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Mineralogy and geochemistry of trachytic rocks from the Lichi Volcanics, Eastern Himalaya: insights into the Kerguelen mantle plume activity in the Eastern himalayan Region

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Acta Geochimica 2024年第1期43卷 180-197页

作者： Pallabi Basumatary Deepshikha Borah Hiredya Chauhan Tribujjal Prakash Bibhuti Gogoi Department of geology Cotton UniversityGuwahatiAssam 781001India wadia institute of himalayan geology DehradunUttarakhand 248001India

The Lichi volcanics are a suite of mafic-intermediate-felsic rocks and are considered coeval with the Abor volcanics(~132 Ma) of the Siang window in the Eastern Himalaya. Here, we present the first report of trachytic rocks from the Lichi volcanics, which are exposed in the Ranga valley, along the Kimin-Yazali road section in the Eastern himalayan Region, Northeast India. The trachytes occur in close association with sandstones of the Gondwana Group of rocks and are characterised based on field, petrographical, and geochemical *** fine-grained trachytes are composed of alkali feldspar, biotite, plagioclase, sodic-amphibole, apatite, illmenite, and titanite. The REE profiles of the evolved trachytic rocks(higher Sio_(2)content) display fractionated trends. The fractionation of accessory mineral phases, like apatite and titanite, was possibly responsible for the strongly fractionated REE patterns of the evolved *** trachytic rocks demonstrate high apatite saturation temperatures of 988 ± 14 ℃(1σ, n = 8). The Aluminium Saturation Index(on diagrams of these peralkaline trachytes define their affinity with A-type granitoids. Elemental ratios like Y/Nb, Nb/U,and Ce/Pb signify that the Lichi trachytes are differentiated products of mantle-derived ocean island basalts. Trace elemental discrimination diagrams Th/Yb versus Nb/Yb, Y versus Nb, and Y + Nb versus Rb reflect a within-plate tectonic regime for the trachytes. From the results presented in this work, we infer that the development of rifting events during the breakup of eastern Gondwana due to the onset of Kerguelen plume activity further led to underplating of basic magma in lower crustal levels. These parental basaltic magmas underwent fractionation processes forming differentiated trachyandesites and *** into consideration the similarities recorded between the Lichi volcanics and Abor volcanics, this study supports the idea that Kerguelen plume ac

关键词： Peralkaline trachytes Trachyandesites A-type granitoids Apatite saturation temperature Abor volcanics Eastern Gondwana

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Evolution of tectonic landscapes and deformation in the southeast Kumaun and western Nepal Himalaya

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Journal of Mountain Science 2024年第8期21卷 2592-2617页

作者： Khayingshing LUIREI Girish Ch.KoTHYARI Param K GAUTAM Ambar SoLANKI Atul Kumar PATIDAR Sentisenla JAMIR Anirudh DATTA Tanupriya CHoUDHURY wadia institute of himalayan geology Dehradun 248001India Department of Petroleum Engineering and Earth Sciences University of Petroleum and Energy StudiesDehradun248007India Department of geology Nagaland UniversityKohima 797004India Academy of Scientific and Innovative Research Ghaziabad 201002India CSE Department Graphic Era deemed to be UniversityDehradun 248002India CSE Department Symbiosis Institute of TechnologySymbiosis International(Deemed University)Pune 412114India

The area of the present investigation’s expanse constitutes the southernmost extent of the southeast Kumaun Himalaya and western Nepal *** approaches have been employed to understand the landforms associated with tectonic deformation,through detailed field investigation supplemented by the geodetic,chronological,and morphometric *** morphogenic expressions of the Main Boundary Thrust(MBT)are reflected in the form of~25 km long E-W trending north dipping fault *** deformation along the strike length of the himalayan Frontal Thrust(HFT)is noticed in the form of uplifted and incised fill terraces,and strath *** deformation within the fluvial sequences in the study area can be visualized in the form of sheared boulders and pebbles,tilted and faulted terrace ***,the chronological data of fluvial landforms in the study area suggests two major phases of tectonic deformations that have occurred around 58.7±10.8 ka and 3.88±0.4 *** chronology of late-Quaternary landforms advocates that the initial stage of aggradations in the himalayan foothills commenced around 75.1±0.58 *** aggradational landforms resulted from the diverse depositional regime as evident from the nature of the sediment sequences from clasts dominated to thick mud *** rate of deformation in the southeastern Kumaun and western Nepal Himalaya is±7 mm/yr,as per the data obtained from the Persistent Scatterer Interferometric Synthetic Aperture Radar(PSInSAR).The landform deformation pattern,phase of incision and aggradation,frequent occurrence of landslides,and recent past earthquake activity within the wide zone of the HFT,the MBT,and Ramgarh Thrust suggests that the southernmost front of the Kumaun Himalaya is active and has potential for future *** foothill zone of himalayan towns are actively growing in terms of population and infrastructural ***,such intradisciplinary studies for tectonically active r

