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Xu Y.,Tianjin Institute of Geology and Mineral Resources | Li C.,Tianjin Institute of Geology and Mineral Resources | Zhao L.,Tianjin Institute of Geology and Mineral Resources | Gao X.,Tianjin Institute of Geology and Mineral Resources | And 2 more authors.
Geological Bulletin of China | Year: 2016

Airgin Sum monzogranite plution is located in western Xilin Gol-Airgin Sum Precambrian block, Inner Mongolia. Its age of 418.5±1.1Ma obtained by LA-MC-ICP-MS U-Pb zircon dating means that Airgin Sum plution was formed at the end of Late Silurian. Its petrology and geochemistry show that Airgin Sum monzogranite is characterized by high silicon (SiO2 74.22%~75.51%) and rich potassium (K2O 5.41%~5.78%)in association with A/CNK ratios ranging from 1.17 to 1.21, suggesting high-K and calc-alkaline strongly peraluminous granite. The monzogranite is strongly enriched in Rb, Th, U, Pb, K and heavy rare earth elements (Yb 3.74×10-6~9.65×10-6) and is also characterized by depletion of Nb, Ta, Ti and P. It is suggested that the strongly peraluminous monzogranite was formed in the post-collisional setting and resulted from partial melting of crustal material after exhumation of overthickened crust. It is thus concluded that the northern orogen in Airgin Sum-Sonidzuoqi had collided between arc and block before Late Silurian, followed by an post-collision and post-orogenic extension setting during Upper Silurian-Middle Devonian. © 2016, Science Press. All right reserved.

Yu Y.-S.,Key Laboratory of Nuclear Resources and Environment ECIT | Yang Z.-S.,Chinese Academy of Geological Sciences | Tian S.-H.,Chinese Academy of Geological Sciences | Gao Y.,Jiangxi Institute of Geological Survey | And 2 more authors.
Geology in China | Year: 2015

The Ri' a copper-polymetallic deposit, as a typical representative copper metallogenesis of the Nixiong orefield and an important part of Cuoqin-Shenzha iron-copper metallogenetic belt, is located in the middle north of Gangdise. The authors analyzed the mineral composition, major elements, trace elements, and U-Th-Pb composition of zircon from biotite granite associated with copper mineralization in the Ri' a copper polymetallic deposit by LA-ICP-MS. The results show that the biotite granite has typical characteristics of I-type granite, belongs to shoshonite series and must have originated from a crustal-mantle provenance. Zircon U-Th-Pb dating yielded 206Pb/238U age of (89.9±1.6)Ma, which is consistent with the age of mafic intrusive in the Ri' a copper-polymetallic deposit. Combined with the results of previous studies, the authors hold that the bimodal magmatism of Early Late Cretaceous was closely related to mineralization of the Ri' a copper-polymetallic deposit. In consideration of the tectonic environment, the authors propose that the magmatism was controlled by the subduction of both Bangong Co-Nujiang ocean crust and Brahmaputra ocean crust.

Li C.,Tianjin Institute of Geology and Mineral Resources | Xu Y.,Tianjin Institute of Geology and Mineral Resources | Zhang Q.,No. 11 of Geological Brigade | Zhou H.,Tianjin Institute of Geology and Mineral Resources | And 5 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2014

The high-Mg andesite occurring in the Zhangsangou and Jinyinbie Formation-Complex in southern Jilin Province is dated at (2493±12) Ma by the SHRIMP zircon U-Pb method, which indicates that it was generated in the Neoarchean period. The high-Mg andesite belongs to the cal-calkaline series. It is geochemically characterized by SiO2 content of 53.93%-57.90%, high MgO (6.54%-8.82 %) and high Mg# (0.68-0.71, avg. 0.69), associated with enrichments of Cr (270.66×10-6-1117.30 ×10-6, avg. 443.62×10-6) and Ni (141.74×10-6-542.98×10-6, avg. 250.50×10-6). According to its high MgO, Cr and Ni, the high-Mg andesite is relate to the partial melting of mantle peridotites in genesis. On the other hand, the andesite is strongly enriched in light rare earth elements (Ce: 38.34×10-6-59.34×10-6) and large-ion-lithophile elements (such as Sr, Cs, K, Pb, Rb and Ba), and is also characterized by depletion of high-field-strength elements (such as Nb, Ta, Ti and P) and heavy rare earth elements (Yb: 1.38×10-6-1.57 ×10-6), which demonstrates geochemical characteristic of the arc volcanic rock. The high-Mg andesite was most likely derived from the products of interaction of slab-derived fluid or melt with mantle peridotites. It can thus be concluded that the high-Mg andesite was derived from the subduction zone and there occurred the modern plate tectonics in the Neoarchean period.

