Mars Gusev rock types, chemistry, interp summary

[aldo12xu]

Hi folks, <br /><br />I prepared a table summarizing observations, geochemistry and current interpretations of the main rock types observed by the Spirit rover at Gusev Crater. The interesting thing I found reading more recent interpretations, is that JPL may be supporting the idea that the Columbia Hills are of meteor impact origin. But it's possible that before the meteorites hit the ground the original formations were pyroclastic deposits with lesser basaltic sandstone. However, because the Hills are strongly altered and we still don't have a handle on the structural geology, there is still a great deal of uncertainty.<br /><br />To keep things concise, the information in the table may seem a little technical. So if anyone has any problems with the terminology there is a link to a geological dictionary at the top of the page.<br /><br />Have a look and feel free to make any comments. The link is on my homepage:<br /><br />

 

[JonClarke]

Very nice work Aldo, and a valuable addition to your site. Are you thinking of doing the same for the Opportunity rocks?<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[aldo12xu]

Thanks Jon!<br /><br />Glad you found the info useful. I probably won't do anything with Opportunity for the time being. I wish I had the time to do everything I wanted with the site.

 

[aldo12xu]

Here's an upated summary with the latest geochem results and geological interp. One thing I was able to sort out in my head after this exercise was the possible stratigraphy, which I humbly present below. Please feel free to comment, as there are still many pieces missing to the puzzle.<br /><br />STRATIGRAPHY (youngest on top, oldest on bottom): <br /><br />ADIRONDACK basaltic flows related to the volcano Appollinaris Patera, 500 km to the north<br />BACKSTAY & IRVINE late stage mafic intrusive dikes cut through all Columbia Hills units <br />HOME PLATE maar type volcanism emplaced through Columbia Hills, interacting with groundwater <br />DESCARTES, CLOVIS & WATCHTOWER meteorite impact ejecta deposits mixing different rock types <br />INDEPENDENCE & WOOLY PATCH phyllosilicates derived from chemical weathering of volcaniclastics <br />WISHSTONE tuff or pyroclastic deposit (impact origin not fully discounted*) <br />PEACE sandstone produced by wind erosion of older ultramafic units <br />SEMINOLE mafic to ultramafic intrusive or extrusive rocks<br /><br />The link to the summary is on my homepage.<br /><br />(PS: Opportunity summary is posted as well.)<br />

 

[3488]

The fact remains that MER A Spirit had to drive over a volcani basalt plain to get to the Columbia Hills. It was interesting to read in Steven Squires 'Roving Mars' that soon ofter the landing of Spirit, it was clear that they had landed on Volcanic lava, not sedimentary rocks or a dried up lake bed.<br /><br />It was obvious to me as the rocks were dark & were filled with Vesicles (gas bubbles).<br /><br />What do you think of the Columbia Hills? Impact related, volcanic, folded or a mixture? <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[aldo12xu]

The rocks making up the hills are all the ones listed above after Adirondack. I think the Columbia Hills represent the northwestern rim of partially buried crater, similar in size to Thira Crater. I think the hills consist mainly of impact material on the upper portions and and primary lithologies at deeper levels. The primary non-ejecta units we've seen so far are Wishstone (ash tuff formed by explosive volcanism) and Seminole (ultramafic flows or intrusives). So my interpretation, based on what I've read, is along the lines of volcanic basement rocks being uplifted by meteorite impact and then covered by ejecta debris.