检索结果-南通市图书馆

Stenian A-type granitoids in the Namaqua-Natal Belt,southern Africa,Maud Belt,Antarctica and Nampula Terrane,Mozambique:Rodinia and Gondwana amalgamation implications

引用

Geoscience Frontiers 2019年第6期10卷 2265-2280页

作者： Tomokazu Hokada Geoffrey H.Grantham Makoto Arima Satoshi Saito Kazuyuki Shiraishi Richard A.Armstrong Bruce Eglington Keiji Misawa Hiroshi Kaiden National Institute of Polar Research 10-3Midori-choTachikawa-shiTokyo190-8518Japan Department of Polar Science The Graduate University for Advanced Studies10-3Midori-choTachikawa-shiTokyo190-8518Japan Department of Geology University of JohannesburgPO Box 524Auckland Park2006South Africa Geological Institute Yokohama National UniversityYokohama240-8501Japan PRISE Australian National UniversityCanberraAustralia Department of Geological Sciences University of SaskatchewanSaskatoonSaskatchewanS7N 5E2Canada Department of Earth Sciences Ehime UniversityMatsuyama790-8577Japan

We carried out SHRIMP zircon U-Pb dating on A-type granitic intrusions from the Namaqua-Natal Province,South Africa,Sverdrupfjella,western Dronning Maud Land,Antarctica and the Nampula Province of northern Mozambique.Zircon grains in these granitic rocks are typically elongated and oscillatory zoned,suggesting magmatic origins.Zircons from the granitoid intrusions analyzed in this study suggest^1025-1100 Ma ages,which confirm widespread mesoproterozoic A-type granitic magmatism in the Namaqua-Natal(South Africa),Maud(Antarctica)and Mozambique metamorphic terrains.No older inherited(e.g.,~2500 Ma Achean basement or^1200 Ma island are magmatism in northern Natal)zircon grains were seen.Four plutons from the Natal Belt(Mvoti Pluton,Glendale Pluton,Kwalembe Pluton,Ntimbankulu Pluton)display 1050-1040 Ma ages,whereas the Nthlimbitwa Pluton in northern Natal indicates older 1090-1080 Ma ages.A sample from Sverdrupfjella,Antarctica has^1091 Ma old zircons along with^530 Ma metamorphic rims.Similarly,four samples analysed from the Nampula Province of Mozambique suggest crystallization ages of^1060-1090 Ma but also show significant discordance with two samples showing younger^550 Ma overgrowths.None of the Natal samples show any younger overgrowths.A single sample from southwestern Namaqualand yielded an age of^1033 Ma.Currently available chronological data suggest magmatism took place in the Namaqua-Natal-MaudMozambique(NNMM)belt between^1025 Ma and^1100 Ma with two broad phases between^1060-1020 Ma and 1100-1070 Ma respectively,with peaks at between^1030-1040 Ma and^1070-1090 Ma.The age data from the granitic intrusions from Namaqualand.combined with those from Natal,Antarctica and Mozambique suggest a crude spatial-age relationship with the older>1070 Ma ages being largely restricted close to the eastern and western margins of the Kalahari Craton in northern Natal,Mozambique.Namaqualand and WDML Antarctica whereas the younger<1060 Ma ages dominate in southern Natal and western Namaqualand and are largely restricted to

关键词： A-type granites mesoproterozoic Natal South Africa Maud Antarctica Mozambique Southern Africa Sri Lanka Zircon chronology

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The boring billion? - Lid tectonics, continental growth and environmental change associated with the Columbia supercontinent

引用

Geoscience Frontiers 2013年第6期4卷 681-691页

作者： Nick M.W.Roberts NERC Isotope Geosciences Laboratory British Geological SurveyKeyworthNottingham NG12 5GGUK

