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Modern Black Sea oceanography applied to the end-Permian extinction event

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Journal of Palaeogeography 2015年第1期4卷 52-62页

作者： Steve Kershaw Institute for the Environment Health and Societies Brunel UniversityKingston LaneUxbridge Middlesex UB8 3PH UK

The modern Black Sea has a mixed upper layer in the top 150-200 m of the water column, below which the water is anoxic, separated from the mixed layer by a redox boundary. There is limited vertical movement of water. Pyrite framboids form in the water column of the anoxic zone, then have been traditionally interpreted to sink immediately and accumulate in the sediments of the Black Sea. Thus the occurrence of framboids in sediments in the rock record is widely interpreted to indicate poorly oxygenated to anoxic conditions in ancient environments. However, in the Permian-Triassic boundary （PTB） microbialites of South China, which formed in shallow marine conditions in contact with the atmosphere, the published occurrence of framboids is inconsistent with abundant gastropod and ostracod shells in the microbialite. Furthermore, in the modern Black Sea, （a） framboids may be suspended, attached to organic matter in the water column, thus not settle to the sea floor immediately after formation; and （b） the redox zone is an unstable complex area subject to rapid vertical water movement including occasional upwelling. The model presented here supposes that upwelling through the redox zone can lead to upward transport of suspended pyrite framboids into the mixed layer. Advective circulation could then draw suspended framboids onto the shelf to be deposited in oxygenated sediments. In the Permian-Triassic transition, if framboids were upwelled from below the redox boundary and mixed with oxygenated waters, sediment deposited in these conditions could provide a mixed signal for potentially misleading interpretations of low oxygen conditions. However, stratigraphic sampling resolution of post-extinction microbialites is currently insufficient to demonstrate possible separation of framboid-bearing layers from those where framboids are absent. Profound differences between microbialite constructors and sequences between the western and eastern Tethys demonstrate barriers to migra

关键词： mass extinction Permian-Triassic boundary microbialite ostracods gastro-pods anoxia Black Sea

Karren of Mushroom Mountain(Junzi Shan) in the Eastern Yunnan Ridge,Yunnan,China:Karstological and Tourist Attraction

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Acta Geologica Sinica(English Edition) 2010年第2期84卷 424-431页

作者： Martin KNEZ Tadej SLABE Karst Research Institute ZRC SAZU Titov trg 26230 PostojnaSlovenia

Mushroom Mountain karren with predominantly flat tops that formed along the stylolites and bedding planes dictated the special features of this karst landscape. Their features and rock relief clearly reflect the geological conditions and development. The subsoil karren with conical tops dissected by subsoil rock relief were exposed from beneath the soil. Below tree vegetation, the subsoil karren are to a great extent covered by moss and lichen, under which they acquire their characteristic shape. On the bare surface they were reshaped by rainwater that carves flutes and solution pans. The old cave that opens below the top of one of the cones reveals the period before its dissection into hills and cones when this part of the karst aquifer was still deep under the water table.

关键词： karst karren cave rock relief development of karst Shizong Yunnan

Origins of the supercontinent cycle

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Geoscience Frontiers 2013年第4期4卷 439-448页

作者： R.Damian Nance J.Brendan Murphy Department of Geological Sciences.316 Clippinger Laboratories.Ohio University.Athens.OH 45701.USA Department of Earth Sciences st.Francis Xavier UniversityAntigonishNova Scotia B2G 2W5.Canada

The supercontinent cycle, by which Earth history is seen as having been punctuated by the episodic assembly and breakup of supercontinents, has influenced the rock record more than any other geologic phenomena, and its recognition is arguably the most important advance in Earth Science since plate tectonics. It documents fundamental aspects of the planet＇s interior dynamics and has charted the course of Earth＇s tectonic, climatic and biogeochemical evolution for billions of years. But while the widespread realization of the importance of supercontinents in Earth history is a relatively recent development, the supercontinent cycle was first proposed thirty years ago and episodicity in tectonic processes was recognized long before plate tectonics provided a potential explanation for its occurrence. With interest in the supercontinent cycle gaining momentum and the literature expanding rapidly, it is instructive to recall the historical context from which the concept developed. Here we examine the supercontinent cycle from this perspective by tracing its development from the early recognition of long-term epi- sodicity in tectonic processes, through the identification of tectonic cycles following the advent of plate tectonics, to the first realization that these phenomena were the manifestation of episodic superconti- nent assembly and breakup.

