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| 1 | U-Pb zircon age of the foliated garnet-bearing granites in western Dabie Mountains,Central China显示文摘U-Pb zircon dating on two foliated garnet-bearing granite samples in the western Dabie ultra-high-pressure (UHP) metamorphic unit yields concordant ages of (234±4) Ma and (227±5) Ma, respectively. These ages, following the UHP peak metamorphism, represent the magma emplacement ages for the foliated garnet-bearing granites. This, for the first time, shows that there are the Triassic granites in the Dabie Mountains. The foliated garnet-bearing granites resemble A-type granite in geochemical characteristics, indicating that they were formed in exten-sional geodynamic setting. The magma formation reflects a reheating event in the Dabie orogenic belt and it enhances the transfer of tectonic regime from collision into extension and promotes the rapid exhumation into lower crust for the UHP metamorphic rocks. | ZHANG Hongfei ZHONG Zengqiu GAO Shan ZHANG Benren LI Huiming | 2001 | Chinese Science Bulletin2001，46，19： | 25 |
| 2 | U-Pb zircon geochronology and Hf isotope study of metamorphosed basic-ultrabasic rocks from metamorphic basement in southwestern Zhejiang:The response of the Cathaysia Block to Indosinian orogenic event显示文摘A combined study using LA-ICP-MS U-Pb dating, Hf isotopes, trace elements and the Ti-in-zircon geo-thermometer was carried out on zircons from the metamorphosed basic-ultrabasic rocks in the meta-morphic basement of the Cathaysia Block, southwestern Zhejiang Province. The formation and meta-morphic ages of the rocks from the metamorphic basement of the Cathaysia Block were determined based on zircon U-Pb geochronology. The age for the magmatic crystalline zircons from the protolith is about 1.85 Ga. The εHf(t) values of the older zircons were from ?7 to ?3, with two-stage model Hf ages (TDM2LC) of about 2.9 to 3.4 Ga, indicating that the source material was derived from anatexis and recy-cling of the Archean crust. The newly formed metamorphic zircons yielded U-Pb ages of 260―230 Ma. The metamorphic temperature calculated using the Ti-in-zircon geothermometer ranged from 610 to 720℃, consistent with the results from petrographic observations, indicating that the Cathaysia Block experienced an amphibolite facies metamorphism during the Indosinian. Results from this study pro-vided an important timeframe for the tectonic evolution in South China and the Southeast Asia during the Late Permian and Early Triassic times. | XIANG Hua ZHANG Li ZHOU HanWen ZHONG ZengQiu ZENG Wen LIU Rui JIN Song | 2008 | Science China Earth Sciences2008，51，6： | 24 |
| 3 | Paleoproterozoic reworking of ancient crust in the Cathaysia Block,South China:Evidence from zircon trace elements,U-Pb and Lu-Hf isotopes显示文摘A combined study of zircon LA-ICP-MS U-Pb dating, trace elements and Hf isotope was carried out for gneissic granite from the Sanzhishu area in Jingning, SW Zhejiang Province. Nearly all the zircons separated from the granite exhibited oscillatory zoning and high Th/U ratios (>0.1). The REE profile showed a pronounced positive Ce anomaly, negative Eu anomaly and an enrichment of HREE, which are typical characteristics of magmatic zircon. Thirteen concordant or nearly concordant analytical data yielded a weighted mean 207Pb/206Pb age of 1860±13 Ma (MSWD=0.084), representing the formation age of the granite. The magmatic zircons had negative εHf(t) values of -15.6 to -10.0 and two-stage Hf model ages of 3.1 to 3.4 Ga, indicating that the granites were formed by reworking of ancient crust. The major- and trace-element data indicate that the gneissic granites are metaluminous high-K calc-alkaline rocks and exhibit the same geochemical characteristics as aluminous A-type granites, implying the emplacement of the granite in a post-orogenic extensional tectonic setting. We conclude that the Pa-leoproterozoic crustal reworking event in the Cathaysia Block of South China marked the transition from assembly to break-up of the Columbia supercontinent. | LIU Rui ZHOU Han Wen ZHANG Li ZHONG ZengQiu ZENG Wen XIANG Hua JIN Song LU Xin Qian LI ChunZhong | 2009 | Chinese Science Bulletin2009，54，9： | 22 |
