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Metabasic Dyke Swarms in a High-Grade Metamorphic Terrane——A Case Study in the Taipingzhai-Jinchangyu Area,Eastern Hebei Province
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作者 Chen Manyun Changchun College of Geology Zhang Zhongmin 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1990年第4期427-441,467,共16页
Geological and petrological studies indicate that three phases of metabasic dykes are present in theTaipingzhai-Jinchangyu area within the high-grade metamorphic terrane of eastern Hebei. Garnet andhornblende in metab... Geological and petrological studies indicate that three phases of metabasic dykes are present in theTaipingzhai-Jinchangyu area within the high-grade metamorphic terrane of eastern Hebei. Garnet andhornblende in metabasic dykes of the second and third phases occur separately, forming two mineral aggregateareas gl+cpx+pl±hy and hb+cpx+pl-hy. P_(H_2O) in the rocks appears to be the main factor controlling theformation of the two aggregate areas. Both were formed simultaneously at the same metamorphic temperature. The second-phase basic dykes underwent metamorphism of pyroxene-granulite facies at a temperature ofsome 825C: later the dykes, together with the third-phase basic dykes experienced metamorphism ofamphibole-granulite facies at a temperature of about 750C under pressure of 0.9GPa. 展开更多
关键词 A Case Study in the Taipingzhai-Jinchangyu Area Eastern Hebei Province Metabasic Dyke Swarms in a high-grade metamorphic terrane
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Petrogenesis of Eclogites in the Light of Punctuated Metamorphic Evolution in Dabie Terrane,China 被引量:1
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作者 You Zhendong Han Yujing +3 位作者 Zhong Zengqin Sang Longkang Chen Nengsong Zhang Zeming(Faculty of Earth sciences, China University of Geosciences, Wuhan 430074) 《Journal of Earth Science》 SCIE CAS CSCD 1995年第1期79-84,共6页
The Dabie metamorphic terrane is tectonically located within the intersection area of the WNW trending east Qinling orogenic belt with the NNE trending west Pacific domain. The Punctuated multistage convergent movemen... The Dabie metamorphic terrane is tectonically located within the intersection area of the WNW trending east Qinling orogenic belt with the NNE trending west Pacific domain. The Punctuated multistage convergent movement and the emplacemeat of YanShanian granitoid intrusions account for the complication of its tectonic framework. The Dabie metamorphic complex is composed of 3 units: supracrustals of early Precambrian age, granite gneiss and metamorphic magic rocks of lats Precambrian age. Three major metsmorphic Stages can be traced, i. e. granulite factes, amphibolite facies of Precambrian and the HP/ LT epidote amphibolite and greenschist facies of Phanerozoic. The Hong'an Group underlying the Dabie complex shows epidote amphibolite facies which is probably synchronous with the amphibolite facies of the Dabie complex. The Protolith of the HP and UHP eclogiter are diversided. The amphibole, epidote and other mineral inclusions within the eclogite minerals testify to the earlier history of Pre-eclogitic metamorphism. The peak metamorphic assemblage coesite-omphacite-garnet is superimposed by amphibolite, epidote amphibolite and greenschist facies of retrograde metamorphism. In many regions the eclogites appear as pods, lenses and layers within ductile shear zones having synkinematic greenschist or epidote amphibolite facies of retrograde metamorphism. The Sm-Nd isochron of whole rock and garnet combined with Ph-Ph dating of zircon crystals from Mifengjian eclogite block in Hubei suggest that the UHI, metamorphism probably took Place nearly 480 Ma Which evideoces one of the most important tertono-thermal events of the punctuated evolution in the Dabie terrane. 展开更多
关键词 UHP metamorphism eclogite petrogensis punctuated metamorphic EVOLUTION Dabie metamorphic terrane.
