The Xialonggang Pb-Zn-Sb deposit is a newly discovered large-scale polymetallic deposit within the Tethyan Himalayan metallogenic belt.Although significant prospecting breakthroughs have been made at Xialonggang in re...The Xialonggang Pb-Zn-Sb deposit is a newly discovered large-scale polymetallic deposit within the Tethyan Himalayan metallogenic belt.Although significant prospecting breakthroughs have been made at Xialonggang in recent years,the geology and mineralization process are poorly understood.This study conducted monazite U-Pb geochronology,fluid inclusion,and O-H-S isotope of the Xialonggang Pb-Zn-Sb deposit.Analytical results indicate that the ore-forming fluids constituted a H_(2)O-NaCl-CO_(2)-CH_(4)-N_(2)system characterized by moderate temperatures(261-314℃)and moderate to low salinities(2.9-8.9 wt%NaCl eqv.).The early-stage fluids exhibited signatures close to magmatic fluids,while the late-stage fluids showed characteristics indicative of mixing between magmatic fluids and meteoric water.Sulfur isotope analysis(mainly range primarily from 1.2‰to 6.44‰,with one sphalerite up to 8.19‰)revealed that a predominantly deep-sourced sulfur composition with minor contribution from sedimentary strata.This study demonstrates that the Xialonggang Pb-Zn-Sb deposit is controlled by the NE-trending fault system.A hydrothermal circulation system driven by substantial deep-seated magmatic heat,leached materials from the surrounding strata.The hydrothermal fluids migrated upwards along the fault system,filling the NE-trending tensional fractures to form a hydrothermal vein-type Pb-Zn-Sb deposit.展开更多
The Qinghai-Tibet Plateau(QTP),the“Third Pole of the Earth,”boasts the most complex,diverse,and unique ecosystem in the world.From tropical vegetation on the southern slopes of the Himalayas to alpine subnival ecosy...The Qinghai-Tibet Plateau(QTP),the“Third Pole of the Earth,”boasts the most complex,diverse,and unique ecosystem in the world.From tropical vegetation on the southern slopes of the Himalayas to alpine subnival ecosystems,and from humid forests in the east to arid Gobi or desert vegetation in the west,the QTP encompasses nearly all the ecosystem types found in the Northern Hemisphere(The Comprehensive ScientificExpedition to Qinghai-Xizang Plateau,Academia Sinica,1988).展开更多
The A＇nyemaqen （阿尼玛卿） ophiolite belt along the southern margin of the East Kunlun （昆仑） Mountains marks the suture formed by the closure of paleo-Tethys. The Dur＇ngoi ophiolite in the eastern part of this b...The A＇nyemaqen （阿尼玛卿） ophiolite belt along the southern margin of the East Kunlun （昆仑） Mountains marks the suture formed by the closure of paleo-Tethys. The Dur＇ngoi ophiolite in the eastern part of this belt consists of meta-peridotite, mafic-ultramafic cumulates, sheeted dikes and basaltic lavas. The meta-peridotites consist of dunite, harzburgite, lherzolite, feldspar-bearing lherzolite and garnet-bearing lherzolite and contain residual spinel with Cr# [100×Cr/（Cr＋Al）] ranging from 30 to 57 and Mg# [100×Mg/（Mg＋Fe2＋）] ranging from 50 to 75, indicating an Al- and Mg-rich series. The meta-peridotites have a relatively narrow range of composition with Mg# of 89.2-92.6, Al2O3 contents of （1-4） wt.% and slightly depleted chondrite normalized REE patterns, indicating that they represent relict mantle material that has undergone intermediate to low degrees of partial melting. Garnets in the lherzolite are andradite, enriched in Ca and Fe and depleted in Mg and AI （And=95-97, Pyr=0.3-5, Gro=0-3）, indicating a metamorphic origin. The cumulate rocks mainly consist of dunite, wehrlite, pyroxenite and gabbro. A well-layered gabbro-pyroxenite complex is defined by modal variations in plagioclase and pyroxene. Blocks of garnet-pyroxenite or rodingite are locally present in the meta-peridotites. Garnets in the cumulate rocks are grossular （Gro=69-90, And=9-19, Br=l-12）, also metamorphic origin. The diabase dikes are moderately depleted in LREE [（La/Sm）N=0.5-0.8] and HREE resulting in slightly convex chondrite-normalized patterns with slightly positive Eu anomalies （δEu=1.1-1.3）. The basaltic lavas have REE patterns similar to those of MORB with （La/Sm）N ratios of 0.5-1 and small negative Eu anomalies. They appear to have been derived from a depleted mantle source and to have undergone little or no differentiation during crystallization. SHRIMP U-Pb dating of zircons from the basalts yields 286pb/238U ages of 276-319 Ma （average 308.0±4.9 Ma）. The Dur＇ngoi ophiolite is interpreted as a dismembered