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  • 1
    Publication Date: 2015-02-12
    Description: Using the Mars Exploration Rover Opportunity , we have compiled one of the first field geologic maps on Mars while traversing the Noachian terrain along the rim of the 22-km diameter Endeavour crater (Lat -2° 16’ 33”, Long -5° 10’ 51”). In situ mapping of the petrographic, elemental, structural, and stratigraphic characteristics of outcrops and rocks distinguishes four mappable bedrock lithologic units. Three of these rock units pre-date the surrounding Burns formation sulfate-rich sandstones and one, the Matijevic formation, represents conditions on early Mars pre-dating the formation of Endeavour crater. The stratigraphy assembled from these observations includes several geologic unconformities. The differences in lithologic units across these unconformities record changes in the character and intensity of the Martian aqueous environment over geologic time. Water circulated through fractures in the oldest rocks over periods long enough that texturally and elementally significant alteration occurred in fracture walls. These oldest pre-Endeavour rocks and their network of mineralized and altered fractures were preserved by burial beneath impact ejecta and were subsequently exhumed and exposed. The alteration along joints in the oldest rocks, and the mineralized veins and concentrations of trace metals in overlying lithologic units is direct evidence that copious volumes of mineralized and/or hydrothermal fluids circulated through the early Martian crust. The wide range in intensity of structural and chemical modification from outcrop to outcrop along the crater rim shows that the ejecta of large (〉8 km in diameter) impact craters is complex. These results imply that geologic complexity is to be anticipated in other areas of Mars where cratering has been a fundamental process in the local and regional geology and mineralogy.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
    Publication Date: 2009-05-23
    Description: The Mars rover Opportunity has explored Victoria crater, an approximately 750-meter eroded impact crater formed in sulfate-rich sedimentary rocks. Impact-related stratigraphy is preserved in the crater walls, and meteoritic debris is present near the crater rim. The size of hematite-rich concretions decreases up-section, documenting variation in the intensity of groundwater processes. Layering in the crater walls preserves evidence of ancient wind-blown dunes. Compositional variations with depth mimic those approximately 6 kilometers to the north and demonstrate that water-induced alteration at Meridiani Planum was regional in scope.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Squyres, S W -- Knoll, A H -- Arvidson, R E -- Ashley, J W -- Bell, J F 3rd -- Calvin, W M -- Christensen, P R -- Clark, B C -- Cohen, B A -- de Souza, P A Jr -- Edgar, L -- Farrand, W H -- Fleischer, I -- Gellert, R -- Golombek, M P -- Grant, J -- Grotzinger, J -- Hayes, A -- Herkenhoff, K E -- Johnson, J R -- Jolliff, B -- Klingelhofer, G -- Knudson, A -- Li, R -- McCoy, T J -- McLennan, S M -- Ming, D W -- Mittlefehldt, D W -- Morris, R V -- Rice, J W Jr -- Schroder, C -- Sullivan, R J -- Yen, A -- Yingst, R A -- New York, N.Y. -- Science. 2009 May 22;324(5930):1058-61. doi: 10.1126/science.1170355.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA. squyres@astro.cornell.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19461001" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment ; Ferric Compounds ; *Mars ; Spacecraft ; Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2004-12-04
    Description: The Microscopic Imager on the Opportunity rover analyzed textures of soils and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on a millimeter scale; image mosaics of cross-stratification suggest that some sediments were deposited by flowing water. Vugs in some outcrop faces are probably molds formed by dissolution of relatively soluble minerals during diagenesis. Microscopic images support the hypothesis that hematite-rich spherules observed in outcrops and soils also formed diagenetically as concretions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Herkenhoff, K E -- Squyres, S W -- Arvidson, R -- Bass, D S -- Bell, J F 3rd -- Bertelsen, P -- Ehlmann, B L -- Farrand, W -- Gaddis, L -- Greeley, R -- Grotzinger, J -- Hayes, A G -- Hviid, S F -- Johnson, J R -- Jolliff, B -- Kinch, K M -- Knoll, A H -- Madsen, M B -- Maki, J N -- McLennan, S M -- McSween, H Y -- Ming, D W -- Rice, J W Jr -- Richter, L -- Sims, M -- Smith, P H -- Soderblom, L A -- Spanovich, N -- Sullivan, R -- Thompson, S -- Wdowiak, T -- Weitz, C -- Whelley, P -- New York, N.Y. -- Science. 2004 Dec 3;306(5702):1727-30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA. kherkenhoff@usgs.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15576607" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment ; Ferric Compounds ; Geologic Sediments ; *Mars ; Minerals ; Silicates ; Spacecraft ; *Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2004-12-04
