气候变化领域集成服务门户(CCPortal): Disturbances in the Sm–Nd isotope system of the Acasta Gneiss Complex—Implications for the Nd isotope record of the early Earth

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DOI	10.1016/j.epsl.2019.115900
	Disturbances in the Sm–Nd isotope system of the Acasta Gneiss Complex—Implications for the Nd isotope record of the early Earth
	Fisher C.M.; Bauer A.M.; Vervoort J.D.
发表日期	2020
ISSN	0012821X
卷号	530
英文摘要	The whole rock 143Nd isotope record of the Acasta Gneiss Complex (AGC) has been used to argue for the development of both depleted mantle and enriched crustal reservoirs during the Hadean. The 147Sm–143Nd isotope compositions of rocks from AGC, however, fall on an array with an errorchron date of ∼3.3 Ga, despite the majority of samples yielding substantially older zircon U–Pb ages. This has led to the suggestion of a major Sm–Nd “resetting” event at this time in the AGC. To better understand the Sm–Nd bulk-rock systematics of the AGC, we investigate the U–Pb age and Sm–Nd isotope compositions of apatite and titanite from the AGC, using the laser ablation split stream (LASS) method. Apatite from all samples yield broadly similar U–Pb dates of ∼1.89 to 1.83 Ga, in agreement with resetting during the 1.9 Ga Wopmay orogen. The Sm–Nd isotope compositions of the apatite, however, lie off the WR errorchron and show a high degree of initial Nd isotope heterogeneity. Conversely, titanite Sm–Nd systematics are consistent with the ∼3.3 Ga whole rock errorchron further supporting Sm–Nd modification at ∼3.3 Ga. Taken together, these show that the oldest rocks in the AGC underwent at least two post-crystallization events (at 3.3 and 1.9 Ga) that modified the Sm–Nd isotope system. These results also demonstrate the relative mobility of the Sm–Nd isotope system during orogenic events, which may compromise the ability to determine robust bulk-rock 143Nd isotope signatures. © 2019 Elsevier B.V.
关键词	Acasta Gneiss Complex apatite Archean LASS Sm–Nd isotopes titanite
英文关键词	Apatite; Errors; Gallium; Laser ablation; Neodymium; Rocks; Silicate minerals; Zircon; Archean; Gneiss complexes; LASS; Nd isotopes; titanite; Isotopes; apatite; Archean; early Earth; gneiss; isotopic composition; neodymium isotope; samarium; titanite; Acasta
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/202583
作者单位	School of the Environment, Washington State University, Pullman, WA 99164, United States; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Geology and Geophysics, Yale University, New Haven, CT 06511, United States; Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53715, United States
推荐引用方式 GB/T 7714	Fisher C.M.,Bauer A.M.,Vervoort J.D.. Disturbances in the Sm–Nd isotope system of the Acasta Gneiss Complex—Implications for the Nd isotope record of the early Earth[J],2020,530.
APA	Fisher C.M.,Bauer A.M.,&Vervoort J.D..(2020).Disturbances in the Sm–Nd isotope system of the Acasta Gneiss Complex—Implications for the Nd isotope record of the early Earth.Earth and Planetary Science Letters,530.
MLA	Fisher C.M.,et al."Disturbances in the Sm–Nd isotope system of the Acasta Gneiss Complex—Implications for the Nd isotope record of the early Earth".Earth and Planetary Science Letters 530(2020).