Juvenile vs. recycled crust in NE China: Zircon U-Pb geochronology, Hf isotope and an integrated model for Mesozoic gold mineralization in the Jiaodong Peninsula

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• 作者：Qiongyan Yang ; ^{ouyangqiongyan1004@163.com" class="auth_mail} ; M. Santosh ; Junfeng Shen ; Shengrong Li
• 关键词：Zircon U&ndash ; Pb geochronology ; Hf isotopes ; Tectonics ; Gold metallogeny ; North China Craton
• 刊名：Gondwana Research
• 出版年：May, 2014
• 年：2014
• 卷：25
• 期：4
• 页码：1445-1468
• 全文大小：6281 K

文摘

The continental crust of the North China Craton (NCC) is a major reservoir of mineral resources with imprints of secular changes in tectonics and metallogeny. The Jiaodong Peninsula, located in the eastern margin of the North China Craton (NCC), is currently one of the largest gold producers over the globe, and preserves the records of multiple magmatic and metamorphic events. Here we characterize the timing and tectonics of the major Mesozoic magmatism and the associated gold metallogeny in this region through a comprehensive U-Pb geochronological and Hf isotope investigation of zircons in a suite of granitoids, mafic magmatic enclaves, melanocratic dikes and melted basement rocks.

The Linglong granite, hosting one of the major gold deposits in Jiaodong, shows emplacement ages between 150 and 160 Ma, and the dominantly negative 蔚_Hf (t) values (鈭?#xA0;34.0 to 鈭?#xA0;23.8) of zircons from this intrusion suggest magma derivation from recycled components in the Archean basement. The Guojialing granodiorite and its mafic magmatic enclaves show similar ages between 123 and 127 Ma, with negative 蔚_Hf (t) values (鈭?#xA0;19.3 to 鈭?#xA0;16.8), corresponding to crustal magma source. The melanocratic dikes, belonging to pre- and syn-mineralization stages, with U-Pb age range of 126 to 166 Ma display large variation in their zircon 蔚_Hf (t) values (鈭?#xA0;25.7 and 2.3) suggesting the involvement of both recycled crustal and juvenile mantle components. Zircons in the melted basement rocks with ages in the range of ca. 127-132 Ma also display both positive and negative 蔚_Hf (t) values (鈭?#xA0;44.6 and 9.8) indicating a mixture of recycled ancient crust and juvenile magmas. Our study shows that although the peak of gold metallogeny coincided with the tectonics associated with Pacific plate subduction which mobilized and concentrated the ores, the source materials of gold mineralization and magmatism had multiple origins including from the Precambrian basement rocks, Mesozoic granitoids and mantle-derived mafic magmas with extensive mixing of crustal, lithosphere mantle and asthenospheric components. A combination of delamination, mantle upwelling, subduction-related metasomatic enrichment and recycling of ancient components facilitated the gold metallogeny in this region. Our study provides a typical case of juvenile and recycled components in the formation and evolution of continental crust and associated mineral resources.