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Petrology of Spinel-Lherzolite xenoliths from Mazéléand Others Northen xenoliths Localities of Cameroon Volcanic Line: Exchange Reactions and Equilibrium State

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Open Journal of Geology 2024年第5期14卷 629-653页

作者： Nguihdama Dagwai Kamgang Pierre Mbowou Gbambié Isaac Bertrand Chazot Gilles Ngounouno Ismaïla Department of Life and Earth Sciences Higher Teachers&#8217 Training College University of Maroua Maroua Cameroon Department of Earth Sciences Faculty of Science University of Yaound&#233 1 Yaound&#233 Cameroon Department of Mineral Prospecting and Exploration Technologies School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Ocean Geosciences Laboratory European University Institute of the Sea (IUEM) Brest France

The alkaline volcanism of the Cameroon Volcanic Line in its northern domain has raised many fresh enclaves of peridotites. The samples selected come from five (05) different localities (Liri, in the plateau of Kapsiki, Mazélé in the NE of Ngaoundéré, Tello and Ganguiré in the SE of Ngaoundéré and Likok, locality located in the west of Ngaoundé). The peridotite enclaves of the above localities show restricted mineralogical variation. Most are four-phase spinel-lherzolites, indicating that this is the main lithology that forms the lithospheric mantle below the shallow zone. No traces of garnet or primary plagioclase were detected, which strongly limits the depth range from which the rock fragments were sampled. The textures and the wide equilibrium temperatures (884˚C - 1115˚C) indicate also entrainment of lherzolite xenoliths from shallow depths within the lithosphere and the presence of mantle diapirism. The exchange reactions and equilibrium state established in this work make it possible to characterize the chemical composition of the upper mantle of each region and test the equilibrium state of the phases between them. Variations of major oxides and incompatible elemental concentrations in clinopyroxene indicate a primary control by partial melting. The absence of typical “metasomatic” minerals, low equilibration temperatures and enriched LREE patterns indicate that the upper mantle below septentrional crust of Cameroun underwent an event of cryptic metasomatic enrichment prior to partial melting. The distinctive chemical features, LREE enrichment, strong U, Ce and Pr, depletion relative to Ba, Nb, La, Pb, and T, fractionation of Zr and Hf and therefore ligh high Zr/Hf ratio, low La/Yb, Nb/La and Ti/Eu are all results of interaction of refractory peridotite residues with carbonatite melts.

关键词： xenoliths Upper Mantle Northern Region Adamawa Cameroon Volcanic Line Exchange Reaction

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Nature and evolution of the lithospheric mantle revealed by water contents and He-Ar isotopes of peridotite xenoliths from Changbaishan and Longgang basalts in Northeast China

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Science Bulletin 2019年第18期64卷 1325-1335页

作者： Qinghu Xu Jiaqi Liu Huaiyu He Yunhui Zhang Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049.China College of Earth Sciences Chinese Academy of SciencesBeijing 100029China Key Laboratory of Earth and Planetary Physics.Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China

The nature and evolution of the lithospheric mantle underlying Northeast(NE)China were investigated by assessing the mineral chemistry,water contents,and noble gas(He-Ar)isotopes of peridotite xenoliths captured by Cenozoic basalts from the Changbaishan and Longgang *** xenoliths,which have863–1141℃ equilibration temperatures,primarily comprise spinel lherzolites and rare spinel *** Mg#(Fo)values of olivine in the peridotite xenoliths vary from 86.9 to *** clinopyroxenes have high Ti/Eu and low(La/Yb)N,and their chondrite-normalized rare earth elements(REEs)exhibit light REE-depletion to-enrichment patterns,indicating that the mantle underneath the investigated region was predominantly subjected to partial melting(1%–10%)and was metasomatized by silicate *** measured3He/4He ratios of the Changbaishan xenoliths have a narrow range from 5.8 Ra to 8.4 Ra with an average of 7.4 ***3He/4He isotopic ratios of the Longgang xenoliths varied from 4.7 Ra to8.1 Ra with an average of 5.9 Ra;slightly lower than the Changbaishan *** whole-rock H2Ocontents of the studied peridotite ranged from 9 to 132 *** high H2O contents in excess of50 ppm(up to 132 ppm)might represent newly accreted and cooled asthenospheric materials,while those with H2O contents lower than 50 ppm(as little as 9 ppm)may represent thinned,relic,ancient lithospheric *** geochemical evidences,in combination with published data,indicated that the lithospheric mantle beneath the Changbaishan and Longgang in NE China is dominated by the younger and more fertile lithospheric mantle with a minor ancient and refractory *** addition,the lithospheric mantle of this area was metasomatized by melts related to the recent subduction event(e.g.,Pacific oceanic plate).Therefore,the westward-dipping Pacific oceanic plate subduction had an important contribution to the transformation of the lithospheric mantle beneath NE China.