关键词： Supercontinent cyclePlate tectonicsTectonic episodicitySecular trends

Biomarkers in the Molar Tooth (MT)Bearing Limestones in the Jilin-Liaoning Area of China

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Chinese Journal Of Geochemistry 2004年第4期23卷 334-341页

作者：旷红伟李艳霞曾艳涛孟祥化葛铭 School of Geophysics and Petroleum Resources of Yangtze University School of Resource and Information of the University of Petroleum Institute of Sedimentary Basin of China University of Geosciences

The origin of Molar Tooth(MT)carbonates has been argued for more than 100 years, which are a kind of Proterozoic carbonates especially composed of microsparite with ptygmatically folded and sheet-like structures. Biomarkers detected in the microcalcsparite from the Wanlong and Xingmincun formations in the Jilin-Liaoning area showed there are abundant normal alkanes, isoprenoids, hopanes, steranes, alkylmethylcyclohexanes, and alkylcyclohexanes, indicating a diversity of biological source: long-chain isoprenoids, the major components of chlorophyll, such as C 19, C 20, a kind of major biomarkers synthesized early by isoprenoid monomers; hopanes a type of characteristic biomarkers from prokaryote, such as archaebacteria and cyanobacteria; sterane a biomarker for eukaryote; and two kinds of alkanes with C 17, C 18 as the main peaks representing aquatic bacteria and with C 23, C 24 as the main peaks representing fungi, respectively. Biomarker analysis showed that MT is the result of bacterial and algal activities, which is a kind of organisms between aerobic and anaerobic bacteria, reproducing well in normal or slightly saline sea water under weak oxidation-reduction conditions, resulting in rapid deposition of calcite as microsparite due to some mechanisms.

关键词： MT 碳酸盐有机物吉林-辽林地区地球化学矿床沉降

Response of Reactive Phosphorus Burial to the Sedimentary Transition from Cretaceous Black Shales to Oceanic Red Beds in Southern Tibet

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Acta Geologica Sinica(English Edition) 2007年第6期81卷 1012-1018页

作者： HUANG Yongjian WANG Chengshan CHEN Xi State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Research Center for Tibetan Plateau Geology China University of Geosciences Beijing 100083 China

The mechanism of sedimentary transition from the Cretaceous black shales to the oceanic red beds is a new and important direction of Cretaceous research. Chemical sequential extraction is applied to study the burial records of reactive phosphorus in the black shale of the Gyabula Formation and oceanic red beds of the Chuangde Formation, Southern Tibet. Results indicate that the principal reactive phosphorus species is the authigenic and carbonate-associated phosphorus （CAP） in the Gyabula Formation and iron oxides-associated phosphorus （FeP） in the Chuangde Formation which accounts for more than half of their own total phosphorus content. While the authigenic and carbonate-associated phosphorus （CAP） is almost equal in the two Formations; the iron oxidesassociated phosphorus is about 1.6 times higher in the Chuangde Formation than that in the Gyabula Formation resulting in a higher content of the total phosphorus in the Chuangde Formation. According to the observations on the marine phosphorus cyde in Modern Ocean, it is found that preferential burial and regeneration of reactive phosphorus corresponds to highly oxic and reducing conditions, respectively, leading to the different distribution of phosphorus in these two distinct type of marine sediments. It is the redox-sensitive behavior of phosphorus cycle to the different redox conditions in the ocean and the controlling effects of phosphorus to the marine production that stimulate the local sedimentary transition from the Cretaceous black shale to the oceanic red beds.

