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Petrology, Metamorphic Process and Genesis of The Dabie--Sulu Eclogite Belt, Eastern--Central china

Acta Geologica Sinica(English Edition) 1996年第2期70卷 134-156页

作者： Zhang Zeming You Zhendong Han Yujing and Sang Longkang Department of earth sciences, china university of geosciences, {3., Hubei Department of earth sciences China University of Geosciences Wuhan Hubei

The Qinling-Dabie-Sulu high-pressure and ultra-high pressure metamorphic belt wasformed by subduction and collision between the North china and Yangtze plates. The study ofthe eclogite belt is very important in understanding the evolution of the Qinling Dabie orogen. Inthe present paper the geology, petrology, minerology and chronology of the eclogites in the Dabieand Sulu areas are described. The principal conclusions of this work are as follows: (1) Based up-on the field occurrence and the P-T conditions of the eclogites, two types of eclogite can be dis-tinguished: Type 1—the low-temperature and high-pressure eclogite in the mid-late Proterozoicmetamorphic series, and Type 2—the ultra-high pressure eclogite in the late Archaean to earlyProterozoic metamorphic complex. In the Dabie area, the ultra-high-pressure eclogite,high-pressure eclogite and epidote-blueschist units are nearly parallel to each other and stretchintermittently from north to south. (2) The P-T conditions of the high-pressure eclogites and ul-tra-high pressure eclogites have been estimated. The former are formed at 450-550℃ and1.4-1.6 GPa; while the latter at 650-870℃ and >2.7-2.9 GPa in the Dabie area and at820-1000℃ and >2.8-3.1 GPa in the Sulu area. The metamorphic temperatures of the eclogitesincrease progressively from west to east. (3. The ultra-high pressure eclogites were subjected to 5stages of metamorphism: pre-eclogite epidote amphibolite facies, peak coesite eclogite facies,post-eclogite amphibolite facies, epidote-blueschist facies or epidote amphibolite facies andgreenschist facies. The general features of the PTt path of the ultra-high pressure eclogite are:clockwise pattern, progressive metamorphism being a process of slow increasing temperature andrapid increasing pressure, and the retrogressive section with nearly isothermal decompression atthe early stage, isobaric cooling at the middle stage and nearly isothermal decompression at thelate stage. (4) At least two stages of high-

关键词： petrology mineral chemistry chronology PTt—path Dabie—Sulu eclogite belt east—central china

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Anatexis in Himalayan crust:Evidence from geochemical and chronological investigations of Higher Himalayan Crystallines

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Science china earth sciences 2005年第9期48卷 1347-1356页

作者： YANG Xiaosong1, JIN Zhenmin2 & MA Jin1 1. State Key Laboratory of earthquake Dynamics, Institute of Geology, china earthquake Administration, Beijing 100029, china 2. faculty of earth sciences, china university of geosciences, wuhan 4.0074. china 1. State Key Laboratory of earthquake Dynamics Institute of Geology China Earthquake Administration 100029 Beijing China 2. faculty of earth sciences China University of Geosciences 430074 Wuhan China

Migmatization in Higher Himalayan Crystallines (HHC) results from anatexis. The widely distributed migmatites in HHC are an important clue to investigate the relationship be- tween anatexis and the origins of Higher Himalayan leucogranites (HHL), and to understand the effect of anatexis on crustal evolution during the post-collision period. We studied in detail the chemical features of three basic constituent parts of the migmatites, i.e. leucosome, mesosome and melanosome, and determined the K-Ar ages of leucosomes. Our studies indicate that type-I leucosome is the product of crystallization of melt generated by partial melting of mesosome at source region, but type-II leucosome and HHL probably underwent crystallization differentiation of plagioclase during melt aggregation and migration. The age of 22.67 Ma of Type-I leucosome, which is a little older than the beginning of MCT movement, indicates that anatexis may have played an important role in the formation of MCT. That the ages of type-II leucosome (ranging from 14.82 to 18.3. Ma) are consistent with that of HHL provides new chronological evidence for the relationship between migmatization and HHL. We obtained a very young age of 6.23.Ma of Type-II leucosome that provides new time constraint on magma activity in the central segment of Higher Himalayas.

关键词： Higher Himalayan Crystallines, migmatite, anatexis, leucosome, K-Ar age.

