An earthquake of Ms=7.4 occurred in Mani, Xizang (Tibet), China on November 8, 1997. The moment tensor ofthis earthquake was inverted using the long period body wave form data from China Digital Seismograph Network(CD...An earthquake of Ms=7.4 occurred in Mani, Xizang (Tibet), China on November 8, 1997. The moment tensor ofthis earthquake was inverted using the long period body wave form data from China Digital Seismograph Network(CDSN). The apparent source time functions (AS TFs) were retrieved from P and S waves, respectively, using thedeconvolution technique in frequency domain, and the tempo-spatial rupture process on the fault plane was imagedby inverting the azimuth dependent AS TFs from different stations. The result of the moment tensor inversionindicates that the P and T axes of earthquake-generating stress field were nearly horizontal, with the P axis in theNNE direction (29), the T axis in the SEE direction (122) and that the NEE-SWW striking nodal plane andNNW-SSE striking nodal plane are mainly left-lateral and right-lateral strike-slip, respectively; that this earthquakehad a scalar seismic moment of 3.4xl02o N. .m, and a moment magnitude of Mw=7.6. Taking the aftershock distribution into account, we proposed that the earthquake rupture occurred in the fault plane with the strike of 250,the dip of 88 and the rake of 19. On the basis of the result of the moment tensor inversion, the theoretical seismograms were synthesized, and then the AS T Fs were retrieved by deconvoving the synthetic seismograms fromthe observed seismograms. The A S T Fs retrieved from the P and S waves of different stations identically suggestedthat this earthquake was of a simple time history, whose ASTF can be approximated with a sine function with thehalf period of about 10 s. Inverting the azimuth dependent A S T Fs from P and S waveforms led to the imageshowing the tempo-spatial distribution of the rupture on the fault plane. From the 'remembering' snap-shots, therupture initiated at the western end of the fault, and then propagated eastward and downward, indicating an overallunilateral rupture. However, the slip distribution is non-uniform, being made up of three sub-areas, one in thewestern end, about 10 km deep ('western area'), another about 55 kin away from the western end and about 35 Iondeep ('eastern area'), the third about 30 km away from the western end and around 40 km deep ('central area').The total rupture area was around 70 km long and 60 km wide. From the 'forgetting' snap-shots, the rupturingappeared quite complex, with the slip occurring in different position at different time, and the earthquake being ofthe characteristics of 'healing pulse'. Another point we have to stress is that the locations in which the ruptureinitiated and terminated were not where the main rupture took place. Eventually, the static slip distribution wascalculated, and the largest slip values of the three sub-areas were 956 cm, 743 cm and 1 060 cm, for the western.eastern and central areas, respectively. From the slip distribution, the rupture mainly distributed in the fault about70 km eastern to the epicenter; from the aftershock distribution. however, the aftershocks were very sparse in thewest to the epicenter while densely clustered in the east to the epicenter It indicated that the Maul Ms=7.9 earthquake was resulted from the nearly eastward extension of the NEE-SWW to nearly E-W striking fault in thenorthwestern Tibetan plateau.展开更多
Robust climate warming has led to significant expansion of lakes in the central Tibetan Plateau. Using remote sensing data, our quantitative analysis indicates that Siling Co, a saline lake in a characteristic endorhe...Robust climate warming has led to significant expansion of lakes in the central Tibetan Plateau. Using remote sensing data, our quantitative analysis indicates that Siling Co, a saline lake in a characteristic endorheic basin in the central region of the Plateau, has expanded more than 600 km2 in area since 1976. Particularly since 1995, the lake has signif- icantly expanded in response to increasing precipitation, decreasing water surface evaporation caused by weaker winds and less solar radiation, and increased glacier meltwater draining to the lake. Glacie^lake interactions are important in governing lake expansion and are also part of a feedback loop that influences the local climate. Worsening climatic conditions (decreased precipitation and increased temperatures) that could have caused the lake to shrink during 1976-1994 were offset by increasing glacier meltwater feeding the lake, which made the lake nearly stable. We demonstrate that this pattern changed during 1995-2009, when glacier meltwater actually decreased but participation runoff increased and evaporation decreased, leading to expansion of the lake. If climatic conditions became suitable for further lake development, which would be indicated by expansion in lake area, glacier meltwater could be saved in a stable reservoir.展开更多
The Xigaze ophiolite crops out in the central segment of the Yarlung Zangbo suture zone,southern Tibet(Fig.1).It is characterized by large amounts of ultramafic units with minor mafic rocks.The mafic rocks consist of ...The Xigaze ophiolite crops out in the central segment of the Yarlung Zangbo suture zone,southern Tibet(Fig.1).It is characterized by large amounts of ultramafic units with minor mafic rocks.The mafic rocks consist of gabbros,展开更多
An Early Paleozoic ophiolitic mélange has recently been documented in the W.Gangma Co area,north-central Tibetan Plateau.It is composed of serpentinite,isotropic and cumulate gabbros,basalt and plagiogranite.Whole-
