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Spatio-temporal carbon isotope variation during the Ediacaran period in South china and its impact on bio-evolution

Science china Earth Sciences 2009年第10期52卷 1520-1528页

作者： WANG XinQiang1 & SHI XiaoYing1,2.1 School of Earth Science and Mineral Resources, china university of geosciences, beijing 100083,{2. 2.State Key Laboratory of Geological Processes and Mineral Resources, beijing 100083,{2. School of Earth Science and Mineral Resources China University of Geosciences Beijing China State Key Laboratory of Geological Processes and Mineral Resources Beijing China

The Ediacaran period is characterized by the extremely negative carbon isotope anomalies and great biotic evolution in Earth history. At least four negative carbon isotope anomalies have been reported from this interval in South china so far. It is traditionally argued that the isotope variations can be used as a useful tool for global correlation of Ediacaran succession; however, more and more researches argued against this idea. We reviewed the previously published carbon isotope data in South china, and distributed the mean values of a certain time to the paleogeographic maps. The results show that the carbon isotope values (δ13C) vary greatly in different environments, but a clear tendency of becoming lighter from shallow platform to deep basin, with a maximum variation up to 1‰ Moreover, the important changes in Ediacaran biota, marked by the introducing of new taxa or ecologic groups, seemed to always postdate the negative anomalies but coincide with the positive shift. If the negative excursions represented the oxidation of a large dissolved organic carbon (DOC) reservoir in the ocean, the diverse Ediacaran organisms and the carbon isotope anomalies may suggest totally different environments: oxic and anoxic/euxinic. We also suggest that the elimination of euxinic state through precipitation of pyrites is one of the important environment factors in prompting the Ediacaran bio-evolution.

关键词： Ediacaran South china carbon isotope spatio-temporal variations bio-evolution

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Phylogeography of regional fauna on the Tibetan Plateau: A review

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Progress in Natural Science:Materials International 2009年第7期19卷 789-799页

作者： Shujuan Yanga, Hailiang Dongb,c, Fumin Lei d a State Key Laboratory of Geological Processes and Mineral Resources, china university of geosciences, beijing 100083,{2. b Geomicrobiology Laboratory, china university of geosciences, beijing 100083,{2. c department of geology, Miami university, Oxford, OH 45056, USA d Institute of Zoology, Chinese Academy of Sciences, beijing 100101,{2. State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Geomicrobiology Laboratory China University of Geosciences Beijing 100083 China department of geology Miami University Oxford OH 45056 USA Institute of Zoology Chinese Academy of Sciences Beijing 100101 China

The studies of uplift and glaciations of the Tibetan Plateau are summarized, and a series of recent case studies of the endemic species based on DNA sequences are detailed. In general, these molecular data show that all the organisms originated from Early Pliocene to Late Miocene, and then multi-stages of divergence/speciation occurred within each taxa following their original occupation on the plateau, mainly as a result of periodic glacial cycles and geographic isolation. The regional fauna may have undergone several range contractions and expansions during the Pleistocene glaciations. However, the population expansion and refugia may vary in space, time, and extent. The regional fauna of the Tibetan Plateau may be combinations of ancient movement from adjacent zoogeographical regions, speciation in situ, and postglacial colonization from adjacent areas. Geomorphic and climatic changes on the plateau definitely have a remarkable influence on the regional and adjacent biogeographic patterns, and the mechanism is very complex.

关键词： Divergence Refugia Postglacial colonization Phylogeography Regional fauna Tibetan Plateau

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An　Outline　of　Mesozoic　to　Paleogene　SequenceStratigraphy　and　Sea－Level　Changes　in　Northern　Himalayas，Southern　Xizang

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Journal of Earth Science 1995年第1期14卷 16-40页

作者： Shi Xiaoying Yin Jiarun(department of geology and Mineral Resources,{2.,beijing 100083)

