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Campaign-style U-Pb titanite petrochronology:Along-strike variations in timing of metamorphism in the Himalayan metamorphic core

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Geoscience Frontiers 2019年第3期10卷 827-847页

作者： Catherine m.mottram john m.cottle Andrew R.C.Kylander-Clark School of Earth and Environmental Sciences University of Portsmouth Department of Earth Science University of CaliforniaSanta Barbara

Present-day along-strike heterogeneities within the Himalayan orogen are seen at many scales, from variations within the deep architecture of the lithospheric mantle, to differences in geomorphologic surface processes. Here, we present an internally consistent petrochronologic dataset from the Himalayan metamorphic core(HmC), in order to document and investigate the causes of along-strike variations in its Oligocene-miocene tectonic history. Laser ablation split-stream analysis was used to date and characterise the geochemistry of titanite from 47 calc-silicate rocks across >2000 km along the *** combined U-Pb-REE-Zr single mineral dataset circumvents uncertainties associated with interpretations based on data compilations from different studies, mineral systems and laboratories, and allows for direct along-strike comparisons in the timing of metamorphic processes. Titanite dates range from ～30 ma to 12 ma, recording(re-)crystallization between 625 ℃ and 815 ℃. Titanite T-t data overlap with previously published P-T-t paths from interleaved peltic rocks, demonstrating the usefulness of titanite petrochronology for recording the metamorphic history in lithologies not traditionally used for thermobarometry. Overall, the data indicate a broad eastward-younging trend along the *** in the duration and timing of metamorphism within the HmC are best explained by alongstrike variations in the position of ramps on the basal detachment controlling a two-stage process of preferential ductile accretion at depth followed by the formation of later upper-crust brittle *** processes, coupled with variable erosion, resulted in the asymmetric exhumation of a younger,thicker crystalline core in the eastern Himalaya.

关键词： Himalaya Petrochronology Titanite metamorphic petrology

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Investigating low dispersion isotope dissolution Lu-Hf garnet dates via in situ Lu-Hf geochronology,Kanchenjunga Himal

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Geoscience Frontiers 2024年第3期15卷 137-145页

作者： Kyle P.Larson john m.cottle mark Button Brendan Dyck Iva Lihter Sudip Shrestha Department of Earth Environmental and Geographic SciencesUniversity of British ColumbiaOkanaganKelownaCanada Department of Earth Science University of CaliforniaSanta BarbaraUSA Fipke Laboratory for Trace Element Research University of British ColumbiaOkanaganKelownaCanada

Re-examination of three specimens from the Kanchenjunga Himal of Nepal via in situ Lu-Hf garnet geochronology yields evidence of multiple garnet growth *** analyses from grain cores in two specimens define Paleozoic regressions whereas analyses from grain rims in the same specimens define low-precision regressions consistent with the timing of Himalayan *** dates contrast with previously published low dispersion,ca.290 ma isotope dissolution(ID)Lu-Hf garnet dates for the same *** of Lu and spot age distribution in representative grains from the specimens examined yields calculated dates that approximate the Permian-age regressions through the original ID *** findings demonstrate that it is possible to generate low dispersion ID Lu-Hf data from multigenerational garnet with significantly different-age growth events when approximately equal proportions of the different age reservoirs are included in multi-component aliquots.

关键词： Lu-Hf geochronology In situ Lu-Hf geochronology Kanchenjunga Himal

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Timing of metamorphism and deformation in the Swat valley, northern Pakistan:Insight into garnet-monazite HREE partitioning

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Geoscience Frontiers 2019年第3期10卷 849-861页

作者： Kyle P.Larson Asghar Ali Sudip Shrestha mathieu Soret john m.cottle Rafique Ahmad University of British Columbia Okanagan Earth Environmental and Geographic Sciences University of Peshawar Department of Geology University of Califomia Santa Barbara Department of Earth Sciences The Bacha Khan University Department of Geology

