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Xiang Y.,Center for Development and Research | Gong Q.,China University of Geosciences | Liu R.,Center for Development and Research | Yang W.,Xinjiang Institute of Geological Survey
Acta Petrologica Sinica | Year: 2014

The geochemical survey data obtained by the RGNR (Regional Geochemistry-National Reconnaissance) project are useful for basic geology research and mineral exploration. Based on the China's National Geochimical Mapping, five geochemical domains (Pal-Asia geochemical domain, Qingling-Qilian-Kunlun geochemical domain, Tethys geochemical domain, Yangtze geochemical domain and Marginal Pacific geochemical domain respectivelly) and 25 geochemical provinces are divided in Chinese land surface. In the western of Yunnan Province, granitic intrutions occurring in arc belt clearly are rich in K2O, Th, U, La, Y, Zr, but poor in Co, Ni, V, Cr, Ti, and Fe2O3. Geochemical survey data in the western of Yunnan Province are precessed on the main component factor analysis method and two main factors are selected. One or F2 represents the element assemblage of Th, Y, U, Zr, La, K2O, Al2O3, and Be, which factor score is calculated as F2 =0. 87Th +0. 86Y +0. 77U +0. 77Zr +0. 67La +0. 61K2O +0. 58 Al2O3+0. 53Be. The other or F1 represents the element assemblage of Fe2O3, Ti, V, Co, Cr, and Ni, which factor score is F1 =0. 95Fe2O3+0. 93V + 0. 93Ti +0. 92 Co +0.81 Cr + 0. 80Ni. The ratio of these two factor scores is used to deduce the granitic intrusions. The drawing methods of geochemical map and geochemical anomaly map are presented which are used commonly in the RGNR project. The areas of F2/F1 with high values and the anomaly areas of F2/F1 coincide well with the outcrops of granitic intrusions in the western of Yunnan Province. The deducing model to recognize granitic intrusions based on geochemical survey data in the western of Yunnan Province is fulfilled in the Chinese land surface with ca. 7 million square kilometers. The middle part of South China is selected to test and apply the deducing model. The results indicate that the anomaly areas of the factor score ratio F2/F1 are consistent well with the outcrops of granitic intrusions in the middle part of South China, especially in the boundary areas of Hunan Province, Guangdong Province and Guangxi Zhuang Autonomous Region. This consistence indicates that the deducing model is feasible to recognize granitic intrusions. This model will play an important potential role on basic geology research in China. Source

Zhu J.,Chinese Academy of science | Zhu J.,University of Chinese Academy of Sciences | Hu R.,Chinese Academy of science | Bi X.,Chinese Academy of science | And 5 more authors.
Acta Petrologica Sinica | Year: 2011

The Yangla copper deposit is located in the middle zone of Jinshajiang suture zone. The Beiwu, Linong and Lunong granitoids exhibit a linear distribution from north to south in the ore district. The three granitoids have similar compositions of major, trace elements and Sr-Nd isotopes, indicating that they have a common magma source. They do not contain muscovita, and have high concentrations of SiO2(64% ∼73% ), K2O (2. 15% ∼4. 05% ) and low P2O3 (0. 04% ∼ 0. 11% ) content. In addition, they have low δ((K2O+Na2O) 2/(SiO2-43); 1.4 ∼ 2.4) and A/CNK (molecular Al 2 O3/(CaO + Na2O+K2O) ; 0.92-1, 11). The granitoids display significantly negative anomalies of Nb, Ta, Ti and P, obvious enrichment of LREE and Rb, Th, U and Pb. The 10000Ga/Al ratios ( 1. 7 ∼ 2. 1 ) of those rocks are lower than typical A-type granites. Moreover, considering the slightly negative Eu anomalies, it is suggested that the three granitoids belong to high-K calc-alkaline, metaluminous-slightly peraluminous I-type granites. Compared with the continental crust (i. e. , the Lincang granite and the Shaba granulite) , the granites have lower ( 87Sr/ Sr86)¡ (0. 7078 ∼0. 7105) and higher εNd(t) (-5. 1∼ -6. 7), with ancient Nd two-stage model age (tDM2 = 1. 5Ga). And there occur a number of coeval mafic microgranular enclaves (MMEs) in these granitoids, suggesting that mantle-drived magmas were involved in the source region (see in a separate article ). By combining with comparative analyses of the tectonic settings, we propose a model in which the Beiwu, Linong and Lunong granitoids were generated under a late collisional or post-collisional setting. Decompression induced those mantle-derived magmas underplated and provided the heat for the anatexis of the crust The hybrid melts ( i. e. , mantle-derived and the lower crustal magmas ) and subsequent fractional crystallization could be responsible for the formation of the Beiwu, Linong and Lunong granitoids. Source

