检索结果-南通市图书馆

Science China Earth Sciences 2008年第6期51卷 855-861页

作者： J. Warren BECK NSF-AMS laboratory University of Arizona

A simple model for reconstructing the paleomagnetic field intensity with (10)~Be production rate was used for the first time in Loess (10)~Be studies of Luochuan profile. Using the LGM (Last Glacial Maxmium) method, the climatic effects and geomagnetic modulation effects on loess (10)~Be was separated and in turn the 80 ka geomagnetic excursion sequence reconstructed, of which the globally remarkable geomagnetic excursion events such as the Laschamp (42 ka), Mono Lake (32 ka) during the Last Glacial period were revealed and the paleo-geomagnetic intensity curve from Loess (10)~Be over the past 80 ka was quantitatively reconstructed. The reconstructed paleo-intensity fits well with the paleo-intensity curves (SINT200 and NAPIS75), which indicates the significance of global criterion of the (10)~Be paleo- intensity curve and the future direction of loess (10)~Be tracing studies. Results show the irregular vari-ability of the East Asian monsoon precipitation in Loess Plateau is the main cause that has resulted in the ambiguity of the geomagnetic modulation of the (10)~Be record in the loess, and the intrinsic source component of the loess (10)~Be and inherited fraction of magnetic susceptibility (SUS) are characterized by the 'quasi-homogeneous distribution' manner.

关键词： (10)~Be LGM geomagnetic excursion paleointensity quasi-homogeneous distribution

Late Maastrichtian–Paleocene chronostratigraphy from Seymour Island,James Ross Basin,Antarctic Peninsula:Eustatic controls on sedimentation

在线全文

学校读者我要写书评

暂无评论

Advances in Polar Science 2019年第3期30卷 303-327页

作者： Manuel MONTES Elisabet BEAMUD Francisco NOZAL Sergio SANTILLANA Instituto Geológico y Minero de Espana(IGME) área de GeologíaGeomorfología y Cartografía GeológicaCalera 128760-Tres CantosMadridSpain paleomagnetic laboratory CCiTUB-Instituto de Ciencias de la Tierra'Jaume Almera’-CSIC Sole i Sabariss/n08028-BarcelonaSpain Instituto Antártico Argentino 25 de Mayo 1143San Martínprovincia de Buenos AiresArgentina

The Paleocene(66–56 Ma)was a critical time interval for understanding the geological history in high palaeolatitudes after the end of Cretaceous event(recovery from mass extinction,palaeoclimate,global sea level changes,among others).The sedimentary succession from Seymour Island(Antarctic Peninsula)provides key reference material from this important phase of the early Cenozoic.A detailed age model is proposed for the López de Bertodano Formation(LBF),Sobral Formation(SF)and Cross Valley–Wiman Formation(CVWF)based on a new magnetostratigraphic section which integrates previous dinoflagellate cyst biostratigraphy,Iridium anomaly(K-Pg boundary),U-Pb zircon dating(airfall tuff)and strontium isotope values from *** new composite magnetostratigraphic section,which includes the Cretaceous–Paleogene boundary,has been correlated to the GPTS from C29r up to *** top of the LBF is confirmed as latest Maastrichtian to earliest Danian(~65.4 Ma)in *** overlying SF is mostly Danian in age(~65.2–~63 Ma)and CVWF is Selandian–Thatenian(~61.3–56.9 Ma).LBF,SF and CVWF are unconformity-bounded units(alloformations)that record the geological evolution of the James Ross Basin during a period of relative decreasing tectonism but coeval with volcanic *** based internal units have been recognized,dividing each formation into allomembers(LBF:Molluscan and Cenozoic;SF:A,B and C;CVWF:Díaz,Ara?ado,Bahía Pingüino).The new age model allows correlation of base-level changes with eustatic sea-level *** bases of the SF and CVWF are correlated with the 65.3 and 61.5 Ma sea level lowstands.

关键词： Paleocene magnetostratigraphy Antarctic Peninsula James Ross Basin Seymour Island

Integrative Neogene stratigraphy, biotas and paleogeographic evolution of the Tibetan Plateau and its surrounding area

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2023年

作者： Tao DENG Xiaomin FANG Qiang LI Shiqi WANG Feixiang WU Sukuan HOU Jiao MA Qigao JIANGZUO Danhui SUN Yan ZHENG Qinqin SHI Boyang SUN Lu LI CAS Center for Excellence in Life and Paleoenvironment Beijing Key laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space Sciences Peking University University of Chinese Academy of Sciences Key laboratory of Vertebrate Evolution and Human Origins Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences and Key laboratory of Continental Collision and Plateau Uplift Institute of Tibetan Plateau Research Chinese Academy of Sciences

