According to an analysis of the geological features in the eastern sector of the Bangong Co-Nujiang River suture zone, the Tethyan evolution can be divided into three stages. (1) The Embryo-Tethyan stage (Pz1): An imm...According to an analysis of the geological features in the eastern sector of the Bangong Co-Nujiang River suture zone, the Tethyan evolution can be divided into three stages. (1) The Embryo-Tethyan stage (Pz1): An immature volcanic arc developed in Taniantaweng (Tanen Taunggyi) Range, indicating the existence of an Embryo-Tethyan ocean. (2) The Palaeo-Tethyan stage (C-T2: During the Carboniferous the northern side of the Taniantaweng Range was the main domain of the Palaeo-Tethyan ocean, in which developed flysch sediments intercalated with bimodal volcanic rocks and oceanic tholeiite, and Pemian-Early Triassic are granites were superimposed on the Taniantaweng magmatic are; on the southern side the Dêngqên-Nujiang zone started secondary extension during the Carboniferous, in which the Nujiang ophiolite developed, and the Palaeo-Tethyan ocean closed before the Middle Triassic. (3) The Neo-Tethyan stage (T3-E): During the Late Triassic the Dêngqên zone developed into a relatively matural ocean basin, in which the Dêngqên ophiolite was formed. By the end of the Triassic intraocean subduction occurred, and the ocean domain was reduced gradually, and collided and closed by the end of the Early Jurassic, forming the Yazong mélange; then the Tethyan ocean was completely closed.展开更多
The area change of heat abnormity is not in accordance with conclusions of former thermal infrared remote sensing studies of the Qinghai-Tibet Plateau, which were that the temperature of Yarlung Zangbo River suture be...The area change of heat abnormity is not in accordance with conclusions of former thermal infrared remote sensing studies of the Qinghai-Tibet Plateau, which were that the temperature of Yarlung Zangbo River suture belt of the southern Plateau is high and the northern temperature is low. The study result in this paper shows that the highest temperature is found in the Bangong Co-Nujiang River suture belt, the Yarlung Zangbo River suture belt temperature is the second highest, and the northern Tibet temperature is the lowest. The study demonstration area was the suture belt areas of the Yarlung Zangbo River and the Bangong Co-Nujiang River in the Qinghai-Tibet Plateau, where the land temperature of the Qinghai-Tibet Plateau and the bore temperature of field land surface were measured and the emissivity of land surface was calculated. In addition, the authors explore the mechanism of the relationship between thermal infrared remote sensing and constructing thermodynamics and reach four new conclusions about the thermodynamics of the Tibet Plateau.展开更多
The Tiegelongnan deposit is a newly discovered super-large porphyry-epithermal Cu-（Au） deposit in the western part of the Bangong Co-Nujiang metallogenic belt, Tibet（China）. Field geology and geochronology indicat...The Tiegelongnan deposit is a newly discovered super-large porphyry-epithermal Cu-（Au） deposit in the western part of the Bangong Co-Nujiang metallogenic belt, Tibet（China）. Field geology and geochronology indicate that the porphyry mineralization was closely related to the Early Cretaceous intermediate-felsic intrusions（ca. 123–120 Ma）. Various epithermal ore and gangue mineral types were discovered in the middle-shallow part of the orebody, indicating the presence of epithermal mineralization at Tiegelongnan. Potassic, propylitic, phyllic and advanced argillic alteration zones were identified. 40Ar/39Ar dating of hydrothermal biotite（potassic zone）, sericite（phyllic zone）, and alunite（advanced argillic zone） in/around the ore-bearing granodiorite porphyry yielded 121.1±0.6 Ma（1σ）, 120.8±0.7 Ma（1σ） and 117.9±1.6 Ma（1σ）, respectively. Five hydrothermal mineralization stages were identified, of which the Stage IV pyrite was Rb-Sr dated to be 117.5±1.8 Ma（2σ）, representing the end of epithermal mineralization. Field geology and geochronology suggest that both the epithermal and porphyry mineralization belong to the same magmatic-hydrothermal system. The Tiegelongnan super-large Cu-（Au） deposit may have undergone a prolonged magmatichydrothermal evolution, with the major mineralization event occurring at ca.120–117Ma.展开更多