The evolution of Earth＇s biosphere,atmosphere and hydrosphere is tied to the formation of continental crust and its subsequent movements on tectonic plates.The supercontinent cycle posits that the continental crust is periodically amalgamated into a single landmass,subsequently breaking up and dispersing into various continental fragments.Columbia is possibly the first true supercontinent,it amalgamated during the 2.0-1.7 Ga period,and collisional orogenesis resulting from its formation peaked at 1.95-1.85 Ga.Geological and palaeomagnetic evidence indicate that Columbia remained as a quasi-integral continental lid until at least 1.3 Ga.Numerous break-up attempts are evidenced by dyke swarms with a large temporal and spatial range; however,palaeomagnetic and geologic evidence suggest these attempts remained unsuccessful.Rather than dispersing into continental fragments,the Columbia supercontinent underwent only minor modifications to form the next supercontinent （Rodinia） at 1.1 -0.9 Ga; these included the transformation of external accretionary belts into the internal Grenville and equivalent collisional belts.Although Columbia provides evidence for a form of ‘lid tectonics’,modern style plate tectonics occurred on its periphery in the form of accretionary orogens.The detrital zircon and preserved geological record are compatible with an increase in the volume of continental crust during Columbia＇s lifespan; this is a consequence of the continuous accretionary processes along its margins.The quiescence in plate tectonic movements during Columbia＇s lifespan is correlative with a long period of stability in Earth＇s atmospheric and oceanic chemistry.Increased variability starting at 1.3 Ga in the environmental record coincides with the transformation of Columbia to Rodinia; thus,the link between plate tectonics and environmental change is strengthened with this interpretation of supercontinent history.

关键词： Rodinia Columbia Supercontinents Continental growth Lid tectonics mesoproterozoic

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Early-middle mesoproterozoic tectonic evolutionary history of the southwestern Yangtze Block,China:lithostratigraphic,geochronologic and elemental geochemical constraints

引用

China Geology 2018年第4期1卷 540-555页

作者： Fu-guang Yin Zhi-ming Sun Guang-ming Ren Chengdu Institute of Geology and Mineral Resources China Geological SurveyChengdu 610081China

During the Early-Middle Proterozoic era,three major lithostratigraphic unit associations,namely Hekou-Dahongshan,Dongchuan,and Kunyang-Huili Groups,were established for the metamorphosed volcanicsedimentary rocks exposed in the southwestern Yangtze Block (SWYB).The integration of petrology, geochemistry and geochronology constrains tectonic framework and evolution of the SWYB,in which four sets of SHRIMP U-Pb zircon ages were obtained from the volcanic rocks interbedded within the Middle Proterozoic successions:1800-1600 Ma,1600-1300 Ma,1300-1100 Ma,and 1100-1000 Ma. Major and trace elemental analysis indicate that four key tectonic evolutionary stages,each coinciding with the above radiometric age set,of the SWYB during the Early-Middle mesoproterozoic.The SWYB was characterized by an east-westerly trending rift in the Hekou,Dongshan,and Dongchuan areas,and separate basin-forming events during 1800-1600 Ma arid 1600-1300 Ma,respectively.In the SWYB,an intracontinental rift basin and a rift basin occurred in the Caiziyuan-Matang and Laowushan areas, respectively in 1300-1100 Ma ago.During 1100-1000 Ma,the SWYB was characterized by the closure of the Caiziyuan-Matang rift-ocean basin,collision between the Huili Blocks and Kunyang Blocks,and presence of volcanic ares in the Tianbaoshan and Fulingpen areas.Accordingly,the SWYB represents a new basin that records the relatively complete assembly process of the Rodina during the Early-Middle mesoproterozoic era.

关键词： Early-middle mesoproterozoic SHRIMP U-Pb dating Tectonostratigraphic framework Tectonic evolution Southwestern Yangtze Block Yunnan Province

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Petrofacies Evolution of Bayana Basin Sandstones of mesoproterozoic Delhi Supergroup, Bharatpur District, Rajasthan, Northwestern India

引用

Open Journal of Geology 2012年第4期2卷 260-270页

作者： Abul Hasnat Masood Ahmad Chayanika Saikia Syed Mohammad Wasim Department of Geology Aligarh Muslim University Aligarh India Directorate General of Hydrocarbons (DGH) Delhi India

The paper embodies results of petrofacies, detrital mineralogy and textural aspects of Bayana Basin sandstones of the Delhi Supergroup. These sandstones consisting of various types of quartz, feldspar, mica, rock fragments and heavy minerals are medium to fine grained and moderately well sorted. These sediments are generally subangular to subrounded with low sphericity. Various factors responsible for modification of the original detrital composition of the sandstones have been critically examined. Distance of transport is one of the factors which control the composition at the time of deposition. The plots of petrofacies in QtnFnL, QmnFnLt, QpnLvnLs and QmnPnK ternary diagrams suggest mainly basement uplift source (Craton interior) in a rifted continental margin basin setting, which has also received sediment input from recycled orogen provenance.

