Phanerozoic continental growth and gold metallogeny of Asia

Gold mineralization in China: Metallogenic provinces, deposit types and tectonic framework

Mesozoic metallogeny in East China and corresponding geodynamic settings — An introduction to the special issue

Tectonic evolution, superimposed orogeny, and composite metallogenic system in China

The giant South China Mesozoic low-temperature metallogenic domain: Reviews and a new geodynamic model

The ore deposits of the Mesozoic age in South China can be divided into three groups, each with different metal associations and spatial distributions and each related to major magmatic events. The first event occurred in the Late Triassic (230–210 Ma), the second in the Mid–Late Jurassic (170–150 Ma), and the third in the Early–Mid Cretaceous (120–80 Ma). The Late Triassic magmatic event and associated mineralization is characterized by peraluminous granite-related W–Sn–Nb–Ta mineral deposits. The Triassic ore deposits are considerably disturbed or overprinted by the later Jurassic and Cretaceous tectono-thermal episodes. The Mid–Late Jurassic magmatic and mineralization events consist of 170–160 Ma porphyry–skarn Cu and Pb–Zn–Ag vein deposits associated with I-type granites and 160–150 Ma metaluminous granite-related polymetallic W–Sn deposits. The Late Jurassic metaluminous granite-related W–Sn deposits occur in a NE-trending cluster in the interior of South China, such as in the Nanling area. In the Early–Mid Cretaceous, from about 120 to 80 Ma, but peaking at 100–90 Ma, subvolcanic-related Fe deposits developed and I-type calc-alkaline granitic intrusions formed porphyry Cu–Mo and porphyry-epithermal Cu–Au–Ag mineral systems, whereas S-type peraluminous and/or metaluminous granitic intrusions formed polymetallic Sn deposits. These Cretaceous mineral deposits cluster in distinct areas and are controlled by pull-apart basins along the South China continental margin. Based on mineral assemblage, age, and space–time distribution of these mineral systems, integrated with regional geological data and field observations, we suggest that the three magmatic–mineralization episodes are the result of distinct geodynamic regimes. The Triassic peraluminous granites and associated W–Sn–Nb–Ta mineralization formed during post-collisional processes involving the South China Block, the North China Craton, and the Indo-China Block, mostly along the Dabie-Sulu and Songma sutures. Jurassic events were initially related to the shallow oblique subduction of the Izanagi plate beneath the Eurasian continent at about 175 Ma, but I-type granitoids with porphyry Cu and vein-type Pb–Zn–Ag deposits only began to form as a result of the breakup of the subducted plate at 170–160 Ma, along the NNE-trending Qinzhou-Hangzhou belt (also referred to as Qin-Hang or Shi-Hang belt), which is the Neoproterozoic suture that amalgamates the Yangtze Craton and Cathaysia Block. A large subduction slab window is assumed to have formed in the Nanling and adjacent areas in the interior of South China, triggering the uprise of asthenospheric mantle into the upper crust and leading to the emplacement of metaluminous granitic magma and associated polymetallic W–Sn mineralization. A relatively tectonically quiet period followed between 150 and 135 Ma in South China. From 135 Ma onward, the angle of convergence of the Izanagi plate changed from oblique to parallel to the coastline, resulting in continental extensional tectonics and reactivation of regional-scale NE-trending faults, such as the Tan-Lu fault. This widespread extension also promoted the development of NE-trending pull-apart basins and metamorphic core complexes, accompanied by volcanism and the formation of epithermal Cu–Au deposits, granite-related polymetallic Sn–(W) deposits and hydrothermal U deposits between 120 and 80 Ma (with a peak activity at 100–90 Ma).

