Clays in Meridiani.

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exoscientist

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Just saw this on Unmannedspaceflight.com:<br /><br />Mineralogy of the light-toned outcrop at Meridiani Planum as seen by the Miniature Thermal Emission Spectrometer and implications for its formation. <br />JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, E12S03, doi:10.1029/2005JE002672, 2006 <br />"Abstract <br />Analysis of Miniature Thermal Emission Spectrometer (Mini-TES) data has led to the recovery of a pure end-member spectral shape related to the light-toned outcrop observed at Meridiani Planum. Data from the MER Mössbauer spectrometer, APXS, and previous Mini-TES measurements were used to constrain a spectral library used to determine the mineralogy of the outcrop from this spectral shape. Linear deconvolution of the outcrop spectral shape suggests that it is composed primarily of Al-rich opaline silica, Mg-, Ca-, and Fe-bearing sulfates, plagioclase feldspar, nontronite, and hematite. Conversion of modeled mineralogy to chemistry shows good agreement with the chemical composition of the outcrops determined by APXS. Details of the analysis procedure and implications for the formation of the outcrop are discussed along with terrestrial analogs of the ancient environment at Meridiani." <br />http://www.gps.caltech.edu/~tglotch/2005JE002672.pdf<br /><br />According to the authors the spectra of the Meridiani bedrock is best matched by a composition that includes 10% nontronite clay.<br /><br /><br />Bob Clark <br /><br /> <br /> <div class="Discussion_UserSignature"> </div>
 
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djtt

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poster's trying to make himself look interesting in the process too.<br />i call another FAIL
 
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JonClarke

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Thank's Robert, this is a most interesting and useful paper, that reports a major advance in our understanding of the mineralogy of this part of Mars. I have saved a copy.<br /><br />The rest of you, rather than making sarcastic comments about a long term and respected poster, how about you ask, if you don't understand? While not a board for specialists this forum exists to discuss space science and astronomy and there are lots of scientists on this board who can explain various matters.<br /><br />Frankly, if people don't understand a well written paper such as this, the problem is theirs, not the author's who are writing for a technical audience. Blaming the paper for their lack of comprehension rather than recognising their deficiencies is childish<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>
 
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3488

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Thanks Robert. I agree with Jon Clarke 100% on this issue. <br /><br />In response to: "Al-rich opaline silica, Mg-, Ca-, and Fe-bearing sulfates, plagioclase feldspar, nontronite, and hematite" composition is indeed very interesting. <br /><br />This suggests to me that there is a good deal of volcanic ash mixed in with the sediments. The Plagioclase Feldspar has indeed sparked my curiosity, along with the abundant sulphates.<br /><br />I would be interested to know, what the abundance by mass of Aluminium & Magnesium? This will tell much about the period of time the originating rock was originally molten (i.e if very high, there would have been more time for it to float to the top, hence the original lava was moten for a great deal of time). <br /><br />Also the high silica values suggest to me 'Andesitic Basalt'. <br /><br />In some ways, this seems to be like the observed values of the high temperature volcanism on the Jupiter moon Io (which has high temperature, magnesium rich lavas' as deduced from the Galileo Orbiter IR measurements).<br /><br />Perhaps before the 'sea formed on Meridiani, there could have been geysers & hot springs.<br /><br />Fair enough, these would have been in sediment form, laid down in water. I suspect & this confirms my own suspicions, that the 'sea' covering Meridiani Planum was indeed, very salty & highly acidic, with a very low PH. <br /><br />Toxic indeed. Could anything living have evolved in that? <br /><br />Please keep us posted Robert.<br /><br />Andrew Brown. <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>
 
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alexblackwell

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<i>Frankly, if people don't understand a well written paper such as this, the problem is theirs, not the author's who are writing for a technical audience. Blaming the paper for their lack of comprehension rather than recognising their deficiencies is childish.</i><br /><br />Well said, Jon. In fact, the lead author of that particular paper commented on it this morning.
 