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The Metamorphic Evolution and Tectonic Significance of the Sumdo High and Ultrahigh Pressure Metamorphic Terrane, Central-South Lhasa Block, Tibet
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作者 ZHANG Cong Thomas BADER +4 位作者 Herman van ROERMUND YANG Jingsui SHEN Tingting QIU Tian LI Peng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第S1期52-,共1页
Asthemaintectoniccomponentofthe Himalayan–Tibetan orogen,the Lhasa terrane has received much attention as it records the entire history of the orogeny.The occurrence of high pressure eclogite in the Sumdo complex in ... Asthemaintectoniccomponentofthe Himalayan–Tibetan orogen,the Lhasa terrane has received much attention as it records the entire history of the orogeny.The occurrence of high pressure eclogite in the Sumdo complex in central Lhasa terrane has a significant importance on the understanding of the Paleo-Tethys subduction and plate itineration processes in this area.The petrological,geochemical and geochronological data of eclogite and associated blueschist and garnet-bearing mica schist from Sumdo,Jilang and Bailang area have been briefly reviewed to explore the origin and metamorphic evolution of this suture.Eclogites from the Sumdo complex have experienced low temperature,high pressure to ultrahigh pressure metamorphism,revealing a fastsubduction and exhumation process in a typical oceanic subduction zone.The large P-T range between different eclogites in the literature may be affected by the big error of unappropriated using geothermobarometry and may also because of slices of subducted blocks derived from different depths juxtapose together during exhumation.By summarizing the U-Pb,Lu-Hf and Sm-Nd ages of eclogites,the eclogite facies metamorphism is likely to occur in early Triassic during 245-225 Ma,but not the previously accepted late Permian at ca.260 Ma by the reinterpretation of the former geochronological data from literature.The opening of Paleo-Tethys Ocean between the Lhasa terrane initiate prior to ca.280 Ma and ultimate closure to integrate the Lhasa terrane was no earlier than225 Ma and may triggered by the initial subduction of Bangong-Nujiang Tethys Ocean in the north. 展开更多
关键词 TIBET The metamorphic Evolution and Tectonic Significance of the Sumdo High and Ultrahigh Pressure metamorphic terrane Central-South Lhasa Block
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The Metamorphic Processes and Its Geological Implications of Gneisses from the Duoba Terrane of Xizang(Tibet) Plateau, China
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作者 LI Peng ZHANG Cong +1 位作者 HUANG Jie YANG Jingsui 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期220-,共1页
A suit of metamorphic rocks experienced amphibolite and partly granulite facies metamorphism exposed on the Lhasa block,which are recognized as the basement of the Lhasa block named as Nyainqentanglha Group in the
关键词 The metamorphic Processes and Its Geological Implications of Gneisses from the Duoba terrane of Xizang TIBET PLATEAU China
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P-T path of metamorphism and U-Pb monazite and zircon age of the Kitoy terrane: Implication for Neoarchean collision in SW Siberian Craton
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作者 Vasiliy P.Sukhorukov Valentina B.Savel’eva +1 位作者 Yingde Jiang Zhiyong Li 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第6期1915-1934,共20页
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-... 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. 展开更多
关键词 Siberian craton NEOARCHEAN Kitoy terrane metamorphISM P-T path
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SHRIMP single zircon U-Pb dating of the Kongling high-grade metamorphic terrain: Evidence for >3.2 Ga old continental crust in the Yangtze craton 被引量:46
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作者 高山 凌文黎 +2 位作者 QIU Yumin Neal J.McNaughton David I.Groves 《Science China Earth Sciences》 SCIE EI CAS 2001年第4期326-335,共10页
Single zircons from two trondhjemitic gneisses and two clastic metasedimentary rocks without Eu anomaly of the Kongling high-grade metamorphic terrain are dated by the in situ SHRIMP U-Pb method. The results show that... Single zircons from two trondhjemitic gneisses and two clastic metasedimentary rocks without Eu anomaly of the Kongling high-grade metamorphic terrain are dated by the in situ SHRIMP U-Pb method. The results show that the trondhjemitic magma emplaced at 2947-2903 Ma. Concordant age of as old as 3.3 Ga is present in the detrital zircons from the clastic metasedimentary rocks. Together with the depleted mantle Nd model age (TDM =3.2-3.3 Ga) of the clastic metasedimentary rocks, this documents the presence of Paleoarchean continental crust in the Yangtze craton. 展开更多
关键词 Kongling high-grade metamorphic terrain zircon U-Pb age SHRIMP Archean Yangtze craton.