关键词： Subcontinental lithospheric mantle Peridotite xenoliths Mineral chemistry He-Ar isotopes Water contents Northeast China

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Characteristics and origin of mafic and ultramafic xenoliths in trachyandesite lavas from Heikongshan volcano,Tengchong,Yunnan Province,China

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Science China Earth Sciences 2010年第9期53卷 1295-1306页

作者： YU HongMei, LIN ChuanYong, SHI LanBin, XU JianDong & CHEN XiaoDe Institute of Geology, China Earthquake Administration, Beijing 100029, China Institute of Geology China Earthquake Administration Beijing China

The trachyandesite lavas from Heikongshan volcano of the Tengchong volcanic cluster, Yunnan Province contain relatively abundant mafic and ultramafic small xenoliths comprising mainly gabbro, pyroxenite and rare lherzolites, all less than 2.5 cm in size. Gabbro xenoliths are characterized by "open" texture represented by relatively abundant vesicles and ground-mass fillings, while pyroxenite xenoliths are characterized by equigranular and poikilitic texture. Their mineral compositions (clinopyroxene ± orthopyroxene ± plagioclase) are similar to those of phenocrysts in lavas, and their equilibration temperature (1000-1125°C) is consistent with the crystallization temperature of the phenocrysts (998-1108°C). Thus, the textures and compositions of these xenoliths are different from those of lower crustal and mantle xenoliths, and were derived from the magma chamber. Among them, the gabbroic xenoliths come from the crystal-bubble-liquid zone at the top of the magma reservoir, while the pyroxenite xenoliths come from the cumulates in the bottom of magma reservoir. The studied single lherzolite xenolith with porphyroclastic texture has similar mineral compositions to the mantle xenoliths from eastern China, and is considered to be of upper mantle origin. It was brought into magma reservoir by replenishment magma, and might have experienced a cooling event before eruption. The formation of xenoliths in trachyandesite flows largely reflects the ascent, storage, evolution and eruption processes of magma.

关键词： magma chamber xenoliths geothermo-barometry trachyandesite Heikongshan volcano Tengchong

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Phlogopite in mantle xenoliths and kimberlite from the Grib pipe,Arkhangelsk province,Russia:Evidence for multi-stage mantle metasomatism and origin of phlogopite in kimberlite

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Geoscience Frontiers 2019年第5期10卷 1941-1959页

作者： A.V. Kargin L.V. Sazonova A.A. Nosova N.M. Lebedeva Yu.A. Kostitsyn E.V. Kovalchuk V.V. Tretyachenko Ya.S. Tikhomirova Institute of Geology of Ore Deposits PetrographyMineralogyand GeochemistryRussian Academy of Sciences (IGEM RAS)MoscowRussia Lomonosov Moscow State University MoscowRussia Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academy of Sciences MoscowRussia AC ALROSA Research Geological Prospecting Enterprise ArkhangelskRussia

