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Wu G.,Chinese Academy of Geological Sciences | Wu G.,Henan Lingbao Jinyuan Mining Ltd Liability Company | Chen Y.,Chinese Academy of Geological Sciences | Chen Y.,Peking University | Zeng Q.,University of Western Australia
Journal of Asian Earth Sciences | Year: 2012

The basement of the Argun massif in the northern Great Hinggan Range consists of the metamorphic supracrustal rocks of the Xinghuadukou Group and associated granitic complexes. The metamorphic supracrustal rocks were previously interpreted as Paleoproterozoic, while the granitic complexes were considered Mesoproterozoic in age. This paper presents new zircon LA-MC-ICP-MS U-Pb ages of biotite-plagioclase leptynite and biotite schist from the Xinghuadukou Group in the Lulin Forest area, Heilongjiang Province; zircon SHRIMP U-Pb ages of biotite-plagioclase gneiss from the Xinghuadukou Group in Lulin Forest; and quartz diorite and monzogranite from the granitic complexes in Mohe County, Heilongjiang Province. New geochronological data from the three metasedimentary rock samples of the Xinghuadukou Group can be preliminarily divided into five groups: (1) 2017-2765. Ma, (2) 1736-1942. Ma, (3) 1359-1610. Ma, (4) 749-1239. Ma, and (5) 448-716. Ma. Except for the zircons of the 448-716. Ma group belonging to a metamorphic origin, the other age groups had the youngest age of 749 ± 17. Ma, indicating that the Xinghuadukou Group formed during the Neoproterozoic era (at least <749. Ma). These detrital zircon ages cluster at ca. 2.0-1.8. Ga and ca. 1.0-0.80. Ga, suggesting that the Argun massif had connections with both Columbia and Rodinia and implying that the provenance of the Xinghuadukou Group metamorphosed sediments must be characteristic of felsic-intermediate igneous rocks with ages of ca. 2.0-1.8. Ga and ca. 1.0-0.80. Ga. The quartz diorite and monzogranite from the granitic complexes of the basement within the Argun massif yielded weighted mean ages of 516 ± 10. Ma and 504 ± 9. Ma, respectively, indicating that these rocks emplaced in the Early Paleozoic. Considering the geochemical and chronological data together, we propose that the Xinghuadukou Group was most likely deposited in a back-arc basin environment, whereas the granitic complexes emplaced in a post-collisional setting. A wide age spectrum of detrital zircons ranging from 749 ± 9 to 2765 ± 11. Ma with ages clustering approximately 2.0-1.8. Ga and 1.0-0.80. Ga suggests that the basement rocks of the Argun massif are chiefly composed of the Neoproterozoic metasedimentary sequence and Early Paleozoic granitic complexes, with a few Meso- to Paleoproterozoic and even Neoarchean metamorphic rocks. © 2011 Elsevier Ltd.


Wu G.,Chinese Academy of Geological Sciences | Wu G.,Henan Lingbao Jinyuan Mining Ltd Liability Company | Chen Y.,Chinese Academy of Geological Sciences | Li Z.,Henan Lingbao Jinyuan Mining Ltd Liability Company | And 3 more authors.
Journal of Asian Earth Sciences | Year: 2014

The Yinjiagou Mo-Cu-pyrite deposit of Henan Province is located in the Huaxiong block on the southern margin of the North China craton. It differs from other Mo deposits in the East Qingling area because of its large pyrite resource and complex associated elements. The deposit's mineralization process can be divided into skarn, sulfide, and supergene episodes with five stages, marking formation of magnetite in the skarn episode, quartz-molybdenite, quartz-calcite-pyrite-chalcopyrite-bornite-sphalerite, and calcite-galena-sphalerite in the sulfide episode, and chalcedony-limonite in the supergene episode. Re-Os and 40Ar-39Ar dating indicates that both the skarn-type and porphyry-type orebodies of the Yinjiagou deposit formed approximately 143Ma ago during the Early Cretaceous. Four types of fluid inclusions (FIs) have been distinguished in quartz phenocryst, various quartz veins, and calcite vein. Based on petrographic observations and microthermometric criteria the FIs include liquid-rich, gas-rich, H2O-CO2, and daughter mineral-bearing inclusions. The homogenization temperature of FIs in quartz phenocrysts of K-feldspar granite porphyry ranges from 341°C to >550°C, and the salinity is 0.4-44.0wt% NaCl eqv. The homogenization temperature of FIs in quartz-molybdenite veins is 382-416°C, and the salinity is 3.6-40.8wt% NaCl eqv. The homogenization temperature of FIs in quartz-calcite-pyrite-chalcopyrite-bornite-sphalerite ranges from 318°C to 436°C, and the salinity is 5.6-42.4wt% NaCl eqv. The homogenization temperature of FIs in quartz-molybdenite stockworks is in a range of 321-411°C, and the salinity is 6.3-16.4wt% NaCl eqv. The homogenization temperature of FIs in quartz-sericite-pyrite is in a range of 326-419°C, and the salinity is 4.7-49.4wt% NaCl eqv. The ore-forming fluids of the Yinjiagou deposit are mainly high-temperature, high-salinity fluids, generally with affinities to an H2O-NaCl-KCl±CO2 system. The δ18OH2O values of ore-forming hydrothermal fluids are 4.0-8.6‰, and the δDV-SMOW values are between -64‰ and -52‰, indicating that the ore-forming fluids were primarily magmatic. The δ34SV-CDT values of sulfides range between -0.2‰ and 6.3‰ with a mean of 1.6‰, sharing similar features with deeply sourced sulfur, implying that the sulfur mainly came from the lower crust composed of poorly differentiated igneous materials, but part of the heavy sulfur came from the Guandaokou Group dolostone. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of sulfides are in the range of 17.331-18.043, 15.444-15.575, and 37.783-38.236, respectively, which is generally consistent with the Pb isotopic signature of the Yinjiagou intrusion, suggesting that the Pb chiefly originated from the felsic-intermediate intrusive rocks in the mine area, with a small amount of lead from strata. The Yinjiagou deposit is a porphyry-skarn deposit formed during the Mesozoic transition of a tectonic regime that is EW-trending to NNE-trending, and the multiepisode boiling of ore-forming fluids was the primary mechanism for mineral deposition. © 2013 Elsevier Ltd.

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