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Zircon U-Pb geochronology of Archean high-grade metamorphic rocks from Xi Ulanbulang area,central Inner Mongolia 被引量:16
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作者 DONG XiaoJie XU ZhongYuan +1 位作者 LIU ZhengHong SHA Qian 《Science China Earth Sciences》 SCIE EI CAS 2012年第2期204-212,共9页
The early Precambrian high-grade metamorphosed basement in the Xi Ulanbulang area, central Inner Mongolia of China, is composed mainly of intermediate granulites and charnockitic gneisses. Both types of the rocks are ... The early Precambrian high-grade metamorphosed basement in the Xi Ulanbulang area, central Inner Mongolia of China, is composed mainly of intermediate granulites and charnockitic gneisses. Both types of the rocks are closely associated spatially and temporally, with a gradual variation between them. In order to understand timing of the high-grade metamorphism, we carried out SHRIMP U-Pb dating of zircons of the rocks. Zircons from the granulites and charnockitic gneisses are similar in structure and age. Zircon cores show magmatic zoning and have ages of 2507-2545 Ma. The ages are interpreted as the forming time of protolith of the granulites and charnockitic gneisses, indicating that a strong magmatism existed at that time in the Yinshan Block. The zircon mantles and rims show homogeneous structures and record a strong granulite facies metamorphism event around 2500 Ma, with a time interval between the metamorphism and magamatism being less than 50 Ma. These suggest that the Western Block was similar to the Eastern Block in tectono-thermal timing at the end of the Neoarchean. 展开更多
关键词 Xi Ulanbulang high-grade metamorphic rocks ZIRCON SHRIMP U-Pb dating
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Oxygen Fugacity and Water Activity during Thermal Peak and Retrogression of Granulites around the Sarvapuram Area, Karimnagar Granulite Terrane, Andhra Pradesh, India
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作者 P.Chandra SINGH D.PRAKASH 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2019年第6期1900-1908,共9页
The investigated area around Sarvapuram represents a part of the Karimnagar granulite terrane of the Eastern Dharwar Craton, India. Garnet–bearing gneiss is hosted as enclaves, pods within granite gneiss and charnock... The investigated area around Sarvapuram represents a part of the Karimnagar granulite terrane of the Eastern Dharwar Craton, India. Garnet–bearing gneiss is hosted as enclaves, pods within granite gneiss and charnockite. It is largely made up of garnet, orthopyroxene, cordierite, biotite, plagioclase, K–feldspar, sillimanite and quartz. The peak metamorphic stage is represented by the equilibrium mineral assemblage i.e. garnet, orthopyroxene, cordierite, biotite, plagioclase, sillimanite and quartz. Breakdown of the garnet as well as preservation of the orthopyroxene–cordierite symplectite, formation of cordierite with the consumption of the garnet + sillimanite + quartz represents the decompressional event. The thermobarometric calculations suggest a retrograde P–T path with a substantial decompression of c. 3.0 kbar. The water activity(XH2 O) conditions obtained with the win TWQ program for core and symplectite compositions from garnet–bearing gneiss are 0.07–0.14 and 0.11–0.16 respectively. The quantitative estimation of oxygen fugacity in garnet–bearing gneiss reveal log f O2 values ranging from-11.38 to-14.05. This high oxidation state could be one of the reasons that account for the absence of graphite in these rocks. 展开更多
关键词 metamorphic conditions oxygen fugacity water activity garnet–bearing gneisses Karimnagar granulite terrane INDIA
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Paleoproterozoic emplacement and Cambrian ultrahigh-temperature metamorphism of a layered magmatic intrusion from the Central Madurai Block,southern India:From Columbia to Gondwana
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作者 Bing Yu M.Santosh +1 位作者 Ming-Xian Wang Cheng-Xue Yang 《Geoscience Frontiers》 SCIE CAS CSCD 2022年第1期28-45,共18页
The Madurai Block in the Southern Granulite Terrane(SGT)of Peninsular India is one of the largest crustal blocks within the Neoproterozoic Gondwana assembly.This block is composed of three sub-blocks:the Neoarchean No... The Madurai Block in the Southern Granulite Terrane(SGT)of Peninsular India is one of the largest crustal blocks within the Neoproterozoic Gondwana assembly.This block is composed of three sub-blocks:the Neoarchean Northern Madurai block,Paleoproterozoic Central Madurai block and the dominantly Neoproterozoic Southern Madurai Block.The margins of these blocks are well-known for the occurrence of ultrahigh-temperature(UHT)granulite facies rocks mostly represented by Mg-Al metasediments.Here we report a dismembered layered mafic–ultramafic intrusion occurring in association with Mg-Al granulites from the classic locality of Ganguvarpatti in the Central Madurai Block.The major rock types of the layered intrusion include spinel orthopyroxenite,garnet-bearing gabbro,gabbro and gabbroic anorthosite showing rhythmic stratification and cumulate texture.The orthopyroxene-cordierite granulite from the associated Mg-Al layer is composed of spinel,cordierite and orthopyroxene.The pyroxene in both rock units is high-Al orthopyroxene formed under UHT metamorphic conditions.Conventional thermobarometry yields near-peak metamorphic conditions of 9.5–10 kbar pressure and a minimum temperature of 980℃.We computed P–T pseudosections and contoured for the compositional as well as modal isopleths of the major mineral phases,which yield temperature above 1000℃.FMAS petrogenetic grid,Al-in-orthopyroxene isopleth,conventional thermobarometry and calculated pseudosection reveal a clockwise pressure–temperature(P–T)path and near isothermal decompression.The U–Pb data on zircon grains from the layered magmatic suite indicate emplacement of the protolith at ca.2.0 Ga and the metamorphic overgrowths yield weighted ^(206)Pb/^(238)U mean ages ca.520 Ma.Monazite from the garnet-bearing gabbro and Opx-Crd granulite yielded ^(206)Pb/^(238)U weighted mean ages of ca.532 Ma and 523 Ma marking the timing of metamorphism.We correlate the layered intrusion to a Paleoproterozoic suprasubduction zone setting,defining the Ganguvarpatti area as part of a collisional suture assembling the Northern and Central Madurai Blocks.The Paleoproterozoic magmatism and late Neoproterozoic-Cambrian UHT metamorphism can be linked to the tectonics of the Columbia and Gondwana supercontinents. 展开更多