We present petrography and mineral chemistry for both phlogopite,from mantle-derived xenoliths (garnet peridotite,eclogite and clinopyroxene-phlogopite rocks) and for megacryst,macrocryst and groundmass flakes from the Grib kimberlite in the Arkhangelsk diamond province of Russia to provide new insights into multi-stage metasomatism in the subcratonic lithospheric mantle (SCLM) and the origin of phlogopite in *** on the analysed xenoliths,phlogopite is characterized by several *** first generation (Phl1) occurs as coarse,discrete grains within garnet peridotite and eclogite xenoliths and as a rock-forming mineral within clinopyroxene-phlogopite *** second phlogopite generation (Phl2) occurs as rims and outer zones that surround the Phl1 grains and as fine flakes within kimberlite-related veinlets filled with carbonate,serpentine,chlorite and *** garnet peridotite xenoliths,phlogopite occurs as overgrowths surrounding garnet porphyroblasts,within which phlogopite is associated with Cr-spinel and minor *** eclogite xenoliths,phlogopite occasionally associates with carbonate bearing veinlet ***,from the kimberlite,occurs as megacrysts,macrocrysts,microcrysts and fine flakes in the groundmass and matrix of kimberlitic *** phlogopite grains within the kimberlite are characterised by signs of deformation and form partly fragmented grains,which indicates that they are the disintegrated fragments of previously larger ***1,within the garnet peridotite and clinopyroxeneephlogopitexenoliths,is characterised bylow Ti and Cr contents (TiO292) typical of primary peridotite phlogopite in mantle peridotite xenoliths from global kimberlite *** formed during SCLM metasomatism that led to a transformation from garnet peridotite to clinopyroxene-phlogopite rocks and the crystallisation of phlogopite and high-Cr clinopyroxene megacrysts before the

关键词： Mantle metasomatism Kimberlite Phlogopite Mantle xenoliths Megacrysts

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Sm-Nd isotopic age and genesis of gabbro xenoliths in Daoxian County, Hunan Province

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Chinese Science Bulletin 1997年第21期42卷 1814-1817页

作者： Guo, F Fan, WM Lin, G Lin, YX Chinese Acad Sci Changsha Inst Geotecton Changsha 410013 Peoples R China

MANY geologists pay attention to Mesozoic tectonomagmatic activity and the associating multi-metal ore deposits in South China. However, the age of the transformatiori of tectonic regimein the area is little studied. Occurrence of gabbro xenoliths in Mesozoic alkaline basalts inDaoxian region, Hunan Province, shows that the lithosphere in the region was intensely ex-tended and thinned during the Mesozoic, followed by underplating of mantle-derived mag-

关键词： gabbro xenoliths Sm-Nd dating petrogenesis.

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Metasomatism-induced wehrlite formation in the upper mantle beneath the Nógrád-G?m?r Volcanic Field(Northern Pannonian Basin):Evidence from xenoliths

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Geoscience Frontiers 2020年第3期11卷 943-964页

作者： Levente Patko Nora Liptai Laszlo Elod Aradi Rita Klebesz Eszter Sendula Robert J.Bodnar Istvan Janos Kovacs Karoly Hidas Bernardo Cesare Attila Novak Balazs Trasy Csaba Szabo Lithosphere Fluid Research Lab Institute of Geography and Earth SciencesEotvos Lor and UniversityBudapestHungary Isotope Climatology and Environmental Research Centre Institute for Nuclear ResearchHungarian Academy of SciencesDebrecenHungary CCFS-GEMOC Department of Earth and Planetary SciencesMacquarie UniversitySydneyAustralia Geodetic and Geophysical Institute Research Centre for Astronomy and Earth SciencesHungarian Academy of SciencesSopronHungary Fluids Research Laboratory Department of GeosciencesVirginia TechBlacksburgVAUnited States MTA CSFK Lendület Pannon LitH2Oscope Research Group Geodetic and Geophysical InstituteResearch Centre for Astronomy and Earth SciencesHungarian Academy of SciencesSopronHungary Instituto Andaluz de Ciencias de La Tierra CSIC&UGRArmillaGranadaSpain Department of Geosciences University of PaduaPaduaItaly Department of Geology Eotvos Lorand UniversityBudapestHungary