fragment of paleo-oceanic crust emplaced during closure of the paleo-Tethyan Ocean basin. Three other suites of oceanic lavas are recognized in the area： island arc volcanic （IAV） rocks, possible back arc basin （BAB） basalts and possible post-collisional volcanic （PCV） and plutonic rocks. The distribution of these rocks suggests north-directed subduction. Opening of the A＇nyemaqen oceanic basin started at least as early as Late Carboniferous （308 Ma） and the basin probably closed during the Early Triassic. The IAV formed in Late Permian （260 Ma）, the BAB in Early-Middle Triassic, and the PCV in Late Triassic. Several large scale, ductile, sinistral strike-slip fault zones, extending hundreds to thousands kilometers, formed along or north of the suture during the Early-Late Triassic, e.g., they are the south margin fault zone of East Kunlun （200-220 Ma）, the Altyn Tagh fault （220-230 Ma）, and the North Qaidam fault zone （240-250 Ma）. These strike-slip faults were probably generated by oblique subduction and closure of the paleo-Tethyan Ocean basin, possibly during exhumation of the subducted plate or uplift of the overriding plate, coincident with post-collisional magmatism.展开更多
Pinusdensata is one of the main constructive species for coniferous forests in southeast Tibet. P. densata forests are important water conservation forests in the drainage basins of the middle and lower reaches of Yal...Pinusdensata is one of the main constructive species for coniferous forests in southeast Tibet. P. densata forests are important water conservation forests in the drainage basins of the middle and lower reaches of Yalu Tsangpo River, Nyang River and Parlung Zangbo River. In this study, with P. densata forest distributed in southeast Tibet as research object, the seed rain, soil seed bank, seed germination and natural regeneration of P. densata were monitored and ana- lyzed by field investigation, located monitoring and indoor experimental analysis. The results showed that the average intensity of the seed rain of P. densata was 249.30±78.42 seeds/m2, in which the intensity of full seeds was 168.09±56.36 seeds/m2, the intensity of seeds damaged by worms was 41.11±20.25 seeds/m2, and the intensity of empty seeds was 40.10±21.04 seeds/m2. The intensity of the seed rain exhibited a single-peak trend of increasing at first and decreasing then over time. The spatial distribution patterns in the whole seed falling process and at different seed falling time all exhibited clumping distribution, and within in certain range, with the distance from the seed tree increasing, the diffusion intensity of the seed rain was weakened, exhibiting approximately normal distribution. In average density of P. densata seeds in the soil seed bank of P. densata was 231 seeds/m2, in which 62.77% of seeds were distributed in the litter layer, and 37.23% of seeds were distributed in the soil layer, and about 8% of seeds were lost during the pro- cess from seed rain to soil seed bank. Field sowing observation showed that the accumulated germination rate curve of P. densata fitted with Logistics equation y= 91.404/（1＋e66194.449）. The height structure, basal diameter structure and age structure of seedlings and young trees of P. densata were all of reverse ＂J＂ type, indicating good natural regeneration of P. densata. This study would provide a science basis for protection and resource management of P. densata, and further enrich the eval- uation content of national ecological safety curtain of the Tibet plateau.展开更多
A wide variety of unusual mantle has been reported from podiform chromitite orebodies Cr-31 and Cr-74 in the Luobusa （罗布莎） ophiolite, Tibet. A detailed investigation of chromitite ore- body Cr-ll, located in the ...A wide variety of unusual mantle has been reported from podiform chromitite orebodies Cr-31 and Cr-74 in the Luobusa （罗布莎） ophiolite, Tibet. A detailed investigation of chromitite ore- body Cr-ll, located in the Kangjinla （康金拉） district at the eastern end of the ophiolite, has revealed many of the same minerals, including diamond, moissanite, and some native elements, alloys, oxides, sulphides, silicates, carbonates, and tungstates. This orebody is particularly rich in diamonds, with over 1 000 grains recovered from about 1 100 kg sample of chromitite. More detailed studies and experiments are needed to understand the origin and significance of these unusual minerals because they have not been found in situ. It is a great breakthrough in mineralogical research that we have picked up more than 40 kinds of minerals from the Kangjinla chromite deposit in Luobusa. It is notable that a large amount of diamonds were firstly discovered from the Kangjinla chromite deposit as well as many other unusual minerals, such as moissanites, rutiles, native irons, and metal alloys. Especially, that diamond was found again in different chromitites in the same ophiolite belt provided new key evidence for discussing the origin of the diamond and the hosted chromitite and ophiolite. The mantle mineral group in Tibet has great significance in mineralogy and geodynamics.展开更多