关键词： MBT HFT Fault trace Quaternary deposits sheared boulders

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Bulk geochemistry,Rb-Sr,Sm-Nd,and stable o-H isotope systematics of the Metzimevin high-grade iron ore deposit,Mbalam iron ore district,southern Cameroon

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Acta Geochimica 2024年第4期43卷 677-706页

作者： Samndong Cyril Tufoin Cheo Emmanuel Suh Tabod Charles Tabod George Lemewihbwen Ngiamte Department of geology Mining and Environmental ScienceThe University of BamendaB.P.39BambiliNorth West RegionCameroon Economic geology Unit Department of GeologyUniversity of BueaP.O.63BueaSouth West RegionCameroon Department of Physics Faculty of ScienceThe University of BamendaB.P.39BambiliNorth West RegionCameroon Department of geology Pan-African University Life and Earth Sciences Institute(PAULESI)University of IbadanIbadanNigeria

Bulk geochemistry,Sr,Nd,and o-H isotope systematics are reported for the first time on banded iron formation(BIF)-hosted high-grade iron ore at the northwestern segment of Congo Craton(CC).Located in Mbalam iron ore district,Southern Cameroon,Metzimevin iron ore deposit is a hematite-magnetite BIF system,dominated by Sio_(2)+Fe_(2)o_(3)(97.1 to 99.84 wt%),with low concentrations of clastic elements e.g.,Al_(2)o_(3),Tio_(2),and HFSE,depicting a nearly pure chemical *** REE+Y signature of the iron deposit displays strong positive Eu anomaly,strong negative Ce anomaly,and chondritic to superchondritic Y/Ho ratios,suggestive of formation by mixed seawater-high temperature hydrothermal fluids in oxidising ***^(87)Sr/^(86)Sr ratios of the BIF are higher than the maximum^(87)Sr/^(86)Sr evolution curves for all Archean reservoirs(bulk silicate earth,Archean crust and Archean seawater),indicating involvement of continentally-derived components during BIF formation and ***Ɛ_(Nd)(t)(+2.26 to+3.77)and Nd model age indicate that chemical constituents for the BIF were derived from undifferentiated crustal source,between 3.002 and 2.88 *** variable and diverse o and H isotope data(−1.9‰to 17.3‰and−57‰to 136‰respectively)indicate that the Metzimevin iron ore formed initially from magmatic plumes and later enriched by magmatic-metamorphic-modified meteoric *** balance calculations indicate mineralisation by combined leaching and precipitation,with an average iron enrichment factor of>2.67 and Sio_(2)depletion factor of>*** is associated with an overall volume reduction of 28.27%,reflecting net leaching and volume collapse of the BIF protholith.

关键词： Bulk geochemistry Rb-Sr Sm-Nd Mitzimevin High-grade iron ore

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Riverine sulfate sources and behaviors in arid environment,Northwest China:Constraints from sulfur and oxygen isotopes

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Journal of Environmental Sciences 2024年第3期137卷 716-731页

作者： Yifu Xu Wenjing Liu Bing Xu Zhifang Xu Key Laboratory of Cenozoic geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