关键词 Mafic-ultramafic layered intrusion Ultrahigh-temperature metamorphism Zircon and monazite geochronology Central Madurai Block Southern Granulite terrane
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Discovery of Paleozoic rocks at northern margin of Sambagawa terrane,eastern Kyushu,Japan:Petrogenesis,U-Pb geochronology and its tectonic implication
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作者 Kenta Kawaguchi Yasutaka Hayasaka +3 位作者 Tomoyuki Shibata Masayuki Komatsu Kosuke Kimura Kaushik Das 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第4期1441-1459,共19页
Ordovician diorite-quartz diorite mylonite(Saganoseki quartz diorite) was discovered in Sambagawa metamorphic terrane at the northern margin of Saganoseki Peninsula,Kyushu Island,Japan.The LA-ICP-MS zircon U-Pb geochr... Ordovician diorite-quartz diorite mylonite(Saganoseki quartz diorite) was discovered in Sambagawa metamorphic terrane at the northern margin of Saganoseki Peninsula,Kyushu Island,Japan.The LA-ICP-MS zircon U-Pb geochronology revealed that the intrusion age of Saganoseki quartz diorite was 473.3±3.6 Ma.These rocks show the volcanic arc affinity based on the trace element composition.On the basis of geochronological and geochemical results,Saganoseki quartz diorite is considered to be a member of the Early Paleozoic igneous rocks of the Kurosegawa tectonic zone.Saganoseki quartz diorite is located just south of the Median Tectonic Line(MTL)and is in close contact with the pelitic and psammitic schist without any brittle shear zone.U-Pb ages of detrital zircon grains from two psammitic schists show the estimated sedimentation age of early Late Cretaceous,indicate that these psammitic schists are the member of Sambagawa metamorphic rocks.Together with these results and the mode of occurrence in the field,we argue that the Early Paleozoic igneous rocks of the Kurosegawa tectonic zone existed as an upper structural unit of the Sambagawa terrane.This relationship is the key to reconstruct the Mesozoic tectonics of Japan as a part of East Asia,and its evolution through time. 展开更多
关键词 Outer zone of southwest Japan Sambagawa metamorphic terrane Kurosegawa tectonic zone LA-ICP-MS zircon U-Pb age Saganoseki quartz diorite
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Metamorphic Evolution and Zircon U-Pb Ages of the Nanshankou Mafic High Pressure Granulites from the Jiaobei Terrane, North China Craton 被引量:13
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作者 Shuang Chen Xu-Ping Li +1 位作者 Fanmei Kong Qingda Feng 《Journal of Earth Science》 SCIE CAS CSCD 2018年第5期1219-1235,共17页
Petrological analysis and LA-ICP-MS zircon U-Pb dating were conducted on high- pressure marie granulites, which occured as xenolith within TTG gneisses, from the Nanshankou Village of the Jiaobei terrane, Shandong Pen... Petrological analysis and LA-ICP-MS zircon U-Pb dating were conducted on high- pressure marie granulites, which occured as xenolith within TTG gneisses, from the Nanshankou Village of the Jiaobei terrane, Shandong Peninsula in the north-eastern part of the North China Craton (NCC). The mafic HP grannlite is composed of garnet, clinopyroxene, orthopyroxene, amphibole and symplectitic clinopyroxene, orthopyroxene, plagioclase, ilmente and magnetite which were formed after the decomposition of porphyroblastic garnet and clinopyroxene. Four stages of metamorphic mineral assemblages for the mafic HP granulites were constrained by detail petrological and mineralogical in- vestigations. The early prograde assemblage is represented by the mineral inclusions within garnet and clinopyroxene porphyroblasts (Opx1+Pl1+Qtz1), recording the metamorphic conditions at -754-757 ℃, 0.63-0.71 GPa; peak metamorphic conditions were determined at -874-891 ℃, 1.32-1.35 GPa with the mineral assemblage of Grt2+Cpx2+Amp2+Pl2+Qtz2. Retrograde minerals derived from symplectitic assemblage Opx3+Cpx3+Amp3+Pl3+Qtz3+Ilm3±Mag3 were formed at 693-796℃, 0.60-0.84 GPa. A final greensehist to sub-greenschist facies event was recorded by the exsolution of actinolite and albite within a retrograded clinopyroxene, as well as the occurrence of prehnite, chlorite and calcite minerals. Accordingly, a clockwise P-T path was concluded on the basis of the different stages of mineral asseblage. Cathodoluminescence imaging, trace element and U-Pb dating of zircons from the mafic HP granulites recorded similar charactistics for three episodes of Paleo-Meso Proterozoic metamorphic events. These are the metamorphic events preserved in mafic and pelitic granulites in the Jiao-Liao-Ji belt (JLJB) with 207 pb/206pb ages of 2.0-1.9 Ga for peak metamorphism and of 1.86-1.84 Ga for decomposing process, followed by a retrograde amphibolite facies metamorphic event related to the post-orogenic extension at the age of 1.76-1.74 Ga, resulting the exhumation of the granulite to the upper crust level. 展开更多
关键词 metamorphISM zircon U-Pb age mafic HP granulite Jiaobei terrane North China Craton.