关键词： Petrofacies Evolution Bayana Basin mesoproterozoic Bharatpur District (India)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake-induced soft-sediment deformation structures in the mesoproterozoic Wumishan Formation,North China,and their geologic implications

引用

Science China Earth Sciences 2007年第3期50卷 350-358页

作者： ZHANG ChuanHeng WU ZhengJie GAO LinZhi WANG Wei TIAN YanLin MA Chao State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China Key Laboratory of Lithospheric Tectonics and Lithoprobing Technology Ministry of EducationChina University of GeosciencesBeijing 100083China School of Geosciences and Resources China University of GeosciencesBeijing 100083China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China

Soft-sediment structures are key to defining seismites. Two soft-sediment deformation horizons, bounded by undeformed carbonate strata, have been found in the Wumishan Formation in the Jumahe region, 175 km southwest of Beijing. One is in the lowest part of Wumishan Formation; and the other is in the uppermost part of Litho-member I. The soft-sediment structures in these two horizons fall into three categories: mould-and-sag structures, hydraulic shatterings and liquefaction dikes. The mould-and-sag structures are divided into two types: one developed in tidal-flat sediments, accompa-nied by many liquefaction-related structures and characterized by autochthonous post-earthquake sediments in sags, and the other type developed in deep-water environments, is not associated with liquefaction structures, and is overlain immediately by seismogenic tsunamites. The hydraulic shat-terings are composed of pockets of fluidization conglomerate, sand intrusions, and syndepositional faults. The liquefaction dikes fall into two categories: hydraulic-fracturing dikes and lateral-spreading dikes. The former are steep, planar, and pinch out upwards. The latter are snake-like and characterized by no diapir-related drag structures in surrounding rocks. Examination of the attitudes and strati-graphic positions of these structures suggests that these soft-sediment structures are seismogenic, and consequently, are seismites. Most seismites in the Wumishan Formation are developed near the former western, margin fault of Yanliao rift. This occurrence suggests that they could be related to movements on this fault. Other geological implications are discussed.

关键词： mesoproterozoic Wumishan Formation soft-sediment structures paleo-earthquakes seismites Yanliao rift

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A New SHRIMP Age of the Xiamaling Formation in the North China Plate and Its Geological Significance

引用

Acta Geologica Sinica(English Edition) 2007年第6期81卷 1103-1109页

作者： GAO Linzhi~(1,*)ZHANG Chuanheng~2 SHI Xiaoying~2 ZHOU Hongrui~2 WANG Ziqiang~2 SONG Biao~(1,3) 1 Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China 2 China University of Geosciences(Beijing),Beijing 100083,China 3 Beijing SHRIMP Central,100037 Beijing,China Chinese Acas Geol Sci Inst Geol Beijing 100037 Peoples R China Beijing SHRIMP Cent Beijing 100037 Peoples R China China Univ Geosci Beijing 100083 Peoples R China

Setting up the hypostratotype of late Precambrian is the main aim of the research on the Meso-and Neoproterozoic in North China.The chronostratigraphic position is the key in this study. However,many key horizons have not been calibrated with the high-quality isotopic ages.Using the reported new U-Pb age with the Sensitive High-Resolution Ion Microprobe（SHRIMPⅡ）,a zircon U- Pb age was obtained of the ash bed in the Xiamaling Formation in North China Plate,yielding a weighted mean;Pb/;U age of 1368±12 Ma.It is the first SHRIMP U-Pb age from the Xiamaling Formation in the North China Plate,and represents the depositing time of the middle part of the Xiamaling Formation.The zircon age plays an important role to understanding geological evolution of the North China Plate during Meso-and Neoproterozoic.

