China's First Independent Cobalt Deposit and its Metallogenic Mechanism:Evidence from Fluid Inclusions and Isotopic Geochemistry

The Tuolugou cobalt deposit is the first independent large-scale Co- and Au-bearing deposit discovered in northwestern China. It is located in the eastern Kunlun orogenic belt in Qinghai Province, and occurs conformably in low-grade metamorphic volcano-sedimentary rock series with well-developed Na-rich hydrothermal sedimentary rocks and typical hydrothermal sedimentary ore fabrics. Fluid inclusions and isotopic geochemistry studies suggest that cobalt mineralizing fluid is dominated by NaCI-H20 system, accompanied by NaCI-CO2-H20-N2 system responsible for gold mineralization. Massive, banded and disseminated pyrite ores have similar compositions of He and Ar isotopes from the mineralizing fluid, with 3He/4He range between 0.10 to 0.31Ra （averaging 0.21Ra）, and 4~Ar/36Ar between 302 and 569 （averaging 373）, which reflects that Co mineralizing fluids derived dominantly from meteoric water deeply circulating. ~34S values of pyrite approaches to zero （~34S ranging from -4.5%o to ＋1.5%o, centering around -1.8%o to -0.2%o）, reflecting its deep source. Ore lead is characterized by distinctly high radiogenesis, with 2~6pb/2~4pb〉19.279, 2~7pb/2~4pb〉15.691 and 2~spb/2~4pb〉39.627, and its values show an increase trend from country rocks, regional Paleozoic volcanic rocks to ores. This may have suggested that high radiogentic ore Pb derived mainly from country rocks by leaching meteoric water-dominated hydrothermal fluid during its circulation at depth. Cobalt occurs mainly in sulfide phase （such as pyrite）, but cobalt enrichment, and presence and increasing contents of Co-bearing minerals have a positive correlation with metamorphic degree. The Tuolugou deposit and other typical strata-bound Co-Cu-Au deposits have striking similarities in the geological features and metallogenic pattern of primary cobalt. All of them are syngenetic hydrothermal exhalative sedimentation in origin.

The Latest In-Situ Uraninite U-Pb Age of the Guangshigou Uranium Deposit, Northern Qinling Orogen, China: Constraint on the Metallogenic Mechanism

Objective The Guangshigou uranium deposit is located in the eastern part of the Shangdan triangular domain, which is currently the most productive pegmatite-hosted uranium deposit in China. Previous studies have focused on the migration and precipitation of uraninite and biotite clusters in the uraniferous pegmatites(Li Yanhe et al., 2016; Yuan et al., 2018). However, the accurate uranium mineralization age still remains poorly constrained, thus

Discussion on Middle Jurassic metallogenic mechanism of Au-Mo polymetallic hydrothermal deposits in eastern Jilin

In the Middle Jurassic,a large-scale tectonic-magmatic activities and hydrothermal mineralization occurred in the eastern Jilin province.The deposit types consist of the orogenic gold deposit,porphyry molybdenum deposit and skarn gold deposit,etc.,which constitute regional hydrothermal metallogenic series.The magmatic bodies related to mineralization belong to calc-alkaline series,which are characterized by active continental margins.The above-mentioned different types of deposits formed in a uniform tectonic setting,which resulted from the combined processes between the subduction of Pacific plate under the Eurasia plate and the persistent post-collisional convergent forces between the North China plate and the Siberian plate.The mineralizations were happening in the deceleration period,after which Paleo-Pacific plate was strongly subducted under the Eurasia continental block,i.e.transition period from compression to extension.

