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Geoscience Frontiers 2020年第6期11卷 1915-1934页

作者： Vasiliy p.Sukhorukov Valentina B.Savel’eva Yingde Jiang Zhiyong Li V.S.Sobolev Institute of Geology and Mineralogy SB RAS 3 Koptyuga Av.Novosibirsk630090Russia Novosibirsk State University 2 Pirogova St.Novosibirsk630090Russia Institute of the Earth Crust SB RAS 128 Lermontova St.Irkutsk664033Russia State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China

the first data on p-t metamorphic conditions coupled with U-pb monazite and zircon age obtained for the Neoarchean Kitoy granulite-gneiss terrane(SW Siberian Craton).Alumina gneisses of the Kitoy terrane indicate two-staged metamorphic evolution.the first stage of regional metamorphism(M1)occurred at high-amphibolite facies conditions at t=780-800℃ and p=8-9 kbar.the second stage(M2)belongs to Mt-Ht/Lp type of metamorphism with the wide temperature interval 600-750℃ and pressure 2-4 kbar.two age peaks were established on the basis of U-pb monazite and zircon dating in garnet-anthophyllite gneisses.Both of them correspond to the Neoarchean age:the age of M1 falls into the interval of ca.2489-2496 Ma,the age of M2-ca.2446-2456 Ma.the high-temperature metamorphism of the Kitoy block and nearly coeval granitoid magmatism can be an evidence for the Neoarchean collision in SW Siberian craton.

关键词： Siberian craton Neoarchean Kitoy terrane Metamorphism p-t path

Spinel + quartz-bearing ultrahigh-temperature granulites from Xumayao,Inner Mongolia Suture Zone,North China Craton:petrology,phase equilibria and counterclockwise p-t path

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Geoscience Frontiers 2012年第5期3卷 603-611页

作者： Huatian Zhang Jianghai Li Shoujie Liu Wenshan Li M. Santosh Honghao Wang School of Earth and Space Sciences Peking University Beijing 100871 China Beijing SHRIMp Center Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China Division of Interdisciplinary Science Faculty of Science Kochi University Kochi 780-8520-Japan China University of Geosciences (Beijing) 29 Xueyuan Road Beijing 100083 China

the Khondalite Belt within the Inner Mongolia Suture Zone （IMSZ） in the North China Craton is a classic example for paleoproterozoic ultrahigh-temperature （UHt） metamorphism. Here we report new spinel-bearing metapelitic granulites from a new locality at Xumayao within the southern domain of the IMSZ. petrological studies and thermodynamic modeling of the spinel -- quartz-bearing assemblage shows that these rocks experienced extreme metamorphism at UHt conditions. Spinel occurs in two textural settings：（1） high Xzn（Zn/（Mg ＋ FeH -- Zn） = 0.071--0.232） spinel with perthitic K-feld- spar, sillimanite and quartz in the rock matrix; and （2）low Xzn （0.045-0.070） spinel as inclusions within garnet porphyroblasts in association with quartz and sillimanite. Our phase equilibria modeling indicates two main stages during the metamorphic evolution of these rocks：（l） near-isobaric cooling from 975 ℃ to 875 ℃ around 8 kbar, represented by the formation of garnet porphyroblasts from spinel and quartz; and（2）cooling and decompression from 850 ℃, 8 kbar to below 750 ℃- 6.5 kbar, represented by the break-down of garnet. the spinel ＋ quartz assemblage is considered to have been stable at peak metamorphism, formed through the break-down of cordierite, indi- caring a near isothermal compression process. Our study confirms the regional extent of UHt metamor- phism within the IMSZ associated with the paleoproterozoic subduction-collision process.

关键词： Ultrahigh-temperaturemetamorphism petrology p-t path Inner Mongolia SutureZone North China Craton

Exhumation p-t path of UHp eclogites in the Hong'an area,western Dabie Mountains,China

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Exhumation P-T path of UHP eclogites in the Hong'an area,wes...

