Zhang W.Y.,Peking University |
Nie F.J.,Institute of Mineral Resources |
Gao Y.G.,Peking University |
Liu Y.,Institute of Mineral Resources
Acta Petrologica Sinica | Year: 2012
Many Triassic alkaline granites have been discovered in southern Siberian plate margin in recent years, and these alkaline granites construct an alkaline granite belt. The Chagan Obo quartz diorile is an important intrusion in this alkaline granite belt. Its formation age was determined as 237Ma using SHRIMP U-Pb method. These alkaline quartz diorites in this intrusion display their SiO 2 contents of 60.70% to 62.67% with an average value of 61.76%, K 2O + Na 2O contents of 9.18% to 10.48% with an average value of 9.74%, and Na 2O > K 2O. These rocks are characterized by total rare earth concentrations from 236.3 × 10 -6 to 260.0 × 10 -6 with an average of 246.5 × 10 -6 and right-decline REE distribution models with EREE/HREE ratios of 18.91 to 20.11 with an average value of 19.48 and slightly negative Eu anomaly. Similarly, they are also characterized by high Sr and Ra but low Y, exhibit Sr, Ra and Y concentrations of 1216 ×10 -6 to 2028 × 10 -6 ( average value of 1707 ×10 -6), 1597 × 10 -6 to 1947 × 10 -6 ( average value of 1717 × 10 -6), and 12.9 × 10 -6 to 16.5 × 10 -6 (average value of 15.3 × 10 -6), respectively. These geochemieal features suggest they belong to adackite-like lithological assemblage. The quartz diorite lithological assemblage shows higher 206Pb/ 204 Pb ( from 18.172 to 18.529 with an average value of 18.314), 208Pb/ 204 Pb (from 37.831 to 38.120 with an average value of 38.016), and ε Nd(t) (from 3.3 to 3.8 with an average value of 3.5) but low 207Pb/ 204Pb ( from 15.465 to 15.529 with an average value of 15.503) and initial 87Sr/ 86Sr values (from 0.70405 to 0.70411 with an average value of 0.70408), which suggest that the original magma of the quartz diorites was derived from partial melting of residual subducted oceanic slabs after collision between Siberia and China-Korean plates. This original magma was contaminated by ultramafie and K-enriched alkaline fluids. Therefore, these quartz diorites are synchronous products of Triassic alkaline granitoid magmatism in northern margin of Sino-Korean plate. The paper provides new evidence for the end time of finally collision between Siberian and Sino-Korean plates.
Li H.,Institute of Mineral Resources |
Wang X.,Institute of Mineral Resources |
Ye H.,Institute of Mineral Resources |
Yang L.,China National Offshore Oil Corporation
Acta Geologica Sinica | Year: 2012
The Mesozoic porphyry assemblage in the Jinduicheng area is a special molybdenum area in China, the Mo deposits, including the Jinduicheng, Balipo, Shijiawan, Huanglongpu, are distributed. The emplacement age and geochemical features of the granites in the Jinduicheng area can provide essential information for the exploration and development of the porphyry molybdenum deposit. In this study, we report LA-ICP-MS zircon U-Pb age and zircon Hf isotopic compositions of granite porphyries from the Jinduicheng area, and provide insights on the petrogensis and source characteristics of the granites. The results show that the zircon U-Pb ages of the Jinduicheng granite porphyry (143±1 Ma) and the Balipo granite (154±1 Ma), agree well with the Re-Os ages of molybdenite in the Jinduicheng molybdenum polymetallic deposit (139±3 Ma) and the Balipo molybdenum polymetallic deposit (156±2 Ma), indicating that the emplacement of granite porphyries occurred between Late Jurassic and Early Cretaceous. Zircons granite from the Jinduicheng area give the values mainly ranging from -10 to -16, and -20 to -24, respectively, corresponding to two-stage model ages (fane: mainly focused on 1.86-2.0 Ga, and 2.2-2.6 Ga, respectively) of zircons of the granite from the Jinduicheng values. The ore-forming materials are mainly derived from crust, with minor mantle substances. Zircons of the granite from the Balipo area give ε Hf (t) values ranging from -18 to -20, -28 to -38, and -42 to -44, respectively, corresponding to two-stage model ages (t dm2= mainly focused on 1.88-3.0 Ga, and 3.2-3.90 Ga, respectively), the ε Hf (t) values of the Jinduicheng porphyry more than that of the Balipo porphyry, and two-stage model ages (foiva) less than that of the BaUpo porphyry, shows that he source of the porphyries originated from ancient lower crustal materials in the Jinduicheng area, and mixed younger components, more younger components contributed for the source of the Jinduicheng porphyry.