The zone of Yulong copper deposit is considered superlarge in scale all over the world, which is a part of Tethys to Himalaya Ore\|forming zone. The geological background of the Jinshajiang and Lancangjiang Faults pro...The zone of Yulong copper deposit is considered superlarge in scale all over the world, which is a part of Tethys to Himalaya Ore\|forming zone. The geological background of the Jinshajiang and Lancangjiang Faults provided utility for accumulated of copper, molybdenum and so on. The Yulong copper zone is the most important characteristic in the east Qinghai—Xizang Plateau (Tibet), which isabout 400km in length from north to south, and 30~70km in width from east to west. The structural channel for ores accumulation was constructed in Yanshan orogeny and the process of ore forming of the zone was mainly in Himalaya orogeny. The Yulong copper zone can be divided into three subzones, each named as north, south and east subzone which the north subzone is 50km in length of about NNW direction. Based on the geological interpretation (Fig.1), we understood that NW structures are distributed mainly in this area, then EW and NNW, and the sigmoid structures extended reflect their extrusion character. The EW and NNW structures are distributed in small scale and extended stable, which are cut to each other. The NNW structure was interpreted as undercover fracture, which may occurred earlier than NW one. Beside, of the structure, there are some differences in image tone, linear, relief, strata combination, structure pattern and so on. Therefore, the undercover fault played key efforts to Yulong copper formation.展开更多
Although large amounts of data have been collected during the past 30 yesrs in the study of the formation, evolution and dynamics of the Tethys Sea by the use of the theory of plate tectonics, a large volume of geolog...Although large amounts of data have been collected during the past 30 yesrs in the study of the formation, evolution and dynamics of the Tethys Sea by the use of the theory of plate tectonics, a large volume of geological and geophysical information has also been accumulated which cannot be explained by the plate tectonic hypothesis. For example, the Qinghai-Xizang Plateau is underlain by many thousands of meters of Ordovician through Eocene, gently-dipping, essentially undeformed, stable platform sequences. Stratigraphic and tectonic investigations reveal that the plateau-wide east-west fracture zones, interpreted as "sutures" in a plate-tectonic model, are not sutures at all. On the other hand, from the Late Carboniferous to the beginning of the Early Permian, it was impossible for the Tethys ocean with a width of several thousand kilometers to."open" and "close" (the speed could not be so great). The east-west fracture zones, with very sharp angles, exerted no control over deposition. Stress analysis of magmatic activity indicates that the Himalayan zone is presently under compression, the Gangdise zone under interwoven comprepsion and tension, and the Qinghai and Deccan Plateaus under weak tension. Lateral compression caused by weak tension at the northern and southern terminations was not enough for Xizang and its surroundings between India and Qinghai Province of China with an area of 2,400,000 km2 to rise to a height of 4,000 m above mean sea level. The authors believe that surge tectonics is the force driving the evolution of the Tethys Sea and the rising of the Qinghai-Xizang Plateau. G. G. T. demonstrates that two surge channels, an upper and a lower, exist in the Yadong-Anduo litho sphere, and the upper mantle in the southern part is uplifted. During the Eocene, as a result of tectogenesis, molten magma poured out from the channel along the Yarlung Zangbo River,forming ophiolites and melanges, and earthquakes and terrestrial heat are also distributed along the fracture zone. Likewise, at an earlier time the Banggong Co-Nujiang and Longmu Co-Yushu Jinshajiang surge channels and their fracture zones formed. During the Miocene, the three surge channels merged laterally, and then the unified rise of the Qinghai-Xizang Plateau took place. The formation and evolution of the surge channels resulted in a variety of worthy Paleozoic, Mesozoic and Cenozoic exploration targets and a series of sedimentary basins with the largest Qamdo Basin occupying 120, 000 km2 with sediments attaining a thickness of 15, 000 m. These basins contain multiple source-beds, reservoirs, traps and seals of different ages, showing oil and gas every-where. In the northern part lithology and facies are more stable than in the southern, and subsequent tectonic overprinting and volcanic activity are relatively weak. At present commercial oil flow has been penetrated by drilling in the Tertiary Lunpola Basin.展开更多
Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data,...Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data, this paper discusses the interannual variability of the heat regime and its relation to atmospheric circulation It is shown that the interannual variability is pronounced, with maximal variability in spring and autumn, and the variability is heterogeneous horizontally. In the years with the weak (or strong) winter cold source, the deep trough over East Asia is to the east (or west) of its normal, which corresponds to strong (or weak) winter monsoon in East Asia. In the years with the strong (or weak) sum mer heat source, there exists an anomalous cyclone (or anticyclone) in the middle and lower troposphere over the QXP and ifs neighborhood and anomalous southwest (or northeast) winds over the Yangtze River valley of China, corresponding to strong (or weak) summer monsoon in East Asia. The summer heat source of the QXP is related to the intensity and position of the South Asia high. The QXP snow cover condition of April has a close relation to the heating intensity of summer. There is a remarkable negative correlation between the summer heat source of the QXP and the convection over the southeastern QXP, the Bay of Bengal, the Indo-China Peninsula, the southeastern Asia, the southwest part of China and the lower reaches of the Yangtze River and in the area from the Yellow Sea of China to the Sea of Japan.展开更多