Ling M.-X.,CAS Guangzhou Institute of Geochemistry | Zhang H.,Northwest University, China | Li H.,CAS Guangzhou Institute of Geochemistry | Liu Y.-L.,CAS Guangzhou Institute of Geochemistry | And 5 more authors.
Lithos | Year: 2014

Granitoids near the Bayan Obo giant rare earth element (REE) deposit at the north margin of the North China Craton (NCC), the world's largest light REE (LREE) deposit, have been taken by some authors as the key factors that controlled the mineralization. In contrast, others proposed that the REE deposit has been partially destructed by these granitoids. Here we report systematic studies on geochronology and geochemical characteristics of granitoids of different distances from the orebodies, to investigate the genesis and their relationship to the giant Bayan Obo deposit. Granitoids studied here, including granites and quartz monzonites, are peraluminous with A/CNK=0.99-1.11, LREE enriched and heavy REE (HREE) depleted, with variable REE concentrations (total REE=54-330ppm) and large negative Eu anomaly (δEu=0.19-0.70). The REE patterns are distinct from those of ore-bearing dolomites. Some samples have slightly higher LREE concentrations, which may have been contaminated by the orebodies during intrusion. Trace elements of the granitoids are characterized by positive Pb anomaly, strong negative Ti anomaly and Nb, Ta and Sr anomalies. The granites exhibit negative Ba anomaly. The granitoids plot within the post-collision granite field in the Pearce diagram, which is consistent with the tectonic regime. The quartz monzonites and one granite have A-type granite characteristics and belong to the A2 subgroup. Zircons in these granitoids have high Th/U values, which are typical for magmatic zircons. High precision U-Pb dating for these zircons by secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) yields Permian-Triassic 206Pb/238U ages ranging from 243.2 to 293.8Ma. The formation of the granitoids is >55Ma later than the latest ore forming age. The zircons have low La concentrations (0.02-12ppm), high (Sm/La)N (0.8-685) and Ce/Ce* (1.4-80). The Ti-in-zircon temperature of the granitoids ranges from 590 to 770°C. All these evidences suggest that the granitoids have no contribution to the formation of the Bayan Obo deposit. Granitoids that are close to the orebodies had limited interaction with it and gained some LREE-enriched characteristics during magmatisms. Nevertheless, their effects to the orebodies are subtle. All the granitoids formed in a post-collisional tectonic regime at convergent margins, which is consistent with plate subduction during the closure of the Palaeo-Asian Ocean, which started in the Neoproterozoic and lasted until the Carboniferous/Permian. © 2014 Elsevier B.V.

Fan B.-X.,Hebei Institute of Regional Geology and Mineral Resources Survey | Ju Y.-J.,Chinese Academy of Geological Sciences | Han K.-Y.,Chinese Academy of Geological Sciences | Wang Z.-Y.,Chinese Academy of Geological Sciences | Wang L.-Y.,Hebei Institute of Regional Geology and Mineral Resources Survey
Geology in China | Year: 2010

This paper systematically describes the basic situation of the computer mapping of Atlas of 1:2 500 000 Geological Maps of Central Asia and Adjacent Areas, which is conducted by the cooperation of experts from China, Russia, Mongolia, Kazakhstan and South Korea. The geographic overview of the mapping region, the drawing of the basic geographical map, the mapping process of the geological map series, the naming rules of each layer, and all parts of the map publication are dealt with in detail. The 1:2 500 000 basic geographical map is the base of the Atlas of Geological Maps of Central Asia and Adjacent Areas, and its mapping process is similar to that of the Geological Map and Metallogenic Regularity and Mineral Energy Resource Prognosis Map. This paper fully summarizes the principles and methods for computer mapping of Atlas of 1:2 500 000 Geological Maps of Central Asia and Adjacent Areas from the design and preparation to the publication.

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