关键词： SHRIMP U-Pb Dating mesoproterozoic Xiamaling Formation North China Plate

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Milankovitch-driven cycles in the Precambrian of China:The Wumishan Formation

引用

Journal of Palaeogeography 2013年第4期2卷 369-389页

作者： Mei Mingxiang Maurice E. Tucker State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences (Beijing) Department of Earth Sciences University of Durham

Carbonate strata of the mesoproterozoic Wumishan Formation in the Jixian area near Tianjin are ~3300 m thick and were deposited over some 100 million years(from ~1310±20 Ma to ~1207±10 Ma).Metre-scale cycles(parasequences) dominate the succession.They are generally of the peritidal carbonate type,and mostly show an approximately symmetrical lithofacies succession with thick stromatolite biostromes and small thromboliteoncolite bioherms constituting the central part and tidal-flat dolomites forming the upper and lower parts.Lagoonal-supratidal dolomitic shales with palaeosol caps make up the topmost layers.The boundaries of the Wumishan cycles are typically exposure surfaces,and there is abundant evidence for fresh-water diagenesis.Widespread 1:4 stacking patterns indicate that the individual Wumishan cycles are sixthorder parasequences,with 4 parasequences constituting one fifth-order parasequence set.Locally,5-8 beds or couplets,can be discerned in some of the cycles.The regular vertical stacking pattern of beds within the sixth-order parasequences,forming the fifth-order parasequence sets,are interpreted as the result of environmental fluctuations controlled by Milankovitch rhythms,namely the superimposition of precession,and short and long-eccentricity.The widespread 1:4 stacking pattern in the cyclic succession,as well as the local 1:5-8 stacking patterns of the beds within the cycles,suggest that the Milankovitch rhythms had similar ratios in the mesoproterozoic as in the Phanerozoic.Based on the cycle stacking patterns,26 thirdorder sequences can be distinguished and these group into 6 second-order,transgressiveregressive megasequences(or sequence sets),all reflecting a composite,hierarchical succession of relative sea-level changes.

关键词： peritidal carbonate cycles Milankovitch rhythms Wumishan Formation mesoproterozoic Tianjin North China

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Basic Lithofacies-Succession Model for the Wumishan Cyclothems: Their Markov Chain Analysis and Regularly Vertical Stacking Patterns in the Third-Order Sequences

引用

Acta Geologica Sinica(English Edition) 2001年第4期75卷 421-431页

作者： MEI Mingxiang, MA Yongsheng and GUO Qingyin Institute of Earth Sciences and Natural Resources, China University of Geosciences, Beijing 100083 China Petrochemical Corporation (SINOPEC), Beijing 100029 China Univ Geosci Inst Earth Sci & Nat Resources Beijing 100083 Peoples R China China Petrochem Corp SINOPEC Beijing 100029 Peoples R China

The mesoproterozoic Wumishan Formation in the Jixian section of Tianjin is a succession of 3300-m-thick carbonate strata formed in a period of about 100 Ma (1310±20 Ma-1207±10 Ma). In this succession of strata, the carbonate metre-scale cyclic sequences belonging to peritidal type with an approximately symmetrical lithofacies-succession are best developed. The wide development of 1:4 stacking patterns shows that these metre-scale cyclic sequences are genetically related to the short-eccentricity cycles, which are called the Wumishan cyclothems that could truly represent sedimentary cycles. Generally, massive and thick-bedded calcareous dolomites and dolomitic limestones of stromatolite biostromes and thrombolite bioherms constitute the central part of the Wumishan cyclothems. The lower and upper parts consist of tidal flat dolostones, sandy-muddy dolostone and the top part is composed of lagoonal facies dolomitic shales with a paleosol cap. Therefore, an approximately symmetrical lithofacies-succession is formed. Many features such as the clear deepening and shoaling vectors of cyclothems, and all kinds of marks of fresh-water diagenesis indicate that the Wumishan cyclothems are the product of autocyclic sedimentation governed by allocyclic high-frequency sea-level changes. The results of a Markov chain analysis reaffirm the existence of the lithofacies-succession model of the Wumishan cyclothems. The boundaries of the Wumishan cyclothems are marked by the instantaneous exposed punctuated surface, which leads to the discrepancy between the cyclothems and the parasequences of the sequence stratigraphy terminology system. It is difficult to form a judgment that the time span of the Milankovitch cycles in the Precambrian is certainly equal to that of the Phanerozoic, but the regularly vertical stacking patterns of the seventh-order rhythms, sixth-order cyclothems and fifth-order parasequence sets still indicate their consistency with the duration of the Milankovitch cycles in the Phanerozoic.

