The eastern Himalayan syntaxis in Namjagbarwa is a high-grade metamorphicterrain formed by the India-Eurasia collision and northward indentation of the Indian continent intoAsia. Right- and left-lateral slip zones wer...The eastern Himalayan syntaxis in Namjagbarwa is a high-grade metamorphicterrain formed by the India-Eurasia collision and northward indentation of the Indian continent intoAsia. Right- and left-lateral slip zones were formed by the indentation on the eastern and westernboundaries of the syntaxis respectively. The Dongjug-Mainling fault zone is the main shear zone onthe western boundary. This fault zone is a left-lateral slip belt with a large component ofthrusting. The kinematics of the fault is consistent with the shortening within the syntaxis, andthe slipping history along it represents the indenting process of the syntaxis. The Ar-Archronological study shows that the age of the early deformation in the Dongjug-Mainling fault zoneranges from 62 to 59 Ma. This evidences that the India-Eurasia collision occurred in the earlyPaleocene in the eastern Himalayan syntaxis.展开更多
To provide scientific basis for appraising natural resources in Mt. Namjagbarwa area, the migration characteristics of geochemical microelements, such as Zn, V, Ti, Pb, Ni, Cu, Cr, Co, Be and Ba, in the landscape zone...To provide scientific basis for appraising natural resources in Mt. Namjagbarwa area, the migration characteristics of geochemical microelements, such as Zn, V, Ti, Pb, Ni, Cu, Cr, Co, Be and Ba, in the landscape zones of alpine scrub and meadow, the mountainous dark coniferous forest, the mountainous mixed broadleaf and coniferous forest, the mountainous quasi-subtropical semi-evergreen broadleaf forest, the mountainous subtropical evergreen broadleaf forest, and the valley quasi-tropical monsoon rainforest have been described in the paper.展开更多
Different types of vegetation patches are alternately and randomly distributed in a timberline ecotone where the upper limit is the treeline and the lower limit is the timberline.However,most studies on timberline/tre...Different types of vegetation patches are alternately and randomly distributed in a timberline ecotone where the upper limit is the treeline and the lower limit is the timberline.However,most studies on timberline/treeline altitudinal distributions have simplified timberline or treeline as continuous curves and disregarded the fuzziness of timberline/treeline and the randomness of different vegetation patch distributions in a timberline ecotone.To study the altitudinal distribution characteristics of timberline and treeline from the perspective of uncertainty theory,we constructed the timberline and treeline elevation cloud models in Mt.Namjagbarwa in east Himalayas.Subsequently,we established multiple linear regression models by using nine influencing factors,namely,aspect,slope,topographic relief,dryness index,average temperature in January and July,latitude,summit syndrome(represented by the vertical distance from the peak),and snow effect(represented by the nearest distance from the snow)as independent variables,and the elevations of timberline/treeline as dependent variables.Then we compared the contributions of the nine factors in timberline,treeline,and the core and peripheral areas of timberline and treeline.The results show that 1)the timberline/treeline elevation cloud model can represent the overall characteristics(especially the uncertainty)of the altitudinal distributions of the timberline/treeline well.The uncertainty of treeline’s altitudinal distribution is higher than that of timberline(entropy and hyper entropy:207.59 m and 70.36 m for treeline elevation cloud;entropy and hyper entropy:191.17 m and 50.13 m for timberline elevation cloud).2)The influence of climate and topography on timberline and treeline are similar.The average temperature in July has a significant negative correlation with the timberline/treeline elevation in Mt.Namjagbarwa,which is the most critical factor that affects timberline and treeline elevation,explaining the altitudinal distribution of 44.01%timberline and 46.74%treeline.However,the contributions of the nine factors in core and peripheral areas of timberline and treeline area are evidently different.展开更多
A large area of high-pressure garnet-kyanite granulite is exhumed in the Namjagbarwa area, which provides a window for observing the deep crust rocks and structures of the Tibetan Plateau. Three mineral assemblages ca...A large area of high-pressure garnet-kyanite granulite is exhumed in the Namjagbarwa area, which provides a window for observing the deep crust rocks and structures of the Tibetan Plateau. Three mineral assemblages can have been distinguished in the garnet-kyanite HP granulites by petrography, i.e. M1. Mus+Bi+P1+Q, M2. Gt+Ky +perphite/antiperphite+Rt+Q, M3. Gt+Sill+Cord+Sp+Ilm ± Opx. Metamorphic conditions of the peak granulite assemblages (M2) formatted by thickening of crusts, with available isotopic ages of 45–69 Ma, are at 1.4—1.8 Gpa and 750—850°. Their retrograde assemblages overprinted by decompressure during the uplift, with available isotopic ages of 18—23 Ma, were formed at 0.60—0.70 Gpa, 621—726°. The thermobarometric evaluation, petrogenetic grid and corresponding isotopic ages indicate a clockwise isothermal decompression metamorphic path. The HP granulite metamorphic history indicates that the collision of the Indian Plate with the Eurasian Plate had begun at 70 Ma, far earlier than the widely accepted 45 Ma.展开更多
