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Influence of edaphic factors on distribution and condition of Himalayan silver birch(Betula utilis D.Don)communities in the northwestern Indian Himalayas
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作者 Khashti DASILA Renu RAWAL +3 位作者 Tanay BARMAN Sher Singh SAMANT Anita PANDEY Veena PANDE 《Journal of Mountain Science》 SCIE CSCD 2024年第2期590-606,共17页
The basic concept of phytosociology is crucial for the assessment of species composition and dynamic ecological succession of forests supporting ecological services,functions,disturbance,and resilience that lead to th... The basic concept of phytosociology is crucial for the assessment of species composition and dynamic ecological succession of forests supporting ecological services,functions,disturbance,and resilience that lead to the development of integrated areas such as ecological niche modeling and contribute to identifying the valuable bio-indicators which can be used in framing conservation and management planning.B.utilis is one of the most dominant tree species of treeline ecotone in the Himalayan Region.The species is also considered as indicator species for monitoring the past and recent climate change impact.The current study was carried out in the natural populations of B.utilis from the sub-alpine zone of North-western Indian Himalaya.The birch dominated forest harbors a total of 305 plant species comprising Angiosperms(51 families,160 genera and 277 species),Gymnosperms(03 families,05 genera and 07 species)and Pteridophytes(07 families,11 genera and 21 species)with Asteraceae,Ranunculaceae and Rosaceae as dominant family.Birch forests are found dominant in shady moist habitat and North West aspect.Geographical characteristics,anthropogenic and developmental activities affect the population structure of B.utilis and associated species.However,the species has fair regeneration status in the study area.The acidic nature of soil pH and spatial variation in edaphic characteristics may be due to geographical differences,rooting patterns and litter accumulation of below and above-ground vegetation.Biomass estimation of a representative population of B.utilis from each site showed that TAGBD,TCD and TBD were found maximum in ST3(Hamta Pass II site).The CCA analysis determined that environmental variables such as altitude,organic matter,available phosphorous,organic carbon,available nitrogen,and electrical conductivity played a significant role in determining tree species composition and distribution in B.utilis dominated forests. 展开更多
关键词 Species composition Indicator species Biomass North-western indian himalaya Regeneration Environmental variables
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Groundwater development in fragile water resource ecosystems in arid or semi-arid areas in north west Indian Himalayas:implication for sustainable development
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《Global Geology》 1998年第1期50-51,共2页
关键词 Groundwater development in fragile water resource ecosystems in arid or semi-arid areas in north west indian himalayas
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Mitigating People-Park Conflicts on Resource Use through Ecotourism:A Case of the Nanda Devi Biosphere Reserve,Indian Himalaya 被引量:4
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作者 Chandra Prakash KALA Rakesh Kumar MAIKHURI 《Journal of Mountain Science》 SCIE CSCD 2011年第1期87-95,共9页
