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Qi S.S.,China University of Geosciences | Qi S.S.,Qinghai Institute of Geological Survey | Qi S.S.,Qinghai Prov Key Laboratory Of Geol Processes And Mineral Resources Of Northern Qinghai Tibetan Plateau | Song S.G.,Peking University | And 6 more authors.
Acta Petrologica Sinica | Year: 2014

Eclogite and the retrograde amphibolic eclogite, occurred as tectonic lenses, are found in the metamorphic basement, western part of the East Kunlun, based on the results of 1 : 250000 regional geological survey. They are intermittently scattering about 20km along Xiaozaohuo-Suhaitu-Xiarihamu-Laningzaohuo area. Most of the eclogites are retrograded into amphibolic eclogites, they consist of the peak metamorphic mineral assemblage (garnet + omphacite + ilmenite + rutile) and the later stage retrograde mineral assemblage (hornblende (green) + plagioclase). The edge of the garnet grains develops needle-like hornblende and particulate plagioclase symplectic corona texture, forming white eye rims about 0.15 ∼ 1cm in size. The composition of garnet is Alm52-53And4.2Spess0.7-1.2 Gross21.7-22Pyr19-20, Jadeite molecular in omphacite is 30.14mol% ∼ 37.7mol%. Estimation of eclogite-facies metamorphic conditions shows P≈20kbar, T≈660 ∼ 700°C, and the amphibolite facies retrograde metamorphic conditions of P≈7kbar, T≈550°C. The rocks had experienced a retrogressive process of significant cooling and decompression. Most of the CL images of zircons from the eclogites show sector zoning or "fir leaves" structure. Th/U ratio ranges in 0.007 ∼ 0.09. Zircon U-Pb age (LA-ICP-MS) is 411.1 ± 1.9Ma (n=17), which represents the peak metamorphism age of eclogite-facies. Combined with the analysis of regional metamorphic and magmatic events, the peak stage of the high-pressure metamorphism is determined to be Late Silurian-Early Devonian, which is probably associated with a massive continent-continent collision event. The discovery is significant for the tectonic study of the Kunlun orogenic belt.


Zhang J.-M.,Qinghai Institute of Geological Survey | Wang Q.-Y.,Qinghai Institute of Geological Survey | Xu H.-Q.,Qinghai Institute of Geological Survey | Yan Y.-F.,Qinghai Institute of Geological Survey
Northwestern Geology | Year: 2012

Metamorphic intrusive rocks (bodies) into Jinshuikou rock group of the were found. The isotope age determination shows they are the Neo-Proterozoic. The metamorphic intrusive rocks (bodies) derived with aluminum calcalkaline series, and resulted from a tectonic environment of synchronous collision. The discovery of metamorphic intrusive rocks (rodies) has important significance to a thorough invest-tigation and study of Presinian period basement in the west of eastern Kunlun Mt. And it is of great significance to resume or confirm the developing and evolvement history of Qimantage tectonomagma belt.


Tian S.H.,Chinese Academy of Geological Sciences | Yang Z.S.,Chinese Academy of Geological Sciences | Hou Z.Q.,Chinese Academy of Geological Sciences | Liu Y.C.,Chinese Academy of Geological Sciences | And 3 more authors.
Acta Petrologica Sinica | Year: 2011

