检索结果-南通市图书馆

Paleomagnetic, tectonic and geochronological constraints for Permian-Triassic oroclinal bending of the Mongolian collage

在线全文

学校读者我要写书评

暂无评论

National Science Review 2023年第2期10卷 9-11页

作者： Karel Schulmann Jean Bernard Edel Ondrej Lexa Wenjiao Xiao D.T■ebínová Richard Spikings Urs Schaltegger Arkadiusz Derkowski Marek Szczerba Centre for Lithospheric Research Czech Geological Survey Institut Terre et Environnement de Strasbourg Université de Strasbourg Institute of Petrology and Structural geology Charles University Xinjiang Research Center for Mineral Resources Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Earth and Environmental Sciences Department of Earth Sciences University of Geneva Institute of geological Sciences Polish Academy of Sciences

The Central Asian Orogenic Belt constitutes the Kazakhstan and Mongolian oroclinal collages located between the Tarim-North China collage(TNC)to the south and the Siberian craton to the north(Fig.1a) [1].While the oroclinal bending of the western Kazakhstan collage is widely accepted by the paleomagnetic and tectonic community,the oroclinal bending model of the eastern Mongolian collage is disputed[2,3].Despite differences,

关键词： ASIAN OROGENIC BELT DEFORMATION SIBERIA ALTAI

Temporal and spatial distribution of microfractures in granites of different structures under triaxial compression and its significance in seismology

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第14期44卷 1321-1325页

作者： Liqiang Liu Shengli Ma Jin Ma Xinglin Lei K. Kusunose O. Nishizawa L. Jouniaux China Seismol Bur Inst Geol Beijing 100029 Peoples R China geol survey Japan Tsukuba Ibaraki 305 Japan Ecole Normale Super Geol Lab F-75231 Paris France CNRS URA 1316 Paris France

The temporal and spatial distribution of microfracturing activity in two kinds of granite under triaxial compression has been studied by using a new acoustic emission system. For Inada granite, there is no clear clustering of acoustic emission events in time and space, thus it is difficult to exactly deduce the time and position of the major fracturing. While for Mayet granite,acoustic emission events are clustered in time and space, so the time and position of the major fracturing can be exactly predicted according to microfracturing process. Such a difference may result from the difference in deformation mode caused by different rock structures.

关键词： rock structure acoustic emission microfracturing temporal and spatial distribution seismicity.

Discovery of fossil monocotyledons from Yixian Formation, western Liaoning

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第3期43卷 230-233页

作者： Zhengyao Cao Shunqing Wu Ping’an Zhang Jieru Li Chinese Acad Sci Nanjing Inst Geol & Palaeontol Nanjing 210008 Peoples R China Fuxin Mineral Coll Fuxin 123000 Peoples R China Reg geol survey Team Liaoning Prov Dalian 116100 Peoples R China

This is the first reports of a few fossil monocotyledons, including \%Liaoxia chenii\% gen. et sp. nov. (belonging to Cyperaceae), \%Eragrosites changii\% gen. et sp. nov. (Gramineae) and a monocotyledonous leaf_shoot, obtained from the Late Jurassic Yixian Formation of western Liaoning Province, NE China. These fossils are the oldest known angiosperms in the world. It may be inferred that the earliest angiosperms probably appeared even earlier than the Late Jurassic.

关键词： western Liaoning Late Jurassic Yixian Formation monocotyledon.

Reconstruction of the mid-Devonian HP-HT metamorphic event in the Bohemian Massif(European Variscan belt)

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2022年第3期13卷 177-195页

作者： Stephen Collett Karel Schulmann Piérig Deiller PavlaŠtípská Vít Peresty Marc Ulrich Yingde Jiang Luc de Hoÿm de Marien Jitka Míková Centre for Lithospheric Research Czech Geological SurveyKlárov 311821 Praha 1Czech Republic Institut Terre et Environnement de Strasbourg UMR 7063 Universitéde Strasbourg—CNRS1 Rue Blessig67084 StrasbourgCedexFrance Institute of Petrology and Structural geology Charles UniversityAlbertov 6Praha 212843Czech Republic State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Laboratories of the czech geological survey Geologická615200 Praha 5Czech Republic