Ecotourism aims to deliver the philosophy of sustainable development through environmental conservation as well as socio-economic development.Areas with rich biodiversity and scenic beauty,like the Indian Himalayan re... Ecotourism aims to deliver the philosophy of sustainable development through environmental conservation as well as socio-economic development.Areas with rich biodiversity and scenic beauty,like the Indian Himalayan region,have been one of the major destination centers for nature lovers from historical time.In view of conserving the rich biodiversity and natural heritage of the Himalayan region 92 protected areas have been set aside,of these Nanda Devi Biosphere Reserve(NDBR) is a well known world heritage site.Over a period of time establishing NDBR has invited conflicts between the local people and reserve authorities on the management approaches and utilization criteria of the natural resources,especially banning the traditional bio-resource collection rights of local community,expeditions,trekking,and other anthropogenic activities in the core zones.The present study aims to understand and analyze the various people-park conflicts,and also to suggest ways to mitigate such conflicts in view of biodiversity conservation and improvement of economic status of local people by promoting ecotourism.With this view the study further discusses the various aspects of ecotourism,its pros and cons,and the avenues of developing appropriate strategies for promotion of ecotourism in buffer zone areas of NDBR. 展开更多
关键词 生物圈保护区 喜马拉雅地区 生态旅游 资源利用 印度 生物多样性保护 案例 可持续发展
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Assessment of Diversity, Distribution, Conservation Status and Preparation of Management Plan for Medicinal Plants in the Catchment Area of Parbati Hydroelectric Project Stage-Ⅲ in Northwestern Himalaya 被引量:4
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作者 S.S. Samant Jitendra S. Butola Aman Sharma 《Journal of Mountain Science》 SCIE CSCD 2007年第1期34-56,共23页
The developmental activities, particularly the construction of hydroelectric projects are causing a great loss of biodiversity in the Indian Himalayan Region. The Himachal Pradesh, a part of IHR is well known for the ... The developmental activities, particularly the construction of hydroelectric projects are causing a great loss of biodiversity in the Indian Himalayan Region. The Himachal Pradesh, a part of IHR is well known for the development of hydroelectric projects. The Parbati H.E. Project is amongst the major projects of the State. The different stages of the project are all causing loss of biodiversity of the area. Stage Ⅲ of the Parbati H.E. Project is a run of the river scheme on the Sainj River downstream of Power House of Parbati H.E. Project Stage Ⅱ. The project shall utilize regulated discharge of Parbati H.E. Project Stage Ⅱ and inflow of River Sainj for power generation, and has been contemplated as a peaking station operating in tandem with Stage Ⅱ. The present study has been undertaken to see the impact of hydroelectric project on the biodiversity, particularly on medicinal plants. A total of 104 species of medicinal plants, belonging to different life forms, i.e., trees (23 spp.), shrubs (22 spp.), herbs (57 spp.) and ferns (2 spp.) were recorded. The species have been analyzed and studied for their distribution, classification, altitudinal zones, part (s) used, indigenous uses, nativity, endemism and rarity.Different parts of these species, such as whole plants, roots (including rhizomes and tubers), leaves, flowers, fruits, seeds, stems, barks, spikes, nuts and insect galls are used by the inhabitants for curing various diseases and ailments. 