| 4 | Caledonian reworking of Paleoproterozoic basement in the Cathaysia Block: Constraints from zircon U-Pb dating, Hf isotopes and trace elements显示文摘A combined study of zircon U-Pb dating, Hf isotopes and trace elements has been carried out for granodioritic neosomes of migmatites from the Tianjingping area in northwestern Fujian Province. Zircons are characterized by zoning, higher Th/U ratios (mostly ≥0.1), HREE enrichment, and positive Ce and negative Eu anomalies, and show features similar to magmatic or anatectic zircons. Apparent 206Pb/238U ages for the zircons are 447±2 Ma (95% conf., MSWD = 0.88), corresponding to a Caledonian event. εHf(t) values are ?13.3 to ?9.7, indicating a crustal source. Two-stage Hf model ages are 1.7 to 1.9 Ga, suggesting that protolith of the migmates was probably formed in the Paleoproterozoic. The granodioritic neosomes have the characteristics of peraluminous calc-alkaline granite, and their REE patterns and trace elements spidergrams show features of middle to upper crustal rocks. Together with previous studies, we conclude that the protolith of the Cathaysia basement in the Tianjingping area was likely formed in the middle-late Paleoproterozoic and experienced partial melting during the Caledonian period. The recognition of Caledonian reworking of the Paleoproterozoic basement in the Cathaysia Block provides a new insight into the tectonic evolution of the Cathaysia Block in the Caledonian pe- riod and the interaction between the Cathaysia Block and the Yangtze Block. | ZENG Wen ZHANG Li ZHOU HanWen ZHONG ZengQiu XIANG Hua LIU Rui JIN Song LU XinQian LI ChunZhong | 2008 | Chinese Science Bulletin2008，53，6： | 21 |
| 5 | Age of granulite from Huangtuling, Dabie Mountain:Pb-Pb dating of garnet by a stepwise dissolution technique显示文摘A new stepwise dissolution scheme, involving acids with different properties, enables the selective recovery of radiogenic and common Pb from a mineral, and makes single-mineral Pb-Pb dating possible. Garnet from a granulite sample from Huangtuling, northern Dabie Mountain yields a Pb-Pb isochron age of (1098 ± 35) Ma, which is interpreted as the timing of peak metamorphism of granulite facies. | Hanwen Zhou Xianhua Li Ying Liu Zhendong You Shutian Suo Zengqiu Zhong | 1999 | Chinese Science Bulletin1999，44，10： | 15 |
| 6 | Location of Triassic Tectonic Suture Between Collided Sino-Korean and Yangtze Cratons in Dabie-Sulu Region, China显示文摘The regional extent and spatial distribution of ultrahigh pressure metamorphic(UHPM) and high pressure metamorphic (HPM) rocks, and the geometrical relationships of various petrotectonic units in the Dabie-Sulu region indicate that the Triassic collisional suture line between the Sino-Korean and Yangtze cratons is situated at the northern margin of the Dabie massif, that is,along the Balifan-Mozitan-Xiaotian fault in the Dabie region, and possibly is linked to the Wulian-Yantai fault in the Sulu region to tbe east. The suture line has been strongly modified duriug and subsequent to UHPM aud HPM events. | Suo Shutian Zhong Zengqiu You Zhendong(Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074) | 1999 | Journal of Earth Science1999，18，4： | 11 |