The Dongmozhazhua Pb-Zn deposit in the Yushu area of Qinghai Province, located in the northeast margin of Qiangtang terrane which is between Jinshajiang suture zone and Bangonghu-Nujiang suture zone, is the typical Pb-Zn deposit in the Cu-Pb-Zn polymetallic mineralization belt for the northern part of the Nujiang-Lancangjiang-Jinshajiang area. On the basis of geological field observations, the authors selected sulfide minerals and barite for S isotope compositions analyses, sulfide minerals, gangue minerals and regional strata for Pb isotope compositions analyses, and gangue minerals for Sr-Nd isotope compositions. values of sulfide minerals are -29% ∼6%. and show peaks at -8% ∼ -6%, reflecting the characteristic of light sulfur. δ34 values of barite are 18.3% ∼ +22. 8%c, implying the derivation of Tertiary continental facies basin. The ore deposit displays wide variations in sulfide S^S values, indicating multiple sulfur sources. On account of the lack of magmatic activity, it is realistic to view the rocks in the basin as the source of sulfur. Sulfur in the rocks was transferred into hydrothermal fluids via fluid-rock interaction. Therefore, the variation in rock types across the basin is likely to influence the variation of sulfur isotopic compositions. Reduced sulfurs were mainly derived from the biogenic sulfate reduction or the thermochemical reduction of sulfur-bearing organic matter, implying that sulfur came from the sedimentary basin. The 206Pb/204 Pb, 207Pb/204 Pb and 208Ph/204 Pb ratios for sulfide minerals vary in ranges of 18.387 ∼ 18.703, 15.391 ∼ 15.768 and 38.372 -38.809, respectively. The 206Pb/204 Pb, 207Pb/204 Pb and 208Pb/204 Pb ratios for gangue minerals are between 18.423 ∼ 18.612, 15.491 ∼ 15.701 and 38.497 ∼ 38.612, respectively. In the diagrams of 207Pb/ 204 Pb-206 Pb/204 Pb and 208 Pb/204 Pb-206Pb/204 Pb, the Pb isotope compositions of the sulfide minerals and gangue minerals fall into the regional upper crust lead zone, similar to MVT deposit, implying that Pb might have come from the upper crust rocks. The (87 Sr/86 Sr)i, εSr(t), (143Nd/144Nd)i and εNd(t) ratios for gangue minerals vary in ranges of 0.70855 ∼0.70928, 58.0∼68.4, 0.512273∼0.512353 and -6.2 ∼ -4. 7, respectively. The Sr-Nd isotope compositions of the gangue minerals indicate that their matter sources also came from the upper crust rocks.


Liu Y.C.,Chinese Academy of Geological Sciences | Hou Z.Q.,Chinese Academy of Geological Sciences | Yu Y.S.,Wuhan Institute of Geology and Mineral Resources | Tian S.H.,Chinese Academy of Geological Sciences | And 2 more authors.
Acta Petrologica Sinica | Year: 2013

