Tongling ore district in Anhui Province is one of the important Cu-Au ore-concentration districts in the Middle-Lower Reaches of Yangtze River structural-magmatic-metallogenetic belt. Late Mesozoic intermediate-acid diorite intrusive rocks dominated by quartz diorite and granodiorite are widely developed in this area, and are closely related to mineralization. A large number of previous studies have been published on the genesis of intrusive rocks in the Tongling ore district, but there are still some controversies. Based on widespread collection of previous research data and results, the quartz diorite from Tongguanshan and the granodiorite from Xinwuli and Hucun in this area are selected to carry out the Sr-Nd isotopes and in situ zircon Hf-O isotopes in order to discuss its petrogenesis. The results show that the structure and mineral composition of quartz diorite and granodiorite are similar, and the major elements, trace elements and rare earth elements are basically the same. They belong to the high-K calc-alkaline rocks and have the characteristics of adakite-like rocks. ISr values of quartz diorite are ranged from 0.707 2 to 0.709 0, εNd（t） = -13.0～-8.3, εHf（t） values of the contain zircons are ranged from -23.5 to -8.7, δ18O = 6.5‰～7.4‰. ISr values of granodiorite are ranged from 0.707 7 to 0.709 8, εNd（t） = -13.6～-8.5, εHf（t） = -19.0～-7.4, δ18O = 6.7‰～8.1‰. The similar geochemical characteristics of Sr-Nd-Hf-O isotopes for quartz diorite and granodiorite indicate that they have the same source of diagenetic material. In addition, quartz diorite and granodiorite in the area contain a large number of inherited zircons of Neoproterozoic ages （mainly 1.0～0.8 Ga）, indicating that the diagenetic material contains a large number of ancient crustal materials. Combining with the regional geological background and tectonic evolution, this paper holds that quartz diorite and granodiorite in the Tongling ore district were formed by the mixing and upward emplacement of enriched lithospheric mantle partial melting magma and crustal adakitic-like magma, and the crustal adakitic-like magma was formed by the melting of the juvenile crust formed after the collision of Neoproterozoic cathaysia block and Yangtze plate. The Late Mesozoic large-scale magmatism in the Tongling ore district was attributed to upwelling and heating of the enriched lithospheric mantle partial melting magma and decompression melting of the thickened crust controlled by the stress changes from the subduction of the Paleo-Pacific plate. And the geotectonic background of the magmatic activities maybe inside of the continental plate.
Xu Xiaochun Liu Zheng Fu Zhongyang Xu Xinyue Xie Qiaoqing. Petrogenesis of quartz diorite and granodiorite in the Tongling ore district, Anhui Province: Sr-Nd-Hf-O isotopic constraints[J]. Chinese Journal of Geology, 2019, 54(3): 711-735.