New metamorphic petrology and geochronology from the Loe Sar dome in the Swat region of northern Pakistan place refined constraints on the pressure, temperature and timing of metamorphism and deformation in that part of the Himalayan orogen. Thermodynamic modelling and monazite petrochronology indicate that metamorphism in the area followed a prograde evolution from ～525 ± 25 ℃and 6 士 0.5 kbar to ～610 ± 25 ℃ and 9 士 0.5 kbar, between ca. 39 ma and 28 ma. Partitioning of heavy rare earth elements between garnet rims and 30-28 ma monazite are interpreted to indicate coeval crystallization at peak conditions. microtextural relationships indicate that garnet rim growth post-dated the development of the main foliation in the area. The regional foliation is folded about large-scale N-S trending fold axes and overprinting E-W trending folds to form km-scale domal culminations. The textural relationships observed indicate that final dome development must be younger than the 30-28 ma monazite that grew with garnet rims post-regional foliation development, but pre-doming-related deformation. This new timing constraint helps resolve discrepancy between previous interpretations,which have alternately suggested that N-S trending regional folds must be either pre-or post-early Oligocene. Finally, when combined with existing hornblende and white mica cooling ages, these new data indicate that the study area was exhumed rapidly following peak metamorphism.

关键词： Pakistan Himalaya monazite petrochronology metamorphism Phase equilibria modelling Deformation

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Re-evaluating monazite as a record of metamorphic reactions

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Geoscience Frontiers 2022年第2期13卷 237-254页

作者： Kyle P.Larson Sudip Shrestha john m.cottle Carl Guilmette T.Alex johnson H.Daniel Gibson Félix Gervais Department of Earth Environmental and Geographic SciencesUniversity of British Columbia Okanagan3247 University WayKelownaBC V1V 1V7Canada Fipke Laboratory for Trace Element Research University of British Columbia Okanagan3247 University WayKelownaBC V1V 1V7Canada Department of Earth Science University of CaliforniaSanta BarbaraSanta BarbaraCA 93106-9630USA Géologie et Génie Géologique UniversitéLavalQuébec CityQuebecCanada Department of Earth Sciences Simon Fraser University8888 University DriveBurnabyBC V5A 1S6Canada Départment des Génies Civil Géologique et des MinesPolytechnique MontréalMontréalQC H3T 1J4Canada

This study presents a re-examination of historical specimens(DG136 and DG167)from the monashee complex in the southeastern Canadian Cordillera that are critical to the current understanding of rare earth element(REE)distribution between garnet and monazite(and other accessory minerals)during ***-hundred and fifty-one new monazite petrochronology spot analyses on 29 different grains across two specimens outline detailed(re)crystallization *** element data collected from the same ablated volume,interpreted in the context of new phase equilibria modelling that includes monazite,xenotime and apatite,link ages to specific portions of the pressure-temperature(P-T)paths followed by the *** linkages are further informed by garnet Lu-Hf geochronology and xenotime *** clockwise P-T paths indicate prograde metamorphism was ongoing by ca.80 ma in both *** structurally deeper specimen,DG136,records peak P-T conditions of~755-770℃and 8.8-10.4 kbar,interpreted to coincide with(re-)crystallization of low Y monazite at~75-70 ***-rim garnet isopleths from DG167 cross in the observed peak assemblage field at~680℃ and 9.3 *** conditions are interpreted to correspond with low Y monazite(re-)crystallisation at~65 *** specimens record decompression along their retrograde path coincident with high Y 70-55 ma and 65-55 ma monazite populations in DG136 and DG167,*** findings broadly agree with those initially reported~20 years ago and confirm early interpretations using trace elements in monazite as generally reliable markers of metamorphic *** phase equilibria modelling and in situ petrochronological analysis,however,provide additional insight into monazite behaviour during anatexis and the effects of potential trace element buffering by REE-bearing phases such as apatite.

关键词： monazite petrochronology Phase equilibria modelling Geochronology P-T-t paths

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Zircon chemistry and new laser ablation U–Pb ages for uraniferous granitoids in SW Cameroon

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Acta Geochimica 2020年第1期39卷 43-66页