Based on electron probe analyses of the minerals and bulk composition of the Cenozoic volcanic rocks from Yumen and Hoh Xil lithodistricts, Qinghai\|Xizang plateau, the forming conditions including the temperature and...Based on electron probe analyses of the minerals and bulk composition of the Cenozoic volcanic rocks from Yumen and Hoh Xil lithodistricts, Qinghai\|Xizang plateau, the forming conditions including the temperature and pressure of those rocks are studied in this paper. According to the thermodynamic calculation results of mineral\|melt equilibrium, the depth of the asthenosphere superface (about 75-130 km) for the northern part of the Qinghai\|Xizang plateau during the Cenozoic is suggested. Finally, this paper indicates that the Cenozoic volcanic rocks in the northern part of the Qinghai\|Xizang plateau mainly consist of shoshonite series. Their forming temperature is 630-1039℃ and forming pressure is between 2.3-4.0 GPa. The rocks were formed in the intracontinental orogenic belt, of which the primary magma was originated from a particular enrichment upper mantle and accreted crust\|mantle belt or directly from asthenospheric superface as a result of partial melting of pyrolite.展开更多
Since the late 1950’s, many Chinese scientists have explored the remains of the Quaternary glaciation in the Qinghai-Xizang (Tibet) Plateau and its surrounding mountains. In the main, 3-4 glaciations have been recogn...Since the late 1950’s, many Chinese scientists have explored the remains of the Quaternary glaciation in the Qinghai-Xizang (Tibet) Plateau and its surrounding mountains. In the main, 3-4 glaciations have been recognized. The largest one occurred in the Late Middle Pleistocene with piedmont glaciers, ice caps and trellis valley glaciers in many high peak regions. But here is no evidence of a unified ice sheet covering the whole plateau as described by M. Kuhle. Due to the further uplifting of the Himalayas and Qinghai-Xizang Plateau the climate became progressively drier, diminishing the extension of glaciers during the Late Pleistocene. The elevation of the snow line during the Last Glaciation was about 4,000 m on the south, east and northeast edges of the plateau and ascended to 5500 m on the hinder northwest of the plateau. The thermal effect of the big plateau massif, the sharp increase of aridity from the southeast rim to the northwest inland area and the abrupt decrease of precipitation during展开更多
The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260~250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies,...The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260~250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies, such as layered intrusions (V\|Ti\|Fe formation), small\|sized mafic\|ultramafic bodies (stocks) and large\|scale basalt (Emeishan Basalt) are constituted of a complete melanocratic rock system.Most of Cu\|Ni\|PGE sulfide deposits are related to small\|sized ultramafic rock bodies. It is a perfect possibility for them to be an affinity of basic eruptive lava and for the neck facies. But in ① Panzhihua\|Center Yunnan Province, the Gaojiacun, also Jinbaoshan, as large stratiform basic\|ultrabasic complex used to be thought that is older one intruded to basement rocks in Precambrian. However, new evidences suggest it is similar with the small\|sized ultramafic rock bodies containing Cu\|Ni\|PGE, and also the both are affinity of the Emeishan Basalt; ② Miyi district, Cu\|Pt mineralization was discovered in the Xinjie bedded basic complex, and in where ophitic olivine\|pyroxenite\|peridotite facies are exactly Pt\|bearing layers; ③ Longzhoushan district, we have recently researched basic\|ultrabasic clusters which intruded into fracture zones, and Cu\|Ni\|Pt, Pd mineralization developed at the salbands.Generally, the basalt is poor in PGE and rich in Cu. It is suggested as the result of PGE dispersion\|concentration processing in the melanocratic rock system when rifting happened.展开更多
The zone of alpine scrub and meadow, characterized by highlandsubpolar humid/subhumid climate, is a transitional area from deep gorges to theplateau proper.The natural zone is unique in physical environments and natur...The zone of alpine scrub and meadow, characterized by highlandsubpolar humid/subhumid climate, is a transitional area from deep gorges to theplateau proper.The natural zone is unique in physical environments and naturalecosystems, and could not be found at the lowlands elsewhere on the earth.Thepredominant type of vegeation is alpine meadow, including Kobresia meadow,herbaceous meadow and swampy meadow. It is an important pasturelands ofanimal husbandry for Tibetan on the plateau. Main vegetion types, animal groups,characteristics of alpine meadow soils, the altitudinal belt and the horizontalzonality of the natural zone, as well as utilization and management of the grasslandsare discussed in the present paper.展开更多
Hydropower development in Xizang(Tibet) Autonomous Region plays a vital role in co-control of local air pollutants and greenhouse gas(GHG) in China. According to emission factors of local air pollutants and GHG of coa...Hydropower development in Xizang(Tibet) Autonomous Region plays a vital role in co-control of local air pollutants and greenhouse gas(GHG) in China. According to emission factors of local air pollutants and GHG of coal-fired power industry in different hydropower service regions, we estimate the effect and synergy of local air pollutants and GHG reduction achieved by hydropower development in Tibet, examine the main factors constraining the effect and synergy, using correlation analysis and multiple regression analysis. The results show that: 1) During the period from 2006 to 2012, the effect of local air pollutants and GHG reduction achieved by hydropower development in Tibet decreased as a whole, while the synergy increased first and decreased afterwards. 2) The effect and synergy of local air pollutants and GHG reduction achieved by hydropower development in Tibet vary significantly across different hydropower service regions. The effect based on emission levels of Central China power grid(CCPG) and Northwest China power grid(NCPG) was more significant than that based on emission level of national power grid(NPG) from 2006 to 2012, and the synergy based on emission levels of CCPG and NCPG was also more significant than that based on emission level of NPG from 2010 to 2012. 3) The main factors constraining the effect and synergy based on emission levels of NCPG and CCPG included SO2 removal rate and NOx removal rate, the effect and synergy based on emission level of NPG was mainly influenced by net coal consumption rate. 4) Transferring hydropower from Tibet to NCPG and CCPG, and substituting local coal-fired power with hydropower can greatly help to co-control local air pollutants and GHG, transform the emission reduction pattern of the power industry and optimize energy structure.展开更多