Clinopyroxene-enriched upper mantle xenoliths classified as wehrlites are common(~20% of all xenoliths) in the central part of the Nograd-G(o| ")m(o|")r Volcanic Field(NGVF),situated in the northern margin of the Pannonian Basin in northern Hungary and southern *** this study,we thoroughly investigated 12 wehrlite xenoliths,two from each wehrlite-bearing occurrence,to determine the conditions of their *** textural features,including clinopyroxene-rich patches in an olivine-rich lithology,orthopyroxene remnants in the cores of newlyformed clinopyroxenes and vermicular spinel forms all suggest that wehrlites were formed as a result of intensive interaction between a metasomatic agent and the peridotite wall *** on the major and trace element geochemistry of the rock-forming minerals,significant enrichment in basaltic(Fe,Mn,Ti) and high field strength elements(Nb,Ta,Hf,Zr) was observed,compared to compositions of common lherzolite *** presence of orthopyroxene remnants and geochemical trends in rock-forming minerals suggest that the metasomatic process ceased before complete wehrlitization was *** composition of the metasomatic agent is interpreted to be a mafic silicate melt,which was further confirmed by numerical modelling of trace elements using the plate *** model results also show that the melt/rock ratio played a key role in the degree of petrographic and geochemical *** lack of equilibrium and the conclusions drawn by using variable lherzolitic precursors in the model both suggest that wehrlitization was the last event that occurred shortly before xenolith entrainment in the host mafic *** suggest that the wehrlitization and the Plio-Pleistocene basaltic volcanism are related to the same magmatic event.

关键词： Wehrlite xenoliths Upper mantle metasomatism Mafic silicate melt Trace element modelling

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Rheology of the lower crust beneath the northern part of North China: Inferences from lower crustal xenoliths from Hannuoba basalts, Hebei Province, China

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Science China Earth Sciences 2007年第8期50卷 1128-1141页

作者： CHEN XiaoDe LIN ChuanYong SHI LanBin Institute of Geology China Earthquake AdministrationBeijing 100029China

Lower crustal xenoliths brought up rapidly by basaltic magma onto the earth surface may provide direct information on the lower crust. The main purpose of this research is to gain an insight into the rheology of the lower crust through the detailed study of lower crustal xenoliths collected from the Hannuoba basalt, North China. The lower crustal xenoliths in this area consist mainly of two pyroxene granulite, garnet granulite, and light-colored granulite, with a few exception of felsic granulite. The equilibration temperature and pressure of these xenoliths are estimated by using geothermometers and geobarometers suitable for lower crustal xenoliths. The obtained results show that the equilibration temperature of these xenoliths is within the range of 785–900°C, and the equilibrium pressure is within the range of 0.8–1.2 GPa, corresponding to a depth range of 28–42 km. These results have been used to modify the previously constructed lower crust-upper mantle geotherm for the studied area. The differential stress during the deformation process of the lower crustal xenoliths is estimated by using recrystallized grain-size paleo-piezometer to be in the range of 14–20 MPa. Comparing the available steady state flow laws for lower crustal rocks, it is confirmed that the flow law proposed by Wilks et al. in 1990 is applicable to the lower crustal xenoliths studied in this paper. The strain rate of the lower crust estimated by using this flow law is within the range of 10?13–10?11 s?1, higher than the strain rate of the upper mantle estimated previously for the studied area (10?17–10?13 s?1); the equivalent viscosity is estimated to be within the range of 1017–1019Pa·s, lower than that of the upper mantle (1019–1021 Pa·s). The constructed rheological profiles of the lower crust indicate that the differential stress shows no significant linear relation with depth, while the strain rate increases with depth and equivalent viscosity decrease with depth. The results support th

关键词： rheology lower crust lower crustal xenoliths Hannuoba basalt North China.

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Decoupling of Lu-Hf and Sm-Nd Isotopic System in Deep-Seated xenoliths from the Xuzhou-Suzhou Area,China: Differences in Element Mobility during Metamorphism

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Journal of Earth Science 2019年第6期30卷 1266-1279页

作者： Fanxue Meng Wenliang Xu Qinglin Xu Jingliang Guo Yu Zhang Shandong Key Laboratory of Depositional Mineralization and Sedimentary Minerals Shandong University of Science and Technology^Qingdao 266590China Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and TechnologyQingdao 266061China College of Earth Sciences Jilin UniversityChangchun 130061China State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China