Changdu region, located in the northeastern margin of Tibetan collisional orogenic belt, is the important part of Southwest 'Sanjiang' metallogenic belt. Carbonate Posted Pb-Zn deposits controlled by thrust nappe structures are abundant and with plenty reserves in this region. Lalongla deposit is located in the southwest of the most famous carbonate-hosted Pb-Zn ore concentration area in Changdu region and is a typical representative. The Pb-Zn mineralization of Lalongla deposit is born in the hanging wall of a thrust fault and ore bodies, mainly produced as lens, distribute along a facies transition between mud shale in Jiapeila Formation and limestone in Bolila Formation in Late Triassic. Breccia and mesh-vein are main ore structures and galena, sphalerite and smithsonite are main ore minerals. The ore-control factor and ore occurrence in this deposit represent a new carbonate-hosted deposit type in 'Sanjiang' metallogenic belt and then it is named as Lalongla type. The main ore-forming process in this deposit can be divided into Period I (shortened form of sulfide period) and Period II (shortened form of sulfide-carbonate period), between which a compressing deformation occurred. Two kinds of fluid inclusion including LV inclusion rich in liquid and LV inclusion rich in CO2 and CH 4 occur in Period I. A microthermal testing work suggests two kinds of hydrothermal fluids in this period, which are with low temperature (130 ∼140°C), high salinity (23% ∼24% NaCleqv) and middle to high density (1. 10 ∼1. 12g. cm) nature and with middle to low temperature (170∼180t), high salinity (23% ∼24% NaCleqv) and middle to low density (1.06 ∼1. 08g. cm-3) nature, respectively. For the two periods, the liquid parts of hydrothermal fluids both belong to Ca2+-Mg 2+-Na+-K+-SO4 2--CI --F-NO3 system and the ion contents, H-0 isotope composition (-137%o∼-110%o for δDv-SM0W and -2. 92%o ∼13. 42%o for δ18 Ov-SM0W), C-O isotope composition of calcite (0. 9%o ∼7. 2%o for δCv-PDB and 9. 1%o ∼26. 5%o for δ18 Ov-SM0W) are all similar to each other, suggesting two resources, including low-temperature, high salinity basin brine and middle-temperature, high-salinity regional fluid composed by evaporated-concentrated seawater cocooned in strata, metamorphic water released by metamorphic rock and the meteoric water, for the hydrothermal fluids. The sulfur isotope composition for the two Periods is still similar. The S S values of sulfide are negative (-24. 7%o ∼-11. 5%o), of barite are positive (11. 3%o ∼22. 9%o) and of gypsum (2. 0%o ∼4. 7%o) are between the two former, suggesting reducing S comes from biological sulfate reduction which derives from the basinal brine descending from overlying Paleogene basin and evaporated-concentrated seawater cocooned in strata, and mixing of two kinds of fluid, which are local fluid rich in reducing sulfur and regional fluid rich in metal, causes the deposition of mineralized minerals. The Pb isotope composition of galena in the two periods are nearly the same and the ranges of 206 Pb/204 Pb,207 Pb/204 Pb and 208 Pb/204 Pb are 18. 8646 ∼18. 8835, 15. 6619 ∼15. 6677 and 38. 9404 ∼38. 9796, respectively, proving that Pb isotope comes from metamorphic basement and limestone (and clastic rock) caprock distributed in the orogenic belt. By comparing Lalongla deposit with carbonate-hosted deposits in 'Sanjiang' belt, the authors finally point out that Lalongla deposit could be classified as MVT-like deposit controlled by thrust nappe and its moralization model can be explained as followings: Structural trap formes in the carbonate formation due to thrust nappe. The basinal brine in Paleogene basin descends, accumulates, and generates the local fluid reservoir rich in H2S accompanied by the biological sulfate reduction. Regional fluid released by the compression deformation migrates along the main detachment zone of thrust nappe, leachs oreforming minerals in strata and generates allochthonous fluid rich in metallic elements. Along extended faults by final stretch of local thrust faults regional fluid ascends to the interface between limestone and mud shale, the favorable space, mixes with local fluid and leads to the uninstall mineralization of metal materials and the lens ore-bodies along the facies transition between different rocks finally form.


Liu Y.C.,Chinese Academy of Geological Sciences | Hou Z.Q.,Chinese Academy of Geological Sciences | Yang Z.S.,Chinese Academy of Geological Sciences | Tian S.H.,Chinese Academy of Geological Sciences | And 4 more authors.
Acta Petrologica Sinica | Year: 2010