Mid-Devonian high-pressure(HP)and high-temperature(HT)metamorphism represents an enigmatic early phase in the evolution of the Variscan *** the Bohemian Massif this metamorphism is recorded mostly in allochthonous complexes with uncertain relationship to the major tectonic *** this regard,the MariánskéLázně Complex(MLC)is unique in its position at the base of its original upper plate(Teplá-Barrandian Zone).The MLC is composed of diverse,but predominantly mafic,magmatic-metamorphic rocks with late Ediacaran to mid-Devonian protolith ***-Devonian HP eclogite-facies metamorphism was swiftly followed by a HT granulite-facies overprint contemporaneous with the emplacement of magmatic rocks with apparent supra-subduction *** Hf in zircon isotopic measurements combined with a review of whole-rock isotopic and geochemical data reveals that the magmatic protoliths of the MLC,as well as in the upper plate Teplá-Barrandian Zone,developed above a relatively unaltered Neoproterozoic lithospheric *** remained coupled with this lithospheric mantle throughout a geological timeframe that encompasses separate Ediacaran and Cambrian age arc magmatism,protracted early Paleozoic rifting,and the earliest phases of the Variscan *** results are presented in the context of reconstructing the original architecture of the Variscan terranes up to and including the mid-Devonian HP-HT event.

关键词： Variscan Orogeny Avalonian-Cadomian Orogeny Eclogite Geochemistry Zircon Lu-Hf geochronology

Nd-Hf Isotopic Decoupling of the Silurian–Devonian Granitoids in the Chinese Altai: A Consequence of Crustal Recycling of the Ordovician Accretionary Wedge?

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2020年第1期31卷 102-114页

作者： Yanqiong Huang Yingd Jiang Yang Yu Stephen Collett Sheng Wang Tan Shu Kang Xu State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China Center for Lithospheric Research Czech Geological SurveyPragueCzech Republic

Voluminous Silurian–Devonian granitoids intruded a greywacke-dominated Ordovician accretionary wedge in the Chinese Altai. These granitoids are characterized by significant Nd-Hf isotopic decoupling, the underlying mechanism of which, so far, has been poorly understood. This issue is addressed in this study by the integration of our new and regional published geological and geochemical data. geological studies indicated a close spatial relationship between the regional anatexis of the Ordovician wedge and the formation of the granitoids, which is characterized by a gradual textural evolution from the partial molten Ordovician wedge sedimentary rocks(the Habahe Group) to the granitoid bodies. Compositionally, these granitoids and the Ordovician Habahe Group rocks displayed close geochemical similarities, in the form of arclike trace elemental signatures as well as comparable Nd isotopic characteristics. Combined with regional available data, we suggest that the Silurian–Devonian granitoids originated from the immature and chemically primitive Habahe Group rocks. Since Nd and Hf isotopic data for the Habahe Group rocks show significant Nd-Hf isotopic decoupling, we propose that the Silurian–Devonian granitoids inherited the Nd and Hf isotopic signatures from their sources, i.e., the Habahe Group rocks. In other words, the Nd-Hf decoupling in the Habahe Group rocks is the primary causative factor leading to the prevailing Nd-Hf isotopic decoupling of the Silurian–Devonian granitoids in the Chinese Altai.

关键词： granitoids crustal recycling Ordovician wedge sediments partial melting Nd-Hf decoupling Chinese Altai geochemistry

扬子地块北缘西乡群孙家河组火山岩形成时代及元素地球化学研究

在线全文

学校读者我要写书评

暂无评论

岩石学报 2009年第12期25卷 3309-3326页

作者：徐学义夏林圻陈隽璐马中平李向民夏祖春王洪亮 CGS Xian Ctr Geol Survey Xian 710054 Peoples R China

西乡群孙家河组为一套低绿片岩相浅变质火山-沉积岩系,主要由基性-中基性-酸性火山岩和凝灰岩、沉凝灰岩、泥岩、硅质岩组成,火山岩岩石类型包括玄武岩、安山岩、英安岩和流纹岩。LA-ICPMS锆石U-Pb定年揭示流纹岩形成时代为832.9±4.9Ma... 详细信息

西乡群孙家河组为一套低绿片岩相浅变质火山-沉积岩系,主要由基性-中基性-酸性火山岩和凝灰岩、沉凝灰岩、泥岩、硅质岩组成,火山岩岩石类型包括玄武岩、安山岩、英安岩和流纹岩。LA-ICPMS锆石U-Pb定年揭示流纹岩形成时代为832.9±4.9Ma,辉石玄武岩的形成时代为845.0±17Ma,两者在误差范围内一致,属新元古代同期岩浆作用产物。元素地球化学研究表明,孙家河组玄武岩属拉斑玄武岩系列,具有受地壳混染的板内玄武岩的地球化学特点。玄武岩-安山岩-英安岩主量元素成分投点呈规律性变化、REE球粒陨石标准化及微量元素原始地幔标准化分配型式具有一致性并相互重叠,不相容元素Th和相容元素Cr相关模拟图中沿分离结晶线分布,证明玄武岩-安山岩-英安岩为同一基性岩浆分离结晶的产物。REE和微量元素分配型式以及微量元素比值时的显著差异,暗示流纹岩与玄武岩-安山岩-英安岩来源于不同源区。Sr-Nd同位素研究表明,玄武岩-安山岩-英安岩样品的ε_(Nd)(t)值均大于0以及在ε_(Nd)(t)-(^(87)Sr/^(86)Sr),图解中位于OIB成分区,表明其源区应为与洋岛玄武岩类似的地幔源区;流纹岩样品具有可与基性熔岩相比拟的ε_(Nd)(t)值,暗示流纹岩最有可能是初生玄武质地壳部分熔融而成。本文所研究的原划孙家河组火山岩系列的形成时代、构造环境的确定以及扬子陆块乃至世界上同一时间内普遍发育大陆裂谷岩浆岩组合的地质事实,说明原划孙家河组以及西乡群中的确存在新元古代的组成部分,它们应是新元古代大陆裂谷的产物,它和扬子地块820Ma后造山裂解环境花岗岩均是新元古代晚期Rodinia超大陆裂解作用的岩浆响应。