| 7 | Partial Melting Processes During Exhumation of Ultrahigh-Pressure Metamorphic Rocks in Dabieshan, China显示文摘Study practice has proved that the ultrahigh pressure metamorphic rocks iu Dabieshan must have exPerienced botk the retrograde metumorphism and partial melting under decompression and amphibolite-facies conditions during their exhumation from mantel depth to lower-middle crust.The retrometamorphism and partial melting of the ultrahigh pressure rocks in association with thermal state changing in the middle-lower crust, under amphibolite-facies conditions, are important physical and chemical processes. It would result in a great detrease in the integrated yield strength, and the enhancement of the de formabilitY or the rocks, promoting the transition from contractional (collision) to extensional defoemational regime. The statement of tbe retrometamorphism and partial melting of the ultrahigh pressure rocks has proved the in-site model for the ultrahigh pressure rocks in Dabieshan. It not only clarifies the evolutiou from the UHP eclogite to the surrounding gneissic rock (so called UHP gueiss) and to the garnet-beariug roliated granites (non-UHP country rocks), but also provides scientific arguments for the establiskment of the dynamic model of the exhumation of UHP metamorphic rocks in Dabiesban. In general, Purely conductive heat transfer from the crust itself is probably insurficient to produce temperature conditions for partial melting, and additional heat sources must have been present during partial melting. We infer that the partial melting and extensional flow are probably driveu by delamination and magmatic underplating of thickeued lithospkeric mantle following the continental oblique collision. | Zhong Zengqiu Zhang Hongfei Suo Shutian You Zhendong(Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074) | 1999 | Journal of Earth Science1999，18，3： | 8 |
| 8 | Garnet-bearing Granulite Facies Rock Xenoliths from Late Mesozoic Volcaniclastic Breccia, Xinyang, Henan Province显示文摘This paper presents the primary results of petrologic,mineralogical and petrochemical studies of garnet beating granulite facies rock xenoliths from Xinyang, Henan Province. These xenoliths, which are found in a pipe of late Mesozoic volcaniclastic breccia, are of high density (3.13-3.30 g/cm3) and high seismic velocity (Vp = 7.04-7.31 km/s), being products of underplating of basaltic magmas and had experienced granulite facies metamorphism. The underplating and metamorphism took place before the eruption of the host rock. Petrographical studies and equilibrium T-P calculations show that these xenoliths were captured at a 49 km depth and experienced at least a 16 km uplift before they were captured. The dynamics of the uplift could be related to the continent-continent collision between the North China plate and the Yangtze plate during the Triassic. | ZHENG Jianping, SUN Min, LU Fengxiang, WANG Chunyangand ZHONG Zengqiu Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China Department of Earth Sciences, The University of Hong Kong, China | 2001 | Acta Geologica Sinica(English Edition)2001，75，4： | 7 |
| 9 | Granulite Genesis and Tectonic Evolution in Tongbai Area:Single Zircon Evaporation Ages and Nd Isotopic Geochemistry显示文摘INTRODUCTIONTongbaiareainCentralChinaisanimportantregionforstudyinggenesisrelationbetweenQinlingorogenicbeltandDabieorogenicb... | Zhang Hongfei Gao Shan Zhang Li Zhong Zengqiu Ling Wenli Wang Linsen Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 | 1998 | Journal of Earth Science1998，17，3： | 6 |
| 10 | Extensional Tectonic Framework of Post High and Ultrahigh Pressure Metamorphism in Dabieshan,China显示文摘INTRODUCTIONThestudyofhigh-pressure(HP)andultrahigh-pressure(UHP)metamorphicrocksisoneofthemajorhottopicsinthesolidearthscien... | Zhong Zengqiu Suo Shutian You Zhendong Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 | 1998 | Journal of Earth Science1998，17，1： | 5 |