关键词： Reactive phosphorus black shale oceanic red beds Cretaceous Southern Tibet China

Background and Research Prospect of Geo-ecological Survey and Monitor in the Critical Zone of Black Soil

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Acta Geologica Sinica(English Edition) 2019年第S1期93卷 126-129页

作者： LI Zhizhong WANG Daming DAI Huimin WANG Xisheng LIANG Shuai XU Jiang YANG Jiajia WANG Lei CHEN Shengbo A lecos DEMETRIADES Veronika KOPACKOVA Igor SAVIN Douglas A.HOWARD Timothy FILLEY GENG Xiaoyuan Shenyang Geological Survey of China Geological Survey Shenyang 110030LiaoningChina China Geological Survey Beijing 100000China Institute of Geomechanics Chinese Academy of Geological SciencesBeijing 100000China British Geological Survey Ctr Environm SciNottingham NG125GGEngland Jilin University Institute of Geology and Mineral Exploration Olympic VillageChangchun 130026JilinChina Czech Geological Survey Remote Sensing DepartmentPrague11821Czech Republic Russian Academy of Sciences Kirensky Institute of Physics Krasnoyarsk660036Russia Department of Geology Arizona State University TempeArizona85287-1404USA Purdue Univ Dept Earth Atmospher&Planetary Sci550 Stadium Mall DrW LafayetteIN 47907USA Kentville Research and Development Centre Agriculture and Agri-Food CanadaKentvilleNS B4N 1J5Cancda

The American Science journal,on the occasion of its 125 publication anniversary,in 2016,released 125 of the most challenging scientific issues(Kennedy et al.,2005)to the *** to the basics,breadth and the influence,25 of the issues which considered to be the most important were screened,including"How many people can the Earth carry?"(Stokstad,2005;Dailyg et al.,1992;Cohen,1995)and"How high will the greenhouse effect make the earth temperature?

关键词： black soils resource black soil critical zone earth critical zone

Re-folded structure of syn-orogenic granitoids(Padrón dome, NW Iberia):Assessing rheological evolution of cooling continental crust in a collisional setting

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Geoscience Frontiers 2019年第2期10卷 651-669页

作者： Rubén Díez Fernández Francisco J.Rubio Pascual Luis Miguel Martín Parra Departamento de Geodinámica Estratigrafía y PaleontologíaFacultad de Ciencias GeológicasUniversidad Complutense de Madrid Instituto Geológico y Minero de Espana

This contribution discusses about the rheological, kinematic and dynamic frameworks necessary to produce recumbent and upright folds from syn-orogenic granitic massifs that were formed during an early stage of magma genesis related to the onset of a migmatitic dome. Syn-kinematic granitoids occurring within the high-grade infrastructure of the Padron migmatitic dome(NW Iberia) are deformed into largescale recumbent folds(D_2) that are later affected by upright folds(D_3). Petrostructural analysis of a selected area of this dome reveals that after a period of crustal thickening(D_1), NNW-directed extensional flow gave way to recumbent folds and penetrative axial plane foliation(S_2). Superimposed subhorizontal compression resulted in upright folds(D_3). A closer view into the dynamics of the dome allows exploring the factors that may condition the nucleation of folds with contrasting geometries during progressive deformation of molten continental crust. The formation of folds affecting syn-kinematic granitoids suggests a cooling metamorphic path in migmatitic domes. Active and passive folding mechanisms require a crystallizing(cooling) magma to nucleate folds. A more competent metamorphic host inhibits fold nucleation from much less competent magmas. As it crystallizes, magma becomes more rigid(competent),and approaches viscosity values of its host. Passive folding is favored when no significant competence contrast exists between magma and host, so this folding mechanism is more likely shortly after magma genesis and emplacement. In such conditions, and under dominant subhorizontal flow accompanied by flattening(D_2),passive folding would produce isoclinal recumbent geometries. Further magma cooling introduces a shift into the rheological behavior of partially molten crust. Thereon, crystallizing magma bodies would represent significant competence contrasts relative to their host. At this point, buckling is a more likely folding mechanism, and more regular, buckle fo

