Heterogeneous martian mantle: Evidence from petrology, mineral chemistry, and in situ U-Pb chronology of the basaltic shergottite Northwest Africa 8653
Heterogeneous martian mantle: Evidence from petrology, mineral chemistry, and in situ U-Pb chronology of the basaltic shergottite Northwest Africa 8653
复制标题
异质火星地幔：来自西北非洲 8653 玄武岩 Shergottite 的岩石学、矿物化学和原位 U-Pb 年代学的证据
DOI：
10.1016/j.gca.2021.05.011
复制
发表时间：
2021-05
影响因子：
5
通讯作者：
Liao S. Y.
中科院分区：
文献类型：
--
作者：
Wu Yunhua;徐伟彪;Li Q.L.;Che X.C.;Liao S. Y.
长石来源于地幔储层，经过不同的岩浆作用，记录了火星地幔的地球化学特征。但是，由于铅同位素组成的地质意义、火星铅污染的作用以及其他因素的影响，菱辉石u -Pb同位素系统仍然模糊不清。本文通过详细的岩石学和矿物学研究，对西北非洲（NWA） 8653玄武岩辉长岩矿物进行了环境pb和/或Pb-Pb分析。该项目的目的是评价NWA 8653的形成过程、结晶年龄以及特征Pb同位素组成。结构、主微量元素组成和地球化学模拟表明，NWA 8653是一种富集的辉长岩，其成因不是地壳同化，而是地幔中贫化组分（如分选的大和980459）和富集组分（如NWA 1068）的混合。坏辉石的U-Pb和Pb-Pb同位素显示其较年轻的结晶年龄（187.6±8.0 Ma）。铅同位素组成在预测初始Pb和4.1 Ga等时线附近，暗斑岩、长石互生，大部分磷酸盐团簇。对于这些矿物，计算表明，来自不同储层的Pb与μ (238U/204Pb)在1.4 ~ 4.7之间的混合可以解释年轻shergotites中明显的4.1 Ga等时线。地幔源间不同程度的混合可能进一步增加了辉石质同位素的非均质性。结果表明，NWA 8653的微量元素和同位素组成来源于非均质地幔源。地幔中不同储层Pb的混合作用对u可忽略的矿物中Pb的形成起着重要作用。该研究为火星地幔高度非均质提供了额外的地球化学证据。
Shergottites were derived from mantle reservoirs through various magmatic processes, recording geochemical signatures of the martian mantle. But the U-Pb isotopic system of shergottites remains obscured including the geological significance of Pb isotope composition, the role of martian Pb contamination, and other factors. Here we presentin situU-Pb and/or Pb-Pb analyses on minerals of the basaltic shergottite Northwest Africa (NWA) 8653 after detailed petrological and mineralogical studies. The aims of the project are to evaluate the formation process, the crystallization age as well as the characteristic Pb isotope composition of NWA 8653. Texture, major and trace element composition plus geochemical modeling suggest that NWA 8653 is an enriched shergottite derived from mixing of depleted (e.g., fractionated Yamato 980459) and enriched components (e.g., NWA 1068) in the mantle, instead of crustal assimilation. U-Pb and Pb-Pb isotopes of baddeleyite reveal a young crystallization age (187.6 ± 8.0 Ma). Pb isotope compositions of maskelynite, feldspathic intergrowth, and the majority of phosphate cluster near the predicted initial Pb and a 4.1 Ga isochron. For these minerals, calculations suggest that mixing of Pb from different reservoirs with μ (238U/204Pb) varying from 1.4 to 4.7 could explain the apparent 4.1 Ga isochron in young shergottites. Variable extents of mixing among mantle sources could further increase the isotopic heterogeneity of shergottites. Our results demonstrate that NWA 8653 was derived from a heterogeneous mantle source in terms of trace element and isotope composition. Mixing of Pb from different reservoirs in the mantle plays an important role in shaping Pb in minerals with negligible U. This study provides additional geochemical evidence for a highly heterogeneous martian mantle.
登录
查看更多内容
影响因子：
5
作者：
R. Moriwaki;T. Usui;M. Tobita;T. Yokoyama
通讯作者：
R. Moriwaki;T. Usui;M. Tobita;T. Yokoyama
DOI：
--
发表时间：
2004-09
期刊：
Antarctic meteorite research
影响因子：
--
作者：
N. Shirai;M. Ebihara
通讯作者：
N. Shirai;M. Ebihara
影响因子：
5.3
作者：
J. Bellucci;A. Nemchin;A. Nemchin;M. Whitehouse;J. Snape;P. Bland;G. Benedix;J. Roszjar
通讯作者：
J. Bellucci;A. Nemchin;A. Nemchin;M. Whitehouse;J. Snape;P. Bland;G. Benedix;J. Roszjar
影响因子：
3.5
作者：
Chenguang Sun;Yan Liang
通讯作者：
Chenguang Sun;Yan Liang
影响因子：
5.3
作者：
Qin Zhou;C. Herd;Q. Yin;Xian‐Hua Li;Fu-Yuan Wu;Qiu-li Li;Yu Liu;G. Tang;T. Mccoy
通讯作者：
Qin Zhou;C. Herd;Q. Yin;Xian‐Hua Li;Fu-Yuan Wu;Qiu-li Li;Yu Liu;G. Tang;T. Mccoy