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标题：A new cache of Eoarchaean detrital zircons from the Singhbhum craton, eastern India and constraints on early Earth geodynamics
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作者：Bulusu Sreenivas ; Sukanta Dey ; Y.J. Bhaskar Rao 等
期刊名称：Geoscience Frontiers
印刷版ISSN：1674-9871
出版年度：2019
卷号：10
期号：4
页码：1359-1370
DOI：10.1016/j.gsf.2019.02.001
语种：English
出版社：Elsevier
摘要：AbstractThe dominant geodynamic processes that underpin the formation and evolution of Earth's early crust remain enigmatic calling for new information from less studied ancient cratonic nuclei. Here, we present U–Pb ages and Hf isotopic compositions of detrital zircon grains from ∼2.9 Ga old quartzites and magmatic zircon from a 3.505 Ga old dacite from the Iron Ore Group of the Singhbhum craton, eastern India. The detrital zircon grains range in age between 3.95 Ga and 2.91 Ga. Together with the recently reported Hadean, Eoarchean xenocrystic (up to 4.24 Ga) and modern detritus zircon grains from the Singhbhum craton, our results suggest that the Eoarchean detrital zircons represent crust generated by recycling of Hadean felsic crust formed at ∼4.3–4.2 Ga and ∼3.95 Ga. We observe a prominent shift in Hf isotope compositions at ∼3.6–3.5 Ga towards super-chondritic values, which signify an increased role for depleted mantle and the relevance of plate tectonics. The Paleo-, Mesoarchean zircon Hf isotopic record in the craton indicates crust generation involving the role of both depleted and enriched mantle sources. We infer a short-lived suprasubduction setting around ∼3.6–3.5 Ga followed by mantle plume activity during the Paleo-, Mesoarchean crust formation in the Singhbhum craton. The Singhbhum craton provides an additional repository for Earth's oldest materials.Graphical abstractDisplay OmittedHighlights•Detrital zircons with ages of 3.95 to 2.9 Ga from the Singhbhum Craton.•Dacite with age of 3505 ± 5 Ma represents the oldest greenstone sequence in India.•Evidence for both juvenile and recycled crust additions through the Paleoarchean.
关键词：KeywordsenU–Pb zircon agesHf isotopesSinghbhum cratonHadeanEoarcheanGeodynamics