The Qinghai-Xizang (Tibet) Plateau and the 'Sanjiang' area②, where are extensively developed theTethys-type marine Triassic sequences with Indosinian tectonic disturbance and magmatism, provide an impor-tant ...The Qinghai-Xizang (Tibet) Plateau and the 'Sanjiang' area②, where are extensively developed theTethys-type marine Triassic sequences with Indosinian tectonic disturbance and magmatism, provide an impor-tant region for the study of the tectonic evolution and the Indosinian movement of China as well as for thestudy of the boundary between Gondwana and Laurasia and the characteristics of the time-space distributionof the Tethys oceanic crust within the territory of China. Over a long period of time in the past, quite a numberof scholars made substantial studies and discussious from various viewpoints on the geotectonie and regionalgeological evolution of this region. Based on some new data obtained recently and the field observations by theauthor, and by using the plate tectonic theory, the author considers that there developed a Pacific-type (activetype) ancient continental margin bordering the Palaeo-Tethys ocean (or North Tethys ocean) in the south inLate Permian to Triassic times in the region of south-central Qinghai, northeastern Xizang (Tibet), western andsouthwestern Sichuan, and western Yunnan. Its characteristics basically represent the Indosinian tectonic evo-lution of this region.展开更多
A mesoscale convective system (MCS) developing over the Qinghai-Xizang Plateau on 26 July 1995 is simulated using the fifth version of the Penn State-NCAR nonhydrostatic mesoscale model (MM5). The results obtained are...A mesoscale convective system (MCS) developing over the Qinghai-Xizang Plateau on 26 July 1995 is simulated using the fifth version of the Penn State-NCAR nonhydrostatic mesoscale model (MM5). The results obtained are inspiring and are as follows. (1) The model simulates well the largescale conditions in which the MCS concerned is embedded, which are the well-known anticyclonic Qinghai-Xizang Plateau High in the upper layers and the strong thermal forcing in the lower layers. In particular, the model captures the meso-α scale cyclonic vortex associated with the MCS, which can be analyzed in the 500 hPa observational winds; and to some degree, the model reproduces even its meso-β scale substructure similar to satellite images, reflected in the model-simulated 400 hPa rainwater. On the other hand, there are some distinct deficiencies in the simulation; for example, the simulated MCS occurs with a lag of 3 hours and a westward deviation of 3–5° longitude. (2) The structure and evolution of the meso-α scale vortex associated with the MCS are undescribable for upper-air sounding data. The vortex is confined to the lower troposphere under 450 hPa over the plateau and shrinks its extent with height, with a diameter of 4° longitude at 500 hPa. It is within the updraft area, but with an upper-level anticyclone and downdraft over it. The vortex originates over the plateau, and does not form until the mature stage of the MCS. It lasts for 3–6 hours. In its processes of both formation and decay, the change in geopotential height field is prior to that in the wind field. It follows that the vortex is closely associated with the thermal effects over the plateau. (3) A series of sensitivity experiments are conducted to investigate the impact of various surface thermal forcings and other physical processes on the MCS over the plateau. The results indicate that under the background conditions of the upper-level Qinghai-Xizang High, the MCS involved is mainly dominated by the low-level thermal forcing. The simulation described here is a good indication that it may be possible to reproduce the MCS over the plateau under certain large-scale conditions and with the incorporation of proper thermal physics in the lower layers.展开更多
The largest Mesozoic northward transgression in Qangtang Basin of Qinghai-Xizang (Tibet) Plateau occurred during the Buqu Stage, Middle Jurassic. Mainly filled with carbonate rocks, the whole basin is composed of tran...The largest Mesozoic northward transgression in Qangtang Basin of Qinghai-Xizang (Tibet) Plateau occurred during the Buqu Stage, Middle Jurassic. Mainly filled with carbonate rocks, the whole basin is composed of transgression-regression sedimentary cycle. Field outcrops and indoor analysis revealed 8 types of sedimentary facies markers in this region. 4 types of sedimentary facies have been recognized: platform facies, platform marginal facies, foreslope facies and basin facies. Influenced by the northern Lazhuglung-Jinshajiang suture zone, central uplift region and southern Bangongco-Nujiang suture zone, these facies belts extended east-west. The sedimentary model was established based on observed depositional features. From their biological features and sedimentary characteristics, it is suggested that the paleoclimate was warm and humid at that time. The Buqu Formation is a promising target for oil and gas exploration in Shuanghu-Duoyong area in future.展开更多
Yongzhu–Guomang Lake ophiolitic melange exposed about 100 km with large scale and complete ophiolitic uint in Xainza County,Xizang(Tibet).It is connected with Nam Lake,Kaimeng ophiolitic mélange to the east,and
The Dongbo ophiolite in the western part of the Yarlung-Zangbo suture zone in southern Tibet rests tectonically on the middle-late Triassic and Cretaceous flysch units,and consist mainly of peridotites,mafic dikes,
A suit of metamorphic rocks experienced amphibolite and partly granulite facies metamorphism exposed on the Lhasa block,which are recognized as the basement of the Lhasa block named as Nyainqentanglha Group in the