Metamorphic Evolution of Chloritoid-Bearing Micaschist from the Variscan Elstergebirge: Evidences for Stacking of High-pressure Rocks in the Saxothuringian Zone of Central Europe

中国科学院地质与地球物理研究所2006学术年会

作者： Jingbo Liu~a,Kai Ye~a,Min Sun~b a State Key Laboratory of Lithosphere tectonic Evolution,Institute of Geology and Geophysics, Chinese Academy of Sciences,Beijing,100029,China b Department of Earth Sciences,the University of Hong Kong,pokfulam Rd.,Hong Kong

Four generations of mineral assemblages have been identified in ultrahigh-pressure (UHp) eclogites from the Hong’an area,recording four metamorphic stages of the exhumation trajectory,i.e.,garnet+omphacite+kyanite+ zoisite/epidote+rutile+coesite formed at the UHp stage,garnet+omphacite+paragonite+phengite+amphibole+epidote+quartz at the high-pressure (Hp) eclogitic stage,amphibole+epidote+albite-oligoclase+paragonite+quartz at the epidote-amphibolite facies(EA) stage,and actinolite+ albite and pumpellyite+albite+K-feldspar+muscovite+chlorite+margarite+epidote+quartz at the greenschist facies(GS) *** formed at the UHp stage was overgrown by atoll garnet at the Hp stage. X-ray images,mineral compositions and compositional profiles indicate that the UHp garnet experienced a variable Fe-Mg modification in response to Fe-Mg exchange between garnet and omphacite prior to the overgrowth of atoll Hp garnet.A volume diffusion zone was also observed between the UHp and Hp garnets.the following p-t conditions were estimated for these mineral assemblages:480 to 560℃and 2.5 to 2.9 Gpa with median values of 520℃and 2.8 Gpa at UHp stage,575 to 685℃and 1.6 to 1.9 Gpa with the average results of 634±37℃and 1.8±0.06 Gpa at the Hp stage,500 to 640℃and 0.4 to 1 Gpa at the EA stage,and 160 to 320℃and 0.2 to 0.8 Gpa at the GS stage.the Hong’an UHp eclogites experienced a temperature increase of over 100℃from the UHp to Hp stages and continued to exhume from the Hp to EA stages through a process of approximately isothermal depression,which was followed by a significantly cooling from the EA to GS stages.In the process of exhumation,UHp eclogites witnessed a series of events involving fluid influx,resulting in the formation of hydrous minerals at different stages. the nature of fluids changed from K-rich at the Hp stage to K-poor at the EA stage and then K-rich again at the GS stage.

关键词： UHp metamorphism Eclogite Coesite p-t path Exhumation the Dabie Mountains

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Journal of Earth Science 2020年第3期31卷 425-446页

作者： Gelareh Rahimi Hans-Joachim Massonne Fakultat Chemie Universitat Stuttgart70569 StuttgartGermany School of Earth Sciences China University of GeosciencesWuhan 430074China

A chloritoid-garnet-bearing micaschist from the southern part of the Elstergebirge was studied to better understand the Variscan orogenic evolution in the Saxothuringian zone of the northwestern Bohemian Massif.Based on the textural relations and compositions of minerals,especially of zoned garnet and potassic white mica,a p-t path was reconstructed using contoured p-t pseudosections.the U-th-pb dating of monazite in the micaschist was undertaken with the electron microprobe.the micaschist experienced p-t conditions along a clockwise path between 16 kbar at 510℃and 5 kbar at 555℃followed by isobaric heating to about 600℃.Monazite ages range between 315 and 480 Ma with the most prominent maxima and side maxima at 346.0±1.1(2σ),357.3±2.3,and 368.3±1.7 Ma.Ages older than 380 Ma were related to detrital monazite pointing to a Devonian sedimentary protolith.Other ages around 325 Ma were assigned to the isobaric heating by nearby post-tectonic granites.the high-pressure event,being the result of the collision of Laurussia and Gondwana after closure of the Rheic Ocean,occurred in the Late Devonian.the exhumation to 15-20 km(5 kbar)ended probably in the Early Carboniferous.the high-pressure micaschists from the Fichtelgebirge to the Erzgebirge crystalline complexes are suggested to represent a single nappe within a metamorphic nappe pile.this nappe is composed of metasedimentary slices,which experienced different peak pressures rather than representing a coherent crustal section.