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Petrogenesis of Indosinian volcanic rocks in Songpan-Garze fold belt of the northeastern Tibetan Plateau:New evidence for lithospheric delamination

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Science china earth sciences 2010年第9期53卷 1316-1328页

作者： CAI HongMing1,2, ZHANG HongFei1,2, XU WangChun1,2, SHI ZhangLiang1,2 & YUAN HongLin3.1 State Key Laboratory of Geological Processes and Mineral Resources, wuhan 4.0074. china 2 faculty of earth {3., china university of geosciences, wuhan 4.0074. china 3.State Key Laboratory of Continental Dynamics, Northwest university, Xi’an 710069, china 1. State Key Laboratory of Geological Processes and Mineral Resources Wuhan 430074 China2. Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China3. State Key Laboratory of Continental Dynamics Northwest University Xi’an 710069 China

In the Songpan-Garze fold belt of the northeastern Tibetan Plateau, an Indosinian lithospheric delamination model has been proposed, based on previous investigation of widespread granitoids. However, this model lacks comparable information from volcanism in the area. During the Indosinian delamination in the Songpan-Garze fold belt, whether partial melting of litho- spheric mantle taken place is debated. This paper reports U-Pb zircon LA-ICP-MS ages, geochemical and Sr-Nd-Hf isotopic compositions from the Aba and Wasai calc-alkaline volcanic rocks in the central Songpan-Garze fold belt. Obtained magma crystallization ages are 210±3.Ma for the Aba andesite and 205±1 Ma for the Wasai andesite. These are consistent with magma crystallization ages of the late Indosinian granitoids in the Songpan-Garze fold belt that formed in a post-collisional tectonic setting. The Aba and Wasai andesites have distinct geochemical singnatures. The former has higher Al2O3. K2O, Rb but lower Na2O, Ba and Sr contents, suggesting differences in their magmatic evolution. The Aba andesites have ISr values of 0.7070-0.7076 and εNd(t) values of -3.9 to -5.3. and the Wasai andesites have ISr values of 0.7075-0.7077 and εNd(t) values of -3.6 to -3.9. Zircons show εHf(t) values of -3.7 to 0.3.for the Aba andesites and -2.7 to 5.5 for the Wasai andesites. Geochemical and Sr-Nd-Hf isotopic compositions indicate that fractional crystallization and crustal assimilation processes are not key roles for their magma evolution, implying that their chemical compositions are those of primary melts. We suggest that the magma of the Aba andesites originated predominantly from a crustal source, with a minor mantle-derived component. The source region of the magma was likely at the crust-mantle boundary. The magma of the Wasai andesites resulted from partial melting of lithospheric mantle, which was probably metasomatized by fluids so that it was amphibole bearing. The petrogenesis of the Aba and Wasai andesite

关键词： volcanism U-Pb dating geochemistry petrogenesis lithospheric delamination Songpan-Garze fold belt

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Devonian Sequence Stratigraphy and Sea Level Change Cycles in South china

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Journal of earth Science 1996年第1期15卷 72-79页

作者： Du Yuansheng Gong Yiming (faculty of earth sciences,{3., wuhan 4.0074. Wu Yi (Guangxi Institute of Geology, Nanning 53.023. Liu Benpei Feng Qinglai (faculty of earth sciences,{3., wuhan 4.0074.

The Devonian is well developed in South china and has drawn a great attention from the geologists both at domestic and abroad. On the basis of study on the sequence stratigraphy in more than 10 sections in Guizhou, Guangxi, Longmenshan and Southern Qinling within South china we have identified 21 sequences and T-R cycles that correspond to third-order sea level changes. These sea level change cycles were controlled by autorhythm(Pragian,Eifelian), allorhythm(Lochkovian,Emsian,Givetian) and coupling rhythm mechanisms (frasian, Famennian and F-F boundary).

关键词： south china Devonian,sequence,sea level change cycle.

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Zircon geochronology and geochemistry of mafic xenoliths from Liaoning kimberlites:Track the early evolution of the lower crust,North china Craton

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Science china earth sciences 2004年第11期47卷 961-972页

作者： ZHENG Jianping1,YU Chunmei1,LU Fengxiang1 & LI Huimin2 1.faculty of earth sciences,{3. university of geosciences,wuhan 4.0074.{3. 2.Tianjin Institute of Geology and Mineral Resources,Tianjin 3.0170,{3. 1. faculty of earth sciences China University of Geosciences 430074 Wuhan China 2. Tianjin Institute of Geology and Mineral Resources 300170 Tianjin China