Characteristics of present-day tectonic movement in the northeastern margin of Qinghai-Xizang plateau (Tibetan) are studied based on earthquake data. Evidence of earthquake activity shows that junctures between blocks...Characteristics of present-day tectonic movement in the northeastern margin of Qinghai-Xizang plateau (Tibetan) are studied based on earthquake data. Evidence of earthquake activity shows that junctures between blocks in this area consist of complicated deformation zones. Between the Gansu-Qinghai block and Alxa block there is a broad compressive deformation zone, which turns essentially to be a network-like deformation region to the southeast. The Liupanshan region, where the Gansu-Qinghai block contacts the Ordos block, is suffering from NE-SW compressive deformation. Junction zone between the Ordos and Alxa block is a shear zone with sections of variable trend. The northwestern and southeastern marginal region of the Ordos is under NNW-SSE extension. The above characteristics of present-day tectonic deformation of the northeastern Qinghai-Xizang plateau may be attributed to the northeastward squeezing of the plateau and the resistance of the Ordos block, as well as the southeastward extrusion of the plateau materials.展开更多
文摘An earthquake of Ms=7.4 occurred in Mani, Xizang (Tibet), China on November 8, 1997. The moment tensor ofthis earthquake was inverted using the long period body wave form data from China Digital Seismograph Network(CDSN). The apparent source time functions (AS TFs) were retrieved from P and S waves, respectively, using thedeconvolution technique in frequency domain, and the tempo-spatial rupture process on the fault plane was imagedby inverting the azimuth dependent AS TFs from different stations. The result of the moment tensor inversionindicates that the P and T axes of earthquake-generating stress field were nearly horizontal, with the P axis in theNNE direction (29), the T axis in the SEE direction (122) and that the NEE-SWW striking nodal plane andNNW-SSE striking nodal plane are mainly left-lateral and right-lateral strike-slip, respectively; that this earthquakehad a scalar seismic moment of 3.4xl02o N. .m, and a moment magnitude of Mw=7.6. Taking the aftershock distribution into account, we proposed that the earthquake rupture occurred in the fault plane with the strike of 250,the dip of 88 and the rake of 19. On the basis of the result of the moment tensor inversion, the theoretical seismograms were synthesized, and then the AS T Fs were retrieved by deconvoving the synthetic seismograms fromthe observed seismograms. The A S T Fs retrieved from the P and S waves of different stations identically suggestedthat this earthquake was of a simple time history, whose ASTF can be approximated with a sine function with thehalf period of about 10 s. Inverting the azimuth dependent A S T Fs from P and S waveforms led to the imageshowing the tempo-spatial distribution of the rupture on the fault plane. From the 'remembering' snap-shots, therupture initiated at the western end of the fault, and then propagated eastward and downward, indicating an overallunilateral rupture. However, the slip distribution is non-uniform, being made up of three sub-areas, one in thewestern end, about 10 km deep ('western area'), another about 55 kin away from the western end and about 35 Iondeep ('eastern area'), the third about 30 km away from the western end and around 40 km deep ('central area').The total rupture area was around 70 km long and 60 km wide. From the 'forgetting' snap-shots, the rupturingappeared quite complex, with the slip occurring in different position at different time, and the earthquake being ofthe characteristics of 'healing pulse'. Another point we have to stress is that the locations in which the ruptureinitiated and terminated were not where the main rupture took place. Eventually, the static slip distribution wascalculated, and the largest slip values of the three sub-areas were 956 cm, 743 cm and 1 060 cm, for the western.eastern and central areas, respectively. From the slip distribution, the rupture mainly distributed in the fault about70 km eastern to the epicenter; from the aftershock distribution. however, the aftershocks were very sparse in thewest to the epicenter while densely clustered in the east to the epicenter It indicated that the Maul Ms=7.9 earthquake was resulted from the nearly eastward extension of the NEE-SWW to nearly E-W striking fault in thenorthwestern Tibetan plateau.
基金funded by the Major State Basic Research Development Program of China (973 Program) under Grant No. 2010CB951701by the Natural Science Foundation of China (No. 41071042)supported by the Innovation Project of Chinese Academy of Sciences (KZCX2-YW-BR-22)
文摘Robust climate warming has led to significant expansion of lakes in the central Tibetan Plateau. Using remote sensing data, our quantitative analysis indicates that Siling Co, a saline lake in a characteristic endorheic basin in the central region of the Plateau, has expanded more than 600 km2 in area since 1976. Particularly since 1995, the lake has signif- icantly expanded in response to increasing precipitation, decreasing water surface evaporation caused by weaker winds and less solar radiation, and increased glacier meltwater draining to the lake. Glacie^lake interactions are important in governing lake expansion and are also part of a feedback loop that influences the local climate. Worsening climatic conditions (decreased precipitation and increased temperatures) that could have caused the lake to shrink during 1976-1994 were offset by increasing glacier meltwater feeding the lake, which made the lake nearly stable. We demonstrate that this pattern changed during 1995-2009, when glacier meltwater actually decreased but participation runoff increased and evaporation decreased, leading to expansion of the lake. If climatic conditions became suitable for further lake development, which would be indicated by expansion in lake area, glacier meltwater could be saved in a stable reservoir.