关键词： Wumishan cyclothems Markov chain analysis mesoproterozoic Jixian section Tianjin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

mesoproterozoic mafic and carbonatitic dykes from the northern margin of the North China Craton:Implications for the final breakup of Columbia supercontinent

Mesoproterozoic mafic and carbonatitic dykes from the northe...

引用

中国科学院地质与地球物理研究所第11届（2011年度）...

作者： M.Santosh Division of Interdsciplinary Science Faculty of ScienceKochi University

The North China Craton(NCC) has figured prominently in recent reconstructions on the Paleoproterozoic supercontinent Columbia.Here we report abundant carbonatitic and mafic dykes from around the giant Bayan Obo rare earth element deposit in the northern margin of the NCC,and present geochemical and isotope geochronological data.The carbonatite(1354±59Ma) and mafic dykes(1227±60Ma) have comparable whole rock Sm-Nd isochron ages and Sr-Nd isotope compositions,suggesting a common source characteristic.Their geochemical characters including major and trace elements as well as REE patterns also attest to a common tectonic environment of magma generation and emplacement within a continental margin rift.The extensive mafic and carbonatitic magmatisms are associated with an extensional event that resulted in the formation of the Bayan Obo rift in the northern margin of the NCC,which we correlate with the final stages of fragmentation of the Columbia supercontinent amalgam.

关键词： Mafic-carbonatitic dykes Rift tectonics Columbia supercontinent mesoproterozoic North China Craton Bayan Obo

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

mesoproterozoic carbonatitic magmatism in the Bayan Obo deposit,Inner Mongolia,North China:Constraints for the mechanism of super accumulation of rare earth elements

Mesoproterozoic carbonatitic magmatism in the Bayan Obo depo...

引用

中国科学院地质与地球物理研究所第11届（2011年度）...

作者： M.Santosh Division of Interdisciplinary Science Faculty of ScienceKochi University

The Bayan Obo mine in North China contains the largest rare-earth element(REE) resources in the world.The mechanism of giant REE enrichment in such a restricted region has been the focus of several studies. Carbonatites are known to contain high concentrations of REE.Three types of carbonatite dykes occur around the Bayan Obo deposit,including dolomite,calcite and calcite-dolomite carbonatite varieties.The contact relations show that the intrusion of calcite carbonatite dykes post-date the dolomite dykes during the process of evolution of the carbonatite magma.The geochemical data show that the content of Sr and light(L) REE in these dykes gradually increases from dolomite[(La/Yb) values range from 1.6 to 3.8],through calcitedolomite [(La/Yb) ranging from 51 to 57],to calcite type[(La/Yb) ranging from 85 to 4617],This evolutionary trend suggests the crystal fractionation of the carbonatite magma,which might have played a critical role for the giant REE accumulation in the Bayan Obo region.Theε(t) values of the carbonatitic dykes show a tight cluster between -0.47 and 0.65,whereas the initial Sr isotope values show a broad range from 0.703167 to 0.708871.The massive ore-hosting dolomite marbles show comparable element content and Nd isotope composition,and a Sm-Nd isochron age similar to that of the carbonatite dykes,implying a close relationship during their magmatic origin.This interpretation is also supported by the intrusive contact between the ore-hosting dolomite marble and mesoproterozoic Bayan Obo group,as well as the presence of wall-rock xenoliths in the dolomite marble.

关键词： Carbonatite REE deposit Petrology Geochemistry mesoproterozoic Bayan Obo China

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：