    Description: The soils at the Opportunity site are fine-grained basaltic sands mixed with dust and sulfate-rich outcrop debris. Hematite is concentrated in spherules eroded from the strata. Ongoing saltation exhumes the spherules and their fragments, concentrating them at the surface. Spherules emerge from soils coated, perhaps from subsurface cementation, by salts. Two types of vesicular clasts may represent basaltic sand sources. Eolian ripples, armored by well-sorted hematite-rich grains, pervade Meridiani Planum. The thickness of the soil on the plain is estimated to be about a meter. The flatness and thin cover suggest that the plain may represent the original sedimentary surface.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Soderblom, L A -- Anderson, R C -- Arvidson, R E -- Bell, J F 3rd -- Cabrol, N A -- Calvin, W -- Christensen, P R -- Clark, B C -- Economou, T -- Ehlmann, B L -- Farrand, W H -- Fike, D -- Gellert, R -- Glotch, T D -- Golombek, M P -- Greeley, R -- Grotzinger, J P -- Herkenhoff, K E -- Jerolmack, D J -- Johnson, J R -- Jolliff, B -- Klingelhofer, G -- Knoll, A H -- Learner, Z A -- Li, R -- Malin, M C -- McLennan, S M -- McSween, H Y -- Ming, D W -- Morris, R V -- Rice, J W Jr -- Richter, L -- Rieder, R -- Rodionov, D -- Schroder, C -- Seelos, F P 4th -- Soderblom, J M -- Squyres, S W -- Sullivan, R -- Watters, W A -- Weitz, C M -- Wyatt, M B -- Yen, A -- Zipfel, J -- New York, N.Y. -- Science. 2004 Dec 3;306(5702):1723-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉U.S. Geological Survey, Flagstaff, AZ 86001, USA. lsoderblom@usgs.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15576606" target="_blank"〉PubMed〈/a〉
    Keywords: Extraterrestrial Environment ; Ferric Compounds ; Geologic Sediments ; *Mars ; Minerals ; Silicates ; Spacecraft ; Spectrum Analysis ; Water
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: On Holsnøy, an island off the coast of Western Norway, an anorthositic complex metamorphosed to granulite facies was partially overprinted by a later eclogite facies metamorphism. Eclogite facies rocks (containing omphacite, garnet, kyanite and hydrous phases such as mica and zoisite) occur in shear zones of various scales and adjacent to veins. Previous studies of shear zones on Holsnøy reported evidence for substantial element mobility (Jamtveit et al., 1990; Mattey et al., 1994). In this work, we compare chemical compositions of granulite and its undeformed eclogitized equivalent adjacent to veins in locations where a single band of granulite can be traced and sampled as it approaches the vein. This tracing is crucial because the pre-granulite rocks cover a substantial compositional range, indicative of a petrologically variable protolith consisting of anorthosite, gabbro and jotunite. We analysed multiple core samples collected across nine separate granulite-eclogite transition zones located at veins in anorthositic, jotunitic and gabbroic protoliths for major and trace elements. For each transition, no compositional difference between the average granulite and average eclogite composition was found at the 90% confidence level except for LOI (loss on ignition), which was consistently significantly higher in the eclogite samples. Although not significant at the 90% confidence level for any single traverse, the average eclogite concentrations of SiO2 , Na2O, Cs, As and Br exceed the average granulite concentrations for eight or all nine of the traverses. For most traverses, statistical analysis of the data limits any gain of SiO2 in the eclogites to no more than a few relative per cent. Other than the introduction of volatile substances, presumably an H2O-rich fluid, eclogitization associated with vein formation was essentially isochemical.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Arising from: T. M. McCollom & B. M. Hynek Nature 438, 1129–1131 (2005); McCollom & Hynek reply The Mars Exploration Rover Opportunity discovered sulphate-rich sedimentary rocks at Meridiani Planum on Mars, which are ...
