Petrology and Mineralogy of the Martian Olivine Gabbroic Shergottite Northwest Africa 13581: Insights into the Enriched Martian Mantle Source
Petrology and Mineralogy of the Martian Olivine Gabbroic Shergottite Northwest Africa 13581: Insights into the Enriched Martian Mantle Source
复制标题
DOI：
10.1016/j.gca.2023.08.003
复制
发表时间：
2023-08
影响因子：
5
通讯作者：
Yunhua Wu;W. Hsu;S. Liao;Zhiyong Xiao;X. Che;Lili Pan;Ye Li;Shaolin Li
中科院分区：
文献类型：
--
作者：
Yunhua Wu;W. Hsu;S. Liao;Zhiyong Xiao;X. Che;Lili Pan;Ye Li;Shaolin Li
辉长岩和微辉长岩shergottites是侵入火成岩在火星上，并表现出各种各样的矿物学和地球化学性质。然而，它们的源储层，岩浆作用和其他shergottite亚型的联系没有得到很好的约束。西北非洲（NWA）13581是一个新发现的过镁铁质橄榄辉长岩，代表shergottite群中的堆晶岩成员。这一样品对辉绿岩的地幔源区特征和岩浆演化提供了新的重要制约。NWA 13581的结构和矿物化学表明了多压结晶条件，上升和就位后氧逸度增加约1个对数单位。地球化学研究表明，该样品是年轻的（150 ± 25 Ma），可能与Zagami（玄武质辉格岩）、NWA 10169（嵌晶辉格岩）和Larkman Nunatak 06319（橄榄-斑状辉格岩）等辉格岩共享类似的富集地幔储集层（初始ε 176 Hfi = −18.4，初始ε 143 Ndi = −7.1）。此外，NWA 13581早期形成的矿物中含有富钾熔体包裹体，这意味着可能来自交代地幔。在其他富集的辉橄榄岩中出现类似的富钾组分，可能表明它们的地幔储集层和结晶过程中有一个共同的过程。总体而言，NWA 13581在嵌晶结构、矿物化学、岩浆演化路径和侵位条件等方面与典型辉长岩型shergottites更接近。提出了NWA 13581和嵌晶辉绿云母在同一岩浆系列中形成的简化模型。岩浆混合和/或同化的主要机制，占其略有不同的矿物模态丰度和定量结构特征。对于来自相似地幔源的样品，辉绿云母的结构和矿物学差异在很大程度上与不同地壳层次的结晶作用有关。
Gabbroic and microgabbroic shergottites are intrusive igneous rocks on Mars and exhibit a wide variety of mineralogical and geochemical properties. However, their source reservoirs, magmatic processes and the link to other shergottite subtypes are not well constrained. Northwest Africa (NWA) 13581 is a newly found permafic olivine gabbro, representing a cumulate member in the shergottite group. This sample provides new critical constraints on the characteristics of mantle sources and magmatic evolution of shergottites. The texture and mineral chemistry of NWA 13581 indicate a polybaric crystallization condition, with an increase in oxygen fugacity of approximately 1 log unit after ascent and emplacement. Geochemical studies suggest that the sample is young (150 ± 25 Ma) and may share a similar enriched mantle reservoir (initial ε176Hfi= −18.4, initial ε143Ndi= −7.1) with shergottites like Zagami (basaltic shergottite), NWA 10169 (poikilitic shergottite) and Larkman Nunatak 06319 (olivine-phyric shergottite). In addition, the presence of potassium-rich melt inclusions enclosed in early-formed minerals of NWA 13581 implies a fertile source, probably originating from a metasomatized mantle. The occurrence of similar potassium-rich components in other enriched shergottites may suggest a common process in their mantle reservoir and during crystallization. Overall, NWA 13581 resembles poikilitic shergottites closer than typical gabbroic shergottites in several aspects such as poikilitic texture, mineral chemistry, magmatic evolutionary path, and emplacement conditions. A simplified model is proposed for the formation of NWA 13581 and poikilitic shergottites in the same magma series. Magma mixing and/or assimilation are not the major mechanism that account for their slightly varied mineral modal abundances and quantitative textural characteristics. For samples derived from similar mantle sources, the textural and mineralogical diversities of shergottites are largely related to crystallization at different crustal levels.