30 species are native to the Himalayan region, 9 species native to the Himalayan region and adjacent countries also and 65 species are non-natives. 9 species are near endemics. Considering the whole Himalaya as a biogeographic unit (sensu lato), the near endemics are endemic to the Himalaya. Among these species, Zanthoxylum armatum is categorized as Endangered and Valeriana wallichii as Vulnerable. Hedychium spicatum, Rhus javanica, Berberis lycium, Thalictrum foliolossum, Salvia lanata, Rubia cordifolia and Bergenia ligulata may be considered as threatened species due to their over exploitation for trade. 90 species are propagated by seeds, 8 species by seeds and rhizomes/roots/tubers, 4 species by seeds and cuttings, and 2 species by sori. A management plan for the cultivation and conservation of the medicinal plants in the dam submergence area, and the commercially viable medicinal plants with high value in the catchment area is suggested. 展开更多
关键词 喜马拉雅西北地区 印度 Parbati水电三期工程 汇流区 药用植物 多样性评价 分布 保护状况 管理计划
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Assessment of Man-made and Natural Hazards in the Surroundings of Hydropower Projects under Construction in the Beas Valley of Northwestern Himalaya 被引量:2
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作者 Sanjeev Sharma Jagdish C. Kuniyal J. C. Sharma 《Journal of Mountain Science》 SCIE CSCD 2007年第3期221-236,共16页
Mountain ecosystem,on the earth,has plenty of natural resources. In Himachal Pradesh all the rivers are snowfed and therefore rich in water resources. These resources have been supporting enough for the generation of ... Mountain ecosystem,on the earth,has plenty of natural resources. In Himachal Pradesh all the rivers are snowfed and therefore rich in water resources. These resources have been supporting enough for the generation of electricity through introducing hydropower projects since the last decade. However,every developmental activity has its own negative impacts on the surrounding environment. Due to the fragile nature of topography and delicacy of ecology of the Himalaya,it results in lot of disturbances because of high degree of human interferences like construction of major hydropower projects. The increased extent of geological hazards,such as landslides,rock fall and soil erosion,have mainly due to alike developmental interventions in the natural ecosystem. So understanding and analysing such impacts of the hydropower projects have mainly been on the environment in various forms but natural hazards have been frequent ones. The present study,therefore,focuses mainly on the Parbati Stage Ⅱ (800 MW) and the Parbati Stage Ⅲ (520 MW) hydropower projects; both of which fall within the Kullu district of Himachal Pradesh. Based on the perception survey of the local communities,the existing land use pattern,status of total acquired land of the residents by hydropower projects,frequent natural hazards and resultant loss to the local communities due to upcoming construction of hydropower projects surrounding to the Parbati Stage Ⅱ and Ⅲ have been analysed in the paper. Also,the preventive measures to mitigate these adverse impacts have been suggested to strengthen these projects in eco-friendly manner in the mountain context. 展开更多