文摘The Xigaze ophiolite crops out in the central segment of the Yarlung Zangbo suture zone,southern Tibet(Fig.1).It is characterized by large amounts of ultramafic units with minor mafic rocks.The mafic rocks consist of gabbros,
文摘An Early Paleozoic ophiolitic mélange has recently been documented in the W.Gangma Co area,north-central Tibetan Plateau.It is composed of serpentinite,isotropic and cumulate gabbros,basalt and plagiogranite.Whole-
文摘The zone of Yulong copper deposit is considered superlarge in scale all over the world, which is a part of Tethys to Himalaya Ore\|forming zone. The geological background of the Jinshajiang and Lancangjiang Faults provided utility for accumulated of copper, molybdenum and so on. The Yulong copper zone is the most important characteristic in the east Qinghai—Xizang Plateau (Tibet), which isabout 400km in length from north to south, and 30~70km in width from east to west. The structural channel for ores accumulation was constructed in Yanshan orogeny and the process of ore forming of the zone was mainly in Himalaya orogeny. The Yulong copper zone can be divided into three subzones, each named as north, south and east subzone which the north subzone is 50km in length of about NNW direction. Based on the geological interpretation (Fig.1), we understood that NW structures are distributed mainly in this area, then EW and NNW, and the sigmoid structures extended reflect their extrusion character. The EW and NNW structures are distributed in small scale and extended stable, which are cut to each other. The NNW structure was interpreted as undercover fracture, which may occurred earlier than NW one. Beside, of the structure, there are some differences in image tone, linear, relief, strata combination, structure pattern and so on. Therefore, the undercover fault played key efforts to Yulong copper formation.
文摘Although large amounts of data have been collected during the past 30 yesrs in the study of the formation, evolution and dynamics of the Tethys Sea by the use of the theory of plate tectonics, a large volume of geological and geophysical information has also been accumulated which cannot be explained by the plate tectonic hypothesis. For example, the Qinghai-Xizang Plateau is underlain by many thousands of meters of Ordovician through Eocene, gently-dipping, essentially undeformed, stable platform sequences. Stratigraphic and tectonic investigations reveal that the plateau-wide east-west fracture zones, interpreted as "sutures" in a plate-tectonic model, are not sutures at all. On the other hand, from the Late Carboniferous to the beginning of the Early Permian, it was impossible for the Tethys ocean with a width of several thousand kilometers to."open" and "close" (the speed could not be so great). The east-west fracture zones, with very sharp angles, exerted no control over deposition. Stress analysis of magmatic activity indicates that the Himalayan zone is presently under compression, the Gangdise zone under interwoven comprepsion and tension, and the Qinghai and Deccan Plateaus under weak tension. Lateral compression caused by weak tension at the northern and southern terminations was not enough for Xizang and its surroundings between India and Qinghai Province of China with an area of 2,400,000 km2 to rise to a height of 4,000 m above mean sea level. The authors believe that surge tectonics is the force driving the evolution of the Tethys Sea and the rising of the Qinghai-Xizang Plateau. G. G. T. demonstrates that two surge channels, an upper and a lower, exist in the Yadong-Anduo litho sphere, and the upper mantle in the southern part is uplifted. During the Eocene, as a result of tectogenesis, molten magma poured out from the channel along the Yarlung Zangbo River,forming ophiolites and melanges, and earthquakes and terrestrial heat are also distributed along the fracture zone. Likewise, at an earlier time the Banggong Co-Nujiang and Longmu Co-Yushu Jinshajiang surge channels and their fracture zones formed. During the Miocene, the three surge channels merged laterally, and then the unified rise of the Qinghai-Xizang Plateau took place. The formation and evolution of the surge channels resulted in a variety of worthy Paleozoic, Mesozoic and Cenozoic exploration targets and a series of sedimentary basins with the largest Qamdo Basin occupying 120, 000 km2 with sediments attaining a thickness of 15, 000 m. These basins contain multiple source-beds, reservoirs, traps and seals of different ages, showing oil and gas every-where. In the northern part lithology and facies are more stable than in the southern, and subsequent tectonic overprinting and volcanic activity are relatively weak. At present commercial oil flow has been penetrated by drilling in the Tertiary Lunpola Basin.
基金the auspices of the National!(G1998040800)CAS's Key Project for Basic Research on the Tibetan Plateau! (KZ951-A1-204, KZ95T-
文摘Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data, this paper discusses the interannual variability of the heat regime and its relation to atmospheric circulation It is shown that the interannual variability is pronounced, with maximal variability in spring and autumn, and the variability is heterogeneous horizontally. In the years with the weak (or strong) winter cold source, the deep trough over East Asia is to the east (or west) of its normal, which corresponds to strong (or weak) winter monsoon in East Asia. In the years with the strong (or weak) sum mer heat source, there exists an anomalous cyclone (or anticyclone) in the middle and lower troposphere over the QXP and ifs neighborhood and anomalous southwest (or northeast) winds over the Yangtze River valley of China, corresponding to strong (or weak) summer monsoon in East Asia. The summer heat source of the QXP is related to the intensity and position of the South Asia high. The QXP snow cover condition of April has a close relation to the heating intensity of summer. There is a remarkable negative correlation between the summer heat source of the QXP and the convection over the southeastern QXP, the Bay of Bengal, the Indo-China Peninsula, the southeastern Asia, the southwest part of China and the lower reaches of the Yangtze River and in the area from the Yellow Sea of China to the Sea of Japan.
基金TheprojectwassupportedbytheNationalNaturalScienceFoundationofChina! (No .492 34 0 80 ) theGeologicalSectionalFoundationofMGM
文摘Based on electron probe analyses of the minerals and bulk composition of the Cenozoic volcanic rocks from Yumen and Hoh Xil lithodistricts, Qinghai\|Xizang plateau, the forming conditions including the temperature and pressure of those rocks are studied in this paper. According to the thermodynamic calculation results of mineral\|melt equilibrium, the depth of the asthenosphere superface (about 75-130 km) for the northern part of the Qinghai\|Xizang plateau during the Cenozoic is suggested. Finally, this paper indicates that the Cenozoic volcanic rocks in the northern part of the Qinghai\|Xizang plateau mainly consist of shoshonite series. Their forming temperature is 630-1039℃ and forming pressure is between 2.3-4.0 GPa. The rocks were formed in the intracontinental orogenic belt, of which the primary magma was originated from a particular enrichment upper mantle and accreted crust\|mantle belt or directly from asthenospheric superface as a result of partial melting of pyrolite.
