Effects of shock and Martian alteration on Tissint hydrogen isotope ratios and water content
Effects of shock and Martian alteration on Tissint hydrogen isotope ratios and water content
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DOI：
10.1016/j.gca.2016.12.035
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发表时间：
2017-03
影响因子：
5
通讯作者：
L. Hallis;G. Huss;K. Nagashima;G. J. Taylor;D. Stöffler;Caroline L. Smith;Martin R. Lee
中科院分区：
文献类型：
--
作者：
L. Hallis;G. Huss;K. Nagashima;G. J. Taylor;D. Stöffler;Caroline L. Smith;Martin R. Lee
蒂森特陨石是一种苦味酸shergottite，于2011年7月18日在摩洛哥坠落地球，是第五颗被目击坠落的火星陨石。Tissint不同矿物的氢同位素比值和水含量是可变的。林伍德岩和冲击熔穴的D/H比值相对于陆地值（δD = 761-4224‰）有所升高。这些高比率的再结晶相表明显着的氢注入富D火星大气在冲击。相比之下，虽然橄榄石有可检测到的水丰度（230-485 ppm），但它的D/H比要低得多（δD = +88至-150 ‰），这表明这些水不是从火星大气注入的。Tissint所经历的最小陆地风化使人们相信橄榄石中的水来自火星，但其高浓度表明直接继承母体熔体是不可能的，特别是考虑到橄榄石结晶的低压。低δD地壳流体的加入，或结晶过程中的后期蚀变，可以解释Tissint橄榄石中相对较高的水含量和较低的D/H比。
The Tissint meteorite, a picritic shergottite, fell to Earth in Morocco on the 18th of July 2011, and is only the fifth Martian meteorite witnessed to fall. Hydrogen isotope ratios and water contents are variable within different minerals in Tissint. Ringwoodite and shock melt pockets contain elevated D/H ratios relative to terrestrial values (δD = 761–4224‰). These high ratios in recrystallized phases indicate significant implantation of hydrogen from the D-rich Martian atmosphere during shock. In contrast, although olivine has detectable water abundances (230–485 ppm), it exhibits much lower D/H ratios (δD = +88 to −150‰), suggesting this water was not implanted from the Martian atmosphere. The minimal terrestrial weathering experienced by Tissint gives confidence that the olivine-hosted water has a Martian origin, but its high concentration indicates direct inheritance from the parental melt is improbable, especially given the low pressure of olivine crystallisation. Incorporation of a low δD crustal fluid, or deuteric alteration during crystallisation, could explain the relatively high water contents and low D/H ratios in Tissint olivine.