Geomorphology of Gale Crater, Rock on! |
Geomorphology of Gale Crater, Rock on! |
Sep 26 2012, 10:22 PM
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#31
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
I'd like a discussion thread about the geology detatched from the time limits of current MSL threads. We had a 'Geomorphology of Cape York' thread that attracted a lot of interesting posts. How about 'Geomorphology of Gale Crater'? I have one or two ideas but many more questions, and I'd like to post them in a longer-running thread away from the day to day imaging discussion. Any other takers?
For starters, does anybody have a contour map of this place like the one at Meridiani with 5m intervals? ADMIN: You have your wishes fulfilled on UMSF (sometimes) |
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Nov 30 2012, 01:04 PM
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#32
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Junior Member Group: Members Posts: 43 Joined: 7-August 12 From: The Netherlands Member No.: 6493 |
QUOTE We see chucks of basalt everywhere BUT what we don't see is the primal intact basalt global covering if there is one. If you refer to the Anderson and Bell paper on this subject: http://marsjournal.org/contents/2010/0004/...s_2010_0004.pdf, you'll find on page 122 a very nice graph showing exactly why we don't see the basalt yet. It's close, but MSL will need to drive towards the mount to find an exposed trough all the way down to the basalt unit. (In many places the dark dunes are actually covering the basalt floor, instead of on the sediment layers, see image 34a on page 109) Greetings, Ludo. |
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Dec 1 2012, 01:06 AM
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#33
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Senior Member Group: Members Posts: 1057 Joined: 17-February 09 Member No.: 4605 |
...... a very nice graph showing exactly why we don't see the basalt yet. It's close, but MSL will need to drive towards the mount to find an exposed trough all the way down to the basalt unit. (In many places the dark dunes are actually covering the basalt floor...) Most of what we see on Mars has a basaltic provenance but as implied by djellison I think that we could be a little more careful in our use of the word. The Anderson and Bell paper refers to the Basal Unit. Basal is by (USGS) definition located at the bottom of a geological unit which in this case I would think is the bottom of the post impact crater fill sequence. I am not sure why the reference to basalt crept in. The final crater floor would have been made up of allogenic breccias and impact melt and I guess this is the Basal Unit referred to by Anderson and Bell. At least that is what I assumed when I first read the paper, which on re-reading, only mentions basalt once in reference to the makeup of dunes. That final crater fill would be pretty deep and beneath that would be fractured pre impact material that, given the size of the impactor, would probably have been subject to a degree of impact metamorphism. |
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