关键词： Saxothuringian micaschist chloritoid garnet monazite dating Variscan p-t path

pressure-temperature Evolution of the Metapelites in the Motuo Area, the Eastern Himalayan Syntaxis

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Acta Geologica Sinica(English Edition) 2014年第2期88卷 544-557页

作者： DONG Hanwen XU Zhiqin LI Yuan LIU Zhao State Key Laboratory of Continental tectonics and Dynamics Institute of GeologyChinese Academy of Geological Sciences China University of Geosciences

the Motuo area is located in the east of the Eastern Himalayan Syntaxis.there outcrops a sequence of high-grade metamorphic rocks,such as metapelites.petrology and mineralogy data suggest that these rocks have experienced three stages of metamorphism.the prograde metamorphic mineral assemblages （M1） are mineral inclusions （biotite ＋ plagioclase ＋ quartz ± sillimanite ± Fe-ti oxides） preserved in garnet porphyroblasts,and the peak metamorphic assemblages （M2） are represented by garnet with the lowest Xsps values and the lowest XFe# ratios and the matrix minerals （plagioclase ＋ quartz ± K-feldspar ＋ biotite ＋ muscovite ＋ kyanite ± siilimanite）,whereas the retrograde assemblages （M3） are composed of biotite ＋ plagioclase ＋ quartz symplectites rimming the garnet porphyroblasts.thermobarometric computation shows that the metamorphic conditions are 562-714℃ at 7.3-7.4 kbar for the M1 stage,661-800℃ at 9.4-11.6 kbar for the M2 stage,and 579-713℃ at 5.5-6.6 kbar for the M3 stage.these rocks are deciphered to have undergone metamorphism characterized by clockwise p-t paths involving nearly isothermal decompression （ItD） segments,which is inferred to be related to the collision of the India and Eurasia plates.

关键词： metamorphic rocks p-t path Motuo area the Eastern Himalayan Syntaxis

p-t paths Derived from Garnet Growth Zoning in Danba Domal Metamorphic terrain, Sichuan province, West China

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Journal of China University of Geosciences 2009年第2期20卷 219-240页

作者：程素华赖兴运游振东 State Key Laboratory of Geological processes and Mineral Resources China University of Geosciences Faculty of Earth Sciences China University of Geosciences

Danba （丹巴） domal metamorphic terrain belongs to Songpan （松潘）-Ganze （甘孜） orogenic belt, where typical Barrovian and Buchan metamorphic zones are preserved. the former included chlorite, biotite, garnet, staurolite, kyanite and sillimanite zones, while the latter only developed silimanite＋muscovite and sillimanite＋K-feldspar zones. Integrated study has been carried on metamorphic reactions of garnet production and consumption, p-t paths and p-t-X-M phase relation and thermal tectonic model for Danba metamorphic zones. petrological textures in thin sections show that garnet production and consumption in kyanite-sillimanite zone is mainly attributed to ChI＋Ms＋pI＋Q= Grt＋Bt＋H20 and kyanite=sillimanite respectively. Based on mineral compositions, the geothermo- barometry gives an average p, t condition of （4.9±0.3）×10^8 pa, 543±30 ℃ for the first growth stage of the garnet and （5.8±0.3）×10^8 pa, 534±29 ℃ for the second stage of garnet growth respectively. Anti-counter clockwise p-t paths were drawn using Gibbs method by NCMnKFMASH system for sample G98686 in the kyanite zone. the p-t-X-M modeling for the first mineral assemblages shows that the prediction is similar to the measured values in gossular, almandine and spessartine but mole fraction of pyrope and Fe/（Fe＋Mg） deviated far from the contours; while that for the second mineral assemblages exhibits that the prediction is consistent with the measured value of pyrope, grossular content and Fe/（Fe＋Mg） of garnet. A thermal tectonic model that there are at least three structure levels across the thrust-decollement zones is presented according to the p-t paths, metamorphic grades and deformation styles for the staurolite-kyanite zone of the Barrovian type metamorphism, which will provide some constraints for the evolution of the nappe complex.

