摘要
Late Mesozoic igneous intrusions and extensional structures in Carboniferous to Permian sequences in the SW Fujian region acted as important controls on the localisation of Fe-polymetallic de-posits.Here we document the identification of extensional deformation at shallow crustal levels and syn-tectonic granites related to normal faults.Based on spatial distribution and structural features,the extensional deformation can be divided into cover-only and basement-intersecting styles.A series of syn-tectonic plutons were emplaced into the footwall of normal faults.Representative samples of the Tangquan Granite have high SiO2(66.4 wt.%-73.9 wt.%)assays and Mg#values(37-59).The samples also have relatively homogenous initial 87Sr/86Sr(0.7083-0.7089)andεNd(-9.2--10.2)values.Geochemical and isotopic evidences indicate that the Tangquan granite originates from a hybrid source including lower crustal-derived felsic and lithospheric mantle-derived mafic magmas.Zircon U-Pb dating indicates that the granodiorite phase from the pluton crystallised at 161±4 Ma and the monzogranite phase crystallised at 159±1 Ma.Combined with the granitic rocks in a wider region of SE China,the widespread granitic magmatism and polymetallic mineralisation have been synchronous during the Late Mesozoic,probably resulting from extensional tectonics related to the lithospheric thinning.
基金
This study is financially supported by the Second Tibetan Plateau Scientific Expedition and Research Program(No.2019QZKK0804)
Major Research Plan of the National Natural Science Foundation of China(No.91755215)
National Natural Science Foundation of China(No.41703037)
the National Key R&D Plan(No.2018YFC0603801)
the Open Research Pro-ject from the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing(No.GPMR201816)
the Fundamental Research Funds for the Central Public Welfare Research Institutes(Nos.KK1914,KK2013)
the Chinese Geological Survey Program(Nos.DD20201173,DD20190379)
Key Laboratory of Regional Geology and Mineralization,Hebei GEO University(No.HGU-RGMKF192).