The Peng Co ophiolite is located to the west of Peng lake in the area of lakes in north Tibet, which belongs to the Baila-Yilashan sub-belt of the the middle Bangong Co-Nujiang ophiolitic belt. The Peng Co ophiolite i...The Peng Co ophiolite is located to the west of Peng lake in the area of lakes in north Tibet, which belongs to the Baila-Yilashan sub-belt of the the middle Bangong Co-Nujiang ophiolitic belt. The Peng Co ophiolite is mainly composed of mantle peridotites, cumulates, diabase dikes. About 70 percent peridotites are harzburgites and 30 percent are lherzolites. Mineral chemistry of the Peng Co lherzolitesare characterized by low Fo contents(88.85–90.33) of olivine and high Al2O3 content(4.26%–7.25%) in pyroxenes. Compared to the primitive mantle, the Peng Co peridotites have relatively higher MgO contents, lower CaO, Al2O3 and TiO2 contents. The total rare-earth element(REE) contents of the lherzolites are 1.11–1.53 ppm, which are lower than those of the primitive mantle. The chondritenormalized REE patterns of the Peng Co peridotites display slight loss in LREE. In the primitive mantle-normalized spider diagram, the Peng Co peridotites exhibit negative Rb and Zr anomalies and intensively positive U, Ta, Sr anomalies. The PGE contents of Peng Co lherzolites are between 22.9–27 ppb. The chondrite-normalized PGE patterns of the Peng Co lherzolites are consistent with that of the primitive mantle. Mineral and whole-rock geochemistry characteristics of the Peng Co lherzolites show an affinity to abyssal peridotites, indicating that it may have formed in the mid-ocean ridge setting. Through quantitative modeling, we conclude that the Peng Co lherzolites formed after 5%–10% degree of partial melting of the spinelphase lherzolite mantle source. The sharp increase of Cr#(56.74–60.84)in Spinel of harzburgites and relatively high Pd/Ir and Rh/Ir ratios suggest that they have experienced melt-rock reaction. The crystallization sequence of Peng Co cumulate is olivine-clinopyroxene-plagioclase. The Mg# value of clinopyroxene in cumulate peridotite ranges from 86.92 to 89.93, and the mean value of Fo is 84.45, which is obviously higher than that of MOR-type ophiolite cumulates. The mineral composition, sequence of magmatic crystallization and mineral components of Peng Co cumulate are similar to those of the cumulate formed by the SSZ-type ophiolite in the subduction zone. Therefore, we can draw a preliminary conclusion that Peng Co lherzolites were formed in an environment of mid oceanic ridge and were remnants of the spinel lherzolite zone which experienced a partial melting of no more than 10%. In the later period, due to the intra-oceanic subduction, it experienced the rock-meltinteraction, and thus formed the SSZ-type cumulate and harzburgite of high Cr value.展开更多
文摘According to an analysis of the geological features in the eastern sector of the Bangong Co-Nujiang River suture zone, the Tethyan evolution can be divided into three stages. (1) The Embryo-Tethyan stage (Pz1): An immature volcanic arc developed in Taniantaweng (Tanen Taunggyi) Range, indicating the existence of an Embryo-Tethyan ocean. (2) The Palaeo-Tethyan stage (C-T2: During the Carboniferous the northern side of the Taniantaweng Range was the main domain of the Palaeo-Tethyan ocean, in which developed flysch sediments intercalated with bimodal volcanic rocks and oceanic tholeiite, and Pemian-Early Triassic are granites were superimposed on the Taniantaweng magmatic are; on the southern side the Dêngqên-Nujiang zone started secondary extension during the Carboniferous, in which the Nujiang ophiolite developed, and the Palaeo-Tethyan ocean closed before the Middle Triassic. (3) The Neo-Tethyan stage (T3-E): During the Late Triassic the Dêngqên zone developed into a relatively matural ocean basin, in which the Dêngqên ophiolite was formed. By the end of the Triassic intraocean subduction occurred, and the ocean domain was reduced gradually, and collided and closed by the end of the Early Jurassic, forming the Yazong mélange; then the Tethyan ocean was completely closed.
文摘The area change of heat abnormity is not in accordance with conclusions of former thermal infrared remote sensing studies of the Qinghai-Tibet Plateau, which were that the temperature of Yarlung Zangbo River suture belt of the southern Plateau is high and the northern temperature is low. The study result in this paper shows that the highest temperature is found in the Bangong Co-Nujiang River suture belt, the Yarlung Zangbo River suture belt temperature is the second highest, and the northern Tibet temperature is the lowest. The study demonstration area was the suture belt areas of the Yarlung Zangbo River and the Bangong Co-Nujiang River in the Qinghai-Tibet Plateau, where the land temperature of the Qinghai-Tibet Plateau and the bore temperature of field land surface were measured and the emissivity of land surface was calculated. In addition, the authors explore the mechanism of the relationship between thermal infrared remote sensing and constructing thermodynamics and reach four new conclusions about the thermodynamics of the Tibet Plateau.