The Kadui blueschist is located in the central section of Yarlung Zangbo suture zone （YZSZ）, southern Tibet, and has been subjected to the subduction of the Neo-Tethyan Ocean below the Asian Plate and provides impor...The Kadui blueschist is located in the central section of Yarlung Zangbo suture zone （YZSZ）, southern Tibet, and has been subjected to the subduction of the Neo-Tethyan Ocean below the Asian Plate and provides important clues for better understanding the evolution of the India-Asia convergence zone. In this paper, the systematical petrographic and mineral chemical studies were carried out on the Kadui blueschist, which reveal a mineral assemblage of sodic amphibole, chlorite, epidote, albite and quartz with accessory minerals of titanite, calcite and zircon. Electron microprobe analyses demonstrate that amphibole shows zoned from actinolite core to ferrowinchite/riebeckite rim composition indicating that the sodic amphibole has formed during a prograde metamorphic event. The protolith of the blueschist is an intermediate-basic pyroclastic rock. The calculated pseudosection indicates a clockwise P-T path and constrains peak metamorphic conditions of about 5.9 kbar at 345 ℃. This condition is transitional between pumpellyite-actinolite, greenschist and blueschist facies with a burial depth of 20-22 km and a thermal gradient of 15-16 ℃/km. This thermal gradient belongs to high pressure intermediate P/T facies series and is possibly related to a warm subduction setting of young oceanic slabs. Our new findings indicate that the Kadui blueschist in the central part of YZSZ experienced a rapid subduction and exhumation process as a response to a northward subduction of the Neo-Tethyan oceanic lithosphere during the initial India-Asia collision stage.展开更多
This study aimed to explore artificial propagation techniques for Glyptosternum maculatum that is endemic in the Yarlung Zangbo River. Total 86 female fish in weight of 0.065-0.250 kg were selected, and the average we...This study aimed to explore artificial propagation techniques for Glyptosternum maculatum that is endemic in the Yarlung Zangbo River. Total 86 female fish in weight of 0.065-0.250 kg were selected, and the average weight of every 15 fish was 0.30 kg. Oxytocic drugs were injected into the base of pectoral fins of the female fish. The results showed that the total amount of female fish with artificial insemination was 59. The gloss weight of the fertilized eggs was 897.5 g with total amount of 57 440, thus the average fecundity was 1 194 eggs/fish. The fecundity showed a positive correlation with body weight （P〈0.01）. The average induction ratio and fertilization rate were 69% and 73.5%, respectively. The optimum water temperature for hatching of the fertilized eggs was 13-14 ℃ with dissolved oxygen of 6.0- 7.2 mg/L. The accumulated temperature for embryonic development of G. maculatum ranged from 2 592 to 2 916℃·h. This set of completely artificial propagation techniques has a very important significance for the artificial breeding of G. maculatum.展开更多
Taking Terminalia chebula Retz. as the control product, the polyphenolic contents of the processed products in Tibetian, Rubia cordifolia L. processed Terminalia chebula Retz. and Euphorbia fischeriana Steud processed...Taking Terminalia chebula Retz. as the control product, the polyphenolic contents of the processed products in Tibetian, Rubia cordifolia L. processed Terminalia chebula Retz. and Euphorbia fischeriana Steud processed Terminalia chebula Retz. were analyzed by HPLC. Polyphenolic contents increased from 4.54% to 5.69% and 7.46%, respectively, which may lead to the change in their pharmacological effects.展开更多
