检索结果-南通市图书馆

Discovery of potassic spilite (or poenite) in Langshan Group of Tanyaokou District,Inner Mongolia,china

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第6期44卷 563-567页

作者： PENG Runmindepartment of geology and Mineral Resources , china university of geosciences, beijing 100083, china department of geology and Mineral Resources China University of Geosciences Beijing China

It is believed that the albite-potash-feldspar-greenschists in the middle Proterozoic Langshan Group in Tanyaokou District are synsedimentary potassic spilite （or poenite） based on the following facts and features: （ ⅰ ） they occur in beds and look blackish （or apple） green and compact; （ ⅱ ） they bear blasto-glomeroporphyritic and blastocrystalloclastic crystals which consist of （altered） albite laths with hollow skeleton crystal texture in which there are slender dark strips and minor pyroxene, and blasto-amygdaloid filled with pyrite, chlorite, magnetite, etc.; （ ⅲ ） the results of the petrochemical diagrams show that they are orthometamorphites; （ Ⅳ ） Sm-Nd isotopic age of them is 1 824 Ma (model age (tDM) is 2 006—2 132 Ma).

关键词： potassic spilite (or poenite) middle Proterozoic Tanyaokou Deposit Inner Mongolia.

Dehydration melting of solid amphibolite at 2.0 GPa: Effects of time and temperature

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第8期48卷 1120-1133页

作者： ZHOU Wenge1, XIE Hongsen1, LIU Yonggang1, ZHENG Xiaogang1, ZHAO Zhidan2 & ZHOU Hui3 1. Laboratory of Material in the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, china 2. department of geology, china university of geosciences, beijing 100083, china 3. department of geology, Peking university, beijing 100871, china 1. Laboratory of Material in the Earth’s Interior Institute of Geochemistry Chinese Academy of Sciences 550002 Guiyang China 2. department of geology China University of Geosciences 100083 Beijing China 3. department of geology Peking University 100871 Beijing China

Two sets of dehydration-melting with a natural solid amphibolite, collected from North Himalayan structure zone, Tibet, have been carried out in multi-anvil apparatus at 2.0 GPa and 800―1000℃, for 12―200 h. One is keeping the pressure at 2.0 GPa and the annealing time of 12 h, changing the temperature (800―1000℃). The other is keeping the pressure at 2.0 GPa and temperature at 850℃, varying the annealing time (12―200 h). The products are inspected with microscope and electron probe. The results indicate that at 2.0 GPa, annealing time of 12 h, garnets, melts and clinopyroxenes occur in amphibolite gradually with increasing temperature and the chemical compositions of melt vary from tonalite to granodiorite, and then to tonalite. However, at 2.0 GPa and 850℃, with the annealing time increasing, the garnets, melts and cli-nopyroxenes also occur in amphibolite gradually and the chemical compositions of melt vary from tonalite to granodiorite. In both cases, melts interconnect with each other when the contents of melt are over the 5 vol.%. the viscosities of the melt produced in amphibolite at temperature higher than 850℃ are on a level with 104 Pa·s. The interconnected melt with such a viscosity may segregate from the source rock and form the magma over reasonable geological time. Therefore, it is believed that at the lower part of the overthickened crust, the tonlitic and grano-dioritic magma may be generated through the dehydration melting of amphibolite.

关键词： solid amphibolite, high pressure, high temperature, time, partial melting.

The Thermal Structure of the Upper Mantle in Eastern china——Inferred from the Petrological Model

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 1991年第2期65卷 195-201页

作者： Deng Jinfu and Zhao Hailing china university of geosciences, beijing 100083, china china university of geosciences Beijing 100083 China

Cenozoic basalt in eastern china contains abundant ultramafic xenoliths which are specimens of pyrolitesreleased during basaltic magma eruption. A total of 405 P-T data of pyroxene in the ultramafic rocks have beencollected, which present a more precise pyroxene geotherm. The average geothermal gradient in the upper man-tle represented by the pyroxene geotherm is about 3.3℃ / km, which is much less than that derived from theconductive thermal model (≈14℃ / km), implying the great significance of convective heat transfer. The calcu-lation shows that the contributions of convective and conductive heat transfers are 79% and 21%, *** perturbation in the thermal structure of the upper mantle is an important manifestation of thetectonothermal event of Cenozoic continental rifting and intense basaltic volcanism in eastern china. Based onthe pyroxene geotherm and its comparison with the current geothermal field derived from the measurements ofthe surface heat flows, it is suggested that the Moho may be a secondary thermal boundary. The currentgeothermal field and the thermal structure of the lithosphere in eastern china may mainly reflect the result ofthe tectonothermal disturbance in the Neogene-Quaternary, in other words, the lithosphere has just begun toCool.