作者： V.F.Embui C.E.Suh J.m.cottle J.Etame J.mendes C.m.Agyingi A.Vishiti E.m.Shemang B.Lehmann Department of Geology University of BueaP.O.Box 63BueaSouth West RegionCameroon Ore Treatment Laboratory Institute of Geological and Mining Research(IRGM)P.O.Box 4110YaoundeNlongkakCameroon Department of Geology Mining and Environmental ScienceUniversity of BamendaP.O.Box 39BambiliCameroon Department of Earth Sciences and Earth Research Institute Webb Hall 2028University of CaliforniaSanta BarbaraCA 93106-9630USA Laboratory of Geosciences Natural resources and Environment Department of Earth SciencesFaculty of ScienceUniversity of DoualaP.O.Box 24157DoualaCameroon Department of Civil Engineering University Institute of TechnologyUniversity of DoualaP.O.Box 8698DoualaCameroon Departamento de Geologia IGEOUniversidade Federal do Rio de JaneiroCidade UniversitariaRio de Janeiro 21910-949Brazil Department of Earth and Environmental Sciences Botswana International University of Science and TechnologyPrivate Bag 16PalapyeBotswana mineral Resources Technical University of ClausthalClausihal-ZellerfeldGermany

The Ekomedion two-mica granite,southwestern Cameroon,has potential for uranium and molybdenum ***,we present LA-ICP-mS U-Pb ages,Lu-Hf isotope characteristics,trace element concentrations and Ti-geothermometry of zircon from this granite hosting U-mo mineralization in pegmatitic *** majority of zircon are CL-dark though some CL-bright cores were also identified.U-Pb zircon age data range from 121±3 to743±11 ma with only 5 of 34 ages being near *** concordant mean age of 603±12 ma is similar to ages of granitic intrusions along the Central African Shear Zone in *** ages with mean of261±6 ma reveal open system behavior with respect to Pb and/or *** e Hfi values range from-20.3 *** implies that U-mo was remobilized during partial melting of the surrounding *** Th/U>0.1 as well as an increasing Hf with decreasing Th/U indicates that fractional crystallization was the main factor that controlled U-mo mineralization in pegmatitic pods.Y and Y/Ho ratios cluster from 29 to 33 close to the chondritic ratio of 28 and indicate fractionation of Y and Ho with low F contents during the earliest stages of *** stage accumulation of F-rich magmatic-hydrothermal fluids impacted U-mo mineralization as a *** contains a prominent negative Eu anomaly pointing to a fractionating system rich in *** Ti-in-zircon temperatures span 672℃to1232℃with the temperatures at the high end reflecting interference from mineral inclusions in the zircon grains while the lower temperature values are linked to crystallization.

关键词： Zircons Uranium-molybdenum Cameroon

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Ambient TSP concentration and dustfall variation in Urumqi,China

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Journal of Arid Land 2014年第6期6卷 668-677页

作者： XiaoXiao ZHANG Xi CHEN YuHong GUO ZiFa WANG LianYou LIU cottle PAUL ShengYu LI HuaWei PI State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of Sciences State Key Laboratory of Atmospheric Boundary Layer and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory of Environmental Change and Natural Disaster Ministry of EducationBeijing Normal University Department of Earth Ocean and Atmospheric SciencesUniversity of British Columbia Vancouver V6T 1Z2Canada

Total suspended particulate （TSP, particle diameter≤100 μm） was the dominant air pollutant and significantly influenced local air quality. In this paper, we investigated the interannual and seasonal variations of TSP and dustfall of the atmosphere over Urumqi, the capital city of Xinjiang Uygur autonomous region, northwestern China, basing on environmental monitoring records and meteorological data from 1986-2012. The results showed that during the study period, annual average TSP concentration decreased from 716 to 260 μg/m3, with an average level of 422.9 μg/m3, while dustfall intensity reduced from 350.4 to 166.6 t/（km2oa）, with an average level of 259t/ km2.a）. Over 50% of the annual pollution days were induced mainly by TSP. Spring and winter had relatively higher dustfall intensities, and dense traffic and residential areas had the highest dustfall intensities in the Urumqi metropolitan area. With an annual average precipitation of less than 300 mm, atmospheric particulates in Urumqi could be hardly removed through wet deposition. During spring and summertime prevailing winds from northwest and northeast could carry aeolian dust particles from sandy deserts to Urumqi. Aeolian dusts from deserts would remain to be a priority regarding air pollution control in arid oasis cities.