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 2013-10-02
    Description: Apollo 12 sample 12032,366-19 is a 21.3 mg granite fragment that is distinct from any other lunar granite or felsite. It is composed of barian K-feldspar, quartz, sodic plagioclase, hedenbergite, fayalite, and ilmenite, with trace amounts of zirconolite, baddeleyite, apatite, and merrillite. The texture of 12032,366-19 is largely a micrographic intergrowth predominantly of K-feldspar and quartz and, to a lesser extent, plagioclase and quartz. Hedenbergite, fayalite, and ilmenite are present in minor but significant quantities—6.0, 3.1, and 1.7 wt%, respectively—and are scattered throughout the feldspar-quartz intergrowths. Trace amounts of Zr-bearing phases are found including zirconolite (0.6 wt%) and baddeleyite (0.04 wt%). Incompatible trace-element concentrations are high in 12032,366-19, particularly the high-field-strength elements, e.g., Zr, Sm, and Th (1500, 25, and 61 μg/g, respectively). The chondrite-normalized, rare-earth-element concentrations form a "V-pattern" that is characteristic of other lunar granitic material. By modeling 12032,366-19 as a derivative from a KREEP-like parent melt, the composition and mineral assemblage can be obtained by extended fractional crystallization combined with separation of the low-density minerals plus trapped melt components prior to final solidification. However, this model cannot quantitatively account for the relatively sodic composition of the plagioclase (An 34–50 ) and requires that the starting melt has Na 2 O of 1.2–1.4 wt%, which is higher than most KREEP compositions. Formation of this assemblage by silicate-liquid immiscibility is neither required nor indicated by petrogenetic modeling.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
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  • 8
    Publication Date: 2016-07-02
    Description: In the search for evidence of past aqueous activity by the Mars Exploration Rover Opportunity, fracture-filling veins and rock coatings are prime candidates for exploration. At one location within a segment of remaining rim material surrounding Endeavour Crater, a set of "boxwork" fractures in an outcrop called Esperance are filled by a bright, hydrated, and highly siliceous (SiO 2 ~ 66 wt%) material, which has overall a montmorillonite-like chemical composition. This material is partially covered by patches of a thin, dark coating that is sulfate-rich (SO 3 ~ 21 wt%) but also contains significant levels of Si, Fe, Ca, and Mg. The simultaneous presence of abundant S, Si, and Fe indicates significant mineralogical complexity within the coating. This combination of vein and coating compositions is unlike previous analyses on Mars. Both materials are heterogeneously eroded, presumably by eolian abrasion. The evidence indicates at least two separate episodes of solute precipitation from aqueous fluids at this location, possibly widely separated in time. In addition to the implications for multiple episodes of alteration at the surface of the planet, aqueous chemical environments such as these would have been habitable at the time of their formation and are also favorable for preservation of organic material.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
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  • 9
    Publication Date: 2016-06-03
    Description: Mars Reconnaissance Orbiter HiRISE images and Opportunity rover observations of the ~22 km wide Noachian age Endeavour Crater on Mars show that the rim and surrounding terrains were densely fractured during the impact crater-forming event. Fractures have also propagated upward into the overlying Burns formation sandstones. Opportunity’s observations show that the western crater rim segment, called Murray Ridge, is composed of impact breccias with basaltic compositions, as well as occasional fracture-filling calcium sulfate veins. Cook Haven, a gentle depression on Murray Ridge, and the site where Opportunity spent its sixth winter, exposes highly fractured, recessive outcrops that have relatively high concentrations of S and Cl, consistent with modest aqueous alteration. Opportunity’s rover wheels serendipitously excavated and overturned several small rocks from a Cook Haven fracture zone. Extensive measurement campaigns were conducted on two of them: Pinnacle Island and Stuart Island. These rocks have the highest concentrations of Mn and S measured to date by Opportunity and occur as a relatively bright sulfate-rich coating on basaltic rock, capped by a thin deposit of one or more dark Mn oxide phases intermixed with sulfate minerals. We infer from these unique Pinnacle Island and Stuart Island rock measurements that subsurface precipitation of sulfate-dominated coatings was followed by an interval of partial dissolution and reaction with one or more strong oxidants (e.g., O 2 ) to produce the Mn oxide mineral(s) intermixed with sulfate-rich salt coatings. In contrast to arid regions on Earth, where Mn oxides are widely incorporated into coatings on surface rocks, our results demonstrate that on Mars the most likely place to deposit and preserve Mn oxides was in fracture zones where migrating fluids intersected surface oxidants, forming precipitates shielded from subsequent physical erosion.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
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  • 10
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    Mineralogical Society of America
    Publication Date: 2014-11-19
    Description: Merrillite, Ca 18 (Ca,)Mg 2 (PO 4 ) 14 –Ca 18 Na 2 Mg 2 (PO 4 ) 14 –Ca 16 REE 2 (Mg,Fe) 2 (PO 4 ) 14 occurs as a primary phosphate along with apatite, in lunar and martian rocks, and in meteorites. It is nominally anhydrous, but attempts to directly measure H in this mineral have not previously been reported. Because of the occurrence on Earth of whitlockite, Ca 18 (Mg,Fe 2+ ) 2 (PO 4 ) 12 [HPO 4 ] 2 , and the apparent incorporation in whitlockite of a merrillite component, the lack of a whitlockite component in extraterrestrial merrillite could be taken as an indicator of low hydrogen fugacity, and this implication has been applied to lunar merrillite. On the other hand, for martian rocks, where magmatic OH or H 2 O contents were likely higher, apatite accordingly contains higher OH contents, yet coexists with anhydrous, Na-rich merrillite. With direct measurements by SIMS, McCubbin et al. (2014) , which is in the July issue of American Mineralogist (p. 1347–1354), show that Shergotty merrillite is anhydrous and infer that the high T of crystallization of Shergotty precluded incorporation of a whitlockite component. The mineral pair apatite-merrillite in extraterrestrial rocks constitutes a powerful pair for recording magmatic conditions; however, as McCubbin et al. show, the implications of these minerals and their compositions must be interpreted in light of careful and complete analyses and crystal chemical constraints.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
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