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JonClarke

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Thanks Alex. It's good to see more evidence of nontronite surfacing, it was hypothesised from the Viking data, as I recall, but then the presence of clays fell out of favour with spectral interpreters.<br /><br />The amorphous Al-silica mineral is most intriguing. Is it poorly ordered kaolinite, intergrown kaolinite and opal or intergrown kaolinite and quartz? Oh for an XRD! It's also interesting that the jarosite appears to be K-rich, perhaps approaching alunite in composition<br /><br />Good to see questioning of the hyperacidity assumption as well, which does not fit well with the degree and uniformity of alteration seen in these materials.<br /><br />Part of the answer may in that we are seeing different mineral assemblages in the same rock, each equilibrated to different conditions. There would be the original sedimentary grains, the evaporite assemblage, and then perhaps a weathering overprint. <br /><br />Another thing to remember is that some minerals form in microenvironments. For example, one location my research group has been working on has near neutrral pH but abundant jarosite which forms in micro acidit environments along sulphide weathering fronts.<br /><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>
 
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alexblackwell

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<p>Another thing to remember is that some minerals form in microenvironments. For example, one location my research group has been working on has near neutrral pH but abundant jarosite which forms in micro acidit environments along sulphide weathering fronts.<br /><br />Interesting. Is this related to or an outgrowth of the work you did in the Atacama, which was published earlier this year in Geomorphology? (EDIT: For non-subscribers, note the paper is freely accessible. In fact, the publishers are offering free access to that issue for the remainder of 2006).<br /><br />You might also be interested in the upcoming Workshop on Martian Sulfates as Recorders of Atmospheric-Fluid-Rock Interactions.<br /><br />Also, there was a slew of science publications this week about Opportunity's results at Meridiani Planum.<br /><br />Squyres et al. have a paper being published in the September 8, 2006, issue of Science:<br /><br />Two Years at Meridiani Planum: Results from the Opportunity Rover <br />S. W. Squyres, A. H. Knoll, R. E. Arvidson, B. C. Clark, J. P. Grotzinger, B. L. Jolliff, S. M. McLennan, N. Tosca, J. F. Bell, III, W. M. Calvin, W. H. Farrand, T. D. Glotch, M. P. Golombek, K. E. Herkenhoff, J. R. Johnson, G. Klingelhöfer, H. Y. McSween, and A. S. Yen<br />Science 313, 1403-1407 (2006)<br />Abstract<br />Supporting Online Material<br /><br />And since it's about Mars, it makes a good cover, too.<br /><br />The</p>
 
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silylene old

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Stevehw, I thought the paper was fine, and packed with information. It is written for those well versed in the field, not for common interpretation. The terminology is typical, and understood for the audience it was intended for.<br /><br />"Deconvolution" is a very established word in analytical and physical chemistry, spectroscopy, optics, seismology and statistics. Using google and typing in "define: deconvolution", I got six definitions from web sources. Google itself gave 2.6M references in which this word has been used. Frankly, I am surprised it isn't in the dictionary!<br /><br />Deconvolution of a spectra is a mathematical process in chemistry and spectroscopy to determine the composition of a mixture from its spectrum. Beer's Law is assumed, and it is assumed that the observed experimental spectrum of the mixture is mathematically formed from the weighted average of the spectra of each individual pure constituent. Assuming that one has accurate spectra of each possible constituent in the mixture, a least squares regression is performed to find the best of composition of constituents' spectra whose weighted sum (Beer's Law) comes closest to the observed spectrum of the mixture.<br /><br />Deconvolution can be very accurate and informative, but the process has some risk involved, risks being: experimental error, propagation of error, not considering the correct possible components in the analysis;and finally the error of the fit often increases if there are too many components in the mixture each with similar individual spectra, or if the mixture consists largely of one dominant component and several small components. This is a procedure we use all the time in our labs. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>
 