Chronology of the tungsten deposits in southern Jiangxi Province, and episodes and zonation of the regional W-Sn mineralization -evidence from high-precision zircon U-Pb, molybdenite Re-Os and muscovite Ar-Ar ages
Feng C.,Institute of Mineral Resources |
Zhang D.,Institute of Mineral Resources |
Zeng Z.,South Jiangxi Geological Survey Party of JBEDGMR |
Wang S.,China Coal Technology and Engineering Co.
Acta Geologica Sinica | Year: 2012
Previous studies have obtained some petrogenetic and metallogenic chronological data with SHRIMP (sensitive high-resolution ion microprobe) zircon U-Pb, zircon LA-ICPMS (laser-ablation-inductively coupled plasma mass spectroscopy) U-Pb, molybdenite Re-Os isochron and muscovite Ar-Ar methods in southern Jiangxi Province and its adjacent areas. Based on these, the purpose of this paper is to study the petrogenetic and metallogenic ages and their time gap for different genetic types of W-Sn deposits, and thus to research their numerous episodes, zonal arrangement and their geodynamic background. The result shows that the large-scale W-Sn mineralization in southern Jiangxi Province occurred in the middle to late Jurassic (170-150 Ma), the skarn W-Sn-polymetallic deposits formed much earlier (170-161 Ma), and all of the wolframite - quartz vein type, greisen type, altered granite type and fractured zone type tungsten deposits formed in the late Jurassic (160-150 Ma). In one ore field or ore district, greisen type tungsten deposits formed earlier than quartz vein type ones hosted in the endo- or exo-contact zone; and quartz vein type hosted in the endocontact zone formed earlier than that of exocontact zone. There is no significant time difference between tungsten-tin mineralization and its intimately associated parent granite emplacement (1-6 Ma). They all formed in the same rock-forming and ore-forming system and under the same geodynamic setting. Regionally, rock-forming and ore-forming processes of the W-Sn deposits in the Nanling region (include southern Jiangxi Province, southern Hunan Province, northern Guangdong Province and eastern Guangxi Zhuang Autonomous Region) exhibit numerous episodes. The mineralization in the Nanling region mainly occurred at (240-210) Ma, (170-150) Ma and (130-90) Ma. The tungsten-tin deposits in this region are centered by the largest scale in southern Jiangxi Province and southern Hunan Province, and become small in the east, west, south and north directions. This displays a zonal arrangement and temporal and spatial distribution regularity. Integrated with the latest research results, it is concluded that the W-Sn mineralization in southern Jiangxi Province and its adjacent areas corresponds to the second large-scale mineralization in South China. The Indosinian W-Sn mineralization formed under the extensional tectonic regime between collisional compressional stages, while the Yanshanian large-scale petrogenetic and metallogenic processes occurred in the Jurassic intraplate extensional geodynamic setting of lithosphere extension.
Zhang R.,Institute of Mineral Resources |
Zhang X.,Institute of Mineral Resources |
Guy B.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP |
Hu S.,Institute of Mineral Resources |
And 2 more authors.