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Call in question and discussion: Are there sandwiched low-grade metamorphic slabs within UHP metamorphic rocks in the Dabieshan terrane? 被引量:2
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作者 ZHAI Mingguo JIANG Laili +1 位作者 WANG Qingchen CONG Bolin 《Chinese Science Bulletin》 SCIE EI CAS 2000年第2期181-189,共9页
Some geologists reported their discovery of sandwiched low-grade metamorphic slabs within UHP metamorphic Complexes in Changpu, Yuexi County, Anhui Province. They also suggested that some coesite-bearing eclogites are... Some geologists reported their discovery of sandwiched low-grade metamorphic slabs within UHP metamorphic Complexes in Changpu, Yuexi County, Anhui Province. They also suggested that some coesite-bearing eclogites are igneous veins, which intruded low-grade metamorphic slabs and other related rocks. Moreover they further called in question to UHP matamorphic process and continental collision tectonism in the Dabieshan terrane. Based on our recent study so-called low-grade metamorphic slabs are strongly deformed fabric, fine-grained and tectonic recrystallized mylonites and tectonites. Their protolith rocks are garnet-bearing orthogneiss, eclogite and marble, as well as a few amounts of strongly deformed acid and basic veins. Their metamorphic, geochemical and geochronological characteristics are also identical with UHPM rocks and regional country orthogneisses. Therefore we conclude that there are not low-grade metamorphic slabs sand wiched with UHP metamorphic rocks in the Dabieshan terrane. 展开更多
关键词 low grade metamorphic slab MYLONITES DABIESHAN UHP metamorphic terrane.
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Petrogenesis of the Neoarchean zincian chromite within ultramafic xenoliths,Bastar Craton,India
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作者 Arpita Karmakar Tushar Meshram +1 位作者 Mohammad Asif Yogesh Pandey 《Acta Geochimica》 EI CAS CSCD 2023年第3期471-487,共17页
The present study reports and discusses the genesis of zincian chromite in the ultramafic xenoliths from the Dongripali area,Bastar craton,Central India.The zincian chromite is in the ultramafic xenoliths of Bengpal s... The present study reports and discusses the genesis of zincian chromite in the ultramafic xenoliths from the Dongripali area,Bastar craton,Central India.The zincian chromite is in the ultramafic xenoliths of Bengpal supracrustal rock hosted by Neoarchaean Bundeli gneisses.Compositionally zincian chromite shows a range of Cr_(2)O_(3)(39.69 to 51.66 wt%),Al_(2)O_(3)(05.30 wt%to 08.71 wt%),FeO(21.74 wt%to 27.51 wt%),Fe_(2)O_(3)(10.19 wt%to 19.36wt%)with higher ZnO content ranging from 1.73 wt%to 4.08 wt%.Accordingly,their Cr#[Cr/(Cr+Al)]varies