关键词： Barrovian zone p-t path p-t-X-M modeling NCMnKFMASH system garnet growth zoning Danba.

phase Equilibrium Modeling of Retrograded Eclogite at the Kekesu Valley, Eastern Segment of SW tianshan Orogen and tectonic Implications

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Journal of Earth Science 2018年第5期29卷 1060-1073页

作者： Bin Xia Qin Yang Neng-Song Chen Zhiqiang Zhou School of Earth Sciences China University of Geosciences State Key Laboratory of Geological processes and Mineral Resources China University of Geosciences Center for Global tectonics China University of Geosciences

In this study, we report newly found strongly retrograded eclogite blocks in the Kekesu Valley, eastern segment of southwestern tianshan, northwestern China. Based on detailed petrographi- cal studies and mineral chemistry analyses, we constrain p-t evolution of two representative samples via phase equilibrium modeling method using tHERMOCALC software. the peak stage is evidenced by the primary inclusions of omphacite＋glaucophane＋lawsonite （inferred）＋chlorite＋white mica in garnet. Using grossular and pyrope isopleth thermobarometry in garnet, the p peak conditions for this stage were con- strained to be -23 kbar, 480-500℃ and the t peak conditions were constrained to be 19-20 kbar, 500-520℃. Subsequent exhumation led to the transformation of lawsonite to epidote. Using Si-in- phengite barometry, the p was constrained to be 16-20 kbar at t of 500-520 ℃ for this stage. Further retrograde stage was evidenced by the mineral assemblages of glaucophane＋garnet＋epidote＋paragonite＋ chlorite＋white mica＋quartz. Later stage retrogression is evidenced by glaucophane＋epidote＋chlorite＋ quartz＋white mica＋albite＋aetinolite with p of 5-9 kbar when t〈490 ~C, indicating the eclogite may have been exhumed to the middle crust level and overprinted by blueschist-greenschist facies metamorphism. the results show that eclogite at the eastern segment of SW tianshan shares similar p-t path to the Hp rocks from the western segment, implying a similar p-t evolution for these rocks.

关键词： eclogite p-t path phase equilibria southwestern tianshan Kekesu Valley.

Recognition　of　Ophiolite　Belt　and　Granulite　in　Northern　Area　of　Mian－Lue，　Southern　Qinling，　China　and　their　Implication

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Journal of Earth Science 1994年第1期13卷 25-27页

作者： Xu Jifeng(Department of Geology, China University of Geosciences, Wuhan 430074)Zhang Benren Han Yinwen(Department of Geochehastry, China University of Geosciences, Wuhan 430074)

A ophiolite belt associated with the tectonic melange is recoghzed in northern area of Mian-Lue, southern Qinling. the ophiolite is considered to originate in a island arc. the occurrence of the ophiolite indicates that a paleo-ocean or finite oceanic basin existed pOSt-prot6rozoic in southern Qiuling, implying the difference of the continental basement of Southern Qinling from the Yangtze craton. the ophiolitc and themelange may mark the paleo-suture zoic between the two plates. the basic granulite is found in eastern area (Anzishan) of the ophiolite belt. the p-t path for metamorphism of the granulite demonstrates a process of continental collision.

关键词： ophiolite granulite paleo-ocean p-t path Southern Qinling.

