Early Paleozoic intracontinental orogeny in the Yunkai domain, South China Block: New insights from field observations, zircon U–Pb geochronological and geochemical investigations

Chaolei Yan 1 Liangshu Shu 1 Michel Faure 2, 3 Yan Chen 2, 3 Cheng Li 1
3 Géodynamique - UMR7327
BRGM - Bureau de Recherches Géologiques et Minières (BRGM), ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327 : UMR7327, INSU - CNRS - Institut national des sciences de l'Univers , UO - Université d'Orléans : UMR7327
Abstract : Debate on whether the Early Paleozoic tectono-magmatic event in South China is related to a subduction–collision or an intracontinental orogen has been lasted for decades within the geoscience community. This study deals with LA-ICP-MS zircon U–Pb ages, whole-rock chemistry, rare earth elements, trace elements and Hf isotopes from granitoid samples collected in the Yunkai domain in order to better constrain the Early Paleozoic tectonic evolution of the South China Block. The weighted mean 206Pb/238U ages for eight samples range from 426 Ma to 443 Ma, representing the crystallization ages of the magma. Fourteen samples were analyzed for geochemistry, all of which are characterized by a peraluminous signature with A/CNK values greater than 1.0. The REE geochemistry reveals enrichment in light rare earth element. LREE/HREE values range from 2.81 to 30.36 and (La/Yb)N vary from 1.23 to 55.14 (mean of 14 analyses is 14.69). All the samples exhibit distinct negative Ba, Sr and Nb anomalies and enrichment in Rb, Th, U and Pb. Hf isotopic analyses indicate negative εHf (t) values mainly ranging from − 3 to − 12, corresponding to two model age distributing from 1637 Ma to 2208 Ma. The geochemical analyses indicate that the Silurian granitic magmas in the Yunkai domain were derived from partial melting of crustal materials with little or no input of mantle source. These new data support the intracontinental subduction model already proposed to account for the Early Paleozoic tectonic, metamorphic and magmatic event of South China.
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Lithos, Elsevier, 2017, 268-271, pp.320-333. 〈10.1016/j.lithos.2016.11.013〉
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Chaolei Yan, Liangshu Shu, Michel Faure, Yan Chen, Cheng Li. Early Paleozoic intracontinental orogeny in the Yunkai domain, South China Block: New insights from field observations, zircon U–Pb geochronological and geochemical investigations. Lithos, Elsevier, 2017, 268-271, pp.320-333. 〈10.1016/j.lithos.2016.11.013〉. 〈insu-01427240〉

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