Dongmozhazhua deposit, located in the northeast margin of Qiangtang terrane which is between Jinshajiang suture zone and Bangonghu-Nujiang suture zone, is a Pb-Zn deposit found in Pb-Zn-Cu-Ag ore-belt in three rivers'areas, and represents one type of hydrothermal deposits in thrust-nappe systems in continental collision orogenic belts. Now, this deposit has the largest resource quantity in the region. Studying on the geological characters and genetic type of this deposit is helpful for us to understand ore-forming rules of the regional Pb-Zn-Cu-Ag ore-belt and look for new deposits. And understanding the ore fluid properties which can be obtained by studying the fluid inclusions is much helpful for us to understand the genetic type of this deposit. So, based on detailed field work for geology of Dongmozhazhua Pb-Zn ore deposit and detailed observation of fluid inclusion sections of ores, the writers have done systematic work on fluid inclusions in this deposit. According to the fluid inclusion petrography there is just one type of fluid inclusions-liquid fluid inclusions in Dongmozhazhua Pb-Zn ore deposit. Based on the results of microscopic measuring temperature work, fluids before, at and after ore-forming stage are not continuous and they have different temperatures and salinities. Fluid at dolomitization stage and barite stage which are before the ore precipitation has middle-low temperatures (140 ∼ 160°C) and low salinities (0.0% ∼ 2. 0% NaCleqv.). While fluid at the ore precipitation stage has low temperatures (120 ∼ 140°C) and high salinities (26.0% ∼ 28.0% NaCleqv.). At the calcite stage after the ore forming the fluid has middle-high temperatures (220-240°C) and low salinities (6.0% ∼ 8.0% NaCleqv.). Based on the results of gas chromatographic GC) analysis, liquid chromatographic (LC) analysis and laser Raman spectrometry (LRM) analysis, the gas compositions of group and single fluid inclusions are mainly H20, CO2, N2, a little CO, CH4, C2H 2, C2H4, C2H6 and a little O2 and the liquid part of ore forming fluid belongs to Ca 2+-Mg2+-Na+-CI-S04 2-F system. By analyzing the data above, the fluids were considered mainly derived from basin brine which had moved for long distances in the basin, meteoric water and evaporated seawater which was kept in the carbonate strata. The fluids changed from weak reducing to oxidizing and then to weak reducing again and the sulfides precipitated more in the oxidizing environment. Before ore-forming stage the fluid with middle-low temperature and low salinity went into the mining area and dolomitized the carbonate rocks. The process of dolomitization made rock porosity increase and prepared first spaces for ore precipitation. At ore-forming stage the basin brine with low temperature and high salinity leached lots of metal cationic ions, such as Ca2+, Mg2+, Pb 2+ and Zn2+ and so on from the regional strata when it moved in the basin and became external fluid rich in metals. By biogenic sulfate reduction (BSR), the sulfates in evaporated seawater kept in the carbonate strata generated many reduced sulfurs and this kind of fluid converged gradually in the mining area. Then the above two kinds of fluids mixed and the sulfides precipitated. This is the main mechanism of ore forming in this deposit. Around 35 Ma when Dongmozhazhua Pb-Zn ore deposit formed the crust in Yushu area was not stable because of strong thrust and slip faults activities in the region. The thrust faults made the depths of the mining area changed in different ore-forming stage which was one factor for ore precipitation and the slip faults made the thrust faults move again which prepared structure paths for fluids to go into the mining area. The characters of geology and ore-fluids of Dongmozhazhua Pb-Zn ore deposit are much similar to those of MVT Pb-Zn deposits in the world. So the writers classify Dongmozhazhua Pb-Zn ore deposit as a MVT-like Pb-Zn ore deposit which is controlled by thrust-nappe system in orogenic belt. Resent years, this kind of Pb-Zn ore deposits found in Tibetan plateau has been reported several times and it becomes a new type of Pb-Zn ore deposits in continental collision orogenic belts. It also designates a new direction for exploration in Tibetan plateau.


Tian S.H.,Chinese Academy of Geological Sciences | Hou Z.Q.,Chinese Academy of Geological Sciences | Yang Z.S.,Chinese Academy of Geological Sciences | Liu Y.C.,Chinese Academy of Geological Sciences | And 3 more authors.
Acta Petrologica Sinica | Year: 2011

