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Science China Earth Sciences 2005年第8期48卷 1089-1105页

作者： FAN Qicheng1,2, ZHANG Hongfu1, SUI Jianli1, ZHAI Mingguo1, SUN Qian2 & LI Ni2 1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2. Institute of Geology, China Seismological Bureau, Beijing 100029, China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Institute of Geology China Seismological Bureau Beijing China

On the basis of mineral assemblage, mineralogy, petrology, and major, trace ele-mental and isotopic geochemistry of the underplated granulite- and eclogite-facies accumulate, peridotite and pyroxenite xenoliths entrained in Hannuoba Cenozoic basalts, this work con-strained the petrological constituents for the crust-mantle transitional zone, which is supported by the results of high-temperature and pressure velocity experiments on rocks and geophysics deep survey. Present lower part of lower crust is mainly composed of granulite-facies mafic accumu-lates (dominantly plagioclase websterite) and crust-mantle transitional zone dominantly com-posed of eclogite-facies pyroxenites with or without garnet and spinel lherzolites; Archaean ter-rain granulite is only nominally early lower crust. Magma underplating in the crust-mantle boundary led to the crustal vertical accretion and the formation of the crust-mantle transitional zone, which is a significant mechanism for the chemical adjustment of the crust-mantle boundary since the Phanerozoic.

关键词： magma underplating, xenolith petrology, geochemistry, cust-mantle boundary constituent, Hannuoba.

Zircon chronology and REE geochemistry of granulite xenolith at Hannuoba

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Chinese Science Bulletin 1998年第18期43卷 1510-1515页

作者： Qicheng Fan Ruoxin Liu Huimin Li Ni Li Jianli Sui Zhuoran Lin State Seismol Bur Inst Geol Beijing 100029 Peoples R China Minist Geol & Mineral Resources Tianjin Inst Geol & Mineral Resources Tianjin 300170 Peoples R China

The lower crustal xenolith of mafic two_pyroxene granulite (the majority) and hypersthene granulite in the Cenozoic basalt at Hannuoba have the characteristics of igneous blastic structure and granulite facies metamorphic recrystallization. Study on the zircon chronology and REE geochemistry of granulite xenolith shows that the underplating of basic magma into the lower crust during late Mesozoic led to the formation of mafic accumulate, which further through metamorphism of granulite facies formed the high_density and high_velocity crustal bottom layer at the lower crust. This suggests that the underplating of mantle magma is the important way for the vertical overgrowth of continental crust since the Phanerozoic and provides new evidence for crust_mantle interaction.

关键词： age of zircon granulite xenolith Hannuoba.

TWO TYPES OF xenolith—MANTLE xenolith AND CRUSTAL xenolith FOUND IN THE CENOZOIC VOLCANIC ROCKS FROM HOH XIL, NORTHERN TIBET PLATEAU

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地学前缘 2000年第S1期7卷 197-198页

作者： Wu Cailai,Yang Jingsui,Li Haibing,Shi Rendeng[WT5,5”BX](Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

It is known that large amounts of Cenozoic high potassium volcanic rocks occur on the Tibetan plateau. The question is where do those high potassium magmas come from? Since the plateau is being compressed by subduction and collision from the surrounding continents,it is a puzzle for us what is the formational environment and tectonic setting of these volcanic rocks? In particular,what is the relationship between these special rocks and formation and uplift of the plateau? We recently carried out an investigation on these Cenozoic volcanic rocks in Hoh Xil,northern Tibetan plateau,including volcanic rocks in the Jingyuhu,Xiongyingtai and Shuangquanzi areas. In the region,some older lava flows occur as thick sheets with a flat surface and weathering crust; while some relatively younger lavas remain a relict volcanic cone or vent. Most of the relict cones are small (1 or close to 1,and mostly belonged to shoshonite\|trachyte association and some to ultra\|potassic rocks. The K\|Ar dating of whole rock and mica shows that the volcanism lasts from middle Miocene (15 47Ma) to Pleistocene (0 69Ma); they are 0 69Ma,13 77Ma and 15 47Ma in Jingyuhu; 11 05Ma,12 22Ma and 12 83Ma in Xiongyingai,; 1 58Ma,2 24Ma,5 23Ma,5 85Ma,8 20Ma,8 41Ma and 10 67Ma in Shuangquanzi.Two types of xenolith and xenocryst were found in Jingyuhu and Xiongyingtai,i.e..,crustal xenolith and mantle xenocryst.