| 11 | Geochemistry of Gneisses from Dabie Complex and Tongbai Complex in Qinling-Tongbai-Dabie Orogenic Belt:Implications for Location of Yangtze-Sino-Korean Suture显示文摘The Dabie complex (DC) and the Tongbai complex (TBC) are separately distributed in the middle and eastern parts of the Qinling-Tongbai-Dabie orogenic belt. In this study, the Dabie complex can be divided into two units: one is the complex with no high pressure and ultrahigh pressure metamorphic rocks (DC1), and the other is the complex containing coesite-bearing eclogite lenses or boudins (DC2). Gneisses are predominant in the TBC, DC1 and DC2. Major and trace element data of gneisses in the TBC, DC1 and DC2 show them to be the orthogneisses. The gneisses in the DC1 have higher incompatible element contents and higher ratios of w(K 2O)/w(Na 2O) and w(La) n/w(Yb) n than those in the DC2. However, no obvious differences arise in other element contents and the ratios of w(La)/ w(Nb), w(Nb)/w(Th), w(Nb)/w(Hf), w(Ba)/w(La), w(Sm)/w(Nd) and w(Th)/w(U) between the gneisses in the DC2 and those in the DC1. These observations suggest that the protoliths of the gneisses in the DC2 have affinities to those in the DC1. The difference between the DC1 and DC2 gneisses in incompatible element contents could reflect the difference in their partial melting extent. The TBC gneisses are geochemically similar to the DC1 gneisses, suggesting that the TBC and DC1 gneisses are the same lithologic unit in the Qinling-Tongbai-Dabie orogenic belt and that they have experienced similar formations and evolution histories. In the Qinling-Tongbai area, the TBC is part of the northern blocks of the Yangtze craton. Given the similarity of geochemical characteristics, the rock assemblage and the ages between the TBC and DC1 gneisses, we can infer that the Dabie complex also belongs to the northern blocks of the Yangtze craton. In terms of the distribution of eclogites and metamorphic facies, we propose that the collisional suture in the Dabie area is distributed along the Xiaotian-Mozitan fault, at the contact with the Shang-Dan-Tongbai fault to the west. | Zhang Hongfei Zhang Benren Zhong Zengqiu Gao Shan Hu Shenghong Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 | 2000 | Journal of Earth Science2000，19，4： | 5 |
| 12 | Relic UHP Structures in Dabie-Sulu Region, China: Structural Expression and Geodynamic Significance显示文摘The present day observed tectonic framework of ultrahigh pressure (UHP) metamorphic belt in the Dabie Sulu region was dominantly formed by an extensional process at 200-170 Ma, under amphibolite facies conditions, following the Triassic collision between the Sino Korean and Yangtze cratons. UHP relic structures, including massive eclogites with a weak foliation, UHP shear zones and A type folds, that are preserved in less retrograde metamorphism and deformation overprinted eclogite lenses can be recognized using the tectonic analysis. Examples are drawn from the Chengmagang area and Hejiawan area, Hubei; Bixiling area, Anhui, and Donghai area, northern Jiangsu. A speculative kinematic model is proposed for the collision between the cratons based on the UHP relic structures studied, in combination with the data of petrography, geochronology and P T path of UHP metamorphic rocks in the studied region which were reported in literature. It is stressed that only the early UHP relic structures, particularly, regionally consistent foliation and stretching lineations, record and reflect the formation of the UHP metamorphic rocks, and the relative dynamic and kinematic process related to the Triassic NNE directed oblique collision between the Sino Korean and Yangtze cratons. | Suo Shutian Zhong Zengqiu You Zhendong Zhou Hanwen Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China | 2000 | Journal of Earth Science2000，19，3： | 5 |