The structural pattern of the eastern Himalayan syntaxis in Namjagbarwa consists of two series of structures with different styles. One series compiles the earlier ductile contractional and lateral-slip deformation sy...The structural pattern of the eastern Himalayan syntaxis in Namjagbarwa consists of two series of structures with different styles. One series compiles the earlier ductile contractional and lateral-slip deformation system, formed by nearly north-south shortening within the syntaxis, left-lateral and right-lateral slipping along its western and eastern boundaries respectively. They were possibly produced by the indentation of the Indian continent into Asian continent after India-Asia collision. The peak deformation-metamorphic ages in these structures are 62-60 Ma, ~23 Ma and ~13 Ma. The other series is composed of ductile-brittle normal faults distributing concentrically and dipping toward the outsides of Namjagbarwa Peak. They were probably the collapse structures caused by rapid uplift in a later time and the beginning ages for the normal faulting are about 7.3-6.3 Ma. Keywords Namjagbarwa - eastern Himalayan syntaxis (EHS) - structural pattern - formation process - structural chronology展开更多
Recently, a series of basic granulite enclosures are found in the granulite gneisses along the right side of the Yarlung Zangbo River, lying west of the Namjagbarwa Mountain. Es-pecially, some high-pressure granulite ...Recently, a series of basic granulite enclosures are found in the granulite gneisses along the right side of the Yarlung Zangbo River, lying west of the Namjagbarwa Mountain. Es-pecially, some high-pressure granulite enclosures have been discovered in eastern gully of the Zhibei village. To the northwest of the high-pressure granulite belt there occur Yarlung Zangbo ophiolite zone. Southeastward the granulites change into amphibolite and green-schist facies rocks, which constitute a complete lower crust section.展开更多
The Mt. Namjagbarwa region (thereafter referred to as MNR) is located in the southeast of Xizang Autonomous Region, China (29°37′51″ N, 95°03′31″E), and belongs to the eastern part of the Himalaya. The h...The Mt. Namjagbarwa region (thereafter referred to as MNR) is located in the southeast of Xizang Autonomous Region, China (29°37′51″ N, 95°03′31″E), and belongs to the eastern part of the Himalaya. The highest peak of the Mt. Namjag.展开更多
Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers for...Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C （10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong） and a series of ESR （electron spin resonance） ages at Linzhi town and previous data by other experts, paleolakes persisted for 691±305 kaBP middle Pleistocene ice age, 75-40 kaBP the early stage of last glacier, 27-8 kaBP Last Glacier Maximum （LGM）, existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale： the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn＇t erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn＇t form stable lake.展开更多
Zelongnong Ravine,a branch ravine of Brahmaputra,is an old large glacier debris-flow ravine.Debris-flows with medium and/or small scales occur almost every year;multiple super debris-flows have also broken out in hist...Zelongnong Ravine,a branch ravine of Brahmaputra,is an old large glacier debris-flow ravine.Debris-flows with medium and/or small scales occur almost every year;multiple super debris-flows have also broken out in history,and have caused destructive disaster to local residents at the mouth of ravine and blocked Brahmaputra.The huge altitude difference and the steep slope of the Zelongnong Ravine provide predominant energy conditions for the debris-flow.The drainage basin is located in the fast uplifted area,where the complicated geologic structure,the cracked rock,and the frequent earthquake make the rocks experience strong weathering,thus plenty of granular materials are available for the formation of debris-flows.Although this region is located in the rain shadow area,the precipitation is concentrated and most is with high intensity.Also,the strong glacier activity provides water source for debris-flow.According to literature reviews,most debris-flows in the ravine are induced by rainstorms,and their scales are relatively small.However,when the melted water is overlaid,the large scale debris-flows may occur.Parametric calculation such as the flow velocity and the runoff is conducted according to the monitoring data.The result shows that large debris-flows can be aroused when the rainstorm and the melted water are combined well,but the possibility of blocking off Brahmaputra is rare.The occurrence of the super debris-flows is closely related to the intense glacier activity(e.g.,glaciersurge).They often result in destructive disasters and are hard to be prevented and cured by engineering measures,due to the oversized scales.The hazard mitigation measures such as monitoring and prediction are proposed.展开更多
基金the National Natural Science Foundation of China (Grants 49802020,49732100 , 40172074) the Specific Project forthe Authors of the Best Dissertations of Chinese Universifies and Colleges (200022).
