气候变化领域集成服务门户(CCPortal): Postcollisional delamination and partial melting of enriched lithospheric mantle: Evidence from Oligocene (ca. 30 Ma) potassium-rich lavas in the Gemuchaka area of the central Qiangtang Block, Tibet

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DOI	10.1130/B31911.1
	Postcollisional delamination and partial melting of enriched lithospheric mantle: Evidence from Oligocene (ca. 30 Ma) potassium-rich lavas in the Gemuchaka area of the central Qiangtang Block, Tibet
	Ou Q.; Wang Q.; Wyman D.A.; Zhang C.; Hao L.-L.; Dan W.; Jiang Z.-Q.; Wu F.-Y.; Yang J.-H.; Zhang H.-X.; Xia X.-P.; Ma L.; Long X.-P.; Li J.
发表日期	2019
ISSN	167606
起始页码	1385
结束页码	1408
卷号	131 期号:2021-07-08
英文摘要	Postcollisional potassium (K)-rich magmatic rocks have important implications for unveiling the deep geodynamic processes active during the evolution of orogenic belts and the surface uplift of plateaus. However, their petrogenesis remains highly controversial. Here we report on zircon U-Pb and mineral 40Ar-39Ar age, zircon Hf-O isotope, mineral composition, whole-rock major and trace element composition, and Nd-Sr isotope data for the postcollisional K-rich lavas in the Gemuchaka area of the central Qiangtang Block (central Tibet). Age dating suggests that these lavas were generated in the late Early Oligocene (ca. 30 Ma). Two series of rocks were recognized: silica-undersaturated and -saturated lavas. Both series are geochemically characterized by continuous variation trends. All rocks are enriched in light rare earth elements (LREEs) relative to heavy REEs (HREEs) and depleted in Ta-Nb-Ti, with negligible Sr and Eu and obviously positive Pb anomalies. The rocks have higher Th/ La (0.2-0.8) and Nb/Ta (18.6-19.8) values than asthenospheric mantle-derived rocks but slightly variable values of εNd(t) (-6.0 to -4.6), (87Sr/86Sr)i (0.7076-0.7083), and zircon εHf(t) (-7.2 to +0.8) and δ18O (7.1-8.5‰). We suggest that the parental magmas of these K-rich lavas were likely derived by variable partial melting of lithospheric mantle metasomatized by subducting continental sedimentderived melts with the addition of minor asthenospheric components. Element modeling results suggest that the basic end members were likely generated by fractionation processes dominated by olivine and minor clinopyroxene from parental magmas, and some other evolved rocks were generated by crystal (olivine, clinopyroxene, Fe-Ti oxides) fractionation from basic magmas. Combining geological and Cenozoic magmatic rock data in the Qiangtang Block, we propose that the Gemuchaka magmatism was most likely triggered by the delamination of lithospheric mantle thickened by early (Paleocene- Eocene) intracontinental subduction and subsequent asthenospheric upwelling. © 2019 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184958
作者单位	State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha, 410083, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China; School of Geosciences, The University of SydneyNSW 2006, Australia; Department of Geosciences, Fort Hays State University, Hays, KS 67601-4099, United States; School of Earth Science, Guilin University of Technology, Guilin, 541004, China; Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
推荐引用方式 GB/T 7714	Ou Q.,Wang Q.,Wyman D.A.,et al. Postcollisional delamination and partial melting of enriched lithospheric mantle: Evidence from Oligocene (ca. 30 Ma) potassium-rich lavas in the Gemuchaka area of the central Qiangtang Block, Tibet[J],2019,131(2021-07-08).
APA	Ou Q..,Wang Q..,Wyman D.A..,Zhang C..,Hao L.-L..,...&Li J..(2019).Postcollisional delamination and partial melting of enriched lithospheric mantle: Evidence from Oligocene (ca. 30 Ma) potassium-rich lavas in the Gemuchaka area of the central Qiangtang Block, Tibet.Bulletin of the Geological Society of America,131(2021-07-08).
MLA	Ou Q.,et al."Postcollisional delamination and partial melting of enriched lithospheric mantle: Evidence from Oligocene (ca. 30 Ma) potassium-rich lavas in the Gemuchaka area of the central Qiangtang Block, Tibet".Bulletin of the Geological Society of America 131.2021-07-08(2019).