The Amdo microcontinent is located within the middle of Bangong-Nujiang suture（BNS） zone in the shape of lens. The basic geological research restricts geologists from understanding the histories of tectonic evolutio...The Amdo microcontinent is located within the middle of Bangong-Nujiang suture（BNS） zone in the shape of lens. The basic geological research restricts geologists from understanding the histories of tectonic evolution of BNS and regional geology more deeply. This paper systematically studies the geochronology and geochemistry of granitic gneisses from Amdo basement. These data provide constraints on formation age, source characteristics and tectonic setting of their protolith. The SHRIMP zircon U-Pb dating is operated for granitic gneisses. Samples AGS-2 and AGS-3（granitic gneiss） yield average zircon U-Pb ages of 485±14 and 487±6 Ma, respectively. These ages should represent the formation age of protolith and indicate that they are formed in the Early Ordovician. Granitic gneisses are characterized by high SiO2, Na2O, K2O and Al2O3, low Fe and Mg, enrichment in light rare earth elements（LREEs） and large ion lithophile elements（LILEs）, depletion in heavy rare earth elements（HREEs） and high field strength elements（HFSEs）, with negative Eu anomaly. The Rittmann index（σ） is 1.77 to 2.60, less than 3.3. The aluminum saturation index（A/CNK） values range from 0.88 to 1.26. These features suggest that protolith of granitic gneisses from Amdo basement show characteristics of calc-alkaline and S-type granite, and they could be derived from partial melting of metamorphic greywackes in the upper crust of low maturity. The tectonic setting is syn-collision. These all suggest that the formation of protolith of granitic gneisses from Amdo are caused by the Early Paleozoic orogeny, which could be related to proto-Tethyan oceanic subduction along Gondwana continental margins, and does not result from the production of Pan-African orogenesis.展开更多
The Triassic in the Qomolongma area, southern Tibet, was deposited under an extensional tectonic setting from the Pangea supercontinent to continental rifting. From the Induan to Rhaetian, 12 depositional sequences (...The Triassic in the Qomolongma area, southern Tibet, was deposited under an extensional tectonic setting from the Pangea supercontinent to continental rifting. From the Induan to Rhaetian, 12 depositional sequences (3rd order) have been recognized, which can be grouped into 5 sequence sets and in turn make up a well defined mesosequence (2nd order). Among the recognized marine transgressions, those at 250 Ma, 239 Ma, 231 Ma and 223 Ma respectively are particularly of significance and can be correlated widely across continents. The study shows that in Triassic the Qomolongma area experienced a sedimentary evolution from epicontinental sea to rift basin with the turning point at ca 228 Ma. During the early and middle epochs, the area was under epeiric sea, with carbonate ramp to mixed shoal environments predominant. In the late Carnian, the strong extension initiated listric faulting, thus resulting in rapid basement subsidence and the onset of a rift basin. From the late Norian to Rhaetian, it manifested as a rapid basin filling process in the area. Coupled with long term sea level fall, the excessive terrigenous influx led to the shift of environment from deep water prodelta to shore and finally to fluvial plain.展开更多
To study the change of the content of chebulinic acid in Terminalia chebula Retz. by different processing methods in Tibet. We taking chebulinic acid as an indicator, the contents in Terminalia chebula Retz. and its p...To study the change of the content of chebulinic acid in Terminalia chebula Retz. by different processing methods in Tibet. We taking chebulinic acid as an indicator, the contents in Terminalia chebula Retz. and its processed products were analyzed by using HPLC. Also, the change rule was explored. Compared with Terminalia chebula Retz., the contents of chebulinic acid have decreased after processing, declining 50.18% for the Rubia cordifolia L. processed product, while 11.2% reduce for the Euphorbia fischeriana Steud processed product. After the specific preparation process in Tibet, the contents of chebulinic acid have reduced significantly, which may lead to different pharmacological effects.展开更多