关键词： total suspended particle dust deposition desert atmospheric environment

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Human-tiger conflict:A review and call for comprehensive plans

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Integrative Zoology 2010年第4期5卷 300-312页

作者： john m.GOODRICH Wildlife Conservation Society BronxNew YorkNYUSA

Human-tiger(Panthera tigris Linnaeus,1758)conflicts(HTC),manifested primarily as attacks on people and domestic animals,exacerbate at least 2 major threats to tigers:(i)conflicts often result in mortality or removal of tigers from the wild;and(ii)they result in negative attitudes towards tigers by local people,thereby reducing support for tiger *** HTC has decreased over the past century,it will likely increase if current and proposed conservation initiatives to double tiger populations are *** HTC could undermine successful conservation initiatives if proactive steps are not taken to reduce *** present paper provides a review of the impacts of HTC and the measures taken to reduce it in ways that reduce negative impacts on both humans and tigers,and stresses the need for development and implementation of comprehensive plans to reduce HTC.

关键词： carnivore depredation human-tiger conflict Panthera tigris tiger

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Fusion of bone marrow-derived cells with cancer cells: metastasis as a secondary disease in cancer

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Chinese Journal of Cancer 2014年第3期33卷 133-139页

作者： john m.Pawelek Department of Dermatology and the Yale Cancer Center Yale University School of Medicine

This perspective article highlights the leukocyte-cancer cell hybrid theory as a mechanism for cancer metastasis. Beginning from the first proposal of the theory more than a century ago and continuing today with the first proof for this theory in a human cancer, the hybrid theory offers a unifying explanation for metastasis. In this scenario, leukocyte fusion with a cancer cell is a secondary disease superimposed upon the early tumor, giving birth to a new, malignant cell with a leukocyte-cancer cell hybrid epigenome.

关键词： Bone marrow-derived cell-cancer cell hybrids metastasis cell fusion

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Synthesis of LiSm_(0.01)mn_(1.99)O_4 by molten salt technique

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Journal of Rare Earths 2010年第2期28卷 255-259页

作者： m Helan L john Berchmans Department of Chemistry Jamal Mohamed College (Autonomous) Electropyrometallurgy Division Central Electrochemical Research Institute

Samarium substituted lithium manganese oxide powders were successfully prepared by molten-salt synthesis(mSS) using eutectic mixture of LiCl,SmCl3.6H2O and mnO2 salt at 700 °*** synthesis was carried out in open *** crystalline powders were characterized for their phase identification using X-ray diffraction(XRD) *** physico-chemical properties of the samarium substituted lithium manganese oxide powders were investigated by thermal analysis(TGA/DTA),FT-IR spectroscopy,EDAX,electron par...

关键词： LiSm0.01mn1.99O4 molten salt synthesis cathode materials rare earth ion

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Fuzzy modeling of Surficial Uranium Prospectivity in British Columbia(Canada)with a Weighted Fuzzy Algebraic Sum Operator

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Journal of Earth Science 2021年第2期32卷 293-309页

作者： Emmanuel john m.Carranza School of Agricultural Earth and Environmental SciencesUniversity of KwaZulu-NatalWestville CampusDurban 4041South Africa

This paper demonstrates knowledge-guided fuzzy logic modeling of regional-scale surficial uranium(U)prospectivity in British Columbia(Canada).The deposits/occurrences of surficial U in this region vary from those in Western Australia and Namibia;thus,requiring innovative and carefully-thought techniques of spatial evidence generation and *** novelty,this papers introduces a new weighted fuzzy algebraic sum operator to combine certain spatial evidence *** analysis trialed several layers of spatial evidence based on conceptual mineral system model of surficial U in British Columbia(Canada)as well as tested various models of evidence ***-linear weighted functions of(a)spatial closeness to U-enriched felsic igneous rocks was employed as U-source spatial evidence,(b)spatial closeness to paleochannels as fluid pathways spatial evidence,and(c)surface water U content as chemical trap spatial *** best models of prospectivity created by integrating the layers of spatial evidence for U-source,pathways and traps predicted at least 85%of the known surficial U deposits/occurrences in>10%of the study region with the highest prospectivity fuzzy *** results of analyses demonstrate that,employing the known deposits/occurrences of surficial U for scrutinizing the spatial evidence layers and the final models of prospectivity can pinpoint the most suitable critical processes and models of data integration to reduce bias in the analysis of mineral prospectivity.

关键词： fuzzy logic mineral systems surficial uranium fuzzy algebraic sum

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