Journal of Himalayan Earth Sciences最新文献

{"title":"Electrical structure of Garhwal Himalayan region, India, inferred from magnetotelluric","authors":"M. Israil, D. K. Tyagi, P. Gupta, S. Niwas","doi":"10.3126/HJS.V5I7.1270","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1270","url":null,"abstract":"Magnetotelluric investigations have been carried out in the Garhwal Himalayan corridor to delineate electrical structure of the crust along a profile extending from Indo-Gangetic Plane to Higher Himalayan region in Uttarakhand, India. The profile passing through major Himalayan thrusts: Himalayan Frontal Thrust (HFF), Main Boundary Thrust (MBT) and Main Central Thrust (MCT), and is nearly perpendicular to the regional geological strike. These Himalayan thrusts are broadly parallel to each other, steeper near surface and become shallow with the depth until they merge with the detachment surface. The main tectonic elements of Garhwal Himalayan region have an average strike of NW-SE (Khattri 1992). Magneto-variation (MV) studies (Arora et al 1982), were carried out over a rectangular array of 24 stations in the Siwalik Himalayan region, indicated the presence of a conductive anomaly, which they interpreted as an extension of the Aravallis and referred to as Trans Himalayan conductor. Subsequently, MT investigations were carried out by Gupta et al (1994) in the Siwalik region over 150 km long Mohand - Ramnagar profile to determine the thickness of Siwalik sediments. They recorded MT data in the frequency range 0.01–100 Hz using short period MT system and estimated geoelectric strike of N 800 W on the basis of","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"20 1","pages":"70-71"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83560082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure of the crust and the lithosphere in the Himalaya-Tibet region and implications on the rheology and eclogitization of the India plate","authors":"G. Hetényi, Jérôme Vergne, J. Nábělek, R. Cattin, F. Brunet, L. Bollinger, M. Diament","doi":"10.3126/HJS.V5I7.1267","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1267","url":null,"abstract":"DOI = 10.3126/hjs.v5i7.1267 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.65-66","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"46 1","pages":"65-66"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83737475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical characters of muscovite from the Pan African Mandi Granite, and its emplacement and evolution","authors":"N. Pant, A. Kundu","doi":"10.3126/HJS.V5I7.1291","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1291","url":null,"abstract":"The Mandi granite, a well known Palaeozoic granite of the Himachal Himalaya, is emplaced in the medium grade metamorphic rocks of Vaikrita Group. The development of andalusite in the contact aureole of Mandi granite indicates its emplacement depth to less than 12-14 km. Several petrological variants such as porphyritic granite, fine-grained porphyritic granite and trondjhemitic granite within the Mandi pluton have been recognized (Chatterjee 1976, Gupta 1994, Kundu et al. in press). Muscovite is a ubiquitous mineral in all of these variants. Muscovite is an indicator of crystallization history of granite. Thus, it is important to assess the magmatic or metamorphic nature of this mica. Muscovite is present in variable amounts in the Mandi granite. They vary from being nearly absent to greater than 10 mode %. Textural features such as subhedral nature, sharp grain boundaries and high modal proportion indicate at least some of these to be a magmatic mineral. Igneous nature of muscovite is also indicated by their chemistry (Higher Ti in porphyritic and trondjhmetic granite in TiO 2 -Fe 2 O 3 -MgO plot; Monier et al., 1984; higher Al and Na and lower Mg and Si; Miller et al. 1981). The metamorphic/later muscovites are clearly distinguishable on chemical criteria. The magmatic muscovites are associated with apatite, monazite and zircon. In deformed granites such coarse grains are commonly present as mica fish. Many of such coarse muscovite grains have a brighter rim which commonly has a trail of small grains of sphene. The rim portion of such grains have higher phengite component (FeO- 4 to 4.5 wt%, MgO = 0.55 to 1.5 wt %) and lower paragonite component (Na/Na+K = 0.03 to 0.04) than the core of the grains. Another textural variety of muscovite is present as fine grained flakes in foliated granites as part of the matrix. It defines the foliation plane in these granites. Such grains have compositions similar to the rim portions of large grains. A cursory examination of the mineral chemistry of muscovite presented above indicate that significant percentage of the muscovites are of primary origin based on their Na/Na+K ratio an observation opposed to that of Nag et al. (2005). The upper