[Objective] This study was to provide theoretical basis for getting sustainable development of rural energy in Tibet into reality.[Method] By reviewing the rural energy resources in Tibet,we analyzed the characteristi...[Objective] This study was to provide theoretical basis for getting sustainable development of rural energy in Tibet into reality.[Method] By reviewing the rural energy resources in Tibet,we analyzed the characteristics and potential of rural biomass utilization in Tibet,and further put forward the sustainable countermeasures on the firewood substitution in Tibet.[Results] Renewable energies including hydraulic,geothermal,solar and wind resources are abundant in Tibet,while there is just a few of fossil energy resources such as oil and coal,with uneven distribution and poor exploration conditions.Traditional consumption of biomass energy resource accounts for a large proportion of the total energy consumption in Tibetan rural districts,which causes potential damage to the fragile ecological environment on the Tibetan Plateau.The excessive use of biomass energy destroyed the vegetation and evoked the environment deterioration such as the intensification of the water and soil loss and the declining of the soil fertility.[Conclusion] It is essential for Tibet to change its rural energy consumption structure,implement the Tibetan firewood alternative energy strategy and try to make full use of renewable energy such as solar energy,wind energy,hydro-energy instead of native vegetation and animal＇s droppings in order to reduce the adverse impacts of the irrational energy consumption on the ecological environment in Tibet.展开更多
基金financially supported by the China Geological Survey(Grant Nos.DD20240014 and DD20243090)Central governmentguided local scientific and technological development fund project(Grant No.XZ202401YD0006-07)Ministry of Natural Resources of China(Grant No.ZKKJ202427)。
文摘The Xialonggang Pb-Zn-Sb deposit is a newly discovered large-scale polymetallic deposit within the Tethyan Himalayan metallogenic belt.Although significant prospecting breakthroughs have been made at Xialonggang in recent years,the geology and mineralization process are poorly understood.This study conducted monazite U-Pb geochronology,fluid inclusion,and O-H-S isotope of the Xialonggang Pb-Zn-Sb deposit.Analytical results indicate that the ore-forming fluids constituted a H_(2)O-NaCl-CO_(2)-CH_(4)-N_(2)system characterized by moderate temperatures(261-314℃)and moderate to low salinities(2.9-8.9 wt%NaCl eqv.).The early-stage fluids exhibited signatures close to magmatic fluids,while the late-stage fluids showed characteristics indicative of mixing between magmatic fluids and meteoric water.Sulfur isotope analysis(mainly range primarily from 1.2‰to 6.44‰,with one sphalerite up to 8.19‰)revealed that a predominantly deep-sourced sulfur composition with minor contribution from sedimentary strata.This study demonstrates that the Xialonggang Pb-Zn-Sb deposit is controlled by the NE-trending fault system.A hydrothermal circulation system driven by substantial deep-seated magmatic heat,leached materials from the surrounding strata.The hydrothermal fluids migrated upwards along the fault system,filling the NE-trending tensional fractures to form a hydrothermal vein-type Pb-Zn-Sb deposit.
基金funded by Key Project of Regional Innovation and Development Joint Fund of National Natural Science Foundation of China(U23A20149)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0502,2024QZKK0200).
文摘The Qinghai-Tibet Plateau(QTP),the“Third Pole of the Earth,”boasts the most complex,diverse,and unique ecosystem in the world.From tropical vegetation on the southern slopes of the Himalayas to alpine subnival ecosystems,and from humid forests in the east to arid Gobi or desert vegetation in the west,the QTP encompasses nearly all the ecosystem types found in the Northern Hemisphere(The Comprehensive ScientificExpedition to Qinghai-Xizang Plateau,Academia Sinica,1988).
基金supported by China Geological Survey (Nos. 1212010918013 and 1212010610105)
文摘The A＇nyemaqen （阿尼玛卿） ophiolite belt along the southern margin of the East Kunlun （昆仑） Mountains marks the suture formed by the closure of paleo-Tethys. The Dur＇ngoi ophiolite in the eastern part of this belt consists of meta-peridotite, mafic-ultramafic cumulates, sheeted dikes and basaltic lavas. The meta-peridotites consist of dunite, harzburgite, lherzolite, feldspar-bearing lherzolite and garnet-bearing lherzolite and contain residual spinel with Cr# [100×Cr/（Cr＋Al）] ranging from 30 to 57 and Mg# [100×Mg/（Mg＋Fe2＋）] ranging from 50 to 75, indicating an Al- and Mg-rich series. The meta-peridotites have a relatively narrow range of composition with Mg# of 89.2-92.6, Al2O3 contents of （1-4） wt.