Major types and time–space distribution of Mesozoic ore deposits in South China and their geodynamic settings

Structural features and metallogenesis of the Carlin-type Jinfeng (Lannigou) gold deposit, Guizhou Province, China

The Lannigou gold deposit,also be called Jinfeng gold deposit,is the largest known Carlin-type gold deposit in Yunnan—Guizhou —Guangxi triangle area in southwestern China.Orebodies are tightly confined to faults,known locally as the F3 and F2.The primary hosts mineral for Au are arsenian pyrites characterized by zonal structure.Re-Os dating on 9 arsenian pyrites from ores were analyzed in two times respectively,and yielded data as follows:Re range from 0.1257 to 1.233 ng/g,Os,from 6.75 to 33.50 pg/g.Corresponding isochron age is 193±13 Ma,which demonstrates mineralization age of gold was early Jurassic.Initial n(187Os)/n(188Os)rate is 1.127±0.043,which suggests that the ore-forming materials originated from the crust,but not from the mantle.Genetic modal is proposed that basin fluid continuously extracted materials including Au from basin sediment,and then become ore-containing fluid.The ore-containing fluid moved upward along unconformity between basin and platform and contemporaneous faults during latter Triassic collisional compression.Ore-containing fluid came into decompressional dilatant zone and gold deposited and formed supper-large gold deposit during early Jurassic extension.Large scale gold metallogeny occurred at the transition from collisional compression to extension tectonic.This model matches the metallogeny age and initial rate.

Re-Os Dating of Arsenian Pyrites from the Lannigou Gold Deposit,Zhenfeng,Guizhou Province,and Its Geological Significances

Gejiu is the largest polymetallic tin ore-field over the world. Kafang copper deposit is a main copper provider in Gejiu. There are two kinds of ore-body in Kafang copper deposit. One is stratiform-like ore-body, and the other is contact ore-body. The main wall-rock alterations comprise skarnization, actinolitization and phlogopitization. The analytical results of electron microprobe show that the clinopyroxene is diopside-andradite series. The end member of garnet is dominated by andradite and grossular, with minor spessartine and almandine. Fluid inclusion analysis indicate that the temperature of ore-forming fluid decreased significantly (260-360°C to 160 - 280°C) and the salinity of ore-forming fluid keeps constant basically ( 1.74% - 12.51% to 1.74% -11.93% ) from main mineralization stage to post mineralization stage. Hydrogen isotope analysis and oxygen isotope analysis show that the ore-forming fluid is dominated by magmatic water in the early stage, but in late stage, it could be mixed with magmatic and meteoric water. The compositions of sulfur isotope show that sulfur of stratiform-like ore-body was derived from Triassic basalt, yet both of Triassic basalt and Yanshanian granite provide sulfur for contact ore-body. The compositions of lead isotope show that the source of ore-forming material of stratiform-like ore-body is Triassic basalt, yet the source of lead of contact ore-body is Yanshanian granite.

Geology, geochemistry and genesis of Kafang copper deposit in Gejiu, Yunnan Province

Many researchers have studied the chronology on the micro-disseminated gold deposits in Yunnan-Guizhou-Guangxi triangle area in southwest China in the past ten years.Reported dating methods comprise Rb-Sr dating on alteration minerals and fluid inclusions,Pb-Pb dating of sulphide,and fission-track dating of quartz.The ages reported range from 276 Ma to as young as 82 Ma,and fall into three groups,i.e.276~259 Ma,206 Ma,and 157~82 Ma.Dating methods and ages reported are analyzecl and compared.The relationship between these ages reported and corresponding tectonic-thermal events are discusseol in this paper.It is considered that Permian basalt erupted during the development of the Youjiang Late Paleozoic basin providing partly Au,and that large scale lithospheric extension and related magmatic activity in 110~80 Ma in south China are the dynamic setting for the large scale metallogenesis of micro-disseminated gold deposits in Yunnan-Guizhou-Guangxi triangle area,part of the south China metallogenic province.The high precision dating methods,such as,Re-Os dating of sulphide and ~(40)Ar-~(39)Ar dating of sericites are proposed to date this type of gold deposits.

Chen Maohong

Papers

Major types and time–space distribution of Mesozoic ore deposits in South China and their geodynamic settings

Structural features and metallogenesis of the Carlin-type Jinfeng (Lannigou) gold deposit, Guizhou Province, China

Re-Os Dating of Arsenian Pyrites from the Lannigou Gold Deposit,Zhenfeng,Guizhou Province,and Its Geological Significances

Geology, geochemistry and genesis of Kafang copper deposit in Gejiu, Yunnan Province

A review on the chronology of micro-disseminated gold deposits in Yunnan-Guizhou-Guangxi triangle area,southwestern China