关键词 高山生态系统 水利工程 生态环境 水资源
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新特提斯洋打开于晚三叠世?——印度大陆北缘沉积响应 被引量:1
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作者 孟中玙 王建刚 李伟桐 《地质学报》 EI CAS CSCD 北大核心 2023年第9期3024-3042,共19页
新特提斯洋是中生代位于北方欧亚大陆和南方冈瓦纳大陆之间的古大洋,它在青藏高原南部地区于新生代早期因印度-欧亚大陆碰撞而消亡,其遗迹为现今的印度河-雅鲁藏布缝合带。新特提斯洋打开以拉萨地块从冈瓦纳大陆的裂离为标志。准确约束... 新特提斯洋是中生代位于北方欧亚大陆和南方冈瓦纳大陆之间的古大洋,它在青藏高原南部地区于新生代早期因印度-欧亚大陆碰撞而消亡,其遗迹为现今的印度河-雅鲁藏布缝合带。新特提斯洋打开以拉萨地块从冈瓦纳大陆的裂离为标志。准确约束新特提斯洋的开启时间是重建冈瓦纳大陆裂解过程和特提斯洋演化历史的关键,但目前学术界对于新特提斯洋的开启时间还存在很大争议,不同学科方法的认识从早二叠世到晚三叠世不等。本文对新特提斯洋南侧印度被动大陆边缘二叠纪—三叠纪沉积地层进行了系统的梳理,研究发现在早二叠世冰期结束之后,印度大陆北缘长期表现为稳定的沉积环境,显著的沉积环境变化仅发生在晚三叠世。晚三叠世的沉积环境变化伴随着沉积和沉降速率增加、沉积物源变化、双峰式火山活动以及古地理格局的重大改变。研究认为,晚三叠世印度大陆北缘沉积作用变化所记录的区域伸展作用很可能代表了新特提斯洋的开启。 展开更多
关键词 新特提斯洋开启 印度大陆北缘 沉积响应 古地理 晚三叠世 特提斯喜马拉雅
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再论印度与亚洲大陆何时何地发生初始碰撞 被引量:32
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作者 黄宝春 陈军山 易治宇 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2010年第9期2045-2058,共14页
印度与亚洲大陆碰撞形成了喜马拉雅造山带.该造山带是当今固体地球科学研究的重点和热点,是建立新的大陆动力学理论的最佳天然实验室.印度与亚洲大陆碰撞时限是正确认识和理解该造山带形成与演化、高原隆升的动力学过程等的起点.近南北... 印度与亚洲大陆碰撞形成了喜马拉雅造山带.该造山带是当今固体地球科学研究的重点和热点,是建立新的大陆动力学理论的最佳天然实验室.印度与亚洲大陆碰撞时限是正确认识和理解该造山带形成与演化、高原隆升的动力学过程等的起点.近南北向陆陆碰撞的最直接证据是碰撞带两侧块体在古纬度上的相互重叠.本文拟通过对相关古地磁资料的分析,结合近年来在拉萨地块南缘林子宗群火山岩和沉积岩夹层上获得的最新古地磁结果,探索当今占地磁数据所限定的印度和亚洲大陆发生初始碰撞的时间和古地理位置.结果表明,拉萨地块林子宗群形成时期(约64~44 Ma)古亚洲大陆最南缘的古地理位置(~10°N)限定了印度与亚洲大陆的初始碰撞最可能发生在65~50 Ma之间;如果以由印度洋海底地形所限定的东冈瓦纳大陆裂解前的印度板块形状为大印度模型,则印度与亚洲大陆的初始碰撞很可能发生在60~55 Ma之间. 展开更多
关键词 拉萨地块 喜马拉雅地块 印度与亚洲大陆 初始碰撞 古地理 古地磁学
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南亚季风降水的双极振荡 被引量:5
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作者 段克勤 姚檀栋 +1 位作者 邰庆国 郭学军 《第四纪研究》 CAS CSCD 北大核心 2006年第2期192-197,共6页
文章利用气象资料揭示在印度半岛南部和北部,南亚季风降水变化在10年尺度以上呈翘翘板变化形式;利用更长的季风降水资料,即300年的喜马拉雅山达索普冰芯降水记录和印度半岛南部石笋降水记录,发现印度南部和喜马拉雅山季风降水呈双... 文章利用气象资料揭示在印度半岛南部和北部,南亚季风降水变化在10年尺度以上呈翘翘板变化形式;利用更长的季风降水资料,即300年的喜马拉雅山达索普冰芯降水记录和印度半岛南部石笋降水记录,发现印度南部和喜马拉雅山季风降水呈双极振荡行为。自1700年以来,喜马拉雅山,即印度北部(或印度半岛南部)季风降水经历了1700~1764年期间的减小(或增加)趋势,1764~1876年期间的增大(或减小)趋势,1876~2000年期间的减小(或增加)趋势。同时,发现印度半岛南部的季风降水同北半球温度变化具有相同的变化特征,而喜马拉雅山季风降水同北半球温度变化具有相反的变化特征。南亚季风降水的这种南北翘翘板变化形式,与跨赤道气流有密切的联系。 展开更多
关键词 南亚季风降水 喜马拉雅山 印度半岛南部
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印度板块的北缘在哪里? 被引量:7
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作者 刘葵 赵文津 +1 位作者 江万 吴珍汉 《地质通报》 CAS CSCD 北大核心 2006年第1期43-47,共5页
通过对INDEPTHII在雅鲁藏布江南的2条南北向深地震反射剖面资料的进一步处理,观察到主喜马拉雅逆冲断裂带(MHT)形成的反射向北逐渐倾没于藏南地壳之下。这一反射一直可延伸至康马穹隆北、浪卡子南,在向北延伸的过程中,断裂带向北倾角逐... 通过对INDEPTHII在雅鲁藏布江南的2条南北向深地震反射剖面资料的进一步处理,观察到主喜马拉雅逆冲断裂带(MHT)形成的反射向北逐渐倾没于藏南地壳之下。这一反射一直可延伸至康马穹隆北、浪卡子南,在向北延伸的过程中,断裂带向北倾角逐渐加大,可以看到MHT反射最北端的反射同相轴向北倾斜的角度到达27°30'~29°,最深处的双程走时达到22.5s左右。根据深地震反射资料并结合大地电磁(MT)资料,提出印度板块在雅鲁藏布江南30~40km(大约28°50'N)处沿MHT俯冲到了藏南的地壳之下,即在地壳范围内印度板块的最北部边缘位于雅鲁藏布江南30~40km处。 展开更多
关键词 主喜马拉雅逆冲断裂带(MHT) 印度板块北缘 深地震反射
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巴基斯坦北部白沙瓦平原碱性火山岩同位素年龄及构造意义——包括一套年龄为26Ma的熔结凝灰岩 被引量:7
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作者 Irshad Ahmad 李美姣 《新疆地质》 CAS CSCD 北大核心 2013年第4期360-370,共11页