% and slightly depleted chondrite normalized REE patterns, indicating that they represent relict mantle material that has undergone intermediate to low degrees of partial melting. Garnets in the lherzolite are andradite, enriched in Ca and Fe and depleted in Mg and AI （And=95-97, Pyr=0.3-5, Gro=0-3）, indicating a metamorphic origin. The cumulate rocks mainly consist of dunite, wehrlite, pyroxenite and gabbro. A well-layered gabbro-pyroxenite complex is defined by modal variations in plagioclase and pyroxene. Blocks of garnet-pyroxenite or rodingite are locally present in the meta-peridotites. Garnets in the cumulate rocks are grossular （Gro=69-90, And=9-19, Br=l-12）, also metamorphic origin. The diabase dikes are moderately depleted in LREE [（La/Sm）N=0.5-0.8] and HREE resulting in slightly convex chondrite-normalized patterns with slightly positive Eu anomalies （δEu=1.1-1.3）. The basaltic lavas have REE patterns similar to those of MORB with （La/Sm）N ratios of 0.5-1 and small negative Eu anomalies. They appear to have been derived from a depleted mantle source and to have undergone little or no differentiation during crystallization. SHRIMP U-Pb dating of zircons from the basalts yields 286pb/238U ages of 276-319 Ma （average 308.0±4.9 Ma）. The Dur＇ngoi ophiolite is interpreted as a dismembered fragment of paleo-oceanic crust emplaced during closure of the paleo-Tethyan Ocean basin. Three other suites of oceanic lavas are recognized in the area： island arc volcanic （IAV） rocks, possible back arc basin （BAB） basalts and possible post-collisional volcanic （PCV） and plutonic rocks. The distribution of these rocks suggests north-directed subduction. Opening of the A＇nyemaqen oceanic basin started at least as early as Late Carboniferous （308 Ma） and the basin probably closed during the Early Triassic. The IAV formed in Late Permian （260 Ma）, the BAB in Early-Middle Triassic, and the PCV in Late Triassic. Several large scale, ductile, sinistral strike-slip fault zones, extending hundreds to thousands kilometers, formed along or north of the suture during the Early-Late Triassic, e.g., they are the south margin fault zone of East Kunlun （200-220 Ma）, the Altyn Tagh fault （220-230 Ma）, and the North Qaidam fault zone （240-250 Ma）. These strike-slip faults were probably generated by oblique subduction and closure of the paleo-Tethyan Ocean basin, possibly during exhumation of the subducted plate or uplift of the overriding plate, coincident with post-collisional magmatism.
基金Supported by Natural Science Foundation of China(31460200)Natural Science Foundation of Tibet Autonomous Region(2016ZR-15-40)~~
文摘Pinusdensata is one of the main constructive species for coniferous forests in southeast Tibet. P. densata forests are important water conservation forests in the drainage basins of the middle and lower reaches of Yalu Tsangpo River, Nyang River and Parlung Zangbo River. In this study, with P. densata forest distributed in southeast Tibet as research object, the seed rain, soil seed bank, seed germination and natural regeneration of P. densata were monitored and ana- lyzed by field investigation, located monitoring and indoor experimental analysis. The results showed that the average intensity of the seed rain of P. densata was 249.30±78.42 seeds/m2, in which the intensity of full seeds was 168.09±56.36 seeds/m2, the intensity of seeds damaged by worms was 41.11±20.25 seeds/m2, and the intensity of empty seeds was 40.10±21.04 seeds/m2. The intensity of the seed rain exhibited a single-peak trend of increasing at first and decreasing then over time. The spatial distribution patterns in the whole seed falling process and at different seed falling time all exhibited clumping distribution, and within in certain range, with the distance from the seed tree increasing, the diffusion intensity of the seed rain was weakened, exhibiting approximately normal distribution. In average density of P. densata seeds in the soil seed bank of P. densata was 231 seeds/m2, in which 62.77% of seeds were distributed in the litter layer, and 37.23% of seeds were distributed in the soil layer, and about 8% of seeds were lost during the pro- cess from seed rain to soil seed bank. Field sowing observation showed that the accumulated germination rate curve of P. densata fitted with Logistics equation y= 91.404/（1＋e66194.449）. The height structure, basal diameter structure and age structure of seedlings and young trees of P. densata were all of reverse ＂J＂ type, indicating good natural regeneration of P. densata. This study would provide a science basis for protection and resource management of P. densata, and further enrich the eval- uation content of national ecological safety curtain of the Tibet plateau.
