LA-ICP-MS Zircon U-Pb Dating, Petrogensis of the Gouhou Complex in the Qinghai Nanshan Tectonic Zone, and its Geological Implications

被引：0
|
作者：
Zhang Y. [1 ,2 ]
Pei X. [1 ]
Li Z. [1 ]
Li R. [1 ]
Liu C. [1 ]
Pei L. [3 ]
Chen Y. [1 ]
Wang M. [1 ]
Chen G. [1 ,4 ]
机构：
[1] MOE Key Laboratory of Western China's Mineral Resources and Geological Engineering, MLR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Faculty of Earth Science and Resources, Xi'an, 710054, Shaanxi
[2] Faculty of Resources and Environmental Engineering, Shandong University of Technology, Zibo, 255049, Shandong
[3] School of Earth Sciences and Resources, China University of Geosciences, Beijing
[4] School of Civil Engineeringy, Nanyang Institutte of Technology, Nanyang, 473000, Henan
来源：
Pei, Xianzhi (peixzh@263.net) | 2017年 / Science Press卷 / 41期
关键词：
Gouhou complex; LA-ICP-MS zircon U-Pb dating; Nanshan; Qinghai province; Northern margin of the West Qinling; Petrogensis; Tectonic setting;
D O I：
10.16539/j.ddgzyckx.2017.05.009
中图分类号：
学科分类号：
摘要：
The Qinghai Nanshan tectonic belt, situated in the northern margin of the Gonghe Basin, is the conjunction area among the West Qinling orogenic belt, South Qilian tectonic belt and Zongwulong tectonic belt. As a magmatic complex in the east part of the Qinghai Nanshan tectonic zone, the Gouhou complex consists of gabbro, gabbro-diorite, quartz diorite, and granodiorite. In this paper, a detailed study of LA-ICP-MS zircon U-Pb geochronology, petrology and geochemistry were carried out on the Gouhou complex. LA-ICP-MS zircon U-Pb ages of the gabbro, gabbro-diorite, quartz diorite, granodiorite and MMEs are 248.8±2.6 Ma, 243.2±2.1 Ma, 243.1±0.9 Ma, 244.0±2.1 Ma and 249±3 Ma, respectively. Geochemically, the gabbros have low Na2O+K2O, but high Fe2O3T and MgO contents, and the gabbro-diorites are enriched in CaO, Al2O3 and Na2O, overall belonging to the calc-alkaline series. The quartz diorite and granodiorite are metaluminous to weak peraluminous and high-K calc-alkaline, whereas the enclaves are of high-K calc-alkaline to alkaline series. All the samples are evidently enriched in LILEs (Cs, Rb, K) and Pb, and depleted in HFSEs (Nb, Ta, Ti) and P, Ba. The REE patterns are right-dippling lines with weak to moderate negative Eu anomalies. The above petrographic and geochemical characteristics of the rocks suggest that mixing of mantle-and crust-derived magmas played an important role in the generation of the Gouhou complex. Partial melting of the wedge mantle, which was metasomatized by hydrous fluids from the subducted slab, generated the primitive basaltic magma. The gabbros were produced by fractional crystallization of mantle-derived primitive magma. The gabbro-diorites were formed through a more complicated process that involves fractional crystallization of the primitive basaltic magma and contamination of crustal material. The quartz diorites and granodiorites crystallized from a hybrid magma formed by mixing of the intermediate-basic magma and intermediate-felsic magma. Considering the regional tectonic evolution, we propose that the Gouhou complex was related to the southward subduction of the Zongwulong oceanic crust from the late stage of Early Triassic to the early stage of Middle Triassic. © 2017, Science Press. All right reserved.
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页码：908 / 932
页数：24
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