In the Northern Himalayan region of Southern Xizang (Tibet),from the Lower Triassic to Upper Eocene 73 Sequences have been identified, with an average duration of 2.9 Ma;these can in turn be grouped into 2. super-Sequences and 6 super-sequence sets. During Mesozoic and Paleogene, several large sea - level falls occurred in the Eastern Neo-Tethys. Among the recognized sea- level falls, the important ones include those at the ages of 2.5 Ma, 2.5 Ma,177 Ma, 138 Ma, 103 Ma and 68 Ma .Those at 2.9 Ma, 2.5 Ma, 157 Ma,80 Ma, 50Ma and 36 Ma are also significant. The third-order Sequences and sea-level cycles Probably reflect mainly global sea - level fluctuations, while the higher rank cycles seem more closely related to the basin evolution of the Neo-Tethys. Based on the study, six major periods have been suggested for ths tectonic evolution of the Eastern Neo-Tethys and the plates, i. e. the Pangea Period (Pre-Triassic), continental rifting Period (Triassic to Early Jurassic ), inter-continental sea Period (Middle Jurassic ), continental divergence period (late Middle Jurassic to Early Cretaceous ), continental convergence period (Late Cretaceous ) and the continental collision Period (Paleogene ). These major Periods can be further subdivided into eight stages according to the basin evolution. In each of the periods and Stages, Sequences and their boundaries show clear characters related to the tectonic background. The study indicater that the initial breakup of the Pangea along the Indus- Yarlung may have taken Place around 2.9 Ma. The Late Bathonian to Early Callovian seems to have been a critical time in the evolution of the Neo-Tethys, with the turning Point around 158 Ma. The blocks split from the northern margin of the Gondwana continual did not obviously drift away from the Indian Plate until Callovian .The oceanic crust subduction in the Neo- Tethys may have Started at 113Ma, while the contraction of the ocean probably began at 107- 103 Ma. The initial contact of

关键词： Sequence stratigraphy sea-level change Mesozoic Cenozoic Northern Himalayas,southern Xizang.

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Jurassic Brachiopods and Paleogeography of North Qinghai-Tibetan Plateau

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Journal of Earth Science 1990年第1期9卷 17-37,135页

作者： Yang Zunyi Shi Xiaoyingdepartment of geology ,{2. , beijing 100083

This paper deals with Jurassic brachiopods from North Tibet and South Qinghai and the stratigraphical subdivision there. Based on faunas and strata,a general outline of the palaeogeographical evolution has been traced out along the line of plate-tectonic movements . In this paper , 10 species of 8 genera are described , among which the species Lacunosella rhombica , Rntithyris vulgaris , Tanyothyris appositus , Apatecosia navicularis and Flabellothyris sp . nov . have been recognized as new .

关键词： Jurassic brachiopods stratigraphy palaeogeography .

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Evidence of Bio-Organic Mineralization

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Journal of Earth Science 1994年第1期13卷 71-78页

作者： Zhang Aiyun Weng Chengmin(department of Enemy Resources geology,{2., beijing 100083)

The marine black shale formations of different epochs are widely seen in china. They usually come cul as ore-bearing horizon and contain different ore-forming element. Why are there so many different associated metallic elements in the marine black shale ? Evidence shows that the answer is bio-mineralization. The bio-mineralizahon in the process of formation of metalliferous black shales can be divided intp twp stages. The first stage is the bio-achvities occurring in the surface layer aquatic body of the ocean .The ore-forming elements could be absorbed by only a few species of organisms as a bioconcentrator. The second stage is the biogeochemical process. The anaerobic bacteria decomposed the organic remains and the metal elements were activated, and migrated and combined with organic matter or clay minerals or sulfide. After sediments were buried deeply, the organic matter were cracked by high earth *** metal elements in organic compound were continuously acivated, and migrated to form matamorphic minerals or hydrothermal minerals in original rocks or quartz veins. The biogenetic marks in the black shale are changed or distorted beyond recognition and not easy to be found.

关键词： Cambrian black shale vanadium tunicate bio-mineralization.

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Cretaceous-Paleocene Foraminiferal Communities from the Western Tarim Basin and Their Environmental Significance

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Journal of Earth Science 1990年第1期9卷 38-46页

作者： Hao Yichun Guo Xianpudepartment of geology ,{2. , beijing 100083

Foraminifera is one of the most important fossil faunas of the marine Cretaceous and Paleocene in the Western Tarim Basin, which can be divided into 9 communities. This paper deals mainly with the changes of environments in which the foraminiferal communities existed,especially with the changes of temperature and salinity revealed by analyses of test composition and trace elements in the tests , and by statistic studies of species density, richness , diversity ,equitability and dominance .

关键词： foraminiferal community ,ecological environment,Cretaceous Paleocene Western Tarim Basin Xinjiang .

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Implications of micro-compositions of garnet and biotite from high-grade meta-pelites

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Progress in Natural Science:Materials International 2006年第2期16卷 209-214页

作者： ZHOU Xiwen, WEI Chunjing, and ZHANG Shangkun ( Institute of geology, CAGS, beijing 100037,{2. School of Earth and Space Sciences, Peking university, beijing 100871,{2. china university of Geo-Sciences, beijing 100083,{2.) Institute of geology GAGS Beijing 100037 China School of Earth and Space Sciences Peking University Beijing 100871 China china university of Geo-Sciences Beijing 100083 China