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JonClarke

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Add hyperspectral remote sensing to the list of disciplines that use the word. Applications include airborne (e.g. HyMap), spaceborne (OMEGA, ASTER, TES), ground (miniTES, as here, PIMA), and bore hole (Hylogger) systems.<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>
 
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bonzelite

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as far as my hobbyist's layperson's knowledge recalls, sulfates are indicative of prior geothermal/fluvial activity. and clays only pose to bolster this premise, i'm assuming. <br /><br />what is left of the clays may indicate that, inasmuch as mars seems geologically dead, it may retain residual activity to the extent that clays are replenished --even if the near-surface traces of clays are ancient. perhaps, as on earth, there is a martian water table of sorts, varying from region to region; the outermost surfaces of the planet making a freeze-dried crust. <br /><br />i'd be very intrigued to bear witness to a rover mission devoted to exploration of caves. to crack some mysteries, we may literally need to crack the surface and go subterrainean.
 
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3488

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Almost certainly the sediments before being laid down are of volcanic origin. The high silicate levels suggest to me an Andesitic type originating basalt, but there appears to be more than one type. It is indeed very complicated.<br /><br />If caves can be found, that will help enormously.<br /><br />Also MER B Opportunity will shortly be arriving at the deep & wide Victoria Crater. Very exciting indeed.<br /><br />Andrew Brown. <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>
 
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exoscientist

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It was mentioned on sci.astro that "clay-like" material was seen at Meridiani by the MER Opportunity rover:<br /><br />http://marsrovers.jpl.nasa.gov/gallery/all/1/p/001/1P128287557EFF0000P2303L2M1.HTML<br /><br />Two separate and independent observational means show <br />there is seasonally varying water content on the Martian surface: one <br />by thermal infrared spectra, the other by the Gamma Ray-Neutron <br />Spectrometer. <br />The thermal infrared was from the TES and Mini-TES instruments showing seasonal variations of carbonate dust on the surface. It was suggested this was formed from water vapor. <br />However, on Earth in nature carbonate is formed from *liquid* water. <br />It is very likely it is formed from liquid water on Mars as well: <br /><br />From: Robert Clark <br />Date: Sat, Feb 11 2006 10:32 pm <br />Email: "Robert Clark" <rgregorycl /> <br />Groups: sci.astro, alt.sci.planetary, sci.physics, sci.geo.mineralogy <br />Subject: Could We Make A "Solar Still" On Mars? <br />http://groups.google.com/group/sci.astro/msg/95e5bae350f8c285? <br /><br />This report shows clays can be formed in short times under martian <br />conditions: <br /><br />MINIMUM TIMES TO FORM CLAY IN MARTIAN SURFACE AND NEAR-SURFACE <br />ENVIRONMENTS. <br />L. Browning1, G. J. Taylor2, and D. Pickett1 <br />1Center for Nuclear Waste Regulatory Analyses, Southwest Research <br />Institute, 6220 Culebra Rd., San Antonio, TX 78228 2 Hawai'i <br />Institute of Geophysics and Planetology, University of Hawaii, <br />Honolulu, HI, 96822 <br />Lunar and Planetary Science XXXIV (2003) 1708.pdf <br />http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1708.pdf <br /><br />I suggest searching the infrared spectra to see if the signatu <div class="Discussion_UserSignature"> </div>
 
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search

Guest
Well spoken JonClarke<br /><br />Only one remark and I include myself in the critic (but I will make the utmost effort to correct myself):<br /><br />Sometimes the links or posts are complex because the person posting does not take the time to reduce the clutter (meaning the more complex language) and therefore broadening the target audience. <br /><br />On the otherhand I must say that it should be in everybody interest to search and investigate what they are reading and if they come to a dead end then ask for further explanation.<br /><br />But one thing is for sure we should not question anybody's intention (I have done that mistake before), only the content.<br /><br />Thanks for that pinpoint reminder
 
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bonzelite

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perhaps MRO will provide some interesting leads as to possible causes of things. it's got ground-penetrating radar.
 
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