基金supported by China Geological Survey (Nos. 1212010610107 and 1212010610105)the National Natural Science Foundation of China (No. 40610098)
文摘A wide variety of unusual mantle has been reported from podiform chromitite orebodies Cr-31 and Cr-74 in the Luobusa （罗布莎） ophiolite, Tibet. A detailed investigation of chromitite ore- body Cr-ll, located in the Kangjinla （康金拉） district at the eastern end of the ophiolite, has revealed many of the same minerals, including diamond, moissanite, and some native elements, alloys, oxides, sulphides, silicates, carbonates, and tungstates. This orebody is particularly rich in diamonds, with over 1 000 grains recovered from about 1 100 kg sample of chromitite. More detailed studies and experiments are needed to understand the origin and significance of these unusual minerals because they have not been found in situ. It is a great breakthrough in mineralogical research that we have picked up more than 40 kinds of minerals from the Kangjinla chromite deposit in Luobusa. It is notable that a large amount of diamonds were firstly discovered from the Kangjinla chromite deposit as well as many other unusual minerals, such as moissanites, rutiles, native irons, and metal alloys. Especially, that diamond was found again in different chromitites in the same ophiolite belt provided new key evidence for discussing the origin of the diamond and the hosted chromitite and ophiolite. The mantle mineral group in Tibet has great significance in mineralogy and geodynamics.
基金financially supported by the National Natural Science Foundation of China(No.41572044)the SDUST Research Fund(No.2015TDJH101)
文摘The Kadui blueschist is located in the central section of Yarlung Zangbo suture zone （YZSZ）, southern Tibet, and has been subjected to the subduction of the Neo-Tethyan Ocean below the Asian Plate and provides important clues for better understanding the evolution of the India-Asia convergence zone. In this paper, the systematical petrographic and mineral chemical studies were carried out on the Kadui blueschist, which reveal a mineral assemblage of sodic amphibole, chlorite, epidote, albite and quartz with accessory minerals of titanite, calcite and zircon. Electron microprobe analyses demonstrate that amphibole shows zoned from actinolite core to ferrowinchite/riebeckite rim composition indicating that the sodic amphibole has formed during a prograde metamorphic event. The protolith of the blueschist is an intermediate-basic pyroclastic rock. The calculated pseudosection indicates a clockwise P-T path and constrains peak metamorphic conditions of about 5.9 kbar at 345 ℃. This condition is transitional between pumpellyite-actinolite, greenschist and blueschist facies with a burial depth of 20-22 km and a thermal gradient of 15-16 ℃/km. This thermal gradient belongs to high pressure intermediate P/T facies series and is possibly related to a warm subduction setting of young oceanic slabs. Our new findings indicate that the Kadui blueschist in the central part of YZSZ experienced a rapid subduction and exhumation process as a response to a northward subduction of the Neo-Tethyan oceanic lithosphere during the initial India-Asia collision stage.
文摘This study aimed to explore artificial propagation techniques for Glyptosternum maculatum that is endemic in the Yarlung Zangbo River. Total 86 female fish in weight of 0.065-0.250 kg were selected, and the average weight of every 15 fish was 0.30 kg. Oxytocic drugs were injected into the base of pectoral fins of the female fish. The results showed that the total amount of female fish with artificial insemination was 59. The gloss weight of the fertilized eggs was 897.5 g with total amount of 57 440, thus the average fecundity was 1 194 eggs/fish. The fecundity showed a positive correlation with body weight （P〈0.01）. The average induction ratio and fertilization rate were 69% and 73.5%, respectively. The optimum water temperature for hatching of the fertilized eggs was 13-14 ℃ with dissolved oxygen of 6.0- 7.2 mg/L. The accumulated temperature for embryonic development of G. maculatum ranged from 2 592 to 2 916℃·h. This set of completely artificial propagation techniques has a very important significance for the artificial breeding of G. maculatum.
基金The Research Platform for the Project of the Application Basic Plan in Sichuan Province(Grant No.2014JY0113)the Project of Department of Science in Sichuan Province(Grant No.14ZA0003)
文摘Taking Terminalia chebula Retz. as the control product, the polyphenolic contents of the processed products in Tibetian, Rubia cordifolia L. processed Terminalia chebula Retz. and Euphorbia fischeriana Steud processed Terminalia chebula Retz. were analyzed by HPLC. Polyphenolic contents increased from 4.54% to 5.69% and 7.46%, respectively, which may lead to the change in their pharmacological effects.
