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Liu F.-S.,China Geological Survey | Wu Z.-H.,Chinese Academy of Geological Sciences | Zhang Y.-Q.,Chinese Academy of Geological Sciences | Yang Z.-Y.,Chinese Academy of Geological Sciences | And 4 more authors.
Geological Bulletin of China | Year: 2014

Based on the recently completed "the Qinghai- Xizang plateau edge Neotectonics and the Quaternary geological research" project during 2011-2013, a series of important progress and achievements have been achieved in many fields of Neotectonics and active tectonics, and including the active fault survey and active tectonic system research around eastern Tibetan plateau, the paleomagnetism studying on shear-rotation deformation of Sichuan-Yunnan block, the Neotectonic and active tectonic surveying and studying around west Qinling mountain, the studying on Neotectonic movement episodesin typical active grabens and faultedvalley of western Yunnanand the Neotectonic background and activity characteristics of Tengchong volcanic etc. These new geological surveying and studying results are all very important for further understanding present-day crustal deformation characteristics and its dynamic mechanism and to explore the control effect to great significance earthquake eventsof active tectonic system in eastern Qinghai-Xizang plateau. The achievements of Neotectonic and active tectonic fields may also be used as important geological basis for scientific decision on the planning and construction of country major engineering projects and land planning and utilization.

Mao X.,China Geological Survey | Mao X.,China University of Geosciences | Wang L.,Chengdu Institute of Geology and Mineral Resources | Li B.,Yunnan Institute of Geological Survey | And 4 more authors.
Acta Petrologica Sinica | Year: 2012

A suit of Early Paleozoic volcanic rocks was recognized from Dazhonghe area in Yunxian-Jinggu volcanic arc belt. LA-ICPMS U-Pb zircon analyses suggest that the volcanic rocks was dated at 421. 3 ± 2. 3Ma and 418. 8 ± 3. 5Ma. The volcanic rocks belong to calc-alkaline serie rocks, with characterized by high Al 2O 3 (12. 73% ∼ 16. 63%), Na 2O (K 2O/Na 2O =0. 56 ∼0. 99) and high Mg # (46. 0 ∼50. 0). Furthermore, they are similar to island arc volcanic rocks of active continental margin, with characterized by enrichment of LREE, weak negative anomaly of Eu, strong negative anomalies of HFSE (Nb, Ta, Ti), positive ε Nd (t) (3. 86 ∼ 4.39) and high Th/Ta (15 ∼ 17). The Late Silurian volcanic rocks in Dazhonghe area were probably generated by fractional crystallization of parent magma or assimilation of shallow crustal materials in the process of magma ascent, which partial melting of the depleted mantle wedge by metasomatism with subduction deposit. Being study in combination with the regional magmatic activities and high-metamorphic events during the same period (410 ∼420Ma), we suggest that the island arc volcanic rocks were resulted from the eastward subduction of Paleo-Tethys ocean, which provide direct petrology evidences of forward arc and its dynamic mechanism for the formation and evolution of the Late Paleozoic Sanjiang multi-island-arc basin system in the western edge of the Yangtze block.

Wang B.,Chengdu Institute of Geology and Mineral Resources | Guo L.,Regional Geological Surveying Party | Wang L.,Chengdu Institute of Geology and Mineral Resources | Li B.,Yunnan Institute of Geological Survey | And 4 more authors.
Acta Petrologica Sinica | Year: 2012

