气候变化领域集成服务门户(CCPortal): The timing of lunar solidification and mantle overturn recorded in ferroan anorthosite 62237

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DOI	10.1016/j.epsl.2020.116219
	The timing of lunar solidification and mantle overturn recorded in ferroan anorthosite 62237
	Sio C.K.; Borg L.E.; Cassata W.S.
发表日期	2020
ISSN	0012821X
卷号	538
英文摘要	Ferroan anorthosite suite (FAS) rocks are widely interpreted to represent primordial lunar crust. Despite their importance in pinpointing the timing of lunar crust formation, robust chronological investigations for this rock type are scarce. Here, we report the Ar-Ar, Rb-Sr, and Sm-Nd isotopic systematics for the FAS troctolitic anorthosite 62237. The Ar-Ar isotopic system has been reset by a thermal event at 3710 ± 48 Ma, and the Rb-Sr isotopic systematics has been disturbed such that a Rb-Sr isochron age cannot be determined. However, an internal isochron for the Sm-Nd isotopic system has yielded an age of 4350 ± 73 Ma (MSWD = 2.0) with an initial ϵ143NdCHUR of −0.53 ± 0.26. The mineral and whole-rock fractions of 62237 plot on the same internal isochron as FAS sample 60025. The combined datasets define an age of 4372 ± 35 Ma (MSWD = 4.0) with an initial ϵ143NdCHUR of −0.17 ± 0.22. Literature Sm-Nd data for FAS and Mg-suite whole-rocks also plot on the 60025-62237 isochron. The coherence of data from both FAS and Mg-suite rocks examined thus far suggests that both rock suites formed contemporaneously from identical, or nearly identical, sources. In addition, the concordance of FAS and Mg-suite ages suggests that primordial crust solidification either involved both magmatic suites, or that Mg-suite magmatism was contemporaneous with FAS magmatism within resolution of the Sm-Nd chronometer. The ages for FAS and Mg-suite also coincide with the formation ages of the mare basalt source regions and urKREEP. Ferroan anorthosite suite rocks and urKREEP are thought to represent primordial LMO solidification products, whereas Mg-suite and the mare basalt source regions are argued to represent mixtures of various LMO crystallization products that were formed during density-driven overturn of the LMO. The concordance of ages implies that the 4372 ± 35 Ma Sm-Nd isochron records the age of mantle overturn, and that overturn occurred during, or shortly after, solidification of the LMO. © 2020 Elsevier B.V.
关键词	Ar-Ar ferroan anorthosite lunar magma ocean overturn Rb-Sr Sm-Nd
英文关键词	Basalt; Binary alloys; Isotopes; Magnesium alloys; Minerals; Moon; Rubidium alloys; Samarium alloys; Solidification; Strontium alloys; Timing circuits; Crystallization products; ferroan anorthosite; Isotopic systematics; Isotopic systems; Magma ocean; overturn; Sm-Nd isotopic systematics; Thermal events; Neodymium alloys; anorthosite; argon-argon dating; lunar crust; magma chamber; overturn; rubidium-strontium dating
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202891
作者单位	Lawrence Livermore National Laboratory, 7000 East Ave. L-231, Livermore, CA 94550, United States
推荐引用方式 GB/T 7714	Sio C.K.,Borg L.E.,Cassata W.S.. The timing of lunar solidification and mantle overturn recorded in ferroan anorthosite 62237[J],2020,538.
APA	Sio C.K.,Borg L.E.,&Cassata W.S..(2020).The timing of lunar solidification and mantle overturn recorded in ferroan anorthosite 62237.Earth and Planetary Science Letters,538.
MLA	Sio C.K.,et al."The timing of lunar solidification and mantle overturn recorded in ferroan anorthosite 62237".Earth and Planetary Science Letters 538(2020).