European Journal of Mineralogy | Year: 2013
Steady-state pyroxene dissolution rates in aqueous solutions have beenmeasured at temperatures from 25 to 374 °Cat a pressureof 23 MPa and at neutral pH. The pyroxene is hedenbergitic clinopyroxene, of composition Na 0.04Ca0.95Mg0.3Fe2+ 0.64Fe3+ 0.06Al0.04Si 1.97O6. All experiments were performed at conditions far from equilibrium in Ti-alloy mixed-flow reactors. In most runs, the reactive solutions were undersaturated with respect to pyroxene and secondary minerals were rarely found at the reacted surface. The dissolution is non-stoichiometric in most cases, while the different chemical elements of the pyroxene are released at different rates. Stoichiometric steady-state dissolution was obtained in neutral solution at 100 °C. The release rates of the different elements vary with temperature and solution chemistry. The dissolution rates (rSi) in neutral pH conditions increase with temperature from 25 to 300 °C, reach a maximum at 300 °C, and then decrease with continued temperature increase. At a given temperature, the rates decrease significantly with increasing pH of the reactive fluid and are also affected by the activities of Ca, Mg, Fe in the solution. At neutral pH, the dependence of the pyroxene dissolution rates on activities of Ca, Mg, Fe and H+ in the fluid can be expressed by the relation: log r+ (T, ai) = log (A - Ea/d2.303 RT) + α log (aH+)Zi/a Mi Zi+) where r+ is the far-from-equilibrium dissolution rate, R the gas constant, T the absolute temperature, Zi valence of metal Mi and ai represents the activity of the subscript aqueous species. Ea equals 22.667 kJ/mole/K and A = 2.011 × 10 -7 mole/cm2/s; α is the empirical reaction rate order, which can be derived from the experimental results. At temperatures below 300 °C, the exchange reactions 2H+ ← Mi 2+, where Mi 2+ refers to divalent cations Mg2+, Fe2+ or Ca2+, dominate in the dissolution. The following evolution of the dissolution with temperature is proposed: at 300 °C, the tetrahedral Si-O bonds break after the Mi 2 +-O bonds in adjacent octahedral positions have been removed by proton exchange reaction, whereas, above 300 °C, the breaking of the octahedral Mi2 +-O bonds occurs after adjacent tetrahedral Si-O bonds have been broken. © 2013 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart.
Seltmann R.,Natural History Museum in London |
Konopelko D.,Saint Petersburg State University |
Biske G.,Saint Petersburg State University |
Divaev F.,Institute of Mineral Resources |
Sergeev S.,Russian Geological Research Institute VSEGEI
Journal of Asian Earth Sciences | Year: 2011
The Hercynian Tien Shan (Tianshan) orogen formed during Late Palaeozoic collision between the Karakum-Tarim and the Kazakhstan paleo-continents. In order to constrain timing of Hercynian post-collisional magmatism, 27 intrusions were sampled for U-Pb zircon dating along a ca 2000 km - long profile in Uzbekistan and Kyrgyzstan. The samples were dated utilizing sensitive high resolution ion microprobe (SHRIMP-II). The obtained ages, together with previously published age data, allowed the timing of Hercynian post-collisional magmatism to be constrained and interpreted in the context of the Paleozoic magmatic evolution of the region. Apart from Hercynian post-collisional magmatism, two older magmatic episodes have been recognized, and the following sequence of events has been established: (1) approximately 10 Ma after cessation of continuous Caledonian magmatism a number of Late Silurian-Early Devonian intrusions were emplaced in the Middle and Northern Tien Shan terranes between 420 and 390 Ma. The intrusions probably formed in an extensional back arc setting during coeval subduction under the margins of Caledonian Paleo-Kazakhstan continent; (2) the next relatively short Late Carboniferous episode of subduction under Paleo-Kazakhstan was registered in the Kurama range of the Middle Tien Shan. Calc-alkaline volcanics and granitoids with ages 315-300 Ma have distinct metallogenic affinities typical for subduction-related rocks and are not found anywhere outside the Middle Tien Shan terrane west of the Talas-Farghona fault; (3) the Early Permian Hercynian post-collisional magmatism culminated after the closure of the Paleo-Turkestan ocean and affected the whole region across terrane boundaries. The post-collisional intrusions formed within a relatively short time span between 295 and 280 Ma. The model for Hercynian post-collisional evolution suggests that after collision the Tien Shan was affected by trans-crustal strike-slip motions which provided suitable conduits for ascending asthenospheric material and heat influx in the crust. This produced both granitoid magmas and hydrothermal fluid flow. As a result post-collisional intrusions and orogenic Au deposits, known in the region, formed coevally and were tectonically controlled; (4) between 240 and 220 Ma a Triassic thermal event affected the region resulting in resetting and growth of new zircon grains which is detected on a regional scale. Probably the influx of heat into the crust during the Triassic was tectonically focused and varied significantly in different terranes. In the region under investigation the Triassic thermal event was not accompanied by any significant magmatic activity. Thus, after cessation of Hercynian post-collisional magmatism ca 280 Ma ago there was a long magmatically quiet period in the Tien Shan. © 2010.