基金supported by the geological survey project of China Geological Survey (Nos. 1212011120185, 1212011221111 and 1212011120182)
文摘The Amdo microcontinent is located within the middle of Bangong-Nujiang suture（BNS） zone in the shape of lens. The basic geological research restricts geologists from understanding the histories of tectonic evolution of BNS and regional geology more deeply. This paper systematically studies the geochronology and geochemistry of granitic gneisses from Amdo basement. These data provide constraints on formation age, source characteristics and tectonic setting of their protolith. The SHRIMP zircon U-Pb dating is operated for granitic gneisses. Samples AGS-2 and AGS-3（granitic gneiss） yield average zircon U-Pb ages of 485±14 and 487±6 Ma, respectively. These ages should represent the formation age of protolith and indicate that they are formed in the Early Ordovician. Granitic gneisses are characterized by high SiO2, Na2O, K2O and Al2O3, low Fe and Mg, enrichment in light rare earth elements（LREEs） and large ion lithophile elements（LILEs）, depletion in heavy rare earth elements（HREEs） and high field strength elements（HFSEs）, with negative Eu anomaly. The Rittmann index（σ） is 1.77 to 2.60, less than 3.3. The aluminum saturation index（A/CNK） values range from 0.88 to 1.26. These features suggest that protolith of granitic gneisses from Amdo basement show characteristics of calc-alkaline and S-type granite, and they could be derived from partial melting of metamorphic greywackes in the upper crust of low maturity. The tectonic setting is syn-collision. These all suggest that the formation of protolith of granitic gneisses from Amdo are caused by the Early Paleozoic orogeny, which could be related to proto-Tethyan oceanic subduction along Gondwana continental margins, and does not result from the production of Pan-African orogenesis.
基金This paper is supported jointly by the National Natural Science Foundation( No.4982 5 10 2 ) and the Ministry of Science and Te
文摘The Triassic in the Qomolongma area, southern Tibet, was deposited under an extensional tectonic setting from the Pangea supercontinent to continental rifting. From the Induan to Rhaetian, 12 depositional sequences (3rd order) have been recognized, which can be grouped into 5 sequence sets and in turn make up a well defined mesosequence (2nd order). Among the recognized marine transgressions, those at 250 Ma, 239 Ma, 231 Ma and 223 Ma respectively are particularly of significance and can be correlated widely across continents. The study shows that in Triassic the Qomolongma area experienced a sedimentary evolution from epicontinental sea to rift basin with the turning point at ca 228 Ma. During the early and middle epochs, the area was under epeiric sea, with carbonate ramp to mixed shoal environments predominant. In the late Carnian, the strong extension initiated listric faulting, thus resulting in rapid basement subsidence and the onset of a rift basin. From the late Norian to Rhaetian, it manifested as a rapid basin filling process in the area. Coupled with long term sea level fall, the excessive terrigenous influx led to the shift of environment from deep water prodelta to shore and finally to fluvial plain.
基金The Research Platform for the Project of the Application Basic Plan in Sichuan Province(Grant No.2014JY0113)the Project of Department of Science in Sichuan Province(Grant No.14ZA0003)
文摘To study the change of the content of chebulinic acid in Terminalia chebula Retz. by different processing methods in Tibet. We taking chebulinic acid as an indicator, the contents in Terminalia chebula Retz. and its processed products were analyzed by using HPLC. Also, the change rule was explored. Compared with Terminalia chebula Retz., the contents of chebulinic acid have decreased after processing, declining 50.18% for the Rubia cordifolia L. processed product, while 11.2% reduce for the Euphorbia fischeriana Steud processed product. After the specific preparation process in Tibet, the contents of chebulinic acid have reduced significantly, which may lead to different pharmacological effects.
基金Supported by Chinese Academy of Sciences-Knowledge Innovation Program Key Direction Project(KZCX2-YW-310)National Basic Research Program of China(2010CB951702)~~
文摘[Objective] This study was to provide theoretical basis for getting sustainable development of rural energy in Tibet into reality.[Method] By reviewing the rural energy resources in Tibet,we analyzed the characteristics and potential of rural biomass utilization in Tibet,and further put forward the sustainable countermeasures on the firewood substitution in Tibet.[Results] Renewable energies including hydraulic,geothermal,solar and wind resources are abundant in Tibet,while there is just a few of fossil energy resources such as oil and coal,with uneven distribution and poor exploration conditions.Traditional consumption of biomass energy resource accounts for a large proportion of the total energy consumption in Tibetan rural districts,which causes potential damage to the fragile ecological environment on the Tibetan Plateau.The excessive use of biomass energy destroyed the vegetation and evoked the environment deterioration such as the intensification of the water and soil loss and the declining of the soil fertility.[Conclusion] It is essential for Tibet to change its rural energy consumption structure,implement the Tibetan firewood alternative energy strategy and try to make full use of renewable energy such as solar energy,wind energy,hydro-energy instead of native vegetation and animal＇s droppings in order to reduce the adverse impacts of the irrational energy consumption on the ecological environment in Tibet.