The remarkable uplift of the Tibetan Plateau in the Neogene had great impacts on the climate and environment of East Asia and even the world. Therefore, establishment of the Neogene stratigraphic framework of the Tibetan Plateau is of great significance to research in various fields of geosciences. Based on marine sediments, the international chronostratigraphic system of the Neogene is divided into six stages in the Miocene and two stages in the Pliocene. Since the beginning of the Cenozoic, the share of terrestrial strata on continents has increased rapidly. By the Neogene, it had far exceeded that of marine strata, and almost all deposits on the Tibetan Plateau and its surrounding areas were terrestrial strata. In China, the Miocene includes five stages and the Pliocene includes two stages. Except for the Tunggurian of the Miocene, which has a lower boundary at 15 Ma, the other stages have the same paleomagnetic definitions and time intervals as the corresponding international marine stages. Mammalian fossils play a very important role in the division and correlation of Cenozoic terrestrial strata, and rodent,carnivore, proboscidean, perissodactyl and artiodactyl fossils are especially important in Neogene terrestrial *** are many basins with well-exposed strata and abundant mammalian fossils in the Tibetan Plateau. The lower boundary stratotype sections of the Neogene Xiejian and Bahean stages are located respectively in the Xining and Linxia basins, and there are precise paleomagnetic dates in coordination with mammalian fossils. The lower boundary stratotypes of other stages can also be effectively determined in the Tibetan Plateau. Many first appearing mammalian genera in East Asia also appeared in the Tibetan Plateau and its surrounding areas, especially in the Linxia Basin on the northeast margin and in the Siwaliks on the southwest margin. Among them, Prodeinotherium first appeared at the bottom of the Miocene in the Siwaliks, and the ear

关键词：

100,000 year precipitation cyclicity in a late Miocene lake from Northeast Tibet

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

100,000 year precipitation cyclicity in a late Miocene lake ...

Movement History of the Microcontinents from the Tibetan Plateau Based on paleomagnetic Results with Sufficient Sampling Units

2017中国地球科学联合学术年会

作者： Junsheng Nie Carmala Garzione Qingda Su Qingsong Liu Rui Zhang David Heslop Cristian Necula Shihong Zhang Yougui Song Key laboratory of Western China’s Environment System College of Earth and Environmental Sciences Lanzhou University Department of Earth and Environmental Sciences University of Rochester Department of Marine Science and Technology South University of Science and Technology of China Research School of Earth Sciences The Australian National University Faculty of Physics Paleomagnetic Laboratory University of Bucharest State Key laboratory of Biogeology and Environmental Geology China University of Geosciences State Key laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences

East Asian summer monsoon(EASM)precipitation received by northern China over the past 800 kyr is characterized by dominant 100 kyr periodicity,attributed mainly to CO2and Northern Hemisphere insolation-driven ice sheet *** we established an EASM record in the late Miocene from lacustrine sediments in the Qaidam Basin,Northern China,which appears to exhibit a dominant 100 kyr periodicity similar to the EASM records

关键词： Northern year precipitation cyclicity in a late Miocene lake from Northeast Tibet CLP

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Journal of Earth Science 2022年第5期33卷 1072-1080页

作者： Yiming Ma Weimin Ruan Chao Niu Tianshui Yang School of Earth Sciences China University of GeosciencesWuhan 430074China College of Earth Sciences Guilin University of TechnologyGuilin 541004China State Key laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing 100083China

paleomagnetic results cannot be applied in global and regional tectonic reconstructions unless the paleosecular variation has been adequately ***,how many sampling sites and samples are enough to calculate a reliable paleopole remains *** on the relation among the sampling sites N,the precision parameter k,the virtual geomagnetic pole scatter s,and the confidence limit A_(95) of the paleopole,we find that 20 sites(samples)or more are required to yield a paleopole with an A_(95)≈5°based on a review of available paleomagnetic results from the Lhasa,Qiangtang and Tethyan *** samplings of Jurassic virtual geomagnetic poles from the Sangri area show that the Fisher mean pole with neglectable angle deviation can be obtained when sampling sites increase to ***-quality paleomagnetic results,with sites/samples number N/n≥~20–30,show that the Qiangtang,Lhasa,and Tethyan Himalaya moved northward in the Late Permian–Middle Triassic,Jurassic,and Cretaceous,respectively,and then accreted to Asia in the Late Triassic,Late Jurassic–Early Cretaceous and Paleocene–Early Eocene,respectively.