文摘The eastern Himalayan syntaxis in Namjagbarwa is a high-grade metamorphicterrain formed by the India-Eurasia collision and northward indentation of the Indian continent intoAsia. Right- and left-lateral slip zones were formed by the indentation on the eastern and westernboundaries of the syntaxis respectively. The Dongjug-Mainling fault zone is the main shear zone onthe western boundary. This fault zone is a left-lateral slip belt with a large component ofthrusting. The kinematics of the fault is consistent with the shortening within the syntaxis, andthe slipping history along it represents the indenting process of the syntaxis. The Ar-Archronological study shows that the age of the early deformation in the Dongjug-Mainling fault zoneranges from 62 to 59 Ma. This evidences that the India-Eurasia collision occurred in the earlyPaleocene in the eastern Himalayan syntaxis.
文摘To provide scientific basis for appraising natural resources in Mt. Namjagbarwa area, the migration characteristics of geochemical microelements, such as Zn, V, Ti, Pb, Ni, Cu, Cr, Co, Be and Ba, in the landscape zones of alpine scrub and meadow, the mountainous dark coniferous forest, the mountainous mixed broadleaf and coniferous forest, the mountainous quasi-subtropical semi-evergreen broadleaf forest, the mountainous subtropical evergreen broadleaf forest, and the valley quasi-tropical monsoon rainforest have been described in the paper.
基金supported by the National Natural Science Foundation of China(Grant No.41401111)the Natural Science Foundation of Shandong Province(Grant No.ZR2021MD080 and Grant No.ZR2014DQ017)the Shandong Agricultural Science and Technology Fund Project(Grant No.2019LY006)。
文摘Different types of vegetation patches are alternately and randomly distributed in a timberline ecotone where the upper limit is the treeline and the lower limit is the timberline.However,most studies on timberline/treeline altitudinal distributions have simplified timberline or treeline as continuous curves and disregarded the fuzziness of timberline/treeline and the randomness of different vegetation patch distributions in a timberline ecotone.To study the altitudinal distribution characteristics of timberline and treeline from the perspective of uncertainty theory,we constructed the timberline and treeline elevation cloud models in Mt.Namjagbarwa in east Himalayas.Subsequently,we established multiple linear regression models by using nine influencing factors,namely,aspect,slope,topographic relief,dryness index,average temperature in January and July,latitude,summit syndrome(represented by the vertical distance from the peak),and snow effect(represented by the nearest distance from the snow)as independent variables,and the elevations of timberline/treeline as dependent variables.Then we compared the contributions of the nine factors in timberline,treeline,and the core and peripheral areas of timberline and treeline.The results show that 1)the timberline/treeline elevation cloud model can represent the overall characteristics(especially the uncertainty)of the altitudinal distributions of the timberline/treeline well.The uncertainty of treeline’s altitudinal distribution is higher than that of timberline(entropy and hyper entropy:207.59 m and 70.36 m for treeline elevation cloud;entropy and hyper entropy:191.17 m and 50.13 m for timberline elevation cloud).2)The influence of climate and topography on timberline and treeline are similar.The average temperature in July has a significant negative correlation with the timberline/treeline elevation in Mt.Namjagbarwa,which is the most critical factor that affects timberline and treeline elevation,explaining the altitudinal distribution of 44.01%timberline and 46.74%treeline.However,the contributions of the nine factors in core and peripheral areas of timberline and treeline area are evidently different.
基金Project supported by the National Natural Science Foundation of China (Grant No. 49732100)the National Key Project for Basic Research, Chinese Academy of Sciences Project for Tibetan Research Project (Grant Nos. KZ951-A1-204, KZ95T-06).
文摘A large area of high-pressure garnet-kyanite granulite is exhumed in the Namjagbarwa area, which provides a window for observing the deep crust rocks and structures of the Tibetan Plateau. Three mineral assemblages can have been distinguished in the garnet-kyanite HP granulites by petrography, i.e. M1. Mus+Bi+P1+Q, M2. Gt+Ky +perphite/antiperphite+Rt+Q, M3. Gt+Sill+Cord+Sp+Ilm ± Opx. Metamorphic conditions of the peak granulite assemblages (M2) formatted by thickening of crusts, with available isotopic ages of 45–69 Ma, are at 1.4—1.8 Gpa and 750—850°. Their retrograde assemblages overprinted by decompressure during the uplift, with available isotopic ages of 18—23 Ma, were formed at 0.60—0.70 Gpa, 621—726°. The thermobarometric evaluation, petrogenetic grid and corresponding isotopic ages indicate a clockwise isothermal decompression metamorphic path. The HP granulite metamorphic history indicates that the collision of the Indian Plate with the Eurasian Plate had begun at 70 Ma, far earlier than the widely accepted 45 Ma.
