Characteristics of cryptoexplosive breccia from the Chating copper-gold deposits, Xuancheng, Anhui province and its metallogenic significance


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Authors: Xie Qiaoqin, Sun Rui, Xu Xiaochun, Xu Xinyue, An Yuhua, Qian Shilong
Year: 2020
Journal: Geological Journal of China Universities 26 (3): 255-264   Article Link (DOI)
Title: Characteristics of cryptoexplosive breccia from the Chating copper-gold deposits, Xuancheng, Anhui province and its metallogenic significance
Abstract: The Chating copper-gold ore in Xuancheng region is a newly discovered large ore deposit in the Mesozoic-Cenozoic volcanic-sedimentary Nanling-Xuancheng basin in recent years, where the deposits are located at shallow depths of the Middle-Lower Yangtze River. This study is focused on the cryptoexplosive breccia pipe developed in the intrusives of quartz-dioriticporphyrite in the Chating copper-gold ore deposits. Based on the detailed core observations and petrographic analysis, characteristics and types of cryptoexplosive breccia are determined, and the relationship between the cryptoexplosive breccia and the copper-gold mineralization is discussed. The cryptoexplosive breccia in the ore deposits can be divided into three types: cryptoexplosivemelt-crystal-lithicbreccia, cryptoexplosive hydrothermal breccia, and cryptoexplosive fracture breccia based on its textures, compositions and abundance of rubbles. The cryptoexplosive breccia appears as an irregular pipe enveloped by the quartz-dioriticporphyrite and shows a regular spatial distribution. From the center of breccia to wall-rock are quartz-dioriticporphyrite, cryptoexplosivemelt-crystal-lithicbreccia, the cryptoexplosive hydrothermal breccia, and the cryptoexplosive fracture breccia, respectively. The spatial relationship between the alterated, mineralized and the cryptoexplosive breccia pipe shows that there exists a genetic link between formation of cryptoexplosive breccia and mineralization. The cryptoexplosion of the melt, liquid and gas originated from intermediate-acid magma induced the
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