¹Yunhua Wu,^2,3Weibiao Hsu,²Shiyong Liao,¹Zhiyong Xiao,⁴Xiaochao Che,⁵Lili Pan,²Ye Li,⁶Shaolin Li
Geochimica et Cosmochmica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.08.003]
¹Planetary Environmental and Astrobiological Research Laboratory, School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai 519082, China
²CAS Center for Excellence in Comparative Planetology, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, China
³Deep Space Exploration Laboratory, University of Science and Technology, Hefei 230026, China
⁴Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 102206, China
⁵School of Earth Sciences and Engineering, Sun Yat-sen University, Zhuhai 519082, China
⁶Astronomical Research Center, Shanghai Science & Technology Museum, Shanghai 201306, China
Copyright Elsevier

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 respects 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.