关键词： paleolatitude evolution Fisher mean random sampling sampling sites and samples continental collision tectonics

The absolute paleoposition of the North China Block during the Middle Ordovician

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2016年第1期59卷 573-582页

作者： WANG Hong Hao LI Jiang Hai ZHANG Hua Tian XU Li LI Wei Bo Key laboratory of Orogenic Belts and Crustal Evolution Ministry of Education School of Earth and Space SciencesPeking University

Present-day hot spots and Phanerozoic large igneous provinces(LIPs) and kimberlites mainly occur at the edges of the projections of Large Low Shear Wave Velocity Provinces(LLSVPs) on the earth's surface. If a plate contains accurately dated LIPs or kimberlites, it is possible to obtain the absolute paleoposition of the plate from the LIP/kimberlite and paleomagnetic data. The presence of Middle Ordovician kimberlites in the North China Block provides an opportunity to determine the absolute paleoposition of the block during the Middle Ordovician. In addition to paleobiogeographical information and the results of previous work on global plate reconstruction for the Ordovician Period, we selected published paleomagnetic data for the North China Block during the Middle Ordovician and determined the most reasonable absolute paleoposition of the North China Block during the Middle Ordovician: paleolatitude of approximately 16.6°S to 19.1°S and paleolongitude of approximately 10°W. The block was located between the Siberian Plate and Gondwana, close to the Siberian Plate. During the Cambrian and Ordovician periods, the North China Block may have moved toward the Siberian Plate and away from the Australian Plate.

关键词：华北块体中奥陶世西伯利亚板块古地磁数据金伯利岩大火成岩省冈瓦纳大陆剪切波速

paleomagnetic results from Late Carboniferous to Early Permian rocks in the northern Qiangtang terrane, Tibet, China, and their tectonic implications

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2017年第1期60卷 124-134页

作者： YANG XingFeng CHENG Xin ZHOU YaNan MA Lun ZHANG XiaoDong YAN ZhaoSheng PENG XiMing SU HaiLun WU HanNing Department of Geology and State Key laboratory of Continental Dynamics Northwest University Xi 'an 710069 China

Results of a systematic paleomagnetic study are reported based on Late Carboniferous to Early Permian sedimentary rocks on the north slope of the Tanggula Mountains,in the northern Qiangtang terrane(NQT),Tibet,*** revealed that magnetic minerals in limestone samples from the Zarigen Formation(CP^z)are primarily composed of magnetite,while those in sandstone samples from the Nuoribagaribao Formation(Pnr)are dominated by hematite alone,or hematite and magnetite in *** thermal,or alternating field,demagnetization allowed us to isolate a stable high temperature component(HTC)in 127 specimens from 16 sites which successfully passed the conglomerate test,consistent with primary *** tilt-corrected mean direction for Late Carboniferous to Early Permian rocks in the northern Qiangtang terrane is D_s=30.2°,I_s=-40.9°,k_s=269.0,a_(95)=2.3°,N=16,which yields a corresponding paleomagnetic pole at 25.7°N,241.5°E(dp/dm=2.8°/1.7°),and a paleolatitude of 23.4°*** results,together with previously reported paleomagnetic data,indicate that:(1)the NQT in Tibet,China,was located at a low latitude in the southern hemisphere,and may have belonged to the northern margin of Gondwana during the Late Carboniferous to Early Permian;(2)the Paleo-Tethys Ocean was large during the Late Carboniferous to Early Permian,and(3)the NQT subsequently moved rapidly northwards,perhaps related to the fact that the Paleo-Tethys Ocean was rapidly contracting from the Late Permian to Late Triassic while the Bangong Lake-Nujiang Ocean,the northern branch of the Neo-Tethys Ocean,expanded rapidly during this time.

关键词：北 Qiangtang 岩层晚含碳早二叠摇磁力集团企业测试 paleomagnetic 杆

New Jurassic paleomagnetic Results from Southeastern China and Their Geological Implication

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2011年第4期85卷 792-800页

作者： WANG Bin ZHANG Guowei State Key laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi＇an 710069ShaanxiChina

A paleomagnetic study was carried out on late Jurassic sediments in the Nanjing area. Stepwise thermal demagnetization was used to isolate the characteristic higher temperature component （HTC）（D=354.0°,I=48.5°,a95=7.8°）,which passes the reversal test.A 24.7±8.7°counter-clockwise rotation relative to the Sichuan area is detected through comparing this new pole（84.4°N,7.0°E, A95=7.7°）with other coeval poles reported from South *** rotation was conducted by sinistral action of slip *** cases presenting in several areas of eastern China indicate that deformation of eastern China is under the effect of subduction from the Pacific Ocean *** difference on the paleolatitude of several areas across the Tan-Lu fault zone is calculated and suggests about at most 250 km offset distance after the later Jurassic.

