Mathematics – Logic
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufm.p13a1259e&link_type=abstract
American Geophysical Union, Fall Meeting 2009, abstract #P13A-1259
Mathematics
Logic
[5410] Planetary Sciences: Solid Surface Planets / Composition, [5415] Planetary Sciences: Solid Surface Planets / Erosion And Weathering, [5464] Planetary Sciences: Solid Surface Planets / Remote Sensing, [5470] Planetary Sciences: Solid Surface Planets / Surface Materials And Properties
Scientific paper
An investigation of Martian high thermal inertia crater surfaces has been made using derived THEMIS thermal inertia data. High thermal inertia surfaces or interpreted bedrock are defined as any pixel in a THEMIS image with a thermal inertia over 1200 J K-1m-2s-1/2 and may refer to in situ rock exposures or rock-dominated surfaces. While three different surface morphologies (valley and crater walls, crater floors, and plains surface) were originally identified [Edwards et al., in press], the focus of this study is to better characterize the compositional, thermophysical, and geological characteristics of the crater floors surface. These surfaces may be related to impact-associated volcanism that often occurs in conjunction with large energetic impacts. These craters are commonly modified, lack a central peak, have shallow sloped walls, and little to no visible ejecta, indicating the relatively old ages of these impacts. They are generally large, ranging in size from 18.5 to 179km in diameter, with an average of ~52km [Edwards et al., in press]. Boulders are also observed in high-resolution imagery (e.g. HiRISE) along with fine scale randomly oriented cracks and fractures. TES spectra for ~60 of the 92 originally identified sites have been examined in detail and can be broken down into two distinctive spectral groups, olivine bearing (~80%, with >10% olivine and often >20%) and non-olivine bearing craters (~20%, with <10% olivine). Additionally, the use of THEMIS and CRISM data provide context and additional compositional information for these exposures. While these locations often occur in low albedo regions on Mars, a clear global spatial correlation between the olivine and non-olivine bearing craters is not observed. The compositional data presented here further support inflationary volcanism associated with large, energetic impacts as the geologic process that formed high thermal inertia crater floors. In this case, magma is likely derived from decompression melting of the mantle due to the removal of overlying material. This magma reaches the surface through fractures and cracks in the basement rock likely caused by the impact event. This is consistent with the observed compositions, as material derived directly from the Martian mantle is expected to be significantly more mafic than the surrounding country rock. These sites are likely locations where the some of the most primitive material on Mars is observed and can be used to illustrate an interesting aspect of alteration processes on the surface. Two possibilities for the observed distributions and compositions are proposed: 1) the types of events where mantle materials erupt onto the surface are rare and occur infrequently, likely early in Mars history; or 2) these surfaces are common but not preserved. They may be the primary source material for the Martian regolith, where olivine-rich materials are readily weathered and altered to other olivine-poor materials commonly observed on Mars. Edwards, C. S., J. L. Bandfield, P. R. Christensen, R. L. Fergason (in press), Journal of Geophys. Res.
Bandfield Joshua L.
Christensen Per Rex
Edwards Christopher S.
Rogers David
No associations
LandOfFree
Compositions of Bedrock Containing Craters on Mars as Viewed by TES, THEMIS, and CRISM 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 Compositions of Bedrock Containing Craters on Mars as Viewed by TES, THEMIS, and CRISM, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compositions of Bedrock Containing Craters on Mars as Viewed by TES, THEMIS, and CRISM will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1767794