DOI: 10.1016/j.epsl.2018.01.031
Scopus记录号: 2-s2.0-85044600726
论文题名: Using the magmatic record to constrain the growth of continental crust—The Eoarchean zircon Hf record of Greenland
作者: Fisher C.M. ; Vervoort J.D.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 488 起始页码: 79
结束页码: 91
语种: 英语
英文关键词: Archean
; crustal growth
; Greenland
; Hf isotopes
; LASS
; zircon
Scopus关键词: Earth (planet)
; Gallium
; Igneous rocks
; Isotopes
; Laser ablation
; Silicate minerals
; Zircon
; Archean
; Crustal growth
; Greenland
; Hf isotope
; LASS
; Hafnium
; Acasta
英文摘要: Southern West Greenland contains some of the best-studied and best-preserved magmatic Eoarchean rocks on Earth, and these provide an excellent vantage point from which to view long-standing questions regarding the growth of the earliest continental crust. In order to address the questions surrounding early crustal growth and complementary mantle depletion, we present Laser Ablation Split Stream (LASS) analyses of the U–Pb and Hf isotope compositions of zircon from eleven samples of the least-altered meta-igneous rocks from the Itsaq (Amîtsoq) Gneisses of the Isukasia and Nuuk regions of southern West Greenland. This analytical technique allows a less ambiguous approach to determining the age and Hf isotope composition of complicated zircon. Results corroborate previous findings that Eoarchean zircon from the Itsaq Gneiss (∼3.85 Ga to ∼3.63 Ga) were derived from a broadly chondritic source. In contrast to the Sm–Nd whole rock isotope record for southern West Greenland, the zircon Lu–Hf isotope record provides no evidence for early mantle depletion, nor does it suggest the presence of crust older than ∼3.85 Ga in Greenland. Utilizing LASS U–Pb and Hf data from the Greenland zircons studied here, we demonstrate the importance of focusing on the magmatic (rather than detrital) zircon record to more confidently understand early crustal growth and mantle depletion. We compare the Greenland Hf isotope data with other Eoarchean magmatic complexes such as the Acasta Gneiss Complex, Nuvvuagittuq greenstone belt, and the gneissic complexes of southern Africa, and all lack zircons with suprachondritic Hf isotope compositions. In total, these data suggest only a very modest volume of crust was produced during (or survived from) the Hadean and earliest Eoarchean. There remains no record of planet-scale early Earth mantle depletion in the Hf isotope record prior to 3.8 Ga. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109982
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: School of the Environment, Washington State University, Pullman, WA, United States
Recommended Citation:
Fisher C.M.,Vervoort J.D.. Using the magmatic record to constrain the growth of continental crust—The Eoarchean zircon Hf record of Greenland[J]. Earth and Planetary Science Letters,2018-01-01,488