文摘Since the late 1950’s, many Chinese scientists have explored the remains of the Quaternary glaciation in the Qinghai-Xizang (Tibet) Plateau and its surrounding mountains. In the main, 3-4 glaciations have been recognized. The largest one occurred in the Late Middle Pleistocene with piedmont glaciers, ice caps and trellis valley glaciers in many high peak regions. But here is no evidence of a unified ice sheet covering the whole plateau as described by M. Kuhle. Due to the further uplifting of the Himalayas and Qinghai-Xizang Plateau the climate became progressively drier, diminishing the extension of glaciers during the Late Pleistocene. The elevation of the snow line during the Last Glaciation was about 4,000 m on the south, east and northeast edges of the plateau and ascended to 5500 m on the hinder northwest of the plateau. The thermal effect of the big plateau massif, the sharp increase of aridity from the southeast rim to the northwest inland area and the abrupt decrease of precipitation during
文摘The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260~250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies, such as layered intrusions (V\|Ti\|Fe formation), small\|sized mafic\|ultramafic bodies (stocks) and large\|scale basalt (Emeishan Basalt) are constituted of a complete melanocratic rock system.Most of Cu\|Ni\|PGE sulfide deposits are related to small\|sized ultramafic rock bodies. It is a perfect possibility for them to be an affinity of basic eruptive lava and for the neck facies. But in ① Panzhihua\|Center Yunnan Province, the Gaojiacun, also Jinbaoshan, as large stratiform basic\|ultrabasic complex used to be thought that is older one intruded to basement rocks in Precambrian. However, new evidences suggest it is similar with the small\|sized ultramafic rock bodies containing Cu\|Ni\|PGE, and also the both are affinity of the Emeishan Basalt; ② Miyi district, Cu\|Pt mineralization was discovered in the Xinjie bedded basic complex, and in where ophitic olivine\|pyroxenite\|peridotite facies are exactly Pt\|bearing layers; ③ Longzhoushan district, we have recently researched basic\|ultrabasic clusters which intruded into fracture zones, and Cu\|Ni\|Pt, Pd mineralization developed at the salbands.Generally, the basalt is poor in PGE and rich in Cu. It is suggested as the result of PGE dispersion\|concentration processing in the melanocratic rock system when rifting happened.
文摘The zone of alpine scrub and meadow, characterized by highlandsubpolar humid/subhumid climate, is a transitional area from deep gorges to theplateau proper.The natural zone is unique in physical environments and naturalecosystems, and could not be found at the lowlands elsewhere on the earth.Thepredominant type of vegeation is alpine meadow, including Kobresia meadow,herbaceous meadow and swampy meadow. It is an important pasturelands ofanimal husbandry for Tibetan on the plateau. Main vegetion types, animal groups,characteristics of alpine meadow soils, the altitudinal belt and the horizontalzonality of the natural zone, as well as utilization and management of the grasslandsare discussed in the present paper.
基金Under the auspices of State Environmental Protection Commonweal Special Program of China(No.201209032)National Natural Science Foundation of China(No.71503118)Basic Research Foundation of National Commonweal Research Institute(No.2013012)
文摘Hydropower development in Xizang(Tibet) Autonomous Region plays a vital role in co-control of local air pollutants and greenhouse gas(GHG) in China. According to emission factors of local air pollutants and GHG of coal-fired power industry in different hydropower service regions, we estimate the effect and synergy of local air pollutants and GHG reduction achieved by hydropower development in Tibet, examine the main factors constraining the effect and synergy, using correlation analysis and multiple regression analysis. The results show that: 1) During the period from 2006 to 2012, the effect of local air pollutants and GHG reduction achieved by hydropower development in Tibet decreased as a whole, while the synergy increased first and decreased afterwards. 2) The effect and synergy of local air pollutants and GHG reduction achieved by hydropower development in Tibet vary significantly across different hydropower service regions. The effect based on emission levels of Central China power grid(CCPG) and Northwest China power grid(NCPG) was more significant than that based on emission level of national power grid(NPG) from 2006 to 2012, and the synergy based on emission levels of CCPG and NCPG was also more significant than that based on emission level of NPG from 2010 to 2012. 3) The main factors constraining the effect and synergy based on emission levels of NCPG and CCPG included SO2 removal rate and NOx removal rate, the effect and synergy based on emission level of NPG was mainly influenced by net coal consumption rate. 4) Transferring hydropower from Tibet to NCPG and CCPG, and substituting local coal-fired power with hydropower can greatly help to co-control local air pollutants and GHG, transform the emission reduction pattern of the power industry and optimize energy structure.
基金A subject of Project Nos.85001 and 851287 funded by the State National Science Foundation.