Yang S.,Hubei University | Yang S.,Xinjiang Institute of Geological Survey | Xiang S.,Hubei University | Zhang X.,Zhengzhou Trade and Industry School | And 2 more authors.
Geological Bulletin of China | Year: 2016

Cenozoic potassic volcanic rocks are widely distributed in the Tibetan Plateau, mainly in northern Tibet and Lhasa block with a few reports in Zhongba terrane. The study of Jiada potassic volcanic rocks found in Zhongba terrane shows that the rocks are almost exclusively trachyte, and the magma erupted incessantly by overflowing and erupting. These rocks are also characterized by high potassium and high aluminum, rich LILE, LREE and Sr, and poor HFSE, Y and Yb, with Eu negative anomaly. Their geochemical characteristicss are similar to those of typical adkite rocks. The LA-ICP-MS zircon U-Pb age of trachyandesites is 17.03±0.32 Ma, which means that these volcanic rocks were formed in Miocene. The Jiada potassic magma was derived from partial melting of thickened crust. The rocks represent post-collisional tectonic setting and extension environment. © 2016, Science Press. All right reserved. Source

Liao S.,Nanjing University | Liao S.,Chengdu Institute of Geology and Mineral Resources | Jiang Y.,Nanjing University | Zhou Q.,Nanjing University | And 3 more authors.
International Journal of Earth Sciences | Year: 2012

The Western Kunlun Orogen occupies a key tectonic position at the junction between the Tarim block and the Tethyan domain. However, the late Paleozoic to early Mesozoic, especially the middle to late Triassic tectonic evolution history of the Western Kunlun Orogen remains controversial. This study reports SHRIMP zircon U-Pb ages and geochemical as well as Sr-Nd-Hf isotopic data for middle to late Triassic Taer pluton in Western Kunlun Orogen, Northwest China. The Taer pluton shows a strong bimodal distribution of compositions, with the felsic rocks dominant and the mafic rocks subordinate. Zircon U-Pb dating reveals that the coexisting mafic and felsic rocks are coeval, both emplacing in a period between 234 and 225 Ma. Most of the studied rocks are potassium rich and can be classified into high-K calc-alkaline to shoshonitic series. They are also strongly enriched in LREE, LILE and depleted in HFSE with strong negative Ti and Nb anomalies, and characterized by enriched Sr-Nd-Hf isotopic signatures. Detailed geochemical and isotopic studies indicate that the Taer pluton was emplaced in a post-collisional extensional setting, with the mafic rocks derived from partial melting of the enriched continental lithospheric mantle in the spinel facies field, and the felsic rocks formed by anatexis of newly underplated basaltic rocks. The existence of middle to late Triassic post-collisional magmas in Western Kunlun region suggests that the final closure of Paleo-Tethys and the initial collision between the Western Kunlun and the Qiangtang terranes may have happened before ~234 Ma, most probably in late Permian, rather than in late Triassic or early Jurassic. In assistance with other geological evidences, such as the presence of early Triassic to late Triassic/early Jurassic S-type magmatism, terrestrial molasse depositions, regional unconformities, and strong deformation, we propose that the Western Kunlun Orogen may have undergone a long post-collisional intracontinental process from early Triassic to late Triassic/early Jurassic. © 2011 Springer-Verlag. Source

Zhuang D.-Z.,Xinjiang Bureau of Geology and Mineral Exploration and Development | Yang W.-Z.,Xinjiang Institute of Geological Survey
Geological Bulletin of China | Year: 2010

Zankan iron deposit is located in Tashikuergan block, controlled by middle-deep metamorphite of Paleoproterozoic, and has obvious regional aero-magnetic anomalies and geochemical anomalies. On the basis of the predicting model of the integrated information of Zankan Iron deposit, and integrating regional geological, aero-magnetic, and geochemical information, the exploration targets of Zankan, Subashi and Tizinafu are given, thus has defined Zankan-Subashi iron mineralization belt. Source

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