Brack, A.; Baglioni, P.; Borruat, G.; Brandstatter, F.; Demets, R.; Edwards, H. G. M.; Genge, M.; Kurat, G.; Miller, M.F.; Newton, E. M.; Pillinger, C.T.; Roten, C.-A. and Wasch, E.
|DOI (Digital Object Identifier) Link:||http://doi.org/10.1016/S0032-0633(02)00018-1|
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The 18 SNC meteorites identified to date are all igneous rocks, being basalts or basaltic cumulates. The lack of sedimentary rocks in this inventory is therefore surprising, in view of the collisional history of Mars and the likelihood that Mars experienced warmer conditions, possibly with a significant hydrosphere, earlier in its history. To address the possibility that sedimentary rocks ejected by impact from the surface of Mars may have reached the Earth, but did not survive terrestrial atmospheric entry, an experiment was performed in which samples of dolomite, a simulated Martian regolith (consisting of basalt fragments in a gypsum matrix) and a basalt were fixed to the heat shield of a recoverable capsule and flown in low Earth orbit. Temperatures attained during re-entry were high enough to melt basalt and the silica fibres of the heat shield and were therefore comparable to those experienced by meteorites. The dolomite sample survived space flight and atmospheric re-entry, in part, as did fragments of the simulated Martian regolith, allowing detailed examinations of these ‘artificial meteorites’ to be conducted for chemical, mineralogical and isotopic modifications associated with atmospheric re-entry. Oxygen three-isotope measurements of the silica ‘fusion crust’ formed on the sample holder during atmospheric re-entry fit on a mixing line, with tropospheric O2 and the interior of the sample holder as end members.
Because much of the surface of Mars is covered by clastic sediments, meteorites of Martian provenance might be expected to be mostly sedimentary rocks rather than igneous ones. However, in the absence of a readily identifiable fusion crust, the extraterrestrial origin of such sedimentary rocks on Earth would most probably not be recognised without detailed petrological-geochemical examination and, ultimately, isotope measurements.
|Item Type:||Journal Article|
|Keywords:||artificial meteorites; Atmospheric entry; Dolomite; Martian sediments; isotopes|
|Academic Unit/Department:||Science > Physical Sciences
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||Users 6044 not found.|
|Date Deposited:||06 Jul 2006|
|Last Modified:||14 Jan 2016 15:56|
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