关键词： The Thermal Structure of the Upper Mantle in Eastern china

Mechanism for calcite dissolution and its contribution to development of reservoir porosity and permeability in the Kela 2 gas field,Tarim Basin,china

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2008年第4期51卷 567-578页

作者： YU BingSong1,3, DONG HailLiang2,3 & RUAN Zhuang1,3 1 State Key Laboratory of Geological Processes and Mineral Resources, china university of geosciences, beijing 100083, china 2 department of geology, Miami university,Oxford, OH 45056, USA 3 Geomicrobiology Laboratory, china university of geosciences, beijing, 100083, china State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China department of geology Miami University Oxford OH 45056 USA Geomicrobiology Laboratory China University of Geoscien

This study is undertaken to understand how calcite precipitation and dissolution contributes to depth-related changes in porosity and permeability of gas-bearing sandstone reservoirs in the Kela 2 gas field of the Tarim Basin, Northwestern china. Sandstone samples and pore water samples are col-lected from well KL201 in the Tarim Basin. Vertical profiles of porosity, permeability, pore water chem-istry, and the relative volume abundance of calcite/dolomite are constructed from 3600 to 4000 m below the ground surface within major oil and gas reservoir rocks. Porosity and permeability values are in-versely correlated with the calcite abundance, indicating that calcite dissolution and precipitation may be controlling porosity and permeability of the reservoir rocks. Pore water chemistry exhibits a sys-tematic variation from the Na2SO4 type at the shallow depth (3600-3630 m), to the NaHCO3 type at the intermediate depth (3630―3695 m),and to the CaCl2 type at the greater depth (3728―3938 m). The geochemical factors that control the calcite solubility include pH, temperature, pressure, Ca2+ concen-tration, the total inorganic carbon concentration (ΣCO2), and the type of pore water. Thermodynamic phase equilibrium and mass conservation laws are applied to calculate the calcite saturation state as a function of a few key parameters. The model calculation illustrates that the calcite solubility is strongly dependent on the chemical composition of pore water, mainly the concentration difference between the total dissolved inorganic carbon and dissolved calcium concentration (i.e., [ΣCO2] -[Ca2+]). In the Na2SO4 water at the shallow depth, this index is close to 0, pore water is near the calcite solubility. Calcite does not dissolve or precipitate in significant quantities. In the NaHCO3 water at the intermedi-ate depth, this index is greater than 0, and pore water is supersaturated with respect to calcite. Massive calcite precipitation was observed at this depth interval and

关键词： calcite dissolution porosity thermodynamic Tarim Basin

Petrogenesis of Songshugou dunite body in the Qinling orogenic belt, Central china: Constraints from geochemistry and melt inclusions

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第8期48卷 1146-1157页

作者： SU Li1,2, SONG Shuguang3 & ZHOU Dingwu1 1. Key Laboratory of Continental Dynamics of the Ministry of Education, department of geology, Northwestern university, Xi’an 710069, china 2. The Geological Lab Center, china university of geosciences (beijing), beijing 100083, china 3. Key Laboratory of Orogenic Belts of the Ministry of Education, department of geology, Peking university, beijing 100871, china 1. Key Laboratory of Continental Dynamics of the Ministry of Education Department of Geology Northwestern University 710069 Xi’an China 2. The Geological Lab Center China University of Geosciences 100083 (Beijing)Beijing China 3. Key Laboratory of Orogenic Belts of the Ministry of Education Department of Geology Peking University 100871 Beijing China

The Songshugou dunite body, which occupies an area of about 20 km2, is the largest ultramafic massif in the eastern Qinling orogenic belt, Central china. The major compo-nent of this body is dunitic rocks including mylonitic dunite and coarse-grained dunite; they oc-cupy about 95 vol% of the total body. Petrography, mineral composition, major and trace ele-ments and primitive melt inclusions have been investigated in this paper; all revealed that this dunite body is the product of melt-rock interaction by porous percolation flow. In comparison with dunite sills or veins in harzburgite from the basal part of Oman ophiolite, this dunite body is characterized by lower contents of Al2O3, CaO and HREE but higher content of highly incom-patible elements and Zr and Hf. The LREE enriched patterns and primitive mantle normalized spidergrams of trace elements are also different from the Oman dunite. Combining with melt in-clusions observed in olivines, we conclude that this dunite body is the product of large- scale porous percolation flow of high-MgO melts within depleted mantle peridotites. The high-MgO magma, in essence, was most probably produced at the hot head of an upwelling mantle plume. The occurrence of the Songshugou dunite body is closely associated with the activity of mantle super-plume in Neo-Proterozoic era in the Yangtze Craton.

关键词： Songshugou dunite body, geochemistry, melt inclusion, mantle plume, Qinling orogenic belt.

