Zhongfa Liu

The geology and geochemistry of the Shizitou molybdenum deposit, Jiangxi province, China: Implications for the geodynamic setting

The Qin-Hang suture zone is the most important polymetallic metallogenic zone in southern China [1-2] and has the greatest resource potential. In recent years, a group of molybdenum (Mo) deposits have been discovered in the northeastern part of the Qin-Hang belt [3]. From Mar. 2006 to Dec. 2014, the Jiangxi Copper Group Geological Exploration Engineering Co., Ltd. conducted prospecting, preliminary exploration and detailed exploration in the Shizitou Mo deposit. The current reserves of the deposit have reached medium size. This paper attempts to characterize the timing of ore formation and the dynamic background of ore formation.

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

Abstract 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.

Identification of Composite Rock Body in Dongguashan Copper (Gold) Deposit, Anhui Province

Dongguashan Copper (gold) deposit is located in the northeast of the Yangtze craton, which belong to the lower Yangtze Syneclise Fanchang Guichi concave fault-fold belt (Tang et al., 1998). It occurred in North East section of Qingshan anticline, secondary structure of DatongShunan multiple syncline. The formation closely related to mineralization including upper Devonaian Wutong formation (D3w) quartz sandstone, middle-upper Carboniferous Chuanshan and Huanglong formation (C2+3) carbonate rock, lower Permian Qixia formation (P1q) limestone, chert and skarn. The complex reticular structure-framework in this area is compesed of NE trending folds and faults of Indosinian and nearly SN-, EWand NNE trending faults, interlayer structure and joint. Magmatic rock emplaced along the complex structure systems, showed dyke and apophysis in shallow. Qingshanjiao composite rock body is closely related to mineralization, composed by granodiorite and porphyraceous quartz monzodiorite.