Yunnan Institute of Geological Survey

Kunming, China

Yunnan Institute of Geological Survey

Kunming, China
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Li J.,Yunnan Institute of Geological Survey | Sun Z.,Yunnan Institute of Geological Survey | Huang L.,Yunnan Institute of Geological Survey | Xu G.,Yunnan Institute of Geological Survey | And 3 more authors.
Yanshi Xuebao/Acta Petrologica Sinica | Year: 2017

Early balanced paragenetic mineral assemblage in retrograded eclogites, which underwent more period remetamorphism, from Mengku area, Shuangjiang County of western Yunnan Province, is hardly found. It is uncertain to estimate pressure and temperature in early metamorphism by means of traditional garnet-clinopyroxene geothermometer and garnet-clinopyroxene-phengite geobarometer. In this article, the authors study compositions change of phengite, garnet and omphacite in the P-T pseudosection, which is calculated by Wei et al. (2009) based on MORB, with pressure and temperature change. By this way, the authors obtain P = 2. 00 ∼ 2. 30GPa and T = 420 ∼ 460°C in the prograde metamorphism, P = 3. 35 ∼4. 46GPa and T = 530-610°C in the peak period metamorphism, P =2. 00 ∼ 2. 50GPa and T = 470 ∼ 540°C in the early period remetamorphism, P = 0. 95 ∼ 1. 43GPa and T = 700 ∼ 750°C in the medium period remetamorphism, they are respectively equivalent to lawsonite blueschist facies to lawsonite-glaucophane eclogite facies, lawsonite eclogite facies, lawsonite-glaucophane eclogite facies and hornblend eclogite facies to high pressure granulite facies. Late period remetamorphism is characterized by a plenty of amphibolites. It can be divided three stages, and shows the continued cooling and pressure reduction process. Based on the research for regional crust's revolution, author discusses geological significances of the P-T-t path in detail.

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.

Zhang H.,Yunnan Institute of Geological Survey | Wu Z.,Chinese Academy of Geological Sciences | Ye P.,Chinese Academy of Geological Sciences | Chen G.,Yunnan Institute of Geological Survey | And 3 more authors.
Geological Bulletin of China | Year: 2015

The study of Cenozoic intermediate-acidic volcanic rocks in Tengchong has been very insufficient in the past. Based on geochemical studies of intermediate-acidic volcanic rocks, the authors divided the Cenozoic volcanic rocks into Sr-high, Yb-low Adak-type dacite and Sr-low, Yb-medium Zhe-Min (Zhejiang-Fujian) type dacite, with the time limit being N2(2.78~4.04 Ma) and Q1(0.73~1.19 Ma)respectively. These intermediate-acidic volcanic rocks were formed during the transform process from stableness to collapse after the orogenic uplift of the Tengchong- Gangdise belt. In Miocene, the stress of Tengchong-Gangdise plateau was transformed from the domination of EW-trending compression to NS-trending strike-slip, and the orogenic belt began breakup. Blocked by the Luxi-Baoshan land mass, the direction of the strike-slip was deflected and resulted in the detachment and formation of rift basin among axial fault slices at the turning end in the early period of the formation of rift, the mantle was decompressed and intruded upward, and the high-pressure part of the lower crust was partly melted to form Adak-ype granitic magma. In early Pleistocene, with the intensification of the rifting, the crust became further thinner, and the lower crust was partly melted under the condition of low pressure to form Zhe-Min type granitic magma. ©, 2015, China Geological Survey. All right reserved.

Yao X.,Kunming University of Science and Technology | Yao X.,Yunnan Institute of Geological Survey | Zhang H.,Yunnan Institute of Geological Survey | Wu Z.,Chinese Academy of Geological Sciences | And 3 more authors.
Geological Bulletin of China | Year: 2016

The Pliocene volcanic rocks in Yingjiang area constitute an important part of Tengchong volcanic rocks, but they are rarely involved in previous studies. In this paper, through the study of petrochemistry and K-Ar geochronology of the volcanic rocks and a comparison with the eastern Tengchong Pliocene volcanic rocks in the Longjiang River Valley area, the authors consider that the Pliocene volcanic rocks in Yingjiang and Tengchong areas seem to be a kind of rift volcanic rocks of the post-tectonic orogenic belt formed under the effect of extension that appeared in the continental tectonic background. With high Al2O3 (15.54%~17.44%) and high K2O (0.94%~3.50%) petrochemical characteristics, the rocks should belong to high potassium calc-alkaline volcanic rock series. They formed in an extensional environment and belong to bimodel volcanic rocks (basalt DI=33~50, dacite DI=62~76). The rocks have the geochemical characteristics of arc volcanic rocks, but they formed in a tensional environment in post-tectonic orogenic belt and had nothing to do with the plate subduction. The rift volcanic rocks of orogenic belts formed in the early orogenic belt and hence were magmatic products in the process of the development of the orogenic belt at a certain stage. © 2016, Science Press. All right reserved.

