geology of Gale Crater and Mount Sharp |
geology of Gale Crater and Mount Sharp |
Jun 21 2014, 01:49 PM
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Junior Member Group: Members Posts: 33 Joined: 16-June 14 From: Sweet Home, Oregon Member No.: 7202 |
The idea that the Lower Formation of Mt. Sharp is of lacustrine origin (lakebed sediments) has rather fallen out of favor recently, but I just finished my essay on Mars, "An Interpretation of the Geology of Gale Crater & Mount Sharp, with Implications for the History & Habitability of Mars," which I have spent over one year researching and writing, and the primary thrust of this paper is to offer a fresh defense of the lacustrine model, incorporating some fairly original ideas on my part. I'm not a professional scientist, but this is a labor of love that springs from a near-lifelong interest in Mars (since I was a young boy in the 1960s). And I'm trying to publicize it prior to Curiosity reaching Mt. Sharp, as that will be a test of my theories, and I'm hoping to get some recognition if I'm right. So here's the link for all interested readers: http://galecratergeology1.tumblr.com/post/...le-crater-mount
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Jul 3 2014, 12:20 AM
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
That's why I would prefer to wait for more reliable data. There are hypotheses ranging from a mild wet early Mars to Kite's snowball. May be both is true in hundreds of millions of years. A one degree change of obliquity on Earth is thought to cause ice ages. What would happen on a 10 degree change? A larger ice shield at the poles may lead to a run-away cooling due to higher albedo. We don't know whether there have been oceans on Mars, and if so, when, and to what extend? What's the consequence for the humidity of the atmosphere, and the amount of snowfall? That's simply too complicated to estimate, at least for me. I'd think, that climate changes on Mars have been much more severe, and more frequent than on Earth, and Mars should be cooler than Earth on average due to the larger distance from the Sun. But if there had been much CO2 or even CH4 in the Martian atmosphere, there might have been a strong greenhouse effect. On the other hand, SO2 resp. elementary sulfur in the atmosphere (due to volcanism) would probably lead to additional cooling.
We also don't know the vertical temperature profile of early Mars. High mountains, like e.g. Kibo (Kilimanjaro) on Earth (still) have an ice cap despite their proximity to the equator. Without additional information, I'd apply this observation also to early Mars, and consider the fainter Sun. With all these uncertainties I can't at least rule out temporary ice caps on Mt Sharp as a valid hypothesis, on the current thin basis of knowledge. |
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Jul 3 2014, 03:36 AM
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Junior Member Group: Members Posts: 33 Joined: 16-June 14 From: Sweet Home, Oregon Member No.: 7202 |
Reply to dialogue between Serpens and Gerald:
I don't agree with Kite's model for the origin of the Mt. Sharp sedimentary column, however I do recognize his contribution to climatic modeling for Mars, such as in: ”Seasonal melting and the formation of sedimentary rocks on Mars, with predictions for the Gale Crater mound.” ¯ Icarus 223 (2013) 181-210. http://gps.caltech.edu/~kite/doc/seasonal_...ntary_rocks.pdf In that article, he presents the results of models that suggest that Gale would be one of the most likely places on Mars to experience liquid water flow, as a result of obliquity-driven precipitation and subsequent ice/snow melt. And I figure that the proof is in the pudding: the entire Gale/Mt. Sharp complex (the mountain, the crater floor, and the crater rim) shows unmistakable signs of repeated aqueous events (as well as glacial and periglacial activity) over a very long time, and the natural interpretation is that these events were obliquity-driven, although volcanism also would be expected to play a major role (during periods of intense volcanism, much carbon dioxide and water vapor would be injected into the atmosphere, and high obliquities correlated with volcanic activity should result in an especially favorable mileau for Gale Crater). I also agree with much of Kite's aeolian model for Gale Crater (I attribute the deflation of the outer portions of the crater fill to such a wind regime).....where I break with him, is in the temporal assignation of the climactic regimes he defines: his description is probably a good one for the latter half of the Hesparian and for the entirety of the Amazonian, but the early history of Gale (and of Mars in general) was FAR wetter than his model suggests (and that's the environment in which the majority of the Mt. Sharp sedimentary column was laid down). Dave |
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