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Ren T.,No. 713 Geological Team | Wang R.-T.,Northwest Bureau of Geological Exploration for Nonferrous Metals | Wang R.-T.,Changan University | Meng D.-M.,Changan University | And 3 more authors.
Northwestern Geology | Year: 2014

On the basis of summing up geological setting and feature of Xiajiadian gold deposit, Shanyang County, Shaanxi province, this paper researched ore-controlled factors, statistic distribution law of ore-forming elements, metallogenic fluid characteristics, isotope features, and created a metallogenic model of this gold deposit. The gold ore body is mainly controlled by ore-bearing rock series and secondary fault in Zhen'an-Banyanzhen fracture. From surface to deep, the grade and thickness of gold ore show wave transformation, and display thinning out and recurrence in trend. Its fluid inclusion mostly consists of gas-liquid two-phase, which is featured by rich CO2 (10%) and low salinity (3%-5%). The homogeneous temperature of main mineralization period concentrates between 240-280 °C , and the metallogenic depth is 3 km. Isotope analysis indicates that metallogenic fluid mainly derives from mix of meteoric water and formation water, with a small part from the deep. In view of the findings, we founded a metallogenic model of Xia-jiadian gold deposit, and concluded that the gold mine was predominantly a tectonic-fluid deposit of orogenic-type, which formed by the sedimentation of mineral substances cyclically leached from ore source bed by underground hot brine driven by gcothcrmal or magma.

Li X.,China University of Geosciences | Li X.,Chinese Academy of Geological Sciences | Wang Y.,Chinese Academy of Geological Sciences | Wang R.,Northwest Bureau of Geological Exploration for Nonferrous Metals | And 4 more authors.
Acta Petrologica Sinica | Year: 2010

The Simaoling gold deposit, located in the Fengtai ore concentration area of the western Qinling and 5km to the west of the super-large Baguamiao orogenic gold deposit, is a new proved Au deposit related to the shear zone. The gold mineralization could be divided into three stages: The early quartz-sericite-sulfide stage, the middle polymetallic sulfide stage, and the late carbonation stage. Studies on fluid inclusions of the early and the middle stages show that the ore-forming fluids belong to the low salinity CO 2-H2O system with intermediate temperature. The diversity of fluid inclusion types is resulted from the fluid immiscibility. In the metallogenic stage, temperature, pressure and salinity of fluids are lower, and the sulfur fugacity is higher, which are in favor of gold precipitation. By contrast with the Baguamiao gold deposit, H, O, S, and C isotope studies indicate that ore-forming fluids of both deposits are derived from the same deep source, and finally mixed with shallow fluids. Due to the Simaoling deposit occurred in higher level than that of the Baguamiao deposit, the gold mineralization is developed in more open environment.

Dai J.-Z.,Northwest Bureau of Geological Exploration for Nonferrous Metals | Li Y.-Q.,Northwest Bureau of Geological Exploration for Nonferrous Metals | Wang S.-J.,717 Team of Northwest Bureau of Geological Exploration for Nonferrous Metals | Liu C.,Shaanxi Nuclear Institute of Geological Survey | And 3 more authors.
Geological Bulletin of China | Year: 2011

Jiuzigou deposit is a newly discovered copper deposit in the Fengxian-Taibai Pb-Zn polymetallic ore district. Siliceous, silicified limestone and quartz-calcite are the main mineralization types. Ore bodies in layered, stratoid and lenticular forms are in conformable contact with the host rocks and cut by late quartz-calcite veins, forming rich ore bodies. Combining geological features with geochemical characteristics, the authors hold that this ore deposit is of the SEDEX-rebuilt type. The Jiuzigou deposit and other ore deposits in this region constitute a typical SEDEX element zoning model. This discovery, in combination with other structural characteristics, will play a significant role in guiding the future exploration in this area.

Dai J.-Z.,Northwest Bureau of Geological Exploration for Nonferrous Metals | Yuan X.-D.,No. 7 7 Geological Party | Chen S.-X.,Bureau of Mineral Resources | Li Y.Q.,Northwest Bureau of Geological Exploration for Nonferrous Metals | And 5 more authors.
Geology in China | Year: 2011

The Wenjiangsi ore deposit in the eastern extension of the West Qinling oroganic belt is a newly - discovered gold deposit hosted in a Triassic (carbon-bearing) calcareous slate sequence. Lenticular ore bodies and ore spots are characterized by disseminated mineralization with Au -As -Sb - Hg -Pb -Zn low -temperature assemblages. From the ore and argillaceous slate to granite veins, Al2O3 and alkaline components (K2O + Na2O) increase, accompanied by decreasing of CaO and K 2O/Na2O. Trace elements (e.g., As, Bi, Co, Ni, Cu, W, V, Tu and U) and REE patterns (∑ REE, LREE/HREE) of disseminated ores are similar to things of hosted calcareous slates, indicating that metals were derived from hosting strata instead of from magmatic intrusions. The discovery of the Wenjiangsi gold deposit makes it possible for further eastward extension of the West Qinling Triassic sequence.

Dai J.-Z.,Northwest Bureau of Geological Exploration for Nonferrous Metals | Dai J.-Z.,Chinese Academy of Geological Sciences | Xie G.-Q.,Chinese Academy of Geological Sciences | Wang R.-T.,Northwest Bureau of Geological Exploration for Nonferrous Metals | And 2 more authors.
Geology in China | Year: 2012

The Yajishan Mo (Cu) deposit is located in southern Xilamulun Mo (Cu) metallogenic belt on the northern margin of North China block, which is one of the largest Mo metallogenic belts in China. Its major ore bodies occur in the vein like or cataclastic form in the monzonitic granite, stricdy controlled by EW- and NEstriking faults. The deposit is obviously of the quartz vein type, and the sulfides in ore veins are dominated by molybdenite, pyrite and chalcopyrite and show veined and disseminated forms in the monzonitic granite. The authors carried out molybdenite Re-Os dating to better understand the mineralization time. Re-Os dating of seven different types of molybdenite separates from the major Mo mineralized bodies gave a weighted average model age of 241.1 + 1.4 Ma, and six samples of the same type yielded isochron age of (240+3.8) Ma. The Re-Os isochron age represents the ore-forming time of the Mo (Cu) deposit and constrains the age of the monzonitic granite to Early - Middle?Triassic. This result not only provides new evidence for the study of molybdenum deposits in the Xilamulun Mo (Cu) metallogenic belt but also has important significance for discussing the largescale mineralization in Early-Middle Triassic on the northern margin of North China block. The corresponding geodynamic background was the closure of the Paleo-Asian Ocean.

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