Re-Os molybdenite ages and zircon Hf isotopes of the Gangjiang porphyry Cu-Mo deposit in the Tibetan Orogen

	Re-Os molybdenite ages and zircon Hf isotopes of the Gangjiang porphyry Cu-Mo deposit in the Tibetan Orogen
	Cheng-Biao Leng; Xing-Chun Zhang; Hong Zhong; Rui-Zhong Hu; Wei-De Zhou; Chao Li
	2013
发表期刊	Mineralium Deposita
卷号	48 期号:5 页码:585-602
摘要	The Miocene porphyry Cu-(Mo) deposits in the Gangdese orogenic belt in southern Tibet were formed in a post-subduction collisional setting. They are closely related to the Miocene adakite-like porphyries which were probably derived from a thickened basaltic lower crust. Furthermore, mantle components have been considered to have played a crucial role in formation of these porphyry deposits (Hou et al. Ore Geol Rev 36: 25-51, 2009; Miner Deposita doi: 10.1007/s00126-012-0415-6, 2012). In this study, we present zircon Hf isotopes and molybdenite Re-Os ages on the newly discovered Gangjiang porphyry Cu-Mo deposit in southern Tibet to constrain the magma source of the intrusions and the timing of mineralization. The Gangjiang porphyry Cu-Mo deposit is located in the Nimu ore field in the central Gangdese porphyry deposits belt, southern Tibet. The copper and molybdenum mineralization occur mainly as disseminations and veins in the overlapped part of the potassic and phyllic alteration zones, and are predominantly hosted in the quartz monzonite stock and in contact with the rhyodacite porphyry stock. SIMS zircon U-Pb dating of the pre-mineral quartz monzonite stock and late intra-mineral rhyodacite porphyry yielded ages of 14.73 +/- 0.13 Ma (2 sigma) and 12.01 +/- 0.29 Ma (2 sigma), respectively. These results indicate that the magmatism could have lasted as long as about 2.7 Ma for the Gangjiang deposit. The newly obtained Re-Os model ages vary from 12.51 +/- 0.19 Ma (2 sigma) to 12.85 +/- 0.18 Ma (2 sigma) for four molybdenite samples. These Re-Os ages are roughly coincident with the rhyodacite porphyry U-Pb zircon age, and indicate a relatively short-lived episode of ore deposition (ca. 0.3 Ma). In situ Hf isotopic analyses on zircons by using LA-MC-ICP-MS indicate that the epsilon (Hf)(t) values of zircons from a quartz monzonite sample vary from +2.25 to +4.57 with an average of +3.33, while zircons from a rhyodacite porphyry sample vary from +5.53 to +7.81 with an average of +6.64. The Hf data indicate that mantle components could be partly involved in the deposit formation, and that mantle contributions might have increased over time from ca. 14.7 to 12.0 Ma. Combined with previous works, it is proposed that the Gangjiang deposit could have resulted from the convective thinning of the lithospheric root, and the input of upper mantle components into the magma could have played a key role in the formation of the porphyry deposits in the Miocene Gangdese porphyry copper belt in the Tibetan Orogen.
学科领域	矿床地球化学
收录类别	SCI
语种	英语
文献类型	期刊论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/5074
专题	矿床地球化学国家重点实验室_矿床地球化学国家重点实验室_期刊论文矿床地球化学国家重点实验室
通讯作者	Cheng-Biao Leng
推荐引用方式 GB/T 7714	Cheng-Biao Leng,Xing-Chun Zhang,Hong Zhong,et al. Re-Os molybdenite ages and zircon Hf isotopes of the Gangjiang porphyry Cu-Mo deposit in the Tibetan Orogen[J]. Mineralium Deposita,2013,48(5):585-602.
APA	Cheng-Biao Leng,Xing-Chun Zhang,Hong Zhong,Rui-Zhong Hu,Wei-De Zhou,&Chao Li.(2013).Re-Os molybdenite ages and zircon Hf isotopes of the Gangjiang porphyry Cu-Mo deposit in the Tibetan Orogen.Mineralium Deposita,48(5),585-602.
MLA	Cheng-Biao Leng,et al."Re-Os molybdenite ages and zircon Hf isotopes of the Gangjiang porphyry Cu-Mo deposit in the Tibetan Orogen".Mineralium Deposita 48.5(2013):585-602.

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