Publication Date:
2008-12-20
Description:
Geochemical models for Mars predict carbonate formation during aqueous alteration. Carbonate-bearing rocks had not previously been detected on Mars' surface, but Mars Reconnaissance Orbiter mapping reveals a regional rock layer with near-infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the Nili Fossae region. The carbonate is closely associated with both phyllosilicate-bearing and olivine-rich rock units and probably formed during the Noachian or early Hesperian era from the alteration of olivine by either hydrothermal fluids or near-surface water. The presence of carbonate as well as accompanying clays suggests that waters were neutral to alkaline at the time of its formation and that acidic weathering, proposed to be characteristic of Hesperian Mars, did not destroy these carbonates and thus did not dominate all aqueous environments.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ehlmann, Bethany L -- Mustard, John F -- Murchie, Scott L -- Poulet, Francois -- Bishop, Janice L -- Brown, Adrian J -- Calvin, Wendy M -- Clark, Roger N -- Marais, David J Des -- Milliken, Ralph E -- Roach, Leah H -- Roush, Ted L -- Swayze, Gregg A -- Wray, James J -- New York, N.Y. -- Science. 2008 Dec 19;322(5909):1828-32. doi: 10.1126/science.1164759.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geological Sciences, Brown University, Providence, RI02912, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19095939" target="_blank"〉PubMed〈/a〉
Keywords:
Extraterrestrial Environment
;
Iron Compounds
;
*Magnesium
;
Magnesium Compounds
;
*Mars
;
Silicates
;
Spacecraft
;
Spectrum Analysis
;
Temperature
;
*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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