Crystal Chemistry and Geochronology of thorium-Rich Monazite from Kovela Granitic Complex,Southern Finland

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Natural Resources 2019年第6期10卷 230-269页

作者： thair Al-Ani pentti Holtta Sari Gronholm Lassi pakkanen Nadhir Al-Ansari Geological Survey of Finland(GtK) Vuorimiehentie 5EspooFinland Lulea University of technology LuleaSweden

Abundant porphyritic granites, including Grt-bearing and Bt-bearing porphyritic granites, and porphyritic potash-feldspar granite (trondhjemite-granitic composition) are widely distributed within the Kovela granitic complex Southern Finland, which associated with monazite-bearing dikes (strong trondhjemite composition). the investigated monazite-bearing dikes are dominated by a quartz + K-feldspar + plagioclase + biotite + garnet + monazite assemblage. the monazite forms complexly zoned subhedral to euhedral crystals variable in size (100 - 1500 μm in diameter) characterized by high th content. the chemical zoning characterised as: 1) concentric, 2) patchy, and 3) intergrowth-like. textural evidence suggests that these accessory minerals crystallized at an early magmatic stage, as they are commonly associated with clusters of the observed variations in their chemical composition are largely explained by the huttonite exchange , and subordinately by the cheralite exchange with proportions of huttonite (thSiO4) and cheralite [Cath(pO4)2] up to 20.4% and 9.8%, respectively. textural evidence suggests that these monazites and associated th-rich minerals (huttonite/thorite) crystallized at an early magmatic stage, rather than metamorphic origin. the total lanthanide and actinide contents in monazite and host dikes are strongly correlated. Mineral compositions applied to calculate p-t crystallization conditions using different approaches reveal a temperature range of 700°C - 820°C and pressure 3 - 6 kbars for the garnet-biotite geothermometry. p-t pseudo-section analyses calculated using tHERMOCALC software for the bulk compositions of suitable rock types, constrain the pt conditions of garnet growth equilibration within the range of 5 - 6 kbars and 760°C - 770°C respectively. Empirical calculations and pseudo-section approaches indicate a clockwise p-t path for the rocks of the studied area. 207pb/206pb dating of monazite by LA-MC-ICpMS revealed a recrystallization period at around 1860 - 1840 Ma. these ages are relat

关键词： Monazite Growth and Recrystallization Monazite Dating p-t path Huttonite Kovela Granitic Complex Finland

Finding of high-pressure mafic granulites in the Amdo basement,central tibet

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Science Bulletin 2010年第32期55卷 3695-3703页

作者： ZHANG XiaoRan1,SHI RenDeng1,HUANG QiShuai1,LIU DeLiang1,CIDAN SuoLang2,YANG JingSui3 & DING Lin1 1 Key Laboratory of Continental Collision and plateau Uplift,Institute of tibetan plateau Research,Chinese Academy of Sciences,Beijing 100085,China 2 School of Sciences,tibetan University,Lhasa 850000,China 3 Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China

High-pressure mafic granulites with a peak mineral assemblage of garnet + clinopyroxene + rutile + quartz were found in the Amdo basement,central tibet. two kinds of symplectites were identified that are composed of orthopyroxene + plagioclase ± spinel and hornblende + plagioclase around garnet,which were interpreted to develop during the retrogressing stages in the granulites. p-t estimates suggested that peak metamorphic conditions were about 860-920°C and 1.46-1.56 Gpa,which retrogressed from post-peak phase at 820-890°C and 0.88-1.15 Gpa to amphibolite facies at 550-670°C and 0.52-0.65 Gpa. these three stages define a clockwise p-t path with near-isothermal decompression and cooling following the peak high-pressure metamorphism. this suggests that the Amdo granulites underwent an initial subduction to a deep crustal level of ～50 km and then were rapidly exhumed to a shallow crustal level (～20 km). the formation of Amdo granulites is considered to result from the arc-continent collision between the Amdo basement and the Qiangtang terrane in the middle Jurassic,which is a crucial step to the tectonic evolution of the tibetan plateau.

关键词： high-pressure granulite p-t path Amdo basement Bangong-Nujiang Suture tibet