Deep metallogenic mechanism in southeastern China based on receiver function data

Crustal deformation and deep metallogenic mechanisms in southeastern(SE)China are still debated.In this study,we applied the receiver function method to measure crustal thickness and Poisson’s ratio for crustal rock using teleseismic data recorded at 207 seismic stations from China Earthquake Administration Network.The results showed that crustal thickness varied from~27 km in the eastern part to~43 km in the western part of the study area,with an average crustal thickness of 31 km.The crust is thick in the west and thin in the east.The observed Poisson’s ratio for crustal rock was relatively high in the southern Cathaysia Block(CB),with an average of 0.295,while in the Qinling—Dabie terrane,it was relatively low,with an average of 0.257.In the middle of the Yangtze craton and central east of the CB,Poisson’s ratio for crustal rock varied from 0.257 to 0.286.By comparing Poisson’s ratio of the intrusive deposits with that of igneous rocks in volcanic complexes,we deduced that the metallic mineral system might be associated with orogenic and hydrothermal deposits.These results indicated that multistage magma and mineralization in the study area might be attributed to the tectonic-magma-thermal event.The high Poisson’s ratio for crustal rock in the southeastern margin of the CB and northeastern Upper Yangtze Craton might be related to Mesozoic lower crustal mafic partial melt,which provides an important environment for various magmatic intrusions and metallogenies.

The Geochemical Characteristics and Metallogenic Mechanism of the Daliangzi Pb-Zn Deposit in Sichuan Province

1 Introduction Daliangzi large-sized Pb-Zn deposit,located in the Western Margin of Yangtze Plate,is typical Pb-Zn deposit in the sichuan-yunnan-guizhou polymetallic metallogenic belt.Ore bodies are hosted in Sinian

Research and exploration progress on lithium deposits in China

Since 2012,some advances have been made through the resource investigation,metallogenesis research,and comprehensive utilizing of lithium deposits in China.Firstly,the progress of lithium exploration has been made in Sichuan,Xinjiang,Qinghai and Jiangxi provinces(autonomous region).Li deposits are not only found within the pegmatite rocks but also within the granitic rocks and sedimentary rocks.Secondly,the methods of geological survey,geochemical and geophysical exploration,remote sensing technology and even drilling technology have been improved,which can be delineating orebodies quickly.Thirdly,the mechanisms of Li mineralization were summarized by analyzing the relationship between the Li contents and kinds of geological phenomena.Based on practice,a new understanding of"multi-cycle,deep circulation,integration of internal and external"metallogenic mechanism or"MDIE"metallogenic mechanism for short has been put forwarded further in this paper,and the"five levels+basement"exploration model has been successfully expanded to guide the prospecting work both in the Jiajika and Keeryin pegmatite ore fields in western Sichuan Province.Besides,new progress has been made in the aspect of amblygonite deposits of granite-type and hydrothermal type in the Mufushan-Jiuling ore district,which points out a new direction for prospecting new types of lithium deposits in China.

A 3D Investigation of Geological Structure and Its Relationship to Mineralization in the Nanling-Xuancheng Ore District,Middle-Lower Yangtze River Metallogenic Belt,China

The Nanling-Xuancheng ore region of Anhui Province is located in the Middle-Lower Yangtze River metallogenic belt.Insufficient exploration and research have been carried out in this newly defined ore district,although the Chating large porphyry Cu-Au deposit and a few middle-sized skarntype Cu polymetallic deposits have been discovered.In this study,we carried out high-resolution seismic reflection,magnetotelluric,gravity,and magnetic investigations,and constructed the 3 D geological structure of the uppermost crust in a depth range of 0-5 km using a comprehensive inversion of the new data constrained by previous deep-drilling data.We hence proposed some new insights to understand the mineralization processes of this district.A system of alternating ridges and valleys is suggested as the major structure pattern,composed of“two-layer structure”of the basins and“three-layer structure”of anticlines.Moreover,a conjugated fault system and its distribution features are revealed in our models,including the Jiangnan fault,Zhouwang fault,and Kunshan thrust nappe.The Jiangnan and Kunshan faults are suggested to have controlled the diagenesis and metallogenesis.Two deep concealed plutons located in Chating and Magushan are found,forming the Mesozoic diorite-felsic intrusions.These intrusions are believed to be the causes of hydrothermal deposits such as the Chating deposit and the Magushan deposit.