The fate of riverine sulfate ion (So_(4)^(2-)) and its environmental effects in arid environment are difficult to evaluate due to its complicated sources and strongly coupled behaviors with water cycle which is significantly modified by *** understand the sulfur cycle in aquatic systems in arid environment,the chemical and sulfur and oxygen isotopic compositions (δ^(34)S_(So4)and δ^(18)o_(So4)) of major rivers around the Badain Jaran Desert,northwestern China,were *** rivers had averaged So_(4)^(2-)content at 1336μmol/L,over 10times higher than the global *** δ^(34)S_(So4)and δ^(18)o_(So4)values ranged from-5.3‰to+11.8‰and+1.6‰to+12.8‰,*** end-member analysis and the inverse model showed that riverine sulfate was mainly derived from evaporites dissolution (0-87%),sulfide oxidation (13%-100%) and precipitation (0-33%),indicating heterogeneity in sulfur sources and behaviors along the river drainage with the lithology variations and climate *** isotopic tools combining with hydro-chemistry compositions could be applied to reveal sulfur cycle in arid *** on the calculation,sulfide oxidation plays the primary role in the headwater and upstream in the Qilian-Mountains area,where sulfide is widely *** the proportion of evaporites dissolution contributing to riverine sulfate is much higher in downstream in a drier ***,less precipitation and higher temperature can lead to more intensive evaporation,affecting the process of sulfide oxidation and enhancing the rates of evaporites dissolution and sulfate precipitation in the basin.

关键词： Sulfur and oxygen isotopes Source apportionment Inverse model Arid environment Inland rivers Northwestern China

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Evaluation of potential landslide damming: Case study of Urni landslide,Kinnaur, Satluj valley, India

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Geoscience Frontiers 2019年第2期10卷 753-767页

作者： Vipin Kumar Vikram Gupta Imlirenla Jamir Shovan Lal Chattoraj wadia institute of himalayan geology Indian institute of Remote Sensing

This work aims to understand the process of potential landslide damming using slope failure mechanism,dam dimension and dam stability evaluation. The Urni landslide, situated on the right bank of the Satluj River, Himachal Pradesh(India) is taken as the case study. The Urni landslide has evolved into a complex landslide in the last two decade(2000-2016) and has dammed the Satluj River partially since year 2013,damaging ～200 m stretch of the National Highway(NH-05). The crown of the landslide exists at an altitude of ～2180-2190 m above msl, close to the Urni village that has a human population of about *** high resolution imagery shows ～50 m long landslide scarp and ～100 m long transverse cracks in the detached mass that implies potential for further slope failure movement. Further analysis shows that the landslide has attained an areal increase of 103,900 ± 1142 m^2 during year 2004-2016. About 86% of this areal increase occurred since year 2013. Abrupt increase in the annual mean rainfall is also observed since the year 2013. The extreme rainfall in the June, 2013; 11 June(～100 mm) and 16 June(～115 mm),are considered to be responsible for the slope failure in the Urni landslide that has partially dammed the river. The finite element modelling(FEM) based slope stability analysis revealed the shear strain in the order of 0.0-0.16 with 0.0-0.6 m total displacement in the detachment zone. Further, kinematic analysis indicated planar and wedge failure condition in the jointed rockmass. The debris flow runout simulation of the detached mass in the landslide showed a velocity of ～25 m/s with a flow height of ～15 m while it(debris flow) reaches the valley floor. Finally, it is also estimated that further slope failure may detach as much as 0.80 ±0.32 million m^3 mass that will completely dam the river to a height of 76±30 m above the river bed.

关键词： Urni landslide Slope stability Rainfall Landslide damming Satluj valley

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Community perspectives on the effectiveness of watershed management institutions in the Himalayas

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Journal of Mountain Science 2024年第4期21卷 1119-1139页

作者： Nisha SILWAL Nabin DHUNGANA Rajan SUBEDI Suraj UPADHAYA Chun-Hung LEE Natural Resources Conservation Nepal(NRCN) ChitwanP.O.Box 44200Nepal Department of Natural Resources and Environmental Studies College of Environmental StudiesNational Dong Hwa UniversityHualien 97401Chinese Taipei institute of Forestry Tribhuvan UniversityPokharaP.O.Box 43Nepal School of Agriculture and Natural Resources Kentucky State UniversityFrankfortKY 40601USA himalayan Conservation and Research institute DolpaP.O.Box 21400Nepal

