Precipitation reconstruction using ring-width chronology of himalayan cedar from western himalaya: Preliminary results     

Ram R Yadav  Won-Kyu Park 《Journal of Earth System Science》2000,109(3):339-345

Himalayan cedar (Cedrus deodara (D. Don) G. Don) due to its long age and wide ecological amplitude in the Himalayan region has strong dendroclimatic potential. A well replicated ring-width chronology of it, derived from the ensemble of tree-ring samples of two adjacent homogeneous sites, has been used to reconstruct precipitation for the non-monsoon months (previous year October to concurrent May) back to AD 1171. This provides the first record of hydrological conditions for the western Himalayan region, India during the whole of the ‘Little Ice Age’ and latter part of the ‘Medieval Warm Period’. The reconstruction revealed the wettest and the driest non-monsoon months during the fourteenth and the thirteenth centuries, respectively. The seventeenth century consistently recorded dry non-monsoon months in the western Himalayan region. Surplus precipitation, especially more pronounced since the 1950s, is recorded in the current century.  相似文献   

TWO EPISODES OF MONAZITE CRYSTALLIZATION DURING METAMORPHISM AND CRUSTAL MELTING IN THE EVEREST REGION OF THE NEPALESE HIMALAYA   总被引：4，自引：2，他引：2  

Robert L. Simpson  Randall R. Parrish  Mike P. Searle  David J. Waters WT  ”BX 《地学前缘》2000,(Z1)

TWO EPISODES OF MONAZITE CRYSTALLIZATION DURING METAMORPHISM AND CRUSTAL MELTING IN THE EVEREST REGION OF THE NEPALESE HIMALAYA  相似文献   

CROSS-SECTIONS OF THE WESTERN HIMALAYAN FOOTHILLS:PROBLEMS IN RESTORATION AND IMPLICATIONS FOR CRUSTAL SHORTENING     

A.K.Dubey    R.Misra    S.S.Bhakuni   《地学前缘》2000,(Z1)

CROSS-SECTIONS OF THE WESTERN HIMALAYAN FOOTHILLS:PROBLEMS IN RESTORATION AND IMPLICATIONS FOR CRUSTAL SHORTENING1　PowersPM ,LillieRJ ,YeatsRS .StructureandshorteningoftheKangraandDehraDunreentrants ,Sub Himalaya ,India[J].GSABulletin ,1998,110 :10 10～ 10 2 7.…  相似文献   

METAMORPHISM IN THE LESSER HIMALAYAN CRYSTALLINES AND MAIN CENTRAL THRUST ZONE IN THE ARUN VALLEY AND AMA DRIME RANGE (EASTERN HIMALAYA)     

Franco Rolfo  Bruno Lombardo  Piero Pertusati  Dario Visonà WT  ”BX 《地学前缘》2000,(Z1)

METAMORPHISM IN THE LESSER HIMALAYAN CRYSTALLINES AND MAIN CENTRAL THRUST ZONE IN THE ARUN VALLEY AND AMA DRIME RANGE (EASTERN HIMALAYA)1　BrunelM ,KienastJR . tudep啨ｔｒｏ structuraledeschevauchementsductileshimalayenssurlatrans versaledel’Everest Makalu (N啨ｐａｌｏｒｉｅｎｔａｌ) [J].CanadianJ .EarthSciences,1986 ,2 3:1117～ 1137. 2　LombardoB ,RolfoF .TwocontrastingeclogitetypesintheHimalayas :implicationsfortheHimalayanorogeny…  相似文献   

PETROLOGY AND AGE OF THE KINNAR KAILAS GRANITE:EVIDENCES FOR AN ORDOVICIAN POST-OROGENIC EXTENSION IN THE HIGHER HIMALAYAN CRYSTALLINE, SUTLEJ, INDIA.     

H. S. Chawla    D. Marquer    J. D. Kramers    I. M. Villa    F. Bussy   《地学前缘》2000,(Z1)

PETROLOGY AND AGE OF THE KINNAR KAILAS GRANITE:EVIDENCES FOR AN ORDOVICIAN POST-OROGENIC EXTENSION IN THE HIGHER HIMALAYAN CRYSTALLINE, SUTLEJ, INDIA  相似文献   

GEODYNAMICS OF THE PAMIRS—HIMALAYA REGION     

T.P. Belousov  Sh.A. MukhamedievWT  ”BX 《地学前缘》2000,(Z1)

GEODYNAMICS OF THE PAMIRS—HIMALAYA REGION  相似文献   

SYNCONVERGENT, DUCTILE N-DIRECTED SHEARING ON THE WESTERN MARGIN OF THE NANGA PARBAT SYNTAXIS, N. PAKISTAN     

Tom Argles  Mike Edwards  Gavin Foster 《地学前缘》2000,(Z1)