白沙瓦平原碱性火成岩省(Peshawar Plain Alkaline Igneous Province,PPAIP)岩体最新错石年龄首次证实,喜马拉雅新生代(渐新世)熔结凝灰岩火山活动时间为(26.7±0.8)Ma。其它数据表明火成岩省内裂谷相关岩浆作用 时期为二叠... 白沙瓦平原碱性火成岩省(Peshawar Plain Alkaline Igneous Province,PPAIP)岩体最新错石年龄首次证实,喜马拉雅新生代(渐新世)熔结凝灰岩火山活动时间为(26.7±0.8)Ma。其它数据表明火成岩省内裂谷相关岩浆作用 时期为二叠纪,持续时间为290-250 Ma。虽火成岩省内岩石从岩石学及地球化学上具典型裂谷特征,被认为与新 特提斯洋初期泛大陆边缘上的裂谷作用相关,但白沙瓦平原二叠纪地层并无与裂谷相关构造痕迹。因此,我们认 为受印度大陆与欧亚大陆碰撞影响,二叠纪裂谷相关构造被改造或分解。主地幔冲断层(MMT)和主边界冲断层 (MBT)间区域的缩短可能指示地下盐岭(Slat Range)蒸发岩向北伸展。喜马拉雅逆冲时期及之后白沙瓦平原新生 代晚期地层发育为逆冲带上的背驮式盆地。这些沉积地层覆盖了二叠纪裂谷相关构造的残存证据。火成岩省火 成岩经喜山期碰撞及新生代岩浆活动而变形变质,该岩浆活动除新发现的哥哈提(Gohati)火山作用外,还包括主地 幔冲断层(MMT)附近区域(如Malakand等)具交叉截切特征的花岗岩侵入作用。清格莱(Chingalai)片麻岩锆石测 年证实,白沙瓦平原前寒武纪基底中存在年龄为(816±70)Ma的岩石,其年龄与拉贾斯坦邦(Rajasthan platform)以南 1 000 km处马拉尼(Malani)火成岩省岩石年龄相对应。 展开更多
关键词 白沙瓦平原火成岩省 锆石年龄 印度板块 喜马拉雅山脉
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Influence of peach(Prunus persica Batsch)phenological stage on the short-term changes in oxidizable and labile pools of soil organic carbon and activities of carbon-cycle enzymes in the North-Western Himalayas 被引量:2
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作者 Sovan DEBNATH Brij Lai ATTRI +6 位作者 Anil KUMAR Arun KISHOR Raj NARAYAN Kanchan SINHA Arpan BHOWMIK Anil SHARMA Desh Beer SINGH 《Pedosphere》 SCIE CAS CSCD 2020年第5期638-650,共13页
The labile organic carbon(C)and C-related enzymes are sensitive indicators capturing alterations of soil organic matter(SOM),even in a short-time scale.Although the effects of crop husbandry and land use change on the... The labile organic carbon(C)and C-related enzymes are sensitive indicators capturing alterations of soil organic matter(SOM),even in a short-time scale.Although the effects of crop husbandry and land use change on these attributes have been well studied,there is no consensus about how plant phenology may impact them.This study aimed to determine the short-term effect o f six distinct phenological stages(PS-1:full bloom;PS-2:fruit set;PS-3:pit hardening;PS-4:physiological maturity;PS-5:60 d after physiological maturity;and PS-6:fall)o f peach on the changes in soil organic carbon(SOC)fractions of different oxidizability,labile C pools,and C-cycle enzyme activities in soils,for two consecutive years(2015 and 2016)in the North-Western Himalayas(NWH).Peach rhizosphere soils were sampled at the topsoil(0-15 cm)and subsoil(16-30 cm)layers,along with rhizosphere soils from adjacent perennial grasses,which served as a control.Values for most of the assessed parameters,including very labile C,labile C,microbial biomass C,permanganate oxidizable C,dissolved organic C,mineralizable C,amylase activity,and carboxymethyl-cellulase activity,were significantly(P<0.05)higher at PS-3 than at other phenological stages of peach.Conversely,a sudden decline in these soil variables was recorded at PS-5,followed by a slight buildup at PS-6,particularly in the topsoil of the peach orchard.Short-term changes in organic C fractions of different oxidizability,influenced by peach phenological stage,significantly(P<0.05)affected C management index,C pool index,and lability index.Both the C management index and lability index showed their highest values at PS-3 and their lowest values at PS-5,clearly indicating short-term accretion and depletion of SOC,in tandem with the peach phenological events.Principal component analysis suggested that a composite of soil indicators,including microbial biomass C,dissolved organic C,amylase,and invertase,could help detect short-term changes in SOC content.It is concluded that peach phenological events had a major impact on the short-term variations of the studied soil variables,which could be attributed to changes in the above-and belowground plant residues,as well as the extent of nutrients and water acquisition. 展开更多