The sustainability of environmental management initiatives,such as watershed management programs,relies on the presence of effective institutions at the watershed ***,there needs to be more empirical evidence from evaluating the effectiveness of watershed-level ***,this study presents a pioneering effort to evaluate the effectiveness of Nepal’s first watershed conservation committee at the watershed scale,focusing on the case of the Khageri Khola watershed in Central *** study involved conducting a household survey,key informant interviews,focus group discussions,and field observations to collect and analyze the *** analysis,index value calculation,and chi-square statistics were then employed to summarize the results regarding local respondents’perceptions of twelve institutional characteristics,their rationalities,and their association with socio-demographic *** results reveal that the watershed conservation committee was perceived as performing well in managing the ***,good interaction,appropriate scale,technical,environmental,social,organizational,and government rationality were perceived as highly effective,with an average index value of less than *** contrast,clarity of objectives and economic rationality showed moderate effectiveness,with an average index value ranging from 0.36 to ***,the results suggested that adaptiveness,compliance capacity,and financial rationality merit increased attention,intending to improve their ***,the results showed the association of socio-demographics with respondents’perceptions of various indicators of institutional characteristics and their ***,the study provides valuable insights for policymakers,researchers,and development practitioners charged with designing sustainable and effective programs and *** enhance the effectiveness and sustainability of watershed management programs,we recommen

关键词： Watershed Watershed institutions Indicators Institutional characteristics Rationalities Nepal.

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Evaluation of potential surface instability using finite element method in Kharsali Village,Yamuna Valley,Northwest Himalaya

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Journal of Mountain Science 2017年第8期14卷 1666-1676页

作者： Imlirenla JAMIR Vikram GUPTA Vipin KUMAR Glenn T.THoNG wadia institute of himalayan geology Department of geology Nagaland UniversityKohima Campus

Kharsali village, located in the Northwest Himalaya near the confluence of the Yamuna River and Unta Gad, is situated on a thick(>150 m) paleolandslide deposit. The village is continuously being eroded at its base by the two rivers. Cracks are noted in most houses while the ancient Shani Temple lying to the south of the village has tilted ~5° towards the northeast. Three slope sections(S-1, S-2, S-3) were modelled and analysed to determine the displacement and shear strain patterns of the slopes. Based on surface failure conditions, potential slope instability of the Kharsali village was evaluated from 2D Finite Element Method(FEM) using Shear Strain Reduction(SSR) analysis in the Phase2 software. Results indicate a critical Stress Reduction Factor(SRF) of 1.5 for the southern edge of the village(S-1) housing the Shani Temple. The development of failure surfaces at its lower portion signifies the propagating, progressive nature of the slope. The S-2 slope section is most vulnerable to slope failure, with a critical SRF of 1.08. This has been inferred by the formation of failure surfaces with displacements of 0.05-0.08 m. The S-3 section in the northern part of the Kharsali shows highest critical SRF of 2.76. The un-metalled road section in the north of the village near S-3 hasdeveloped a failure surface with displacement of 0.003-0.004 m, and a zone of subsidence. The S-3 section is relatively stable, whereas the S-2 section is the most vulnerable portion of the village.

关键词： Finite element method Kharsali Yamuna valley Landslide Slope stability NorthwestHimalaya

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Early Cambrian Ichnofossils from the Mussoorie Syncline and revision of Trace Fossil Biozonation of the Lesser Himalaya, India

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Acta Geologica Sinica(English Edition) 2014年第2期88卷 380-393页

作者： Birendra P. Singh Kapesa Lokho Naval Kishore Nancy Virmani Center of Advanced Study in geology Panjab University wadia institute of himalayan geology

A new locality bearing ichnofossils of the Cruziana Assemblage Zone-Ⅲ from the Mussoorie syncline,Lesser Himalaya,is located in rocks of Member-B of the Dhaulagiri Formation,Tal Group,exposed along the Maldewta-Chhimoli fresh road cut *** site yielded ichnofossils Bergaueria perata,Cochlichnus anguineus,？Diplocraterion isp.,Dimorphichnus obliquus,diplichnitiform Cruziana bonariensis,Diplichnites gouldi,Glockeria isp.,Helminthopsis isp.,Monomorphichnus lineatus,Phycodes palmatum,Palaeophycus striatus,Planolites beverleyensis,Planolites montanus,Treptichnus ***,scratch marks and an undetermined worm *** Early Cambrian age （Cambrian Series 2） is assigned to the ichnofossil-bearing strata based on the stratigraphic position between the Drepanuroides and Palaeoolenus trilobite zones.A revised Cambrian ichnofossil zonation is presented for the Tal Group of the Mussoorie *** with their occurrence on rippled surfaces,and the lateral displacement of some trackways （due to current action）,a sub-aqueous shallow-marine depositional setting is proposed for the rocks of Member-B.