in a narrow range from 0.83 to 0.85.Its calculated melt composition supports metamorphic or post-magmatic nature rather than common occurrences such as inclusion in diamonds,meteorites,and association with any sulfide-rich mineralised belt.This reveals that the post-magmatic processes play a vital role in transforming chromite to zincian chromite.The empirical thermometric calculation from chromite,amphibole,and pyroxene support their metamorphic origin and formed during low-P and high-T amphibolite grade facies of metamorphism(~700℃).The Neoarchaean granitic magmatism has a significant role in generating and transferring the heat during contact metamorphism with hydration of ultramafic xenoliths and further alteration,i.e.,serpentinisation.The olivine is a major repository for Mn,Zn,and Co in peridotite/ultramafic;these elements get mobilised during the metamorphism and serpentinisation.This is a possible reason for the mobilisation of zinc and incorporation in the chromite within altered ultramafic.As a result,chromiterich ultramafic xenolith subjected to metamorphic process gets enrichment of Zn and Fe due to elemental exchange.It converts common chromite into zincian chromite,as reported in altered ultramafics elsewhere. 展开更多
关键词 Zincian chromite ULTRAMAFIC Neoarchaean granitic magmatism high-grade metamorphism
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Diachroneity of continental subduction and exhumation:Constraints from the Permian-Triassic HP metamorphic terrane in the Tongbai orogen, central China 被引量:7
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作者 LIU XiaoChun JAHN Bor-Ming LI SanZhong 《Chinese Science Bulletin》 SCIE EI CAS 2013年第35期4397-4404,共8页
High-pressure(HP)metamorphic terrane in the Tongbai orogen comprises two HP slices(I and II)and a tectonic mélange zone in the northeast and a blueschist-greenschist zone in the southwest.HP slice I is represente... High-pressure(HP)metamorphic terrane in the Tongbai orogen comprises two HP slices(I and II)and a tectonic mélange zone in the northeast and a blueschist-greenschist zone in the southwest.HP slice I is represented by the northern and southern eclogite zones on the two sides of the Tongbaishan antiform.HP slice II is represented by retrograded eclogite-bearing metamorphic enclaves in Cretaceous gneissic granites in the Tongbai Complex.U-Pb,Lu-Hf,Rb-Sr and40Ar/39Ar multichronometric data indicate that the peak metamorphism of HP slice I took place at^255 Ma,whereas the metamorphic ages of HP slice II are as young as232–220 Ma.By contrast,the tectonic mélange zone near the suture was metamorphosed at^256 Ma.Such a diachroneity of different slices across the direction of the orogen in the Hong’an-Dabie-Sulu HP/UHP terrane is ubiquitous,and