Based on detailed studies on the compositional zoning of garnet and biotite in pelitic rocks from the Jingshan group of granulite facies in north Jiaodong, P-T pseudosections with isopleths of Fe/(Fe + Mg) in garnet and biotite were calculated in the KF-MASH system for two representative rocks of sillimanite-garnet-cordierite-biotite gneiss ( Vbi/ Vg>1 ) and sillimanite-garnet gneiss (Vbi/ Vg2. using the software THERMOCALC and the internally consistent thermodynamic dataset. With a comparison of the calculated Fe/(Fe+ Mg) values in garnet and biotite in the peak P-T fields constrained by peak mineral assemblages with the measured ones, it is concluded that the coarse garnet crystals with diffusion zoning from high grade meta-pelites can preserve their peak compositions even when they have experienced a cooling event, and that biotite crystals surrounded by fetsic minerals in biotite-rich rocks with Vbi/Vg> 1 can nearly preserve their peak compositions, and biotites in garnet-rich rocks with Vbi/Vg2.cannot preserve their peak compositions due to the influence of grain-boundary fluid.

关键词： high-grade meta-pelites THERMOCALC P-T pseudosection peak compositions of garnet and biotite.

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The refined theory of transversely isotropic piezoelectric rectangular beams

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Science china(Physics,Mechanics & Astronomy) 2006年第4期49卷 473-486页

作者： GAO Yang1 & WANG Minzhong2.1. College of Science, china Agricultural university,{2., china 2. State Key Laboratory for Turbulence and Complex Systems and department of Mechanics and Engi- neering Science, Peking university, beijing 100871, china College of Science China Agricultural University Beijing China State Key Laboratory for Turbulence and Complex Systems and department of Mechanics and Engineering Science Peking University Beijing China

The problem of deducing one-dimensional theory from two-dimensional theory for a transversely isotropic piezoelectric rectangular beam is investigated. Based on the piezoelasticity theory, the refined theory of piezoelectric beams is derived by using the general solution of transversely isotropic piezoelasticity and Lur'e method without ad hoc assumptions. Based on the refined theory of piezoelectric beams, the exact equations for the beams without transverse surface loadings are derived, which consist of two governing differential equations: the fourth-order equation and the transcendental equation. The approximate equations for the beams under transverse loadings are derived directly from the refined beam theory. As a special case, the governing differential equations for transversely isotropic elastic beams are obtained from the corresponding equations of piezoelectric beams. To illustrate the application of the beam theory developed, a uniformly loaded and simply supported piezoelectric beam is examined.

关键词： rectangular beams, the refined theory, piezoelectric, transversely isotropic.

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Cretaceous-Early Eocene Tectonic Stress Field in china

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Acta Geologica Sinica(English Edition) 1989年第3期63卷 227-239页

作者： Wan Tianfeng and Zhu Hong china university of geosciences, beijing,{2. 2.an Tianfeng male born in 1938 engaged in geological education since 1959 and now is a professor of the Teaching and Research Group of Structural Geology China University of Geosciences Beijing 100083. china university of {2. Beijing China

The Cretaceous-early Eocene tectonic stress field in china was reconstructed using the data of 369 largeand medium-scale flexural folds and 157 joint sets. It was found that the maximum compressive principal stress axis in eastern china dips 32. NE (nearly horizontal), and strikes SW 2.2., whereas that in western china dips 15° NE (also nearly horizontal) and trends SW 195°. The estimation of the dip angles of fold limbs and the palaeotectonic stress values indicates that there was a tendency of gradual weakening of tectonism from southwestern to northeastern china in the Cretaceous-early Eocene. At the depth of 2.3 km, the differential stress value changes from 183 MPa in Tibet to 100 MPa in North and East china.The authors consider that the tectonic stress of this period was related to the north-northeastward movement and push of the Indian-Australian plate.

关键词： Cretaceous-Early Eocene Tectonic Stress Field in china

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The refined theory of deep rectangular beams based on general solutions of elasticity

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Science china(Physics,Mechanics & Astronomy) 2006年第3期49卷 291-303页

The problem of deducing one-dimensional theory from two-dimensional the- ory for a homogeneous isotropic beam is investigated. Based on elasticity theory, the re- fined theory of rectangular beams is derived by using Papkovich-Neuber solution and Lur’e method without ad hoc assumptions. It is shown that the displacements and stresses of the beam can be represented by the angle of rotation and the deflection of the neutral surface. Based on the refined beam theory, the exact equations for the beam without transverse surface loadings are derived and consist of two governing differential equations: the fourth-order equation and the transcendental equation. The approximate equations for the beam under transverse loadings are derived directly from the refined beam theory and are almost the same as the governing equations of Timoshenko beam theory. In two ex- amples, it is shown that the new theory provides better results than Levinson’s beam the- ory when compared with those obtained from the linear theory of elasticity.

关键词： deep rectangular beams,the refined theory,Papkovich-Neuber solution,Lur'e method,governing equation

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