关键词：地块北缘西乡群孙家河组火山岩形成时代微量元素地球化学化学研究 Yangtze Plate northern Xixiang Group volcanic rocks study 拉斑玄武岩系列 trace element 新元古代英安岩流纹岩安山岩岩浆分离结晶

Shifts of the Kuroshio axis over the last 20 000 years

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第12期43卷 1053-1056页

作者： Jian Zhimin Y. Saito Wang Pinxian Li Baohua Chen Ronghua Tongji Univ Lab Marine Geol Shanghai 200092 Peoples R China geol survey Japan Marine Geol Dept Tsukuba Ibaraki 305 Japan Chinese Acad Sci Nanjing Inst Geol & Paleontol Nanjing 210008 Peoples R China State Ocean Adm Inst Oceanog 2 Hangzhou 310012 Peoples R China

Core 255 from the southern Okinawa Trough was selected to monitor the shift of the Kuroshio axis over the last 20 000 years. During the last glacial maximum the Kuroshio axis had ever shifted outside the Okinawa Trough. It entered the Okinawa Trough again at about 6 500 a BP, leading to abrupt increase of sedimentation rate, distinctly coarser sediment and remarkably increased abundance of foraminiferal indicators of the Kuroshio in the core. But, during about 4 000-3 000 a BP the abundance of the Kuroshio indicator Pulleniatina obliquiloculata sharply decreased again, indicating that the Kuroshio axis had ever shifted easterly for a short period or the Kuroshio was weakened and that moment.

关键词： Kuroshio paleooceanography AMS 14C dating foraminifera Okinawa Trough.

DESCRIPTIONS OF TWO SPECIES OF CHAETETES FROM THE MOSCOVIAN OF NORTH CHINA.

在线全文

学校读者我要写书评

暂无评论

地质学报 1928年第Z1期 235-237+239-241页

作者：朱森 geol. survey of China.

Corallum massive, composed of long irregular prismatic and often curved corallites, which are completely amalgamated by means of their epithecae and show no trace of divisional lines between them. Epitheca imperforate... 详细信息

关键词： DESCRIPTIONS OF TWO SPECIES OF CHAETETES FROM THE MOSCOVIAN OF NORTH CHINA very

The bio-barite in witherite deposits from Southern Qinling and its significance

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2004年第10期14卷 49-55+98页

作者： Lv Zhicheng 1,2 ,LIU Congqiang 2 ,LIU Jiajun 2 and WU Fengchang 2 (1.Development and Research Center,China geological survey,Beijing100037,China 2.Institute of Geochemistry,Chinese Acade-my of Sciences,Guiyang550002,China) China geol survey Ctr Res & Dev Beijing 100037 Peoples R China Chinese Acad Sci Inst Geochem Guiyang 550002 Peoples R China

Being stratiform or stratoid,the Huangboshuwan witherite deposit at Zhiyang and the Wenyuhe witherite-barite deposit at Zhushan occur in the lower Lower Cambrian siliceous rocks and the orebodies are remarkably controlled by lithological character and *** and oxygen isotopic studies of witherite,barytocalcite and calcite have shown that the carbon,involved in the formation of these minerals,was derived largely from organic carbon resultant from degradation,polycondensation and dehydroxylation of bio-organic matter in sediments at the early stage of *** occurrence of bio-barite strongly evidenced that Ba 2+ was concentrated and settled down in the form of bio-barite on the seafloor as a result of biological processes,thereafter forming the initially enriched orebodies of barium *** witherite was metasomatic products of bio-barite under the action of sulfate-reducing bacteria and organic and inor-ganic reduction.

关键词： bio-barite carbon and oxygen isotopes early diagenesis witherite deposits