关键词： paleomagnetism late Jurassic Ning-wu basin

Rapid drift of the Tethyan Himalaya terrane before two-stage India-Asia collision

在线全文

学校读者我要写书评

暂无评论

National Science Review 2021年第7期8卷 86-98页

作者： Jie Yuan Zhenyu Yang Chenglong Deng Wout Krijgsman Xiumian Hu Shihu Li Zhongshan Shen Huafeng Qin Wei An Huaiyu He Lin Ding Zhengtang Guo Rixiang Zhu State Key laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Innovation Academy for Earth Science Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences College of Resources Environment and Tourism Capital Normal University Department of Earth Sciences Utrecht University State Key laboratory of Mineral Deposits Research School of Earth Sciences and Engineering Nanjing University Key laboratory of Continental Collision and Plateau Uplift Institute of Tibetan Plateau Research Chinese Academy of Sciences Key laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences CAS Center for Excellence in Life and Paleoenvironment

The India-Asia collision is an outstanding smoking gun in the study of continental collision *** and when the continental collision occurred remains a long-standing *** we present two new paleomagnetic data sets from rocks deposited on the distal part of the Indian passive margin,which indicate that the Tethyan Himalaya terrane was situated at a paleolatitude of ～19.4° S at ～75 Ma and moved rapidly northward to reach a paleolatitude of ～13.7°N at ～61 *** implies that the Tethyan Himalaya terrane rifted from India after ～75 Ma,generating the North India *** document a new two-stage continental collision,first at ～61 Ma between the Lhasa and Tethyan Himalaya terranes,and subsequently at ～53-48 Ma between the Tethyan Himalaya terrane and India,diachronously closing the North India Sea from west to *** scenario matches the history of India-Asia convergence rates and reconciles multiple lines of geologic evidence for the collision.

关键词： India-Asia collision Tethyan Himalaya terrane North India Sea two-stage continental collision

Miocene Bahean stratigraphy in the Longzhong Basin, northern central China and its implications in environmental change

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2006年第12期49卷 1270-1279页

作者： LI Jijun1,2, ZHANG Jun1, SONG Chunhui1, ZHAO Zhijun2, ZHANG Yong1, WANG Xiuxi 1, ZHANG Jianming1 & CUI Qiaoyu1 1. Key laboratory of Western China’s Environmental Systems (Ministry of Education) & College of Earth and Environment Sciences, Lanzhou University, Lanzhou 730000, China 2. Jiangsu Key laboratory of Environmental Change and Ecological Construction & College of Geography, Nanjing Normal University, Nanjing 210097, China Key laboratory of Western China’s Environmental Systems (Ministry of Education) & College of Earth and Environment Sciences Lanzhou University Lanzhou China Jiangsu Key laboratory of Environmental Change and Ecological Construction & College of Geography Nanjing Normal University Nanjing China

Fossil mammal-riched Neogene strata are widely distributed in the southeast corner of the huge Longzhong Basin at Tianshui, Gansu Province, northern central China. Hipparion weihoense, a typical member of late Middle Miocene Bahean stage, was recently excavated at Yaodian along a well-exposed outcrop. Owing to the importance of the Bahean stage in the mammalian evolution and its potential for environmental change, we suggested a name of Yaodian Formation for the stratigra- phy, which is correlated to the Bahe Formation at Lantian, Shaanxi. High resolution paleomagnetic dating of the section shows that the Yaodian Formation covers the period between 11.67 Ma and 7.43 Ma, with the site bearing Hipparion weihoense being estimated at about 10.54―10.30 Ma, providing first magnetostratigraphic chronology for the Bahean Stage. The Yaodian Formation consists of fluvial channel deposits (11.67―10.40 Ma) at the bottom, floodplain deposits in the middle (10.40―9.23 Ma) and shallow lake sediments at the top (9.23―7.43 Ma). This upward fining sequence suggests that the relief in nearby mountain ranges such as West Qinling to the south and Huajia Ling to the north was greatly reduced after long-term denudation, fluvial transport capacity was low, and finally the drainage system was disintegrated, replaced with broad-shallow lakes in which only fine sediments like mud and marlite were deposited, indicating an old stage of development of a planation surface. A remarkable shift in ecology and climatic environment was found at 7.4―7.7 Ma when paleoclimate changed from early warm humid to late dry as indicated by sedimentary facies changed from early shallow lake sequence to late eolian red clays and a former coniferous-deciduous mixed forest was replaced by grassland, leading to great growth of Hipparion Fauna of Baodean stage in the region. Therefore, it is estimated that the present high relief of Qinling and drainage pattern did not come into being until Late Pliocene in response

关键词： Bahean stage,magnetostratigraphy,Yaodian Formation,Neogene,Longzhong Basin.