Mafic xenoliths from Paleozoic Fuxian kimberlites (Liaoning Province) mainly in- clude garnet granulite, with minor pyroxene amphibolite, meta-gabbro and pyroxene syenite. The SiO2 contents of the xenoliths are from 47.3.wt% to 49.9 wt%. The granulites are mainly coarse-medium grained and reasonably with well-developed granoblastic (mostly polygonal) texture, contain the assemblage of garnet + plagioclase + pyroxene + K-feldspar ±phlogopite. The mineral assemblage of the amphibolites is plagioclase + pyroxene + amphibole ±K-feldspar, with the equilibrium temperature and pressure conditions of 744—821℃ and 0.76—0.88 GPa. The granulites are regarded as derivation from the lower crust depth (more than 29 km), below the amphibolites. Garnet granulites compositionally correspond to sub-alkalic basalt, and have wide ranges of Ni abundance (13.—840 ppm), and Nb/Y (0.12—1.85), Nb/U (3.51—53.86) and Ta/U (0.3.—2.48). The amphibolite and the syenite correspond to alkalic basalt. The Fuxian ma- fic xenoliths are regarded as the metamorphic product of the underplated magmas (including fractional crystallization or not) experienced the contamination with the pre-existed crustal com- ponents, and partly effected by kimberlitic magmas. The concordant ages of zircons for the gab- bro (2610—2580 Ma) and the near-concordant upper intercept ages of zircons for the garnet granulite and pyroxene amphibolite (2578—253. Ma) indicate that they are currently known as the oldest deep-seated xenoliths from the lower crust of the North china Craton. These ages recorded the formation of the united Eastern Block of the North china Craton, That is, Neoar- chean (2.6—2.5 Ga) is an important continental crustal growth period of the North china Craton. The lower intercept age of the garnet granulite (1853.Ma) recorded an important tectonic thermal event in Paleoproterozoic. This event was probably related to collision of the East and West block, and resulted in the final assembly of the North china

关键词： mafic xenolith, petrochemistry, zircon geochronology, petrogenesis, lower crustal evolution, North china Craton.

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New stylophorans(Echinodermata) from the Upper Cambrian of Guangxi,South china

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Science china earth sciences 2008年第2期51卷 181-186页

作者： HAN NaiRen1 & CHEN GuiYing1,2 1 Department of Resources and Environmental Engineering, Guilin university of Technology, Gulin 541004, china 2 faculty of {3. sciences, china university of Geoscience, wuhan 4.0074. china Department of Resources and Environmental Engineering Guilin University of Technology Gulin 541004 China faculty of earth sciences China University of Geoscience Wuhan 430074 China

This paper describes for the first time the cornute stylophorans (Echinodermata) in china. The new material came from the Guole Formation of the Furongian (Late Cambrian) in the Guole area of Jingxi, Guangxi Province, South china. These new cornute specimens are preserved in situ and found along with well-preserved trilobites and brachiopods. One new species, Phyllocystis jingxiensis sp. nov., is proposed to accommodate these unusual materials. The new species is defined by the small, heart-shaped theca with the frame composed of ten narrow, smooth and thick marginal plates, three adoral plates and distinctive zygal and aulacophore. Both supracentrals and infracentrals are polygonal-outlined. The marginal plate M1' on the inferior face extends posteriorly to form zygal that possesses a broadened proximal end and the proximal portion joining with the conjunction between M4 and M5 on the inferior face. Aulacophore comprises ten segments at its proximal part and is conical at the middle part (named stylocone). Its distal portion is rather long and bears conspicuous ambulacrum grooves. Tectals are horizontally arranged on superior face and obliquely arranged on inferior face. Both cothurnopore and anal pyramid are vaguely seen on the right anterior corner and the extremity of theca's superior face.

关键词： Phyllocystis Stylophora Echinodermata Cambrian Guangxi South china

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Uppermost Permian Radiolaria from Southwestern china

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Journal of earth Science 1998年第3期17卷 52-59页

作者： Feng Qinglai Fang Nianqiao Zhang Zhenfang Huang Junhua faculty of earth sciences,{3., wuhan 4.0074

The uppermost Permian radiolarian fauna of Southwestern china described here includes 11 genera and 17 species, of which 2 species are new. Preliminary geochemistry research indicates that the sediments yielding the fauna are with anoxic feature. This study contributes to a better understanding on the evolution of Permian radiolarias and the cause of end Permian radiolarian extinction.

关键词： Radiolaria Permian paleontology Southwestern china.

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A New Accumulation Model of Coal Seams in France Extensional Basins

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Journal of earth Science 2000年第3期19卷 103-107页

作者： Wang Hua Wang Genfa faculty of earth Resources, china university of geosciences,{3.