The Mohailaheng and Dongmozhazhua Pb-Zn deposits in the Yushu area of Qinghai Province, located in the northeast margin of Qiangtang terrane which is between Jinshajiang suture zone and Bangonghu-Nujiang suture zone, are the two typical Pb-Zn deposits in the Cu-Pb-Zn polymetallic mineralization belt for the northern part of the Nujiang-Lancangjiang-Jinshajiang area. The authors thought the sources of ore-froming material were derived from the sedimentary strata by the research of sulfur, lead, strontium and neodymium isotope compositions of the Dongmozhazhua lead-zinc ore deposit. On the basis of geological field observations, the authors also made the research on the Mohailaheng lead-zinc ore deposit and selected sulfide minerals and barite for S isotope compositions analyses, sulfide minerals, gangue minerals and regional strata for Pb isotope compositions analyses, and gangue minerals for Sr-Nd isotope compositions. δ34 S values of sulfide minerals are -30.0‰ - +7.4‰, and show peaks at -18‰ - -2‰, reflecting the characteristic of light sulfur. δ34S values of barite are 20.2‰ - +24.2‰, implying the derivation of Tertiary continental facies basin. The ore deposit displays wide variations in sulfide δ34S values, indicating multiple sulfur sources. On account of the lack of magmatic activity, it is realistic to view the rocks in the basin as the source of sulfur. Sulfur in the rocks was transferred into hydrothermal fluids via fluid-rock interaction. Therefore, the variation in rock types across the basin is likely to influence the variation of sulfur isotopic compositions. Reduced sulfurs were mainly derived from the biogenic sulfate reduction or the thermochemical reduction of sulfur-bearing organic matter, implying that sulfur came from the sedimentary basin. The 206Pb/204Pb, 207Pb/204Pb and 206Pb/204Pb ratios for sulfide minerals vary in ranges of 18.298-18.694, 15.298-15.721 and 38.169-38.894, respectively. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios for gangue minerals are between 18.418-18.672, 15.418-15.719 and 38.403 38.845, respectively. In the diagrams of 207Pb/204Pb- 206Pb/204Pb and 208Pb/204Pb- 206Pb/204Pb, the Pb isotope compositions of the sulfide minerals and gangue minerals fall into the regional upper crust lead zone, similar to MVT deposit, implying that Pb might have come from the upper crust rocks. The (87Sr/86Sr)i, εSr(t) , (143Nd/144Nd)i and εNd(t) ratios for gangue minerals vary in ranges of 0.70851-0.70906, 57.4-65.2, 0.512265-0.512361 and -6.5 - -4.6, respectively. The Sr-Nd isotope compositions of the gangue minerals indicate that their matter sources also came from the upper crust rocks. On the whole, the characters of sulfur, lead, strontium and neodymium isotope compositions of the Mohailaheng lead-zinc ore deposit in the Yushu area are the same as those of the Dongmozhazhua lead-zinc ore deposit, implying that they both derived from the sedimentary strata. Together with the geological and geochemical features of the Mohailaheng and Dongmozhazhua Pb-Zn deposits, the authors discussed their dynamical settings.


Peng G.,Central South University | Peng G.,Qinghai Institute of Geological Survey | Gao G.,Central South University
Geotectonica et Metallogenia | Year: 2013

Chinese Altay region is one of the important parts of Altay metallogenic belt of central Asia, and is a well-known mineralization area of non-ferrous metals, rare metals and precious metals. There are more than 100, 000 pegmatite veins in Chinese Altay region, 90% of which occur in more than 30 pegmatite ore fields. In this paper, the Azubai pegmatite ore field in the central Altay, which is around 500 km2 with the centre coordinate of 88°48'E and 47°56'N, is studied. Remote sensing images of ASTER, RapidEye, QuickBird and ENVISAT-ASAR are used to extract prospecting information on pegmatite deposits in the Azubai region. Greisenization and albitization are the main alterations closely associated with mineralization. Based on the spectral characteristics, the method of Feature-orientated Principal Component Selection (FPCS) was used to optimize the ASTER band combination of 1-4-6-7 and 1-4-6-9 to extract greisenization and albitization respectively. ASTER thermal infrared data were used to estimate the surface content of SiO2, K2O and Na2O based on empirical formula, which provide effective technical support for the classification of magmatic rocks and effective basis for mapping and locating of the contact zones of different lithologies. It is the high reflectivity of pegmatite in the spectral range from visible to near infrared that provides the important physical basis for automatic identification and remote sensing interpretation of pegmatite. The pegmatite interpreted from QuickBird image with spatial resolution of 0.61 m was used to validate the automatic extraction of pegmatite from RapidEye image with 5m spatial resolution whose accuracy is about 86%. ASAR image is only used to do some preliminary experiment to identify pegmatite. Due to the lower spatial resolution, the extracted pegmatite from ASAR image was not used for metallogenic prediction. The conjunction parts of geological structures, contact zones of lithologies and superposed parts of pegmatite enrichment zones and alteration anomalies are the important basis for metallogenic prediction. According to above factors derived from remote sensing, four target areas were delineated, which will provide guidance for further prospecting.