Qin Y.,Chinese Academy of Geological Sciences |
Wang D.,Institute of Mineral Resources |
Wu L.,Anhui Geological Survey |
Wang K.,Anhui Geological Survey |
Mei Y.,Yichang Institute of Geology and Mineral Resources
Acta Geologica Sinica | Year: 2010
Dongyuan W deposit is a newly-found large-scale scheelite deposit, which is also the biggest one in south of Anhui province. The discovery of the Dongyuan W deposit set the direction for mineral exploration and laid groundwork for further exploration. This paper preliminarily analyzed regional structural background and metallogenic controlling factors, firstly obtained U-Pb age of zircon by using SHRIMP. The results showed that ore-forming age of the granite-porphyry in the Dongyuan porphyry W deposit is 148. 6 ±1. 8 Ma (n = 16, MSWD=1. 5), and the granite porphyry rock was product of late Jurassic magmatic movement. The results also suggested that the regional tungsten mineralization might extend from South China to the Middle and Lower Reach of the Yangtze River.
Nurtaev B.,Institute of Geology and Geophysics |
Kharin V.,Institute of Mineral Resources |
McCann T.,University of Bonn |
Valdivia-Manchego M.,University of Bonn
Journal of Geodynamics | Year: 2013
The Nuratau Fault Zone in eastern Uzbekistan forms part of the western prolongation of the Tien Shan, an extensive orogenic zone located along the margin of the Central Asian Orogenic Belt. The Nuratau region is geologically complex, forming part of the suture zone between the Kazakh-Kyrgyz continent and the Alai microcontinent. A model is proposed suggesting modified N-directed subduction model, where an extensive fold-and-thrust belt developed in the Nuratau region. This, coupled with significant transform activity would have resulted in major segmentation of the existing stratigraphy in the region, as well as the development of a foredeep basin to the north of the fold-and-thrust belt. Regional suturing and collision was variable. Indeed, the collisional history probably involved multi-phase subduction/accretion of various microcontinents, ancient island arcs, and fragments of oceanic islands. Final collision would have produced an eroding basinal high in the region of the Nuratau mountains, which issued sediment both northwards into the remnant basin of the Turkestan Ocean, but also to the south into the newly forming Amu Darya Basin. © 2013.
Zeng Q.,University of Western Australia |
Zeng Q.,Institute of Mineral Resources |
Mccuaig T.C.,University of Western Australia |
Tohver E.,University of Western Australia |
And 2 more authors.
