Rock-forming mechanism of Qingshanjiao intrusion in Dongguashan copper (gold) deposit, Tongling area, Anhui province, China

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• 作者：Zhong-fa LIU^a ; ^b ; Yong-jun SHAO^a ; ^b ; ^{shaoyongjun@126.com" class="auth_mail" title="E-mail the corresponding author} ; Han-tao WEI^a ; ^b ; Cheng WANG^a ; ^b
• 关键词：Qingshanjiao intrusion ; geological and geochemical characteristics ; rock-forming and geodynamic setting ; magma derivation ; rock-forming ; Dongguashan copper (gold) deposit
• 刊名：Transactions of Nonferrous Metals Society of China
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：26
• 期：9
• 页码：2449-2461
• 全文大小：4291 K

文摘

Dongguashan deposit is a large porphyry-skarn copper (gold) deposit in Tongling ore district. The Qingshanjiao intermediate acid intrusion of Yanshanian had a direct genetic relationship with mineralization. The magma origin, rock-forming dynamic background and rock-forming process were studied, and the rock-forming mechanism of Qingshanjiao intrusion was discussed, based on geological characteristics, detailed observation of petrography and systematic investigation of petrochemistry, trace elements and REE geochemistry characteristics of Qingshanjiao intrusion. The results show that Qingshanjiao rock body belongs to high-K calc-alkaline series with higher LREE elements, Th, Rb and Sr abundance, but depleted in HREE elements, Ba, Nb and Ta. The primary magma originated from the mantle-crust mixtures which were caused by basaltic magma of mantle mixing with syenite magma of partial melting of the lower crust, and the formation environment of Qingshanjiao intrusion was emplaced in the transitional environment from compression to extension. The Harker diagram and hybrid structures of plagioclase and potassium feldspar indicate that the fractional crystallization occurred in the process of magmatic evolution. The petrochemistry, trace elements and REE geochemistry characteristics indicate that the magma was contaminated by crustal material during the rock-forming. These results suggested that the Qingshanjiao intrusion was formed by fractional crystallization and assimilation and hybridization of mantle-crust magma in the transitional environment from compression to extensional.