Guo T.-Z.,Qinghai Institute of Geological Survey | Liu R.,Qinghai Institute of Geological Survey | Chen F.-B.,Qinghai Institute of Geological Survey | Bai X.-D.,Qinghai Institute of Geological Survey | Li H.-G.,Qinghai Institute of Geological Survey
Geological Bulletin of China | Year: 2011

Wulanwuzhuer porphyritic syenite granite in Qimantag region is characterized by high silica, high alkali (AR 3.02-5.88, NK/A 1.04-1.17, and A/CNK 0.96-1.07), high TFeO/MgO ratio, poor CaO and MgO, relatively high ΣREE, slight enrichment of LREE, indistinct light and heavy REE fractionation, negative Eu anomalies, somewhat right-oblique "V"-shaped REE patterns, significant enrichment of Rb, K, Th and other large ion lithophile elements, relative enrichment of Zr, Hf and other high field strength elements, and relative depletion of such elements as Ba, Sr, P, Ti, and Nb. These characteristics suggest an aluminous A2-type granite, whose formation might have been associated with the young crust formed by oceanic crust and island arc. Using LA-MC-ICPMS zircon U-Pb dating, the authors obtained the 206Pb/238U age of Wulanwuzhuer granite of 388.9±3.7 Ma (MSWD=3.1), which represents the formation age of the rock. In combination with geochemical and structural features and regional geological setting, the authors hold that the intrusive body was formed in a relative extension environment during post-orogenic or late orogenic evolution.


Liu S.-Y.,Qinghai Institute of Geological Survey | Liu S.-Y.,Laboratory of Geological Processes and Mineral Resources in the Northern Qinghai Tibet Plateau | Yang W.-F.,Qinghai Institute of Geological Survey | Yang W.-F.,Laboratory of Geological Processes and Mineral Resources in the Northern Qinghai Tibet Plateau
Northwestern Geology | Year: 2010

The Tuolugou cobalt (gold) deposit is one of typical volcanic sedimentary-exhalative deposits occurring in Ordovician-Silurian volcanic-sedimentary rocks in Qinghai Province, discovered in recent years. Through the analysis for the geological background of ore formation and geological characteristics of deposit and adopted the remote sensing technique method, the author summarized characteristics of the source bed,ore-controlling structures and mineralization alterration information in the ETM + images, from the remote sensing angle and according to the distribution of remote sensing anomaly; and considered that the east and west extension areas in the Tuolugou cobalt (gold) deposit and the north wing of the Jiuqigou anticlinorium are better to prospect.


Peng G.-X.,Central South University | Peng G.-X.,Qinghai Institute of Geological Survey | Chen F.-R.,Henan University | Pang Y.,Central South University
Applied Mechanics and Materials | Year: 2013

Angou deposit locates in the southern part of east Qinling Metallogenic Belt. A few Mo-Pb deposits have been discovered in this region. This paper demonstrates that there is a close relationship between carbonitization and molybdenum mineralization. Therefore carbonitization can be an important prospecting marker for molybdenum. Four Hyperion bands, with the wavelength of 420nm, 803nm, 2324nm and 2385 nm respectively, were selected for principal component analysis to extract carbonitization anomalies. Field work results show good relationship between carbonitization anomaly and molybdite and molybdenum ore bodies. The zones with intensive carbonitization anomalies have good prospecting potential. © (2013) Trans Tech Publications, Switzerland.

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