Mineralogy and crystal structure determination of Mg-fillowite

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第5期48卷 635-646页

作者： MA Zhesheng 1 , SHI Nicheng 1 & YE Danian 2 1. china university of geosciences, beijing 100083, china 2. Institute of geology, Chinese Academy of Sciences, beijing 100029, china 1. china university of geosciences 100083 Beijing China 2. Institute of geology Chinese Academy of Sciences 100029 Beijing China

Accurate crystal structure determination of complex phosphate Mg-fillowite ? Na2Ca(Mn4Mg2Fe)7[PO4]6 has been finished. Mg-fillowite occurs in muscovite-pegmatite in the Altay area, Xinjiang, china. It is of the trigonal lattice, with space group R-3, unit cell a=1.5143(3) nm, c=4.3191(2) nm, V=8.5736 nm3, Z = 18. The R-factor of the determination accuracy is R (I > 2σ ( I )) = 0.0776. The cationic polyhedra consist of two kinds of structural units: compound col- umn and screw column. In three-dimensional space, they are linked with each other through corner sharing or edge sharing to build the entire structure. There are 45 atoms in an asymmetric unit and 720 atoms in a unit cell. In terms of types and connection manners of the coordination polyhedra, the degree of complicity is rarely seen in all mineral crystal structures. Study of such a structure is significant for the classification of phosphate and the building rule of coordination polyhedra in a complex crystal structure.

关键词： Mg-fillowite, complex phosphate, crystal structure, coordination polyhedron.

Identifying rock blocks based on hierarchical rock-mass structure model

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2009年第10期52卷 1612-1623页

作者： XU NengXiong School of Engineering and Technology, china university of geosciences, beijing 100083, china School of Engineering and Technology China University of Geosciences Beijing 100083 China

Rock-masses are divided into many closed blocks by deterministic and stochastic discontinuities and engineering interfaces in complex rock-mass engineering. Determining the sizes, shapes, and adjacent relations of blocks is important for stability analysis of fractured rock masses. Here we propose an algorithm for identifying spatial blocks based on a hierarchical 3D Rock-mass Structure Model (RSM). First, a model is built composed of deterministic discontinuities, engineering interfaces, and the earth's surface, and the deterministic blocks surrounded by these interfaces are traced. Then, in each deter-ministic block, a network model of stochastic discontinuities is built and the stochastic blocks are traced. Building a unitary wire frame that connects all interfaces seamlessly is the key for our algorithm to identify the above two kinds of blocks. Using this algorithm, geometric models can be built for block theory, discrete element method, and discontinuous deformation analysis.

关键词： rock-mass engineering discontinuity block identification 3D Rock-mass Structure Model network model of stochastic discontinuities

Origin,evolution and extinction of Cathaysia flora

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第2期44卷 100-108页

作者： SUN Keqinchina university of geosciences, beijing 100083, china china university of geosciences Beijing China

Recent research results showed that the Cathaysia flora originated and developed from the global uniform Lepidodendropsis flora of the Early Carboniferous, which had already become an independent flora in the early Late Carboniferous (Namurian B to C). The center of origin of the Cathaysia flora is restricted to the North china Plate. On the basis of the successional characteristics of the Cathaysia flora in different geological ages, it may be divided into seven evolutionary stages. The evolutionary trend of the Cathaysia flora, as a whole, was characterized by the gradual increase of the typical Cathaysian elements in the sequence from the early Late Carboniferous to the early Late Permian, which began to decline during the late Late Permian. The climatic differentiation, tectonic movement,oceanic circulation, palaeogeographical environment, extraterrestrial event and plant evolution caused the mass extinction of the Cathaysia flora on a large scale by the end of the Permian.

关键词： Asia Cathaysia flora origin evolution extinction Late Carboniferous Permian.

Oxfordian (Jurassic) mayaitid (ammonite) dispersal in the Tibetan Himalaya as the first signal of the establishment of the Indo-Austrai subrealm

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2003年第4期13卷 44-49页

作者： YIN Jiarun(china university of geosciences, beijing 100083, china) china Univ Geosci Beijing 100083 Peoples R China

New fossil collections in the Lanongla area, Tibetan Himalaya enables the establishment of the Upper Jurassic ammonoidsuccession. Middle Oxfordian ammonite-fauna is characterized by endemic epimayaittds with a marine deepening event, suggesling a high stand of sea Ievel in the Tibetan Himalaya. Distribution of mayaitids around the Eastern Gondwana can be regarded as the first signal of the Indo-AustraI Subrealm that was progressively established during the Late Jurassic and Early Cretaceous times.

关键词： Jurassic Oxfordian ammonites Tibetan Himalaya Indo-Austral Subrealm.