关键词： xenolith xenocryst shoshonite trachyte Cenozoic volcanic r ock Tibet Hoh Xil

Petrology of lherzolite xenoliths of HosséréSédévolcano(Adamawa plateau,Ngaoundéréarea,Cameroon)

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地球化学学报(英文) 2023年第5期42卷 817-831页

作者： O.F.Nkouandou J.M.Bardintzeff Fagny Mefire Njankouo Ndassa A.A.Sahabo H.Adama Department of Earth Sciences Faculty of SciencesUniversity of NgaoundereP.O.Box.454NgaoundereCameroon Univ Paris-Saclay Sciences de la TerreVolcanologie-PlanetologieUMR CNRS 8148 GEOPSBat.50491405 OrsayFrance Laboratoire de volcanologie Institut de Recherches Geologique et Minie`reB.P.370BueaCameroon

Numerous mantle xenoliths 6–12 cm in size and sub-angular to rounded in shape occur within Mio-Pliocene basanite lavas of the monogenic volcano of HosséréSédé in the Adamawa plateau.xenoliths of spinel lherzolite exhibit protogranular,equigranular or porphyroclastic texture.Microprobe chemical analyses show that olivine is highly magnesian(Fo_(88-90)),clinopyroxene crystals are diopside and augite(Wo_(41.6–49.6)En_(45.3–53.7)Fs_(4.2–6.2)),orthopyroxene crystals are enstatite(Wo 1.4–1.5 En_(88.6–89.0)Fs_(9.6–9.9))and spinel crystals are mainly Al-spinel associ-ated to minor Cr-spinel.Estimated temperatures and pressures through empirical formulas show that HosséréSédé noliths have equilibrated between 1085 and 1204℃and 1.08 to 1.57 GPa,corresponding to sampling depths of 36 and 52 km.Detailed petrographical and mineral chemistry of HosséréSédénoliths evidences the com-plex nature and composition of the subcontinental lithosphere under the Adamawa plateau.This may involve a probable uplift of the whole area after a limited exten-sional event,possible metasomatism through melt infiltration during shearing of the lithospheric mantle along the Pan African strike-slip fault system.

关键词： Cameroon Adamawa HosséréSédé Subcontinental lithosphere xenolith Peridotite Lherzolite

Distribution of trace elements in spinel and garnet peridotites

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Science China Earth Sciences 2000年第2期43卷 166-175页

作者：徐义刚 Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China

The distribution of trace elements in the upper mantle has been discussed on the basis of the trace element abundances in bulk rocks and constituent minerals of two spinel and garnet facies peridotite xenoliths in alkali basalts from eastern China. The data presented are consistent with the suggestion that highly incompatible elements (Rb, Ba, Th, U, Sr, Nb, Ta) mainly reside in intergranular components, and to a lesser extent in fluid inclusions in minerals. The LILE composition in olivine and orthopyroxene can be seriously affected by the presence of fluid inclusions. Consequently the subsolidus partitioning of the LILE cannot be used to infer the olivine-melt and orthopyroxene-melt partition coefficients for these elements. There is a significant difference in (Opx/Cpx)HREE ratios for spinel and garnet peridotites, suggesting a P-T control on equilibrium partition coefficients.

关键词： trace elements distribution peridotite xenolith upper mantle ICP-MS.