文摘The Qinghai-Xizang (Tibet) Plateau and the 'Sanjiang' area②, where are extensively developed theTethys-type marine Triassic sequences with Indosinian tectonic disturbance and magmatism, provide an impor-tant region for the study of the tectonic evolution and the Indosinian movement of China as well as for thestudy of the boundary between Gondwana and Laurasia and the characteristics of the time-space distributionof the Tethys oceanic crust within the territory of China. Over a long period of time in the past, quite a numberof scholars made substantial studies and discussious from various viewpoints on the geotectonie and regionalgeological evolution of this region. Based on some new data obtained recently and the field observations by theauthor, and by using the plate tectonic theory, the author considers that there developed a Pacific-type (activetype) ancient continental margin bordering the Palaeo-Tethys ocean (or North Tethys ocean) in the south inLate Permian to Triassic times in the region of south-central Qinghai, northeastern Xizang (Tibet), western andsouthwestern Sichuan, and western Yunnan. Its characteristics basically represent the Indosinian tectonic evo-lution of this region.
基金the Chinese National Climbing Project"The Tibetan PlateauMeteorological Experiment"and in part by the NationalNatural Science Foundation of China under Grant No.49675296.
文摘A mesoscale convective system (MCS) developing over the Qinghai-Xizang Plateau on 26 July 1995 is simulated using the fifth version of the Penn State-NCAR nonhydrostatic mesoscale model (MM5). The results obtained are inspiring and are as follows. (1) The model simulates well the largescale conditions in which the MCS concerned is embedded, which are the well-known anticyclonic Qinghai-Xizang Plateau High in the upper layers and the strong thermal forcing in the lower layers. In particular, the model captures the meso-α scale cyclonic vortex associated with the MCS, which can be analyzed in the 500 hPa observational winds; and to some degree, the model reproduces even its meso-β scale substructure similar to satellite images, reflected in the model-simulated 400 hPa rainwater. On the other hand, there are some distinct deficiencies in the simulation; for example, the simulated MCS occurs with a lag of 3 hours and a westward deviation of 3–5° longitude. (2) The structure and evolution of the meso-α scale vortex associated with the MCS are undescribable for upper-air sounding data. The vortex is confined to the lower troposphere under 450 hPa over the plateau and shrinks its extent with height, with a diameter of 4° longitude at 500 hPa. It is within the updraft area, but with an upper-level anticyclone and downdraft over it. The vortex originates over the plateau, and does not form until the mature stage of the MCS. It lasts for 3–6 hours. In its processes of both formation and decay, the change in geopotential height field is prior to that in the wind field. It follows that the vortex is closely associated with the thermal effects over the plateau. (3) A series of sensitivity experiments are conducted to investigate the impact of various surface thermal forcings and other physical processes on the MCS over the plateau. The results indicate that under the background conditions of the upper-level Qinghai-Xizang High, the MCS involved is mainly dominated by the low-level thermal forcing. The simulation described here is a good indication that it may be possible to reproduce the MCS over the plateau under certain large-scale conditions and with the incorporation of proper thermal physics in the lower layers.
基金Sponsored by National Ninth Five Year Plan Science and Technology Project (970204-01-01).
文摘The largest Mesozoic northward transgression in Qangtang Basin of Qinghai-Xizang (Tibet) Plateau occurred during the Buqu Stage, Middle Jurassic. Mainly filled with carbonate rocks, the whole basin is composed of transgression-regression sedimentary cycle. Field outcrops and indoor analysis revealed 8 types of sedimentary facies markers in this region. 4 types of sedimentary facies have been recognized: platform facies, platform marginal facies, foreslope facies and basin facies. Influenced by the northern Lazhuglung-Jinshajiang suture zone, central uplift region and southern Bangongco-Nujiang suture zone, these facies belts extended east-west. The sedimentary model was established based on observed depositional features. From their biological features and sedimentary characteristics, it is suggested that the paleoclimate was warm and humid at that time. The Buqu Formation is a promising target for oil and gas exploration in Shuanghu-Duoyong area in future.
文摘Yongzhu–Guomang Lake ophiolitic melange exposed about 100 km with large scale and complete ophiolitic uint in Xainza County,Xizang(Tibet).It is connected with Nam Lake,Kaimeng ophiolitic mélange to the east,and
文摘The Dongbo ophiolite in the western part of the Yarlung-Zangbo suture zone in southern Tibet rests tectonically on the middle-late Triassic and Cretaceous flysch units,and consist mainly of peridotites,mafic dikes,
基金funded by grants from the NSF China(No.41572051)the China Geological Survey(No.DD20160022-01)project from Institute of Geology,Chinese Academy of Geological Sciences(J1518)
文摘A suit of metamorphic rocks experienced amphibolite and partly granulite facies metamorphism exposed on the Lhasa block,which are recognized as the basement of the Lhasa block named as Nyainqentanglha Group in the
基金State Natural Science Foundation of China !(49732090) the Development Program on National Key Basic Researches under the Pro
文摘Characteristics of present-day tectonic movement in the northeastern margin of Qinghai-Xizang plateau (Tibetan) are studied based on earthquake data. Evidence of earthquake activity shows that junctures between blocks in this area consist of complicated deformation zones. Between the Gansu-Qinghai block and Alxa block there is a broad compressive deformation zone, which turns essentially to be a network-like deformation region to the southeast. The Liupanshan region, where the Gansu-Qinghai block contacts the Ordos block, is suffering from NE-SW compressive deformation. Junction zone between the Ordos and Alxa block is a shear zone with sections of variable trend. The northwestern and southeastern marginal region of the Ordos is under NNW-SSE extension. The above characteristics of present-day tectonic deformation of the northeastern Qinghai-Xizang plateau may be attributed to the northeastward squeezing of the plateau and the resistance of the Ordos block, as well as the southeastward extrusion of the plateau materials.