关键词： Recumbent folds Migmatitic domes Partial melting Crustal-derived granitoids Orogenic collapse Variscan orogen

基于航磁资料对智利塔拉帕卡地区的构造解释及意义

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地球物理学进展 2024年第2期39卷 510-524页

作者：黄毓森朱小三王涛卢民杰童英黄河中国地质科学院地质研究所北京100037

智利塔拉帕卡地区西部阿卡塔玛和东部多明戈断裂系统控制了塔拉帕卡地区自西向东迁移的构造-岩浆活动和成矿类型.本文对智利塔拉帕卡地区航磁数据进行处理和解释,揭示了该地区近南北向、北西向和近东西向区域性深大断裂构造的位置及平... 详细信息

智利塔拉帕卡地区西部阿卡塔玛和东部多明戈断裂系统控制了塔拉帕卡地区自西向东迁移的构造-岩浆活动和成矿类型.本文对智利塔拉帕卡地区航磁数据进行处理和解释,揭示了该地区近南北向、北西向和近东西向区域性深大断裂构造的位置及平面分布特征,查明了塔拉帕卡地区火山机构基本上沿着深大断裂系统边界分布;确定了该地区大型斑岩矿床大多分布于磁异常和居里面变化的梯度带上、断裂系统的边缘部位及火山机构周边的规律;分析了阿卡塔玛和多明戈两大区域断裂系统形成原因,探讨了智利北部地区断裂构造系统与岩浆活动关系.为研究智利塔拉帕卡地区的地质、构造特征以及圈定找矿远景区提供基础性信息.

关键词：安第斯造山带航磁异常构造解释多明戈断裂系统阿卡塔玛断裂系统斑岩成矿

Late Permian to Triassic intraplate orogeny of the southern Tianshan and adjacent regions, NW China

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Geoscience Frontiers 2014年第1期5卷 83-93页

作者： Wei Ju Guiting Hou School of Earth and Space Science Peking University The Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education

The South Tianshan Orogen and adjacent regions of Central Asia are located in the southwestern part of the Central Asian Orogenic Belt. The formation of South Tianshan Orogen was a diachronous, scissors-like process, which took place during the Palaeozoic, and its western segment was accepted as a site of the final collision between the Tarim Craton and the North Asian continent, which occurred in the late Palaeozoic. However, the post-collisional tectonic evolution of the South Tianshan Orogen and adjacent regions remains debatable. Based on previous studies and recent geochronogical data, we suggest that the final collision between the Tarim Craton and the North Asian continent occurred during the late Carboniferous. Therefore, the Permian was a period of intracontinental environment in the southern Tianshan and adjacent regions. We propose that an earlier, small-scale intraplate orogenic stage occurred in late Permian to Triassic time, which was the first intraplate process in the South Tianshan Orogen and adjacent regions. The later large- scale and well-known Neogene to Quaternary intraplate orogeny was induced by the collision between the India subcontinent and the Eurasian plate. The paper presents a new evolutionary model for the South Tianshan Orogen and adjacent regions, which includes seven stages：（I） late Ordovician-early Silurian opening of the South Tianshan Ocean; （11） middle Silurian-middle Devonian subduction of the South Tianshan Ocean beneath an active margin of the North Asian continent; （111） late Devonian-late Carboniferous closure of the South Tianshan Ocean and collision between the Kazakhstan-Yili and Tarirn continental blocks; （IV） early Permian post-collisional magmatism and rifting; （V） late Permian-Triassic the first intraplate orogeny; （Vt） Jurassic-Palaeogene tectonic stagnation and （VII） Neocene-Quaternary intraplate orogeny.

关键词： Central Asian Orogenic Belt Northern Xinjiang South Tianshan Ocean Tectonics Tarim-North Asia collision