| 13 | Fluid-Rock Interaction of Shear Zones in Continental Crust:as Evidenced by Xincheng-Xishui and Hetai Shear Zones显示文摘There is a coupling of thermal, mechanical, chemical and fluidal processes in a continental shear zone. Both Xincheng-Xishui and Hetai shear zones are typical continental crust shear zones of greenschist facies environment. The representative mylonite zones of the shear zones are studied with whole rock major and trace element analyses. The chemical compositional variation tendencies in both shear zones are very similar and the gain-loss ratios of various components in the mylonitic rocks are reflected in the mass balance equations. The enrichment of those immobile high-field-strengh elements is considered to he related to the volume loss of the myionitic rocks in a shear zone. Based on the volume loss expression Cs/Co=1/(1-V),the fractional volume losses (V)are 37.5% and 36.5%-42.3% respectively for mylonites and ultramylonites in the Xincheng-Xishui shear zone and 11% and 28% respectively for mylonites and phyllonites in the Hetai shear zone. The high volume loss and large removal of SiO2 | Zhong Zengqiu You Zhendong Xu QidongFaculty oj Earth Sciences, China University of Geosciences, Wuhan 430074 | 1995 | Journal of Earth Science1995，14，2： | 4 |
| 14 | Structural Evidence for the in-situ Origin of the HP and UHP Eclogites in the Dabie-Sulu Orogenic Belt显示文摘Whether the HP and UHP metamorphic rocks of the Dabie-Sulu orogenic belt are of an 'in-situ' or 'foreign' origin is a long-standing dispute among geologists. Eclogites preserved today in the HP and UHP units constitute merely 5-10%, which are not isolated exotic bodies tectonically intruding into amphibolite facies gneiss, but remnants of once pervasive or widespread eclogite-facies terranes or slabs. The present spatial distribution and forms of the eclogites have resulted from polyphase and progressive deformation and strain partitioning of the HP and UHP slabs. From their formation in deep mantle to their exhumation to the surface, the eclogites have experienced long-term deformation with different strain regimes. The dominant regime responsible for the present spatial distribution and forms of the eclogites is the shear process. The deformation patterns of the eclogites and gneiss matrix also clearly show that the eclogites were metamorphosed in situ. The original distribution area of the eclogites is much larger than that seen today. | ZHONG Zengqiu, YANG Qijun, SUO Shutian, ZHOU Hanwen and YOU Zhendong China University of Geosciences, Wuhan, Hubei 430074 E-mail: zqzhong@cug.edu.cn Hao Ziguo and Liu Xinzhu | 2003 | Acta Geologica Sinica(English Edition)2003，77，3： | 4 |
| 15 | Polyphase Deformation of the Weihai-Rongcheng UHP Unit Rocks,NE Sulu:Insights into the Tectonic Evolution of the Dabie-Sulu UHP and HP Belts,China显示文摘Different scales of structural data reveal a complex deformation history of ultrahigh- pressure (UHP) rocks exposed in the Weihai-Rongcheng area, NE Sulu (northern Jiangsu-eastern Shandong), eastern China. Excluding pre-UHP deformations, at least five major sequential deformational stages (D1–D5) are recognized. The first deformation (D1) produced a weak foliation and lineation in massive eclogites. The foliated eclogite with a dominant foliation containing a stretching and mineral lineation was developed during the D2 deformation. Both the D1 and D2 deformations occurred under UHP metamorphic conditions, and are well preserved in the eclogite bodies. D3 structures which developed shortly after the formation of granulite/amphibolite facies symplectites are characterized by imbricated associations marked by a regional, steeply dipping foliation, compositional layering, eclogite boudinage, isoclinal folds and reverse ductile shear zones. The D3 deformation was accompanied by decompressional partial melting. A regional, gently dipping amphibolite facies foliation and stretching lineation, low-angle detachments, and dome- and arc-shaped structures formed during the D4 deformation stage dominate to some degree the map pattern of the Weihai-Rongcheng UHP domain. The last stage of deformation (D5) gave rise to the final exhumation of the UHP rocks. D5 is characterized by development of brittle-dominated high-angle faulting associated with emplacement of large volumes of undeformed granite plutons and dykes dated at 134–100 Ma. The deformational and metamorphic sequence followed by the