stability of muscovite has been considered as 4 kbar and in view of the emplacement of Mandi granite at equivalent depth, as inferred from the development of andalusite in the contact zone, the emplacement conditions are well constrained. Micas of the Mandi granite and associated rocks have been used to decipher the emplacement conditions and evolutionary history of Mandi granite.","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"10 1","pages":"98-98"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81891739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Silurian acanthomorphitae acritarch from the Shiala Formation, Tethys Garhwal Himalaya, India","authors":"H. Sinha","doi":"10.3126/HJS.V5I7.1331","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1331","url":null,"abstract":"The Tethyan-Tibetan sedimentary belt extends from Nanga Parbat in the west to Namcha Barwa in the east and divisible into five sub basins, which are resting over the Central Crystalline basement in the south. These continuous sedimentary sequences vary in thickness from 5000 to 16000 m and range in age from Precambrian to Eocene (?). In north they are terminated by the Indus-Tsangpo Suture Zone. The five subdivisions are developed in the Kashmir, Zanskar, Spiti-Kinnur and Garhwal-Kumaon Basin. The present study is confined to the Lower Palaeozoic sequences of Garhwal-Kumaon basin, which is best known for biostratigraphy and sedimentological studies (Shah and Sinha 1974, Sinha 1989, Sinha et al. 1998, Sinha et al. 2005, Sinha and Mishra 2006, Bagati et al. 1991, among others) in the TethyanTibetan belt. The Ordovician-Silurian strata known as Shiala Formation in the Garhwal-Kumaon basin vary from 400-500 m thickness and are not easily accessible for field work. The Shiala Formation conformably overlies the Garbyang Formation, which is characterised by green shales at the bottom and arenaceous component increases gradually reflecting coarsening upward sequence. The Shiala Formation has been assigned a mid to late Ordovician age based on index forms of brachiopod taxa (Sinha","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"46 1","pages":"150-151"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85437449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crustal velocity structure from surface wave dispersion tomography in the Indian Himalaya","authors":"W. Caldwell, S. Klemperer, S. S. Rai, J. Lawrence","doi":"10.3126/HJS.V5I7.1240","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1240","url":null,"abstract":"Background A network of 15 broadband seismographs in a ~500 km long, N-S array recorded 12 months of data in 2002-2003 (Rai et al. 2006). The array traverses the NW Himalaya, from the Indian plain in the south, across the Indus-Tsangpo Suture and the Tso Morari Dome, to the southern flank of the Karakoram in the north. Magnetotelluric (MT) studies in this region reveal low-resistivity zones which may be indicative of fluids, graphite, or partial melts in the mid-crust. We have tested these hypotheses by creating 1-D models of crustal shear wave velocity. The models contain lowvelocity zones at 25–40 km depth; these may be indicative of fluids or partial melts. Methods Our models are obtained by inverting group velocity dispersion curves of Rayleigh waves in the period range of roughly 4–60 s. Numerous magnitude 4 events, several magnitude 5 events, and one magnitude 6 event occurred 900 km or less from the array. We find dispersion curves by analyzing the z-component of fundamental mode Rayleigh waves using Robert Herrmann’s Computer Programs in Seismology (Herrmann and Ammon 2002). We invert the dispersion curves using these programs to create 1-D models of crustal shear wave velocity structure. The inversion is done to 150 km depth, but we consider only the upper 60 km of the models. Results","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"55 1","pages":"33-33"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83180163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectonometamorphic evolution of collisional orogenic belts in the Korean Peninsula: Implications for East Asian tectonics","authors":"M. Cho","doi":"10.3126/HJS.V5I7.1245","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1245","url":null,"abstract":"DOI = 10.3126/hjs.v5i7.1245 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.40","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"4 1","pages":"40-40"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86392449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Amphibole compositions as indicators of deep crustal and mantle processes in subduction zones: case study - Tso Morari metamafics, Ladakh, Himalaya","authors":"Preeti Singh, N. Pant, A. Kundu, T. Ahmad, P. K. Verma","doi":"10.3126/HJS.V5I7.1325","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1325","url":null,"abstract":"DOI = 10.3126/hjs.v5i7.1325 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.144","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"16 1","pages":"144-144"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75664886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soft sediment deformation structures in the Late Quaternary sediments of Ladakh: evidence of multiple phases of palaeoearthquakes in the North western Himalayan Region","authors":"B. Phartiyal, Anupam Sharma","doi":"10.3126/HJS.V5I7.1297","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1297","url":null,"abstract":"Ladakh, situated in the tectonically active terrain, in the vicinity of the Indus Suture Zone (ISZ), Shyok Suture Zone (SSZ) and Karakoram Fault (KF), is rich in Quaternary deposits and is truly a treasure trove for Quaternary researchers. This work presents the palaeoseismic signatures as recorded in the Quaternary sediments of the Spituk-Leh (along ISZ) and the Khalsar palaeolakes (along SSZ and KF). These two palaeolakes were a result of a regional tectonic activity at 35,000-40,000 yrs BP. 9 levels of soft-sediment deformation structures (seismites) are recorded from a >27 m thick, clay, sand sequence of the Spituk-Leh palaeolake. The deformation levels are confined to the lower 13 m of the sequence (0.5, 2.7, 3.2, 3.6, 5.5, 8.1, 9.8, 12.2 and 13.1 m). The upper part of the paleolakes seems to have stable tectonic conditions. About 90 km north of this section and separated by the Ladakh batholith, in the ~11 m thick section of Khalsar palaeolake shows 8 levels of soft-sediment deformation structures at 1.2, 1.5, 4.2, 4.5, 5.4, 8.8, 9.2 and 10.8 m levels. Deformation sediments are composed of alternations of clay, silts and sand and are restricted to single stratigraphic layers bounded by undeformed beds suggesting synsedimentary deformation. They are simple and complex convolutes, pinch and swell bedding, microfolds and microfaults, flame-like structures, pseudonodules or cycloids, clay diapirs, ball and pillow structures, pillar structures, sedimentary dykes, mud lenses, etc. Lying in the vicinity of the active faults the ISZ, SSZ and KF, these two palaeolake systems record multiple phases of seismic tremors of magnitude >5 due to release of stress along these fault systems during the late Quaternary times.","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"93 1","pages":"107-107"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82092609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Remote Sensing based Study of Retreat of and Accompanying Increase in Supra-glacial Moraine Cover over a Himalayan Glacier","authors":"A. Shukla, R. Gupta, M. Arora","doi":"10.3126/HJS.V5I7.1323","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1323","url":null,"abstract":"DOI = 10.3126/hjs.v5i7.1323 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.142","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"25 1","pages":"142-142"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82030708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Northeast Tibetan Crustal Structure from INDEPTH IV Controlled- Source Seismic Data","authors":"M. Karplus, S. Klemperer, Zhao Wenjin, Wu Zhenhan, Shi Danian, Sun Heping, Lawrence D. Brown, Chen Chen, J. Mechie, R. Kind, F. Tilmann, Y. Makovsky, R. Meissner","doi":"10.3126/HJS.V5I7.1274","DOIUrl":"https://doi.org/10.3126/HJS.V5I7.1274","url":null,"abstract":"76 Since 1992, project INDEPTH (International Deep Profiling of Tibet and the Himalaya) geoscientists from Chinese, American, British, German, and Canadian institutions have collaborated to collect high-quality seismic, MT, and geologic data along a roughly north–south transect from the Himalaya to northern Tibet. The current field effort from 2007–2009, INDEPTH IV, targets the NE margin of the plateau, with goals of testing models of subduction (relict and current) near the Kunlun and Jinsha sutures and probing the deep geometry of key features such as the Kunlun and Altyn Tagh Faults. Our new datasets are intended to shed light on the possible existence of a lower-crustal flow channel beneath northern Tibet, analogous to the weak (and flowing?) lower crust evidenced by INDEPTH observations of mid-crustal low seismic velocities, seismic bright spots and high electrical conductivities (Nelson et al. 1996) in southern Tibet. INDEPTH IV further aims to evaluate the possible subduction of Asian crust from the north beneath the Kunlun suture (Kind et al. 2002) and to probe whether the Kunlun and Jinsha sutures act as crustal-scale faults. Active seismic experiment, summer 2007","PeriodicalId":42873,"journal":{"name":"Journal of Himalayan Earth Sciences","volume":"4 1","pages":"76-77"},"PeriodicalIF":0.4,"publicationDate":"2008-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79900713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}