rim. (c) Direct measurement of ejecta thicknesses in places where it is possible to infer the pre-ejecta surface. [In (A)-(C), the primary x-axis is normalized by the Cordillera rim radius (RCR=465 km). The black model fit to all data in (A)-(C) has ejecta thicknesses T=3500(r/RCR)-2.5].
Fassett Caleb
Head James W.
Neumann Gregory A.
Smith Douglas E.
Zuber Maria T.
No associations
LandOfFree
The Thickness of Proximal Ejecta from the Orientale Basin as revealed by the Lunar Orbiter Laser Altimeter (LOLA) does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Thickness of Proximal Ejecta from the Orientale Basin as revealed by the Lunar Orbiter Laser Altimeter (LOLA), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Thickness of Proximal Ejecta from the Orientale Basin as revealed by the Lunar Orbiter Laser Altimeter (LOLA) will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1499358