UHP rocks in the Weihai-Rongcheng area is similar to that studied in the entire Dabie-Sulu UHP and HP metamorphic belts from microscopic to mapping scale. Based on structural data, combined with available petrographic, metamorphic and geochronological data, a speculative tectonic evolutionary model for the Dabie-Sulu UHP and HP belts is proposed, involving continental subduction/collision between the Sino-Korean and Yangtze cratons and subsequent polyphase exhumation histories of the UHP and HP metamorphic rocks. | SUO Shutian ZHONG Zengqiu ZHOU Hanwen YOU Zhendong | 2007 | Acta Geologica Sinica(English Edition)2007，81，1： | 4 |
| 16 | Pb Isotope Mapping in the Tongbai-Dabie Orogenic Belt, Central China显示文摘摘要:在华中的 Tongbai-Dabie orogenic 带是在 Yangtze 和诺思中国 cratons 之间的 collisional 带的部分。它代表之一最广泛超离频压力(UHP ) 并且高压(HP ) 在世界上的变形岩石。在这个区域印射的 Pb 同位素是一个重要方法抑制外壳的结构和构造进化并且在垂直的构造的栈以内识别构造边界。把 Dabie 的作文基于 Pb 同位素建筑群( DBC ), Tongbai 建筑群( TBC ), UHP 和 HP 变形岩石和联系 foliated 花岗石,从北方 Huaiyang ( NHY )的更低的变形岩石在 Tongbai-Dabie orogenic 的构造的带,和白垩纪花岗石系上带子,我们决定了 Tongbai-Dabie orogenic 带的 Pb 同位素 geochemical 地图。Pb 同位素作文在每地质的身体或 lithotectonic 单位以内是类似的 Pb 同位素地图表演,而是不同 lithotectonic 单位的 Pb 同位素作文在 Tongbai-Dabie orogenic 带显示出系统的变化。NHY 构造的带在 Pb 同位素作文与 Tongbai-Dabie UHP-HP 变形的带强烈形成对照。沿着 Xiaotian-Mozitan 的线指责,这被建议, Tongbai-Dabie UHP 和 HP 的北方限制变形岩石,代表一条重要构造边界。在 Tongbai-Dabie HP-UHP 变形的带以内,到 Xiaotian-Mozitan 差错的南方,以在不同主要 lithotectonic 单位之中的不同 lithotectonic 单位和空间关系的 Pb 同位素作文的垂直变化被抑制了。 | ZHANG Li ZHONG Zengqiu WANG Linsen Zhang Benren | 2008 | Acta Geologica Sinica(English Edition)2008，82，1： | 3 |
| 17 | Geochemical Characteristics of Pb Isotope of High-Pressure Metamorphic Rocks and Foliated Granites from HP Unit of Tongbai-Dabie Orogenic Belt显示文摘Whole-rock Pb isotopic compositions of the high-pressure (HP) metamorphic rocks, consisting of two-mica albite gneisses and eclogites, and foliated granites from the HP metamorphic unit of the Tongbai-Dabie orogenic belt are firstly reported in this paper. The results show that the HP metamorphic rocks in different parts of this orogenic belt have similar Pb isotopic compositions. The two- mica albite gneisses have 206 Pb/ 204 Pb=17.657-18.168, 207 Pb/ 204 Pb=15.318-15.573, 208 Pb/ 204 Pb=38.315-38.990, and the eclogites have 206 Pb/ 204 Pb=17.599-18.310, 207 Pb/ 204 Pb=15.465- 15.615 , 208 Pb/ 204 Pb=37.968-39.143. The HP metamorphic rocks are characterized by upper crustal Pb isotopic composition. Although the Pb isotopic composition of the HP metamorphic rocks partly overlaps that of the ultrahigh-pressure (UHP) metamorphic rocks, as a whole, the former is higher than the latter. The high radiogenic Pb isotopic composition for the HP metamorphic rocks confirms that the subducted Yangtze continental crust in the Tongbai-Dabie orogenic belt has the chemical structure of increasing radiogenic Pb isotopic composition from lower crust to upper crust. The foliated granites, intruded in the HP metamorphic rocks post the HP/UHP metamorphism, have 206 Pb/ 204 Pb=17.128-17.434, 207 Pb/ 204 Pb=15.313-15.422 and 208 Pb/ 204 Pb=37.631-38.122, which are obviously different from the Pb isotopic compositions of the HP metamorphic rocks but similar to those of the UHP metamorphic rocks and the foliated garnet-bearing granites in the UHP unit. This shows that the foliated granites from the HP and UHP units have common magma source. Combined with the foliated granites having the geochemical characteristics of A-type granites, it is suggested that the magma for the foliated granites in the UHP and HP unit would be derived from the partial melting of the retrometamorphosed UHP metamorphic rocks exhumed into middle to lower crust, and partial magmas were intruded into the HP unit. | Zhang Li Zhang Hongfei Zhong Zengqiu Zhang Benren Wang Linsen Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 | 2003 | Journal of China University of Geosciences2003，14，4： | 3 |