Liu G.,Wuhan University | Liu G.,Yunnan Institute of Geological Survey | Feng Q.,Wuhan University | Shen J.,Wuhan University | And 4 more authors.
Palaios | Year: 2014

Variations in sponge form diversity, abundance, and spicule size provide a potential record of paleoenvironmental changes associated with the end- Permian biotic crisis. Changes in three common spicule forms (Oxea A, Oxea B, and Orthopentactines) were analyzed in uppermost Permian (Changhsingian) and lowermost Triassic (Induan) strata at two localities in South China. The deeper-water Dongpan section exhibits decreasing spicule size as well as a strong decline in spicule-form diversity prior to the end-Permian crisis. In contrast, the shallower-water Maanying section exhibits an increase in spicule size and a more limited loss of form diversity over the same interval. In both study sections, the end-Permian crisis was accompanied by a miniaturization stage marked by a rapid decline in average spicule sizes (by >50% for Oxea A and Oxea B). Paleoproductivity proxies suggest that the decline of sponges was related to a general collapse of marine productivity. The timing and intensity of the sponge biocrisis varied between the two sections, however, with an earlier onset of miniaturization and a complete disappearance of sponges prior to the Early Triassic at Dongpan, versus a later onset of miniaturization and survival of several sponge forms into the Early Triassic at Maanying. These differences are attributed to relatively less hostile conditions (e.g., less frequently or less intensely reducing) in shallower-water environments during the end-Permian crisis. © 2013, SEPM (Society for Sedimentary Geology).

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.

Wang Y.B.,Chinese Academy of Geological Sciences | Han J.,Chinese Academy of Geological Sciences | Zeng P.S.,Bureau of Mineral Resources | Wang D.H.,Chinese Academy of Geological Sciences | And 3 more authors.
Acta Petrologica Sinica | Year: 2010

Granodiorite intrusions (from south to north, namely, Lunong, Linong, Jiangbian, and Beiwu pluton) and diabase dyke are spatially and temporally associated with the copper mineralization in Yangla copper deposit, Deqin County, Yunnan, Southwest China. They commonly distributed in Yangla copper deposit. To constrain the age of a number of major granodioritic plutons and diabase dyke related to Cu mineralization, U-Pb anarysis of zircon was conducted. Hafnium isotope data was also acquired through laser-ablation multicollector ICPMS anarysis of zircon, with the aim of gaining insight into the age and nature of the source region of the plutons. Four age groups have been identified from five igneous samples: Middle Triassic (238 ∼ 239Ma, Linong pluton, Lunong pluton), Middle-Late Triassic (228Ma, Jiangbian pluton), Late Triassic (222Ma, diabase dyke) and Late Triassic (214Ma, Beiwu pluton). While the Re-Os isochron age for molybdenite from Linong Cu ore body was 228Ma to 230Ma. These data suggest that the formation of different granodiorite plutons by multi-stages of gushing emplacement of the magmas. The ore-forming of Yangla copper is developed in Middle Triassic. Hafnium analysis shows the Triassic granodiorites having negative and positive and variable εHf(t) values (-4. 3 ∼ +2. 4) and Mesoproterozoic (1. 1 ∼ 1. 5Ga) depleted-mantle model ages, which is interpreted to reflect the derivation from an isotopically heterogeneous, mixing source of mantle with crust source. The source region for these magmas may be tentatively correlated with the Mesoproterozoic material of Yangtze Craton, which has been suggested to underlie the Yangla: however, further work is necessary to demonstrate this suggestion.

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.

Xu G.,Yunnan Institute of Geological Survey | Zeng W.,Yunnan Institute of Geological Survey | Sun Z.,Yunnan Institute of Geological Survey | Huang L.,Yunnan Institute of Geological Survey | And 3 more authors.
Geological Bulletin of China | Year: 2016

Retrograded eclogites are exposed in structural-sheet form in Naka River, Kongjiao and some other areas north of Mengku Town, Shuangjiang County of west Yunnan Province and occur in Ordovician Wanhe ophiolite mélange belt. According to different retrograde degrees, the exlogites can be divided into retrograded eclogites, garnet-amphibolite and garnet-bearing amphibolite. The main minerals include garnet, clinopyroxene, amphibole, and plagioclase together with minor rutile, phengite, jadeite, epidote, biotite, apatite, quartz etc. Omphacite, which is a typical HP-UHP metamorphic mineral, only exists as inclusions in a small amount of garnet and amphibole. Petrological and mineralogical characteristics show that the mineral assemblage at the metamorphic peak is Omp+Gt +Ru+Q+Phen. Due to the growth of radial bulging cracks around some quartz inclusions in garnet, it is held that some quartz inclusions belong to retrograded coesite. The retrograded eclogite therefore must have undergone UHP metamorphism. © 2016, Science Press. All right reserved.

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