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Tang J.-X.,Chinese Academy of Geological Sciences | Zhang Z.,Chengdu University of Technology | Li Z.-J.,Chengdu University of Technology | Sun Y.,Chengdu University of Technology | And 5 more authors.
Acta Geoscientica Sinica | Year: 2013

Located in the south of western Bangong Co-Nujang River metallogenic belt of north Gangdise, the Ga'erqiong-Galale copper-gold ore field possesses lots of ore body types (porphyry type, skarn type and iron oxide-copper-gold type) and high gold grade (up to 205 g/t) and unique structural position, thus having great research significance. According to systematic summary of ore concentration areas and systematic analysis of data, the authors identified ore characteristics, found a large number of native gold and intermetallic compounds, and summarized the metallogensis. It is considered that metallization was mainly associated with emplacement of quartz diorite and granodiorite in the late phase of Yanshanian period, the evolution time between diagenesis and mineralization was about 1 Ma, and the mineralization in the area was characterized by the vertical zoning of copper-gold in the upper part and molybdenum in the lower part. S, Pb isotopes suggest that the metallogenic material had characteristics of crust-mantle mixing. During the emplacement and fractionation evolution of metaluminous-weak peraluminous calc-alkaline-high-K calc-alkaline magmatite, the porphyry-skarn type copper-gold-molybdenum ore bodies were formed in the area of pluton uplifting and along the contact zone between the pluton and the Cretaceous carbonate, whereas iron oxide-copper-gold type ore bodies were formed at the edge of pluton's tectonic fracture zone (F1 fault). On such a basis, the authors have established the porphyry-skarn-iron oxide-copper-gold type "three-position" mineralization deposit model of magmatite- strata-ore-controlling structure. Based on these data, the authors indicate the prospecting direction in search for new ore bodies in the ore field. Source


This paper deals with the sedimentation records of POPs such as OCPs and PCBs in sediments along the cross section of flood plain of Gangjiang River so as to determine the history of organic pollution. Classification of molecular stratigraphy was carried out on the basis of the evolution of the concentration of organic compounds, which indicates that there exist high concentrations of residual HCHs, DDTs and PCBs at the depth from 26 to 46 cm, with high level of residual DDTs being found even in deeper areas. Although the concentrations of residual OCPs and PCBs do not exceed the contamination standard, special attention should be paid to the potential release of such pollutants to the surrounding environment. The sedimentation records of POPs are consistent with the development history of Ganjiang River and hence such studies contribute to the study of the age of contemporary sediments. Source


Shi Z.-G.,Chinese Academy of Geological Sciences | Gao L.-Z.,Chinese Academy of Geological Sciences | Li T.-D.,Chinese Academy of Geological Sciences | Ding X.-Z.,Chinese Academy of Geological Sciences | And 4 more authors.
Geology in China | Year: 2014

The outcropped Neoproterozoic strata are relatively complete from old to young in Lushan area, and hence this area is significant for analyzing the tectonic evolution of the whole "Jiangnan Orogen". The Hanyangfeng Formation, which exists only in Hanyang peak of the Lushan Mountain, is mainly composed of terrestrial eruptional metacrystal or phenocryst-rare rhyolite. The authors obtained the high-precision SHRIMP zircon U-Pb weighted mean age(838±4 Ma, corresponding MSWD=1.12) of the metamorphic rhyolite of the Hanyangfeng Formation in the Lushan area, and also obtained LA-ICP-MS zircon U-Pb weighted mean age(852±4 Ma, corresponding MSWD=0.037) of this Formation. These new data indicate that the Hanyangfeng Formation does not belong to the Banxi period. The authors initially hold that the Hanyangfeng Formation ought to be located under the tectonic transformation of the Willing movement (820± Ma). The new research result confirms that the Hanyangfeng Formation is of the same volcanic-sedimentary strata as the Shaojiwa Formation, and therefore it may be a significant indicator to the tectonic setting. Actually, the sequence relationship of the Hangyangfeng Formation and the Shaojiwa Formation to the Xingzi Complex group shows upside-down phenomenon, suggesting that there probably existed a significant geological movement in the Lushan area during the late Qingbaikou period. Source


Gao L.-Z.,Chinese Academy of Geological Sciences | Huang Z.-Z.,Jiangxi Institute of Geological Survey | Ding X.-Z.,Chinese Academy of Geological Sciences | Liu Y.-X.,Chinese Academy of Geological Sciences | And 2 more authors.
Geological Bulletin of China | Year: 2012

Zircon dating of tuff bed in the Xiushui Formation of the Shuangqiaoshan Group has yielded an age of 824 Ma±5 Ma, with MSWD equal to 1.3, and there are three groups of zircon U-Pb ages for the Majianqiao Formation, of which, one is identical with the age of the Xiushui Formation (824Ma±5Ma, MSWD=1.9), and the youngest age is 769Ma±8Ma (MSWD=0.55). In combination with the SHRIMP U-Pb dating of the tuff bed of the Shuangqiaoshan Group in the eastern part of the Jiangnan oregen, the data of the Fanjingshan and Xiajiang groups in the western part and some ages of the Lengjiaxi and Banxi groups, the authors hold that the Shuangqiaoshan Group should belong to Neoproterozoic strata below the Wuling Movement. According to the isotopic data, the Majianqiao Formation should be assigned to the sedimentary strata of the Banxi stage. These ages are very important for regional stratigraphic correlation of the corresponding period and tectonic evolution. The zircon U-Pb ages mentioned above demonstrate that Neoproterozoic strata were developed around the age of 820 Ma in northwestern Jiangxi Province. The results obtained also influence the stratigraphic subdivision and correlation of the metamorphosed rocks in whole Jiangnan old land and help geologists solve the problem of geological background and ore-forming conditions of the Jiangnan orogen. Source


Li B.,Hunan Institute of Geological Survey | Li B.,Hubei University | Xiang S.-Y.,Hubei University | Feng D.-X.,Geothermal Geological Survey Party | And 3 more authors.
Geological Bulletin of China | Year: 2012

There are Mesozoic intrusive rocks along the Lancang River in Chala area of eastern Tibet, which mainly occur as complex batholiths and apophyses and lenticular granite that intruded in Early Carboniferous Kagongyanka Formation and Jitang Group metamorphic rocks. The intrusive rocks are mainly composed of monzonitic granite and granodiorite with a little diorite. So far, the genesis of these rocks, including their formation age and tectonic significance, has been poorly studied. In this paper, four granite samples were used for LA-ICP-MS U-Pb dating, and the dating results show that the age of a sample is 219.8 Ma ± 2.4 Ma, and the ages of the other three samples are 239.2 Ma ± 1.7 Ma, 241.5 Ma ± 2.3 Ma and 242.5 Ma ± 1.6 Ma respectively, suggesting similar formation ages in Middle-Late Triassic period. Geochemical studies indicate that these granites were formed in intraplate syncollisional to post-colli sional tectonic setting which underwent the evolution from early collision to the last stage of orogeny. The environment was a tectonic regime of the transformation stage regarded as a "post-orogenic" tectonic environment which was produced by crust anatectic melting as a result of crust extension and rapid uplift after the collision between the eastward Lancangjiang plate and the Changdu micro-plate. Source

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