基金This study was financially supported by the National Natural Science Foundation of China (Grant Nos. (49802020, 49732100, 40172074)the Specific Project for the Author of the Best Dissertations of Chinese Universities and Colleges (Grant No. 200022).
文摘The structural pattern of the eastern Himalayan syntaxis in Namjagbarwa consists of two series of structures with different styles. One series compiles the earlier ductile contractional and lateral-slip deformation system, formed by nearly north-south shortening within the syntaxis, left-lateral and right-lateral slipping along its western and eastern boundaries respectively. They were possibly produced by the indentation of the Indian continent into Asian continent after India-Asia collision. The peak deformation-metamorphic ages in these structures are 62-60 Ma, ~23 Ma and ~13 Ma. The other series is composed of ductile-brittle normal faults distributing concentrically and dipping toward the outsides of Namjagbarwa Peak. They were probably the collapse structures caused by rapid uplift in a later time and the beginning ages for the normal faulting are about 7.3-6.3 Ma. Keywords Namjagbarwa - eastern Himalayan syntaxis (EHS) - structural pattern - formation process - structural chronology
基金Project supported by the National Natural Science Foundation of China and the National Key Project KJ 85-07-01-04.
文摘Recently, a series of basic granulite enclosures are found in the granulite gneisses along the right side of the Yarlung Zangbo River, lying west of the Namjagbarwa Mountain. Es-pecially, some high-pressure granulite enclosures have been discovered in eastern gully of the Zhibei village. To the northwest of the high-pressure granulite belt there occur Yarlung Zangbo ophiolite zone. Southeastward the granulites change into amphibolite and green-schist facies rocks, which constitute a complete lower crust section.
文摘The Mt. Namjagbarwa region (thereafter referred to as MNR) is located in the southeast of Xizang Autonomous Region, China (29°37′51″ N, 95°03′31″E), and belongs to the eastern part of the Himalaya. The highest peak of the Mt. Namjag.
基金supported by Project No.1212011120185 sponsored by China Geological Survey
文摘Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C （10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong） and a series of ESR （electron spin resonance） ages at Linzhi town and previous data by other experts, paleolakes persisted for 691±305 kaBP middle Pleistocene ice age, 75-40 kaBP the early stage of last glacier, 27-8 kaBP Last Glacier Maximum （LGM）, existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale： the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn＇t erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn＇t form stable lake.
文摘在西藏墨脱公路断裂构造的遥感勘察中,以Landsat-7 ETM+卫星影像为信息源,以ENVI 4.0软件为图像处理平台,运用数据集成、图像融合、主成分分析及方向滤波等图像处理技术对断裂构造信息进行增强处理;以基于地学知识的遥感构造分析技术对南迦巴瓦峰地区的断裂构造特征进行全面解译和识别,并在ArcG IS 8.2的支持下进行断裂构造专题制图及信息提取,查明了公路方案线区域内断裂构造的分布及发育特征,为墨脱公路工程线路方案选择、工程地质条件评价提供了科学依据。
基金supported by the National Natural Science Foundation of China(Grant No.40871024 & 40971014)
文摘Zelongnong Ravine,a branch ravine of Brahmaputra,is an old large glacier debris-flow ravine.Debris-flows with medium and/or small scales occur almost every year;multiple super debris-flows have also broken out in history,and have caused destructive disaster to local residents at the mouth of ravine and blocked Brahmaputra.The huge altitude difference and the steep slope of the Zelongnong Ravine provide predominant energy conditions for the debris-flow.The drainage basin is located in the fast uplifted area,where the complicated geologic structure,the cracked rock,and the frequent earthquake make the rocks experience strong weathering,thus plenty of granular materials are available for the formation of debris-flows.Although this region is located in the rain shadow area,the precipitation is concentrated and most is with high intensity.Also,the strong glacier activity provides water source for debris-flow.According to literature reviews,most debris-flows in the ravine are induced by rainstorms,and their scales are relatively small.However,when the melted water is overlaid,the large scale debris-flows may occur.Parametric calculation such as the flow velocity and the runoff is conducted according to the monitoring data.The result shows that large debris-flows can be aroused when the rainstorm and the melted water are combined well,but the possibility of blocking off Brahmaputra is rare.The occurrence of the super debris-flows is closely related to the intense glacier activity(e.g.,glaciersurge).They often result in destructive disasters and are hard to be prevented and cured by engineering measures,due to the oversized scales.The hazard mitigation measures such as monitoring and prediction are proposed.