This paper, based on the sedimentary features of the coal seams in the typical extensional (faulted) coal basins between two inland mountainous areas of the Central Massif (France) deals with the accumulation mechanism and the corresponding sedimentary tectonic conditions of these thick coalbeds, and proposes a new coal accumulation model for the inland lacustrine basin thick coalbeds. The presence of a great number of gravity flow sediments such as detrital flow, diluted slurry flow or turbidity current sediments in the coal seams, and that of the contemporaneous gravity slump and deformation structure in the coal seam itself both indicate that the lacustrine environment in the accumulation of the thick coalbeds was characterized by the relatively deep flood and violent sedimentation. This model can not only interpret reasonably the accumulation mechanism of the thick coalbeds developed in the fault basins in the Central Massif, France, but also show its features distinctively from those of the accumulation model of the traditional thick coalbeds.

关键词： thick coalbeds accumulation model sedimentary architecture Central Massif France.

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Geochemistry of Sedimentation and Diagenesis in Qixia Formation (Early Permian) of Badong, Hubei Province, china: Implications for T-R Cycle Interpretation

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Journal of earth Science 1999年第2期18卷 56-62页

作者： Yan Jiaxin Zhao Laishi faculty of earth sciences,{3., wuhan 4.0074.Fang Nianqiao Department of Geology and Mineral Resources,{3., Beijing 100083

Combined with sedimentary observation and mineralogical research on a type of drusy celestite of early diagenesis in origin, this geochemical study on the Qixia Formation at the Shuibuya Section, Badong County, Hubei Province of south china evaluates the contribution of sedimentation and diagenesis to the mass fractions of CaO, Al 2O 3. MgO, SiO 2, Fe 2O 3. Na 2O, K 2O, Mn, Sr, P and Ba in the carbonates. The Sr, initially released from the stabilization of carbonate calcium mineral, precipitated with sulfate ion as celestite in early diagenetic environment, where sulfate reduction was the minimum. Then it redistributed in burial diagenetic environment, where celestite was replaced by calcite. The fractions of the MgO and SiO 2 in the carbonates were mainly modified by the early dolomitization and silicification respectively. That of the Na 2O was overprinted by the burial diagenesis. Multivariate statistical analysis on data of sixty bulk rocks indicates that the mass fractions of the Al 2O 3. K 2O, Fe 2O 3. Mn, CaO, P and Ba were affiliated with the sedimentary factor despite the obvious decrease of CaO during early dolomitization and silicification. Among them, the Al 2O 3.and K 2O mainly represent the detrital components. In addition, a dysaerobic sedimentary background was confirmed by trace element measurement and information derived from the formation of the celestite. This genetic discrimination facilitates the interpretation of the transgressive regressive (T R) cycle and specialities featured this unusual carbonate unit.

关键词： sedimentation diagenesis celestite geochemistry T R cycle.

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Partial Melting and Its Implications for Understanding the Seismic Velocity Structure within the Southern Tibetan Crust

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Acta Geologica Sinica(English Edition) 2003年第1期77卷 64-71页

作者： YANG Xiaosong, MA Jin, JIN Zhenmin, GAO Shan and MA Shengli Geology Institute, china Seismological Bureau, Beijing 100029 Laboratory of Tectonophysics, china Seismological Bureau, Beijing 100029 faculty of {3. sciences, china university of geosciences, wuhan, Hubei 4.0074 china Seismol Bur Inst Geol Beijing 100029 Peoples R China china Seismol Bur Lab Tectonophys Beijing 100029 Peoples R China china Univ Geosci Fac Earth Sci Wuhan 430074 Hubei Peoples R China

In order to constrain the crustal wave velocity structure in the southernTibetan crust and provide insight into the contribution of crustal composition, geothermal gradientand partial melting to the velocity structure, which is characterized by low average crustalvelocities and widespread presence of low-velocity zone(s), the authors model the crustal velocityand density as functions of depth corresponding to various heat flow values in light of velocitymeasurements at high temperature and high pressure. The modeled velocity and density are regarded ascomparison standards. The comparison of the standards with seismic observations in southern Tibetimplies that the predominantly felsic composition at high heat flow cannot explain the observedvelocity structure there. Hence, the authors are in favor of attributing low average crustalvelocities and low-velocity zone(s) observed in southern Tibet mainly to partial melting. Modelingbased on the experimental results suggests that a melting percentage of 7-12 could account for thelow-velocity zone(s).

关键词： partial melting intracrustal low-velocity zone high-pressure andhigh-temperature experiments Tibetan plateau

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