it can be interpreted by a syn-subduction detachment/exhumation model.Furthermore,the metamorphic age of HP slice I in the Tongbai orogen is older than that of the equivalent HP slice in the Hong’an orogen by^15 Ma,suggesting that the diachroneity may have also existed along the direction of the orogen.A seesaw-type subduction/exhumation model is proposed to explain this age disparity and the subduction of the South China Block becomimg shallower towards the west. 展开更多
关键词 超高压地体 变质地体 大陆俯冲 中国南方 造山带 桐柏山 穿时 折返
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柴北缘超高压带中锡铁山榴辉岩的变质时代 被引量:60
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作者 宋述光 张聪 +1 位作者 李献华 张立飞 《岩石学报》 SCIE EI CAS CSCD 北大核心 2011年第4期1191-1197,共7页
锡铁山地体位于柴北缘超高压变质带的中部,是柴北缘超高压变质带的重要组成部分。该地体由花岗质片麻岩、泥质片麻岩和相对较少的榴辉岩透镜体组成。大部分榴辉岩都经历了不同程度的后生合晶和角闪岩相退化变质改造。虽然近年来进行了... 锡铁山地体位于柴北缘超高压变质带的中部,是柴北缘超高压变质带的重要组成部分。该地体由花岗质片麻岩、泥质片麻岩和相对较少的榴辉岩透镜体组成。大部分榴辉岩都经历了不同程度的后生合晶和角闪岩相退化变质改造。虽然近年来进行了大量的锆石U-Pb年代学研究,但榴辉岩相高压-超高压变质的时代一直存在争议,并且以前对锡铁山榴辉岩相变质时代的认识一直与相邻的绿梁山、鱼卡和其东部的都兰等地区的超高压变质年龄有明显的冲突。本文通过锡铁山榴辉岩锆石U-Pb年代学的研究,获得榴辉岩相变质锆石的206Pb/238U加权平均年龄为433±3Ma,与鱼卡地区榴辉岩的形成年龄一致,代表大陆俯冲时期的高压-超高压变质年龄。该研究对进一步了解锡铁山榴辉岩地体的变质演化和大陆地壳深俯冲有重要意义。 展开更多
关键词 高压-超高压变质带 榴辉岩 变质年龄 大陆俯冲 锡铁山地体 柴北缘
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拉萨地体东南部变质岩的成因与中-新生代造山作用 被引量:20
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作者 董昕 张泽明 +5 位作者 刘峰 王伟 于飞 林彦蒿 姜洪颖 贺振宇 《岩石学报》 SCIE EI CAS CSCD 北大核心 2012年第6期1765-1784,共20页
本文对青藏高原拉萨地体东南部林芝地区分布的变质岩进行了岩石学和年代学研究,结果表明这套岩石在中-新生代经历三期变质作用,形成了三个变质带,它们是:(1)米林变质带,经历了高温中压麻粒岩相峰期变质作用和角闪岩相退变质作用,峰期麻... 本文对青藏高原拉萨地体东南部林芝地区分布的变质岩进行了岩石学和年代学研究,结果表明这套岩石在中-新生代经历三期变质作用,形成了三个变质带,它们是:(1)米林变质带,经历了高温中压麻粒岩相峰期变质作用和角闪岩相退变质作用,峰期麻粒岩相的变质作用温、压条件为830~900℃和0.9~1.3GPa,变质时代为90~80Ma的晚白垩世;(2)八一变质带,经历了低压角闪岩相变质作用,变质作用温、压条件为625~679℃,0.4~0.55GPa,变质作用时间为55~50Ma的始新世;(3)布久变质带,经历中压角闪岩相变质作用,变质作用温、压条件为615~663℃和0.5~0.8GPa,变质作用时间为32~26Ma的渐新世。研究表明,拉萨地体东南部的中高级变质岩系的原岩主要由形成在晚古生代的沉积岩和古生代-新生代的岩浆岩组成,变质沉积岩的物质源区具有格林威尔和泛非造山作用的构造热事件记录,表明拉萨地体具有冈瓦纳大陆的构造亲缘性。我们认为,拉萨地体东南部的晚白垩世高温中压变质作用发生在新特提斯大洋岩石圈向拉萨地体之下俯冲所导致的安第斯型造山作用过程中,始新世的低压角闪岩相变质作用发生在印度与欧亚碰撞和深俯冲的新特提斯洋壳断离过程中,而渐新世的中压角闪岩相变质作用发生在印度大陆向欧亚大陆之下的持续俯冲,地壳加厚过程中。因此,拉萨地体东南部的高级变质岩揭示了俯冲/碰撞复合造山带上盘中、下地壳的组成与构造演化历史。 展开更多
关键词 拉萨地体 高级变质岩 多期变质作用 中-新生代 复合造山作用
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青藏高原拉萨地体南部林芝岩群的物质来源与形成年代:岩石学与锆石U-Pb年代学 被引量:47
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作者 董昕 张泽明 +4 位作者 王金丽 赵国春 刘峰 王伟 于飞 《岩石学报》 SCIE EI CAS CSCD 北大核心 2009年第7期1678-1694,共17页
