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Evidence from Hydrogen Isotopes in Meteorites for a Subsurface Hydrogen Reservoir on MarsThe surface geology and geomorphology of Mars indicates that it was once warm enough to maintain a large body of liquid water on its surface, though such a warm environment might have been transient. The transition to the present cold and dry Mars is closely linked to the history of surface water, yet the evolution of surficial water is poorly constrained. We have conducted in situ hydrogen isotope (D/H) analyses of quenched and impact glasses in three Martian meteorites (Yamato 980459, EETA79001, LAR 06319) by Cameca ims-6f at Digital Terrain Models (DTM) following the methods of [1]. The hydrogen isotope analyses provide evidence for the existence of a distinct but ubiquitous water/ice reservoir (D/H = 2-3 times Earth's ocean water: Standard Mean Ocean Water (SMOW)) that lasted from at least the time when the meteorites crystallized (173-472 Ma) to the time they were ejected by impacts (0.7-3.3 Ma), but possibly much longer [2]. The origin of this reservoir appears to predate the current Martian atmospheric water (D/H equals approximately 5-6 times SMOW) and is unlikely to be a simple mixture of atmospheric and primordial water retained in the Martian mantle (D/H is approximately equal to SMOW [1]). Given the fact that this intermediate-D/H reservoir (2-3 times SMOW) is observed in a diverse range of Martian materials with different ages (e.g., SNC (Shergottites, Nakhlites, Chassignites) meteorites, including shergottites such as ALH 84001; and Curiosity surface data [3]), we conclude that this intermediate-D/H reservoir is likely a global surficial feature that has remained relatively intact over geologic time. We propose that this reservoir represents either hydrated crust and/or ground ice interbedded within sediments. Our results corroborate the hypothesis that a buried cryosphere accounts for a large part of the initial water budget of Mars.
Document ID
20150019423
Acquisition Source
Johnson Space Center
Document Type
Abstract
Authors
Usui, Tomohiro
(Tokyo Inst. of Tech. Tokyo, Japan)
Alexander, Conel M. O'D.
(Carnegie Institution of Washington Washington, DC, United States)
Wang, Jianhua
(Carnegie Institution of Washington Washington, DC, United States)
Simon, Justin I.
(NASA Johnson Space Center Houston, TX, United States)
Jones, John H.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
October 15, 2015
Publication Date
August 16, 2015
Subject Category
Exobiology
Lunar And Planetary Science And Exploration
Report/Patent Number
JSC-CN-33257
Meeting Information
Meeting: 2015 Goldschmidt Conference
Location: Prague
Country: Czechoslovakia
Start Date: August 16, 2015
End Date: August 21, 2015
Sponsors: Goldschmidt (Th.) A.G.
Distribution Limits
Public
Copyright
Public Use Permitted.
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