关键词 carbon fractions fruit orchard indian himalaya plant phenology rhizosphere soil soil biological indicators
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Paleoproterozoic granitic gneisses of the Dinggye and LhagoiKangri areas from the higher and northern Himalaya,Tibet:Geochronology and implications 被引量:6
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作者 LIAO QunAn LI DeWei +2 位作者 LU Lian YUAN YieMing CHU LingLin 《Science China Earth Sciences》 SCIE EI CAS 2008年第2期240-248,共9页
Granitic gneisses have been widely found in crystalline rocks in the Dinggye area of the Higher Himalaya (HHM) and the LhagoiKangri area of the North Himalaya (NHM), Tibet. In the HHM, the gneisses intruded in the gra... Granitic gneisses have been widely found in crystalline rocks in the Dinggye area of the Higher Himalaya (HHM) and the LhagoiKangri area of the North Himalaya (NHM), Tibet. In the HHM, the gneisses intruded in the granulite-amphibolite facies metamorphosed sedimentary rocks, known as Nyalam group. In the NHM, the gneisses intruded in the amphibolite facies metamorphosed ones, known as LhagoiKangri group. These granitic gneisses are peraluminous monzonitic granites in terms of their mineral assemblage, and are considered as being derived from metamorphosed sedimentary rocks by anatexis based on the transitional relationship of the gneisses with their migmatitized wall rocks. Zircons are similar in crystal shape and interior structure from both gneisses. Most of them are euhedral or subhedral elongated prism-shaped transparent crystals, with fine oscillatory zoning, showing the magmatic genesis. Some of them are short prism-shaped and with relict core inherited from magma source and oscillatory zoning mantle crystallized from magma. SHRIMP U-Pb dating of zicons shows that both the granitic gneisses in the HHM and NHM are Paleoproterozoic (1811.6±2.9 Ma and 1811.7±7.2 Ma, respectively). These ages are similar to those (1815 to 2120 Ma) from granitic gneiss which is widely distributed in the Lesser Himalaya (LHM). The ages of inherited zircons (>2493.9±7.0 Ma, 2095.8± 8.8 Ma, 1874±29 Ma) exhibit the possible presence of several thermal events in Paleoproterozoic. All of the ages suggest the same India basement beneath the different units in Himalaya area, and do not support the idea that the HHM and NHM are accretionary terranes in Pan-Africa orogenic event. The fact that the basement in HHM is as old as or even younger than LHM is inconsistent with the presently prevalent orogenic models such as either extrusion of low-viscosity mid-crust or orogenic channel. 展开更多
关键词 HIGHER himalaya PALEOPROTEROZOIC GRANITIC GNEISS indian basement GEOCHRONOLOGY
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Nd isotopic compositions of the Tethyan Himalayan Sequence in southeastern Tibet 被引量:21
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作者 DAI JinGen YIN An +1 位作者 LIU WenCan WANG ChengShan 《Science China Earth Sciences》 SCIE EI CAS 2008年第9期1306-1316,共11页