This paper presents whole-rock Hf isotopic data for a suite of eclogite and garnet clinopyroxenite xenoliths hosted in the Early Cretaceous dioritic intrusions from the Xuzhou-Suzhou area along the southeastern margin of the Eastern Block of the North China Craton(NCC).Six of the eight studied xenolith samples plot significantly above the terrestrial Hf-Nd isotopic array and haveεHf(0)value up to+*** the samples define a well correlated 147 Sm/144 Nd-143 Nd/144 Nd age of 2081 Ma,which is considered to record the granulite-facies *** contrast,the Lu-Hf isotope system faithfully records the protolith *** mineralogical assemblage,especially garnet and/or zircon(rutile to some extent)mainly controlled the decoupling of Hf-Nd *** metamorphic modification on protolith characteristics and the differences in element mobility during metamorphism may also reinforce the observed decoupling between the Sm-Nd and Lu-Hf isotope systems;i.e.,the absence of the correlations inεNd-εHf and also 87 Sr/86 Sr-143 Nd/144 Nd *** Lu/Hf isochron age of 2424 Ma is similar to the zircon age peak of the studied xenoliths and the dominant age of NCC basement,indicating that the igneous protolith has an affinity to the Archean basement of the ***,the positiveεHf(t)values at 2500 Ma indicate a crustal growth event of 2500 Ma in the NCC.

关键词： lower-crust xenoliths Hf-Nd isotopes metamorphism modification crustal growth

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Source of the Ore-forming Adakitic Porphyry at the Beiya Super-large Au Deposit, Western Yangtze Craton: New Evidence from Zircon U-Pb Ages of the Amphibolite xenoliths

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Acta Geologica Sinica(English Edition) 2020年第1期94卷 208-209页

作者： LIU Siqi ZHENG Yuanchuan SHEN Yang HOU Zengqian WANG Lu WANG Zixuan State Key Laboratory of Geological Processes and Mineral Resources and School of Earth Science and ResourcesChina University of GeosciencesBeijing 100083China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China

Objective The Beiya super-large Au-rich porphyry deposit(304 t Au,2.4 g/t Au)is located within the western Yangtze craton,to the southeast of the Sanjiang Tethyan Orogen(Fig.1).The ore-forming porphyry is adakitic,characterized by high Sr/Y and La/Yb ratios coupled with low Y and Yb contents,and is generally thought to be derived from partial melting of thickened mafic lower *** lower crust underneath the western Yangtze craton is mainly composed of ancient crust with Archean ages,juvenile crust resulting from the Neoproterozoic subduction(740–1000 Ma),and late Permian juvenile crust related to the Emeishan mantle *** lower crustal end-member has played a critical role in genesis of the Beiya ore-forming porphyry can be constrained by zircon U-Pb ages of amphibolite xenoliths hosted in the ore-forming porphyry,because these xenoliths represent direct samples of the *** this study,we present new zircon U-Pb ages of these amphibolite xenoliths to have insight into the nature of the Beiya adakitic porphyry source.

关键词： Western Yangtze Craton New Evidence from Zircon U-Pb Ages of the Amphibolite xenoliths Source of the Ore-forming Adakitic Porphyry at the Beiya Super-large Au Deposit

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Underplating of Mesozoic Mantle-derived Magmas in Tongling, Anhui Province: Evidence from Megacrysts and xenoliths

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Acta Geologica Sinica(English Edition) 2004年第1期78卷 131-136页

作者： DUYangsong LEEHyunkoo QINXinlong KeyLaboratoryofLithosphereTectonicsandExploration MinistryofEducation29XueyuanRoadBeijing100083 DepartmentofGeology ChungnanNationalUniversity220KungdongYuseongKuTaejon305-764RepublicofKorea FacultyofEarthSciencesandMineralResources ChinaUniversityofGeosciences29XueyuanRoadBeijing100083

Lithological observations and mineralogical analyses on pyroxene and hornblende megacrysts and pyroxene and hornblende cumulates in xenoliths in the Mesozoic plutons of the Tongling region, Anhui Province, provide evidence for the magmatic underplating of mantle-derived alkali-olivine basalt at circa 140 Ma. The pyroxene and hornblende megacrysts and cumulates were formed through the AFC process at depths ranging from 27 to 35 km.

关键词： magma underplating megacrysts xenoliths Tongling in Anhui Province

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