关键词： Ichnology Cruziana Assemblage Zone Cambrian Series 2 shallow-marine northern India

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Geochronological and geochemical constraints on the petrogenesis and geodynamic process of Hemler,Vlinder,and Il'ichev seamount lavas in NW Pacific

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Science China Earth Sciences 2024年第6期67卷 1856-1871页

作者： Xun WEI Yan ZHANG Xuefa SHI Hui ZHANG Key Laboratory of Marine geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China Laboratory for Marine geology Qingdao Marine Science and Technology CenterQingdao 266237China Shandong Key Laboratory of Deep Sea Mineral Resources Development(Preparatory) Qingdao 266061China

oceanic intraplate volcanoes with linear age progressions are usually accepted to be derived from melting of an upwelling mantle *** seamount groups in NW Pacific,however,show complex age-distance relationships that are difficult to explain using the classic“mantle plume hypothesis”,and thus their origins are *** this study,we present ^(40)Ar-^(39)Ar age,geochemical,and Sr-Nd-Pb-Hf isotopic data of lavas from Hemler,Vlinder,and Il’ichev seamounts in NW Pacific,to elucidate their petrogenesis and geodynamic *** lavas from Hemler,Vlinder,and Il’ichev seamounts are classified as alkali basalt,basanite/nephelinite,and *** with Mg o>8 wt.%exhibit high contents of Cao,Feo^(T),and Tio_(2),similar to the composition of melts formed from reaction between carbonated eclogite-derived melts and fertile *** lavas have elevated Zr/Hf ratios(40.6-45.2)and negative Zr and Hf anomalies,indicating the presence of a carbonate component in the mantle *** are enriched in incompatible trace elements and have enriched mantle 1(EM1)-like SrNd-Pb-Hf isotopic *** isotopic compositions of Vlinder,Il’ichev basanite,and Hemler lavas in this study are similar to the Rarotonga *** occurring at the same seamount,the Il’ichev alkali basalts display more depleted SrNd-Hf isotopic compositions compared to Il’ichev *** to plate tectonic reconstruction results,the ages of Hemler(100.1 Ma),Vlinder pre-(100.2 Ma)and post-shield(87.5 Ma),and Il’ichev(56.4 Ma)lavas clearly deviate from the Macdonald,Arago,Rarotonga,and Samoa hotspot tracks,indicating that they cannot directly originate from mantle *** propose that in the mid-Cretaceous,when the Pacific plate passed over Rarotonga hotspot,melting of Rarotonga plume formed the Vlinder(main-shield stage),Pako,and Ioah *** Rarotonga(and possibly Samoa)plume materials would have been dispersed into the surrounding asthenosphere by mantle conve

关键词： Mantle plume Magellan seamount trail Carbonated mantle component Hotspot Lithosphere extension

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Ichnofossils from the Miocene Middle Bhuban Formation, Mizoram, Northeast India and their Paleoenvironmental Significance

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Acta Geologica Sinica(English Edition) 2013年第5期87卷 1460-1471页

作者： Kapesa LoKHo Birendra P.SINGH wadia institute of himalayan geology (WIHG) Center of Advanced Study in geology Panjab University

An ichnofossil assemblage is preserved in sediments of the Middle Bhuban Formation, Surma Group, of Miocene age from the Durtlang and Chanmari sections, Aizawl district, Mizoram, northeastern India. The studied sections comprise a thick, bioturbated and thinly bedded sandstone-silty shale facies. The preserved ichnofossils show high density and low diversity with the assemblage represented by feeding and resting traces, i.e., Psilonichnus upsilon Frey et al., 1984, ophiomorpha isp., Teichichnus spiralis Mikulas. 1990, Skolithos isp., Palaeophycus isp., and other horizontal burrows. Sedimentary structures associated with these traces are mainly cross bedding, flaser bedding and slump structures. Considering the distribution of the Psilonichnus ichnogenus across an integrated ichnological-sedimentological framework, the stratigraphic interval of the Middle Bhuban Formation, in which they occur, are interpreted to have been deposited under a shallow, marginal-marine channel complex dominated by tidal channels developed in quiet, brackish-water portions of a delta plain.

关键词： Ichnology Miocene (Burdigalian) Psilonichnus Skolithos Assam-Arakan Basin

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