Chagele skarn-porphyry deposit have been recently discovered in Tibet, which is located in middle of the Gangdese (or central Lhasa Terrane) metallogenic belt. However, it is absence of the high-precision chronology of porphyritic intrusion and deposit so far. The zircon U-Pb and Molybdenites Re-Os ages are reported in this study, with the bulk-rock major element, trace element and zircon Hf isotopic data on the ore-bearing rocks in Chagele deposit. Zircon U-Pb age of granitic porphyry is divided into two groups, 72. 2 ∼70. 1 Ma and 65. 2 ∼64. 4Ma, which probably record the early tectonic-magmatic event and the latter magmatic crystallization, respectively. Molybdenites Re-Os isotopic dating shows that the molybdenite is formed at 71. 5 ± 1. 3Ma, which is consistent with the early magmatism in the studying area. These new data in this studying, combing with the extensive volcanism of Linzizong Group, suggest that different sizes of mineralization were formed at different stages of the entire collision process between India and Eurasia. The ore-bearing porphyry of Chagele deposit have high SiO2, K2O, Rb, Th, and U contents, coupled with low Ti02, P205 contents and strong negative anomalies of Ba, Nb, Ta, Sr, P and Eu, variable εHf(t) (- 7. 9 ∼ - 2. 2) and ancient tBM (1.3-1. 6Ga). These geochemical features suggest that the samples of Chagele deposit are similar to the peraluminous of S-type granites. This paper suggests that the Late Cretaceous magmatism and mineralization in middle of the Gangdese metallogenic belt could be produced by partial melting of ancient crust materials of the Lhasa microcontinent accompanying with fractional crystallization, which are probably induced by underplating of mantle-derived magmas in the main collision setting of the collision between Indian and Eurasia. We also believe that the zonation of the ore-forming element in the Gangdese metallogenic belt is associated with source material of magma during subduction or collision process of the Neo-Tethyan oceanic.

Sun Y.,Chinese Academy of Geological Sciences | Wu Z.,Chinese Academy of Geological Sciences | Ye P.,Chinese Academy of Geological Sciences | Zhang H.,Yunnan Institute of Geological Survey | And 2 more authors.
Tectonophysics | Year: 2016

The constraints of surface heat flow and lithospheric structure were used to investigate the dynamics of the Tengchong volcanic region based on thermal-mechanical modeling. Three different boundary conditions representing three types of tectonic movements were modeled to discuss the thermal state and lithospheric deformation. The compressive model shows that the subduction of the Indian plate causes the upwelling of asthenosphere beneath the Tengchong block. In this process, upwelling of the asthenosphere causes thinning of the lithosphere beneath the Tengchong block. However, the surface heat flow of this model is not consistent with the observations. The regional extension model shows that, under the extension, the asthenosphere upwells along the preexisting weak suture zone in the southeastern Tibetan plateau. The thickness of lithosphere is the thinnest along the suture zone, and the surface heat flow is the highest. However, the extension time was found to generally need 10-15. Myr to conform to the surface heat flow, however, this is not consistent with accepted geochronological data. When a boundary condition from compression to extension is imposed, both the surface heat flow and the lithospheric structure fit well with the observations. The results show that the subduction of the Indian plate leads to the upwelling of the asthenosphere which causes a thinned lithosphere beneath the Tengchong block. Since the late Miocene (8-5. Ma), the extension or extrusion has been predominant. The thermal erosion of the lithosphere caused by upwelling of the asthenosphere renders the lithosphere even thinner along the Bangong-Nujiang suture zone. The upwelling of the asthenosphere provides an upward driving force and high-temperature environment for the Tengchong volcanic region. These findings suggest that the origin of the Tengchong volcanic region is caused by both the subduction of the Indian plate and regional extension across the Bangong-Nujiang suture zone. © 2016 Elsevier B.V.

Yin F.-G.,Chengdu Center | Zhang H.,Yunnan Institute of Geological Survey | Huang Y.,Guizhou Institute of Geological Survey | Ye P.-S.,Chinese Academy of Geological Sciences | And 3 more authors.
Geological Bulletin of China | Year: 2012

The Dali-Ruili railway is an important part of the south line of the Fanya railway. In order to solve the complex geological problems in railway building, China Geological Survey carried out 1:50000 regional geological mapping and environment hazard investigation from January 2008 to December 2010. Six working items were set up, which included twenty-two 1:50000 mapping items and one comprehensive research item. Important progresses were made in such basic geological aspects as structure, petrology, strata and paleontology through systematic regional geological survey. A number of high-precision age data were obtained. The Baoshan block is considered to be a part of the Gondwana continent. Luxi tectonic melange belt was discovered, which is thought to be a part of the Nujiang tectonic melange belt.

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