SYNCONVERGENT, DUCTILE N-DIRECTED SHEARING ON THE WESTERN MARGIN OF THE NANGA PARBAT SYNTAXIS, N. PAKISTAN1　BurgJ P ,ChaudryMN ,GhazanfarM ,etal.StructuralevidenceforbackslidingoftheKohistanarcinthecollisionalsystemofnorthwestPakistan[J] .Geology 1996 ,2 4 ( 8) ,739～ 74 2 . 2　ChamberlainCP ,ZeitlerPK ,EricksonE .ConstraintsonthetectonicevolutionofthenorthwesternHimalayafromgeochronologicandpetrologicstudiesofBabusarPass,Pakistan[J] .Journa…  相似文献   

Catastrophic mass movement of 1998 monsoons at Malpa in Kali Valley, Kumaun Himalaya (India)   总被引：1，自引：0，他引：1  

S. K. Paul  S. K. Bartarya  Piyoosh Rautela  A. K. Mahajan 《Geomorphology》2000,35(3-4)

A devastating landslide on 18 August 1998 near Malpa Village in Kali Valley of Higher Kumaun Himalaya killed 221 persons. The landslide was a complex rock fall–debris flow. The mass movement generated around one million cubic metres of debris and partially blocked the Kali River, Malpa Gad (a tributary of Kali) being blocked completely. The rock mass failed primarily due to the near vertical slopes hanging over the valley along joints, the formation of structural wedges along the free face, the sheared rock mass due to the close proximity of major tectonic planes, and the enhanced pore–water pressure due to prolonged heavy precipitation in the preceding days. The mesoscopic shear zone, exhibiting ramp and flat structure in quartzites, shows a southward thrust movement that might have generated shear stress in the rocks. The slide clearly demonstrates the distressed state of the rock mass in the Himalayan region due to the ongoing northward drift of the Indian plate.  相似文献   

Petrological constraints on the tectonic setting of the Kathmandu Nappe in the Langtang–Gosainkund–Helambu regions,Central Nepal Himalaya          下载免费PDF全文

G. Rapa  C. Groppo  P. Mosca  F. Rolfo 《Journal of Metamorphic Geology》2016,34(9):999-1023

The Gosainkund–Helambu region in central Nepal occupies a key area for the development of Himalayan kinematic models, connecting the well‐investigated Langtang area to the north with the Kathmandu Nappe (KN), whose interpretation is still debated, to the south. In order to understand the structural and metamorphic architecture of the Greater Himalayan Sequence (GHS) in this region, a detailed petrological study was performed, focusing on selected metapelite samples from both the Gosainkund–Helambu and Langtang transects. The structurally lowest sample investigated belongs to the Lesser Himalayan Sequence; its metamorphic evolution is characterized by a narrow hairpin P–T path with peak P–T conditions of 595 ± 25 °C, 7.5 ± 1 kbar. All of the other samples here investigated belong to the GHS. Along the Langtang section, two tectono‐metamorphic units have been distinguished within the GHS: the Lower Greater Himalayan Sequence (L‐GHS), characterized by peak P–T conditions at 728 ± 11 °C, 10 ± 0.5 kbar (corresponding to a T/depth ratio of 22 ± 1 °C km^?1), and the structurally higher Upper Greater Himalayan Sequence, with peak metamorphic conditions at 780 ± 20 °C, 7.8 ± 0.8 kbar (corresponding to a T/depth ratio of 31 ± 4 °C km^?1). This confirms the existence of a main tectono‐metamorphic discontinuity within the GHS, as previously suggested by other authors. The results of petrological modelling of the metapelites from the Gosainkund–Helambu section show that this region is entirely comprised within a sub‐horizontal and thin L‐GHS unit: the estimated peak metamorphic conditions of 734 ± 19 °C, 10 ± 0.8 kbar correspond to a uniform T/depth ratio of 23 ± 3 °C km^?1. The metamorphic discontinuity identified along the Langtang transect and dividing the GHS in two tectono‐metamorphic units is located at a structural level too high to be intersected along the Gosainkund–Helambu section. Our results have significant implications for the interpretation of the KN and provide a contribution to the more general discussion of the Himalayan kinematic models. We demonstrate that the structurally lower unit of the KN (known as Sheopuri Gneiss) can be correlated with the L‐GHS unit; this result strongly supports those models that correlate the KN to the Tethyan Sedimentary Sequence and that suggest the merging of the South Tibetan Detachment System and the Main Central Thrust on the northern side of the KN. Moreover we speculate that, in this sector of the Himalayan chain, the most appropriate kinematic model able to explain the observed tectono‐metamorphic architecture of the GHS is the duplexing model, or hybrid models which combine the duplexing model with another end‐member model.  相似文献   

Effects of topography and land use on woody plant species composition and beta diversity in an arid Trans-Himalayan landscape,Nepal   总被引：1，自引：1，他引：0  

Shishir Paudel  Ole R. Vetaas 《山地科学学报》2014,11(5):1112-1122

Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only（Pisang site） while the other pair has clear differences in land use in addition to slope exposure（Braka site）. In each site, we sampled 72 plots（36 on each slope） in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis（CA） results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables（e.g., radiation index） affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Br  相似文献