The Himalayan orogen consists of three major lithologic units that are separated by two major north-dipping faults: the Lesser Himalayan Sequence (LHS) below the Main Central Thrust (MCT), the Greater Himalayan Crysta... The Himalayan orogen consists of three major lithologic units that are separated by two major north-dipping faults: the Lesser Himalayan Sequence (LHS) below the Main Central Thrust (MCT), the Greater Himalayan Crystalline Complex (GHC) above the MCT, and the Tethyan Himalayan Sequence (THS) juxtaposed by the South Tibet Detachment fault (STD) over the GHC. Due to widespread meta-morphism and intense deformation, differentiating the above three lithologic units is often difficult. This problem has been overcome by the use of Sm-Nd isotopic analysis. The previous studies suggested that the LHS can be clearly distinguished from the GHC and THS by their Nd isotope compositions. However, the lack of detailed and systematic Sm-Nd isotopic studies of the THS across the Himalaya in general has made differentiation of this unit from the nearby GHC impossible, as the two appear to share overlapping Nd compositions and model ages. To address this problem, we systematically sam-pled and analyzed Nd isotopes of the THS in southeastern Tibet directly north of Bhutan. Our study identifies two distinctive fields in a εNd -TDM plot. The first is defined by the εNd(210 Ma) values of -3.45 to -7.34 and TDM values of 1.15 to 1.29 Ga from a Late Triassic turbidite sequence, which are broadly similar to those obtained from the Lhasa block. The second field is derived from the Early Cretaceous meta-sedimentary rocks with εNd(130 Ma) values from -15.24 to -16.61 and TDM values from 1.63 to 2.00 Ga; these values are similar to those obtained from the Greater Himalayan Crystalline Complex in Bhutan directly south of our sampling traverse, which has εNd(130 Ma) values of -10.89 to -16.32 and Nd model ages (TDM) of 1.73 to 2.20 Ga. From the above observations, we suggest that the Late Triassic strata of the southeast Tibetan THS were derived from the Lhasa block in the north, while the Early Cretaceous strata of the THS were derived from a source similar to the High Himalayan Crystalline Complex or Indian craton in the south. Our interpretation is consistent with the existing palaeocurrent data and provenance analysis of the Late Triassic strata in southeastern Tibet, which indicate the sediments derived from a northern source. Thus, we suggest that the Lhasa terrane and the Indian craton were close to one another in the Late Triassic and were separated by a rift valley across which a large submarine fan was transported southward and deposited on the future northern margin of the Indian continent. 展开更多
关键词 himalayaN OROGEN SM-ND isotopic systematics Greater himalayaN Crystalline Complex TETHYAN himalaya SEQUENCE Lhasa ter- rane indian CRATON
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早白垩世存在刚性/准刚性大印度板块的古地磁学新证据 被引量:3
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作者 张也 黄宝春 赵千 《科学通报》 EI CAS CSCD 北大核心 2019年第21期2225-2244,共20页
白垩纪期间特提斯喜马拉雅地块与印度克拉通之间的构造关系,是正确认识印度与欧亚大陆碰撞(简称印欧碰撞)模式的关键.本研究通过对特提斯喜马拉雅东部浪卡子县工布学乡下白垩统桑秀组岩石的系统古地磁学和年代学研究,结合早白垩世冈瓦... 白垩纪期间特提斯喜马拉雅地块与印度克拉通之间的构造关系,是正确认识印度与欧亚大陆碰撞(简称印欧碰撞)模式的关键.本研究通过对特提斯喜马拉雅东部浪卡子县工布学乡下白垩统桑秀组岩石的系统古地磁学和年代学研究,结合早白垩世冈瓦纳大陆的重建和印度板块白垩纪的运动轨迹,在对比分析特提斯喜马拉雅地块早白垩世以来古地磁数据的基础上,提出印欧初始碰撞前存在一个刚性/准刚性的大印度板块,印欧碰撞仍为经典的陆陆碰撞.首先,对采样剖面顶部砂岩和底部安山岩的U-Pb锆石年代学研究限定了桑秀组火山岩的喷发年龄为早白垩世的~134 Ma.其次,岩石磁学研究表明携带高温(高场)特征剩磁分量的主要磁性载体为磁铁矿和钛磁铁矿;进一步古地磁测试分析在采样剖面褶皱两翼共23个采点中获得了可靠的特征剩磁组分,经相邻熔岩流古地磁方向去重检验后的特征剩磁平均方向和对应古地磁极位置分别为D*/I*=308.7°/-57.6°, k=29.5,α95=8.5°(N=11)和6.3°N,308.6°E(A95=9.1°).特征剩磁分量在99%置信水平上通过了褶皱检验和地球磁场长期变模型的检验,指示其为早白垩世末期区域褶皱形成之前获得的剩磁组分,并有效地平均掉了古地球磁场的长期变化.因此,该特征剩磁组分很可能代表了桑秀组火山岩形成时获得的原生剩磁.结果表明,早白垩世特提斯喜马拉雅地块的观测古纬度和古磁偏角与由同时期印度板块古地磁参考极计算获得的期望古纬度和古磁偏角完全一致,指示藏南桑秀组火山岩形成时期特提斯喜马拉雅与印度克拉通之间具有刚性/准刚性板块的特征. 展开更多
关键词 特提斯喜马拉雅 大印度板块 早白垩世 古地磁学 印欧碰撞 刚性板块
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