Petrochemistry and Zircon U-Pb Geochronology of Felsic xenoliths in Late Cenozoic Gem-Related Basalt from Bo Phloi Gem Field, Kanchanaburi, Western Thailand

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Journal of Earth Science 2021年第4期32卷 1035-1052页

作者： Alongkot Fanka Chidchanok Kasiban Toshiaki Tsunogae Yukiyasu Tsutsumi Chakkaphan Sutthirat Department of Geology Faculty of ScienceChulalongkorn UniversityPathumwanBangkok 10330Thailand Graduate School of Life and Environmental Sciences University of TsukubaIbaraki 305-8572Japan Department of Geology University of JohannesburgAuckland Park 2006South Africa Department of Geology and Paleontology National Museum of Nature and ScienceIbaraki 305-0005Japan

The Cenozoic basalts exposed in Bo Phloi Gem Field,Kanchanaburi Province,western Thailand are a host to different gem materials(e.g.,sapphire,black spinel,black pyroxene and zircon)as well as other xenocrysts and xenoliths from the deep-seated formations onto the earth surface.However,only felsic xenoliths have never been investigated and reported in detail though they are in fact significant evidence of ancient tectonic processes of this area.In this study,the felsic xenoliths were sampled and classified,on the basis of petrochemistry,into granite,syenogranite,and syenite.However,they contain similar mineral assemblages including essentials of quartz,K-feldspar,and plagioclase with different proportions and accessories of biotite,zircon,and opaque minerals.Moreover,large phenocrysts of K-feldspar and plagioclase commonly present as a primary texture which are frequently corroded and replaced by‘sieved texture’with secondary cumulative fringe of tiny feldspar and quartz.These secondary textures clearly indicate quenching after re-heating during transportation by basaltic magma.Geochemical analyses indicate that the alkaline and peraluminous magma show enrichment of Rb and depletion of Ba,Nb,Ta,Ti with steep slope of LREE/HREE enrichment patterns.These evidences suggest low-degree partial melting of crustal materials related to the collisional S-type granite magmatism.In addition,U-Pb dating of zircon from a felsic xenolith yields 211.6±1.3 Ma comparable to the Late Triassic magmatism of the central belt granite in this region which is resulted from the collision between Sibumasu and Indochina terranes.

关键词： basalt granite sapphire tectonic Thailand xenolith

Mantle-derived xenoliths and the Token of a Modern Back-Arc Geotherm Beneath Eastern China

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Science China Chemistry 1994年第4期37卷 472-480页

作者：金振民 H.W.GreenII R.S.Borch 金淑燕 T.N.Tingle T.E.Young Department of Geology university of CaliforniaDavisCA95616USA Department of Geology University of California Daves CA95616USA. Division of Geomechanics China University of Geosciences Wuhan 430074 PRC

xenoliths of garnet and spinel-garnet 1herzolite from Mingxi, Eastern China have been studied in terms of comprehensive methods of mineralogy, petrology, fabrics, mierostructures and infrared spectrum. The temperature and pressure equilibration of the xenolith have been calculated using the TEMPEST program with the two-pyroxene geothermometer of Bertrand and Mercier (1985) combined with the geobarometer of Nickel and Green (1985). The temperature and pressure of xenoliths range from^1300 K at 1. 9 GPa (60 km) to ~1500 K at 2. 6 GPa (80 km). The geotherm inferred from xenolith is excellently consistent with the measured surface heat flow (70 mW/m2) in Mingxi. A character of geothermal curve and conductive type suggest that these xenoliths are from the lithosphere, not from the asthenosphere. The geotherm and mierostructures and preferred orientations of minerals in the xenolith are consistent with tecon-ic thinning of the lithosphere in the present-day extensional back-arc environment.

关键词： mantle xenolith spinel-garnet Iherzolite geotherm thermal structure of the lithosphere extensional back-arc environment.

Thermal State and Structure of the Lithosphere beneath Eastern China: A Synthesis on Basalt-Borne xenoliths

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Journal of Earth Science 2010年第5期21卷 711-730页

作者：黄小龙徐义刚 Key Laboratory of Isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences

Application of reliable thermobarometer on garnet-bearing mantle xenoliths and granulite xenoliths entrained by Cenozoic basalts in eastern China reveals two main types of geotherm. The first type, as exampled by Hannuoba （汉若坝）, Mingxi （明溪） and probably Northeast China, is characterized by constant slope of data in the P-T space. The second type, as exampled by the high geotherms of Niishan （女山） and probably Xinchang （新昌）, is characterized by variable slopes, with the samples with pressure 〈2 MPa defining a slow slope, whereas the samples with pressure 〉2 MPa define a virtually vertical slope. The different slopes in the second type of geotherm may correspond to different heat transfer mechanisms, with conductive transfer for the shallow upper mantle and advective transfer for the deep mantle. This observed transition in thermal transfer mechanism is consistent with theoretical modeling. The two types of geotherm are not mutually exclusive, because the second type may characterize the thermal state of whole lithospheric section including both mechanical boundary layer （MBL） and thermal boundary layer （TBL）, while the first type may only depict the MBL. The variable geotherms for different regions are indicative of a heterogeneous lithospheric structure in eastern China. （a） Eastern North China craton （NCC） is characterized by a second-type geotherm, corresponding to a thin lithosphere （-70 km）. Comparison of the equilibrium temperatures of spinel peridotites with this geotherm constrains the depth to Moho in eastern North China craton to be 30 kin. In contrast, western NCC （Hannuoba： the first-type geotherm） possesses a relatively low thermal gradient, indicative of a thick lithosphere （〉90-100 km） and a thick crust-mantle transition zone. The dramatic change in crustal and mantle structure across the DTGL （Daxing＇anling （大兴安岭）- Talhangshan （太行山） gravity lineament） is consistent with recent seismic studies. （b） There is a decrease in thermal gradient and in lithospheric thickness from the coast （Xinchang： the sec

关键词： geotherm thermobarometry garnet-bearing peridotite and pyroxenite granulite xenolith lithosphere eastern China.

Textural and chemical zoning in garnets related to mantle metasomatism and deformation processes

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Chinese Science Bulletin 2000年第2期45卷 174-180页

作者： ZHANG Hongfu Menzies M.A. ZHOU Xinhua LU Fengxiang Laboratory of Lithosphere Tectonic Evolution Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China Depement of Geology Royal Holloway University of London EghamSurrey TW20 0EXUK China University of Geosciences Wuhan 430074China

A few texturally-zoned garnets were found in a polymict peridotite (JJG1414) from the Cretaceous kimberlite, Kimberley South Africa. The systematic analyses of electron and ion microprobe as well as laser fluorination technique reveal the existencal of marked elemental and oxygen isotopic zonation in these gamed. corresponding to the textural zonation. The rims are normally enriched in Ca, Ti, Cr, LREE. Sr, Nb, and depleted in Mg, Al and 18O. It is demonstrated that these gamats were infiltrated by melts/fiuids, probably representing the disequilibrated products of fluid-asssted mantle deformation.

关键词： South African kimberlite polymict xenolith garnet zoning mantle. metasomatism and deformation.

Gold contents of both mantle-derived xenoliths and sulfides in them from eastern China

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Science China Earth Sciences 2008年第4期51卷 499-508页

作者： KeFen Yue Ying He State Key Laboratory of Continental Dynamics Department of Geology Northwest University Xi’an 710069 China Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Department of Chemistry Northwest Univ

The gold contents of 59 samples of mantle-derived xenoliths, along with 85 samples of sulfide assem-blages in them, of Cenozoic basalt from eight districts in eastern China are analyzed. The gold contents of mantle xenoliths usually fall in the range of 10-9―10-8, whereas those of the sulfide assemblages fall in the range of 10-4―10-2. This implies that the latter are several hundred thousand times higher than the former, and thus that Au in the mantle is concentrated mostly in sulfide assemblages. Gold con-tents of both mantle-derived xenoliths and sulfide assemblages in them are inhomogeneous spatially, but their distribution rules are similar. Except the samples from Hainan Province, either the mantle xenoliths with high gold content or sulfide assemblages of the mantle-derived xenoliths with high gold content are distributed mostly on the north and south margins of the North China platform (Hannuoba of Hebei Province and Linqu, Changle of Shandong Province), corresponding to districts with concen-trated gold deposits in northwest Hebei Province and Jiaodong Peninsula of Shandong Province. This may reflect the correlativity in age, nature and composition between the continental crust and the un-derlying lithospheric mantle. The underlying lithospheric mantle of the North China platform is an an-cient gold-rich lithospheric mantle. The gold-rich lithospheric mantle may be the material source of later activation, enrichment, transportation and mineralization of gold by auriferous CO2 mantle fluids.

关键词： mantle xenolith sulfide gold content gold deposits-concentrated districts