本文对位于青藏高原拉萨地体东南部林芝岩群中的变质岩进行了岩石学和年代学研究。研究表明,林芝岩群由角闪岩相的变质沉积岩和正片麻岩组成。变质沉积岩主要为含石榴石白云斜长角闪片岩、含石榴石云母石英片岩、含石榴石黑云钾长片麻... 本文对位于青藏高原拉萨地体东南部林芝岩群中的变质岩进行了岩石学和年代学研究。研究表明,林芝岩群由角闪岩相的变质沉积岩和正片麻岩组成。变质沉积岩主要为含石榴石白云斜长角闪片岩、含石榴石云母石英片岩、含石榴石黑云钾长片麻岩、大理岩和石英岩等,代表性矿物组合包括石榴石+斜长石+角闪石+石英+黑云母+白云母,或石榴石+斜长石+钾长石+石英+夕线石+黑云母+白云母。花岗质片麻岩(含二云母片麻岩)的矿物组合是石英+斜长石+钾长石+黑云母+白云母。锆石U-Ph年代学分析表明,变质沉积岩中的碎屑锆石主要为岩浆成因,获得了2708~63Ma的^(206)Pb/^(238)U 年龄范围,在~1100Ma和~550Ma出现两个年代峰值。碎屑锆石的变质增生边给出了35Ma的变质年龄。正片麻岩获得了496Ma的锆石结晶年龄和1158Ma的继承年龄。基于上述研究结果、区域对比和相邻变质岩石中获得的多期变质年龄,我们认为林芝岩群的原岩很可能形成在早古生代,其沉积物质主要来源于印度陆块,与特提斯喜马拉雅早古生代的岩石一起同为印度大陆北缘的沉积盖层,在环冈瓦纳大陆周缘造山过程中被寒武纪花岗岩侵入。在新特提斯洋向北的俯冲过程中,林芝岩群经历了晚中生代的安第斯型造山作用,在印度与欧亚大陆的俯冲-碰撞过程中,林芝岩群部分地经历了新生代的变质和岩浆作用再造。本研究证明,林芝岩群并不是传统上认为的拉萨地体的前寒武纪变质基底,其角闪岩相至麻粒岩相变质作用发生在中、新生代。 展开更多
关键词 林芝岩群 沉积源区 变质演化 地质年代学 拉萨地体 青藏高原
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青藏高原拉萨地体北部的前寒武纪变质作用及构造意义 被引量:28
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作者 张泽明 董昕 +3 位作者 耿官升 王伟 于飞 刘峰 《地质学报》 EI CAS CSCD 北大核心 2010年第4期449-456,共8页
青藏高原南部拉萨地体中分布的角闪岩相至麻粒岩相变质岩一直被认为是前寒武纪变质基底,但并没有获得可靠的年代学证据。本文运用原位锆石U-Pb定年方法,在拉萨地体北部那果地区的变质岩中获得了约720Ma的变质年龄,从而证明拉萨地体北部... 青藏高原南部拉萨地体中分布的角闪岩相至麻粒岩相变质岩一直被认为是前寒武纪变质基底,但并没有获得可靠的年代学证据。本文运用原位锆石U-Pb定年方法,在拉萨地体北部那果地区的变质岩中获得了约720Ma的变质年龄,从而证明拉萨地体北部在新古元代经历了角闪岩相变质作用和近同期的岩浆作用。基于这一成果和在拉萨地体中、南部高级变质岩中陆续获得的中、新生代变质年龄,对拉萨地体变质作用的时、空变化及其成因进行了初步探讨。 展开更多
关键词 拉萨地体 念青唐古拉岩群 锆石U-PB年龄 前寒武纪变质作用 青藏高原
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苏鲁地体超高压和退变质时代的厘定:来自片麻岩锆石微区SHRIMP U-Pb定年的证据 被引量:50
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作者 刘福来 许志琴 宋彪 《地质学报》 EI CAS CSCD 北大核心 2003年第2期229-237,T005,T006,共11页
锆石微区矿物包体的激光拉曼和阴极发光测试以及相应的SHRIMP U-Pb定年结果表明,苏鲁地体片麻岩锆石微区记录了十分复杂的年代学信息。其中副片麻岩锆石核部记录了345~743 Ma的继承性锆石年龄,标志着原岩碎屑锆石来源的复杂性;含柯石... 锆石微区矿物包体的激光拉曼和阴极发光测试以及相应的SHRIMP U-Pb定年结果表明,苏鲁地体片麻岩锆石微区记录了十分复杂的年代学信息。其中副片麻岩锆石核部记录了345~743 Ma的继承性锆石年龄,标志着原岩碎屑锆石来源的复杂性;含柯石英的锆石微区记录了220~234 Ma的超高压变质年龄;而含石英包体的边部则记录了202~219 Ma的退变质年龄。正片麻岩继承性锆石核部所记录的年龄为574~680 Ma,表明原岩锆石曾经历了部分Pb丢失,原岩的形成年龄应大于680 Ma;含柯石英锆石微区所记录的超高压变质年龄为224~242 Ma;而锆石边部所记录的退变质年龄为209~219 Ma。两类片麻岩锆石微区所隐藏的超高压变质和退变质年龄信息十分相近,平均值分别为229±4Ma和211±4Ma,标志着苏鲁地体超高压变质时代应为印支期,相应的构造抬升速率约5.6 km/Ma。该项成果不仅确定了苏鲁地体超高压变质和退变质时代,而且对于深入探讨苏鲁地体快速折返过程中的动力学机制有着重要的科学意义。 展开更多
关键词 苏鲁地体 矿物包体 片麻岩 锆石 年代学信息 退变质年龄 动力学机制 U-PB定年
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南苏鲁芝麻房石榴石橄榄岩中橄榄石的“C”类组构及其形成条件探讨 被引量:15
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作者 许志琴 陈晶 +5 位作者 王勤 曾令森 杨经绥 陈方远 李天福 梁凤华 《岩石学报》 SCIE EI CAS CSCD 北大核心 2005年第2期389-397,共9页
上地幔地震的各向异性主要归因于橄榄石的优选方位,不同的橄榄石优选方位模式可以作为上地幔不同动力学作用的指示剂。不同应力和含水量条件下的高温变形实验已经确定出五类橄榄石组构模式(“A”型、“B”型、“C”型、“D”型和“E”型... 上地幔地震的各向异性主要归因于橄榄石的优选方位,不同的橄榄石优选方位模式可以作为上地幔不同动力学作用的指示剂。不同应力和含水量条件下的高温变形实验已经确定出五类橄榄石组构模式(“A”型、“B”型、“C”型、“D”型和“E”型)。本文运用电子背散射(EBSD)技术对来自苏鲁超高压变质带南部的芝麻房石榴石橄榄岩的橄榄石进行了优选方位测定,不同变形程度的橄榄石均显示了[100]轴近垂直于面理和[001]轴近平行于线理的特征,为“C”类组构模式,可见组构类型与变形程度没有关系,并且橄榄石组构所显示的NW向SE的剪切指向,与围岩-正、副片麻岩中形成于折返过程的石英优选方位所显示的SE向NW的剪切指向完全不同,说明芝麻房石榴石橄榄岩中橄榄石的“C”类组构是折返前形成的。结合橄榄石结构水的测量和已有的芝麻房石榴石橄榄岩形成的温压条件,推测该组构形成于含水俯冲带中,认为芝麻房石榴石橄榄岩的原岩来自于高含水的上部地幔楔碎块,与俯冲的陆壳物质一起经历了超高压变质作用并最终折返至地表。 展开更多
关键词 橄榄石 优选方位 俯冲带 超高压变质作用 苏鲁地区
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