基金jointly sponsored by the Public Science and Technology Research Funds Projects,Ministry of Land Resources of the People’s Republic of China(project No.201511017 and 201511022-02)the Basic Research Fund of the Chinese Academy of Geological Sciences(Grant No.YYWF201608)+3 种基金the National Natural Science Foundation of China(Grant No.41402178)Geological Survey Project of the China Geological Survey(project 1212011405040)Golden Dragon Mining Co.Ltd.(project XZJL-2013-JS03)China Scholarship Council
文摘The Tiegelongnan deposit is a newly discovered super-large porphyry-epithermal Cu-（Au） deposit in the western part of the Bangong Co-Nujiang metallogenic belt, Tibet（China）. Field geology and geochronology indicate that the porphyry mineralization was closely related to the Early Cretaceous intermediate-felsic intrusions（ca. 123–120 Ma）. Various epithermal ore and gangue mineral types were discovered in the middle-shallow part of the orebody, indicating the presence of epithermal mineralization at Tiegelongnan. Potassic, propylitic, phyllic and advanced argillic alteration zones were identified. 40Ar/39Ar dating of hydrothermal biotite（potassic zone）, sericite（phyllic zone）, and alunite（advanced argillic zone） in/around the ore-bearing granodiorite porphyry yielded 121.1±0.6 Ma（1σ）, 120.8±0.7 Ma（1σ） and 117.9±1.6 Ma（1σ）, respectively. Five hydrothermal mineralization stages were identified, of which the Stage IV pyrite was Rb-Sr dated to be 117.5±1.8 Ma（2σ）, representing the end of epithermal mineralization. Field geology and geochronology suggest that both the epithermal and porphyry mineralization belong to the same magmatic-hydrothermal system. The Tiegelongnan super-large Cu-（Au） deposit may have undergone a prolonged magmatichydrothermal evolution, with the major mineralization event occurring at ca.120–117Ma.
基金granted by National Natural Science Foundation of China(41720104009)China Geology Survey Project(DD20160023-01)Foundation of MLR(201511022)
文摘The Peng Co ophiolite is located to the west of Peng lake in the area of lakes in north Tibet, which belongs to the Baila-Yilashan sub-belt of the the middle Bangong Co-Nujiang ophiolitic belt. The Peng Co ophiolite is mainly composed of mantle peridotites, cumulates, diabase dikes. About 70 percent peridotites are harzburgites and 30 percent are lherzolites. Mineral chemistry of the Peng Co lherzolitesare characterized by low Fo contents(88.85–90.33) of olivine and high Al2O3 content(4.26%–7.25%) in pyroxenes. Compared to the primitive mantle, the Peng Co peridotites have relatively higher MgO contents, lower CaO, Al2O3 and TiO2 contents. The total rare-earth element(REE) contents of the lherzolites are 1.11–1.53 ppm, which are lower than those of the primitive mantle. The chondritenormalized REE patterns of the Peng Co peridotites display slight loss in LREE. In the primitive mantle-normalized spider diagram, the Peng Co peridotites exhibit negative Rb and Zr anomalies and intensively positive U, Ta, Sr anomalies. The PGE contents of Peng Co lherzolites are between 22.9–27 ppb. The chondrite-normalized PGE patterns of the Peng Co lherzolites are consistent with that of the primitive mantle. Mineral and whole-rock geochemistry characteristics of the Peng Co lherzolites show an affinity to abyssal peridotites, indicating that it may have formed in the mid-ocean ridge setting. Through quantitative modeling, we conclude that the Peng Co lherzolites formed after 5%–10% degree of partial melting of the spinelphase lherzolite mantle source. The sharp increase of Cr#(56.74–60.84)in Spinel of harzburgites and relatively high Pd/Ir and Rh/Ir ratios suggest that they have experienced melt-rock reaction. The crystallization sequence of Peng Co cumulate is olivine-clinopyroxene-plagioclase. The Mg# value of clinopyroxene in cumulate peridotite ranges from 86.92 to 89.93, and the mean value of Fo is 84.45, which is obviously higher than that of MOR-type ophiolite cumulates. The mineral composition, sequence of magmatic crystallization and mineral components of Peng Co cumulate are similar to those of the cumulate formed by the SSZ-type ophiolite in the subduction zone. Therefore, we can draw a preliminary conclusion that Peng Co lherzolites were formed in an environment of mid oceanic ridge and were remnants of the spinel lherzolite zone which experienced a partial melting of no more than 10%. In the later period, due to the intra-oceanic subduction, it experienced the rock-meltinteraction, and thus formed the SSZ-type cumulate and harzburgite of high Cr value.