Geological Journal | Year: 2014
The Qinling Orogen is located between the North China and South China cratons. The Mianlue Suture is the key boundary between the orogen and the South China Craton marking where the South China Craton subducted northward beneath the North China Craton during the late Triassic. Another older suture, the Shangdan Suture, divides the orogen into the North Qinling and South Qinling terranes. Our new geochronological data on eight granite plutons in the South Qinling Terrane indicate that the major phase of the Zhongchuan Granite is 219.5±2.1Ma, Luchuba is 217.1±1.0Ma, Baijiazhuang is 215.9±3.0Ma, Jiaochangba is 213.9±1.7Ma, Lvjing is 214.5±2.1Ma, Xiba is 215.6±1.8Ma, Wenquan is 217.3±2.1Ma and Fengxian is 240.9±1.0Ma. Compiled results reveal widespread magmatism began in the northwestern part of the South Qinling Terrane at ~240-250Ma and episodically progressed to the southeast in the North Qinling Terrane. Magmatism was then widespread throughout the South Qinling Terrane during the Late Triassic. A new division of Triassic intrusions has been proposed across the Qinling Orogen based on critical geochemical and geochronological differences. First, the western part of the South Qinling Terrane, (western South Qinling suite), is significantly enriched in large ion lithophile elements, including Cs, Rb, U, Th and K, whereas the eastern part of the South Qinling Terrane, (eastern South Qinling suite), has moderate enrichment in these elements. Second, there is an obvious transition from calcium to potassium enrichment in the Late Triassic western-South-Qinling suite, whereas the Late Triassic eastern South Qinling suite appears to follow a curved trajectory starting from high Na through K to high Ca. Third, the Ba and Sr concentrations of the western South Qinling suite have marked troughs, whereas the eastern South Qinling suites have relative enrichment of the two elements. The source of the Triassic magma becomes increasingly juvenile towards the east-southeast in the Qinling Orogen. Geochemical and isotopic data indicate that there are differences in the granites across the Chengxian-Huixian-Fengxian Fault within the western South Qinling Orogen, which highlight the tectonic significance of this northeast-trending fault that is now recognized as a significant boundary within the orogen. The identification of such a large-scale structure should attract some exploration attention, since this fundamental lineation is likely to be associated with some large mineral systems. © 2014 John Wiley & Sons, Ltd.
Zhang R.H.,Institute of Mineral Resources |
Zhang X.T.,Institute of Mineral Resources |
Hu S.M.,Institute of Mineral Resources
Sensors and Actuators, B: Chemical | Year: 2013
This H2S sensor, constructed from an Ag/Ag2S-based sensing element and coupled with a Zr/ZrO2 reference electrode, and YSZ/HgO/Hg electrode, had been tested for its potential response to H 2S concentrations in fluids at temperatures from 0 °C to 400 °C and pressures up to 25 or 33 MPa, and is well suited for determining dissolved H2S concentrations in aqueous media at elevated temperatures from 0 °C to 400 °C and at high pressures. The Ag/Ag 2S electrode is made of an Ag wire with an Ag2S film coating, which can be pressurized and heated at high pressures and temperatures. The Nernstian response of the Ag/Ag2S-YSZ/HgO/Hg cell potential to H2S concentrations at 400 °C and 25 MPa is described as.ΔE(V)=0.625+0.0667logmH2S The Nernstian response of the Ag/Ag2S-Zr/ZrO2 potential to H2S at 1 °C and 33 MPa is described as:ΔE(V)=-0.261-0.02966logmH2S. © 2012 Elsevier B.V. All rights reserved.
Nie F.-J.,Institute of Mineral Resources |
Jiang S.-H.,Institute of Mineral Resources
Resource Geology | Year: 2011
Twenty-one Mo-W-Cu deposits and prospects have been discovered in the Honggor-Shamai district, Inner Mongolia, north China during past 5 years. This district is located in the central and western parts of the Chagan Obo-Aoyoute-Chaobulen tectono-magmatic belt, which is part of the Central Asian Orogenic Belt. The Mo-W-Cu deposits in the district are associated with Mesozoic granitoid intrusions and occur as veins, stockwork, and dissemination. The geological features of these newly discovered deposits are similar to porphyry-type deposits worldwide. Two mineralization events have been identified: Indosinian (235-224Ma) and Yanshanian (137-131Ma). It is proposed that these deposits and prospects in the Honggor-Shamai district were related to the post-collisional extension linked to the Indosinian orogeny during the Middle-Late Triassic period, but some of those deposits were overprinted by mineralization associated with the Cretaceous magmatic-hydrothermal (Yanshanian) event. © 2011 The Authors. Resource Geology © 2011 The Society of Resource Geology.