| 18 | Sequence of Ductile Shear Zones in UHP Metamorphic Province with in Dabie Massif,China显示文摘INTRODUCTIONOverthelasttwodecadesconsiderableadvanceshavebeenmadetowardsrecognizingandunderstandingthetectonicsignificanceofd... | Suo Shutian Zhong Zengqiu Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 | 1998 | Journal of Earth Science1998，17，3： | 2 |
| 19 | Multi-Layered Low-Angle Ductile Detachment System in Dabie-Sulu UHPM and HPM Belts, China显示文摘The present-day observed crustal-scale tectonic style of ultrahigh-pressure metamorphic (UH-PM) and high-pressure metamorphic (HPM ) belts in the Dabie-Sulu region was dominantly formedby extensional processes, postdating the Triassic collision between the Sino-Korean and Yangtze cratons. The extensional structures overprinting the previous structures related to contraction that produced the thickened continental crust of the UHPM and HPM belts, in particular display the typical features of a Cordilleran-type metamorphic core complex, in which at least four regionalscale, low-angle ductile shear zones that constitute a detachment system, are recognized in the Dabie region. In the Sulu region, the extensionaI structures show in the form of small-scale domes or a regional-scale SE-dipping pseudo-monocline. The geometry and the kinematics of tbe detachment zones are briefly described and their significance for the exhumation of UHPM and HPM rocks is discussed. It is iniliated that the subhorizontal crustal-scale extensional flow in the middle-lower crust, under amphibolite- to greenschist-facies conditions, was an important tectonothermal process at 200- 170 Ma and the exhumation or the UHPM and HPM rocks was achieved at least in part along multi-layered detachment zones. The regional detachment system has been the main factor enabling UHPM and HPM rocks to be brought from middle-lower crustal levels to middle-upper crustal levels. | Suo Shutian Zhong Zengqiu(Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074) | 1999 | Journal of Earth Science1999，18，3： | 2 |
| 20 | Metamorphic P-T-t Path of UHT Granulites from the North Tongbai Orogen, Central China显示文摘Although zircon U-Pb geochronometer has been widely used for dating metamorphism in moderate-to high-grade metamorphic rocks, it is still difficult to link the zircon U-Pb age to pressure and temperature(P-T) conditions. In this study, zircon trace elements and Hf isotopes and REE partitioning between zircon and garnet are adopted to track the formation condition of zircon in the granulites from North Tongbai Orogen, Central China. Combined with previous metamorphic P-T path results, a quantitative integrated anticlockwise P-T-t path was established for Tongbai granulites. These granulites recorded an early low-P heating followed by a dramatic pressure increase. Evidence for the prograde history(M1) is provided by cordierite, orthopyroxene and biotite inclusions in garnet. The prograde metamorphism occurred at around 443±3 Ma, with P-T conditions of ca. 730–820 ℃ and <6 kbar. The peak metamorphic(M2) condition is >920 ℃ and 8.5–10 kbar and the peak metamorphism age is ca. 432±4 Ma. At around 419 Ma, the granulites suffered an amphibolite-facies retrograde metamorphism(M3), represented by the replacement of garnet by biotite and plagioclase, and clinopyroxene by amphibole, with metamorphic condition of ca. 700 ℃ and ca. 7 kbar. The last retrograde metamorphism(M4) is a greenschist-facies overprint with an age of ca. 404 Ma. It is concluded that the metamorphism of Tongbai granulite lasted for more than 40 Ma, including a stage of more than 20 Ma granulite-facies metamorphism. The prolonged granulite-facies metamorphism resulted from the continuous northward subduction of the Shangdan oceanic crust beneath the North Qinling terrane. | Hua Xiang Zeming Zhang Liming Zhao Zengqiu Zhong Hanwen Zhou | 2018 | Journal of Earth Science2018，29，5： | 1 |
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