检索结果-南通市图书馆

Acta Geochimica 2007年第3期26卷 305-311页

作者： LAI Shaocong, QIN Jiangfeng, LI Yongfeng, and LIU xin state key Laboratory of {2. dynamics, Department of Geology, northwest university, xi’an 710069, china state key Laboratory of {2. dynamics Department of Geology Northwest University Xi’an China

Neogene volcanic rocks in the Belog Co area, Qiangtang, northern Tibet, are represented by a typical intermediate-basic and intermediate alkaline rock association, with latite-trachyte as the main rock type. The results of chemical analysis are: SiO2.52.–62., Al2.3>15%, Na2./K2.>1 and MgO3.30%. In addition, the volcanic rocks are LREE-enriched with LREE/HREE=10–13, (La/Yb)N=15–19, and show a weak negative Eu anomaly with δEu=0.71–0.89. The close relationship between Mg# and SiO2.and the co-variation of the magmatophile elements and ultra-magmatophile elements such as La/Sm-La and Cr-Tb indicate that this association of volcanic rocks is the product of comagmatic fractional crystallization. The rock association type and lower Sm/Yb values (Sm/Yb=3.2.–3.97) imply that this association of volcanic rocks should have originated from partial melting of spinel lherzolite in the lithospheric mantle. On the other hand, the weak negative Eu anomaly and relative depletion in Nb, Ta and Ti reflect the features of terrigenous magma. So the Neogene Belog Co alkaline volcanic rocks should be the result of partial melting of the special crust-mantle transition zone on the Qinghai-Tibet Plateau.

关键词： major and trace elements Cenozoic volcanic rock mantle-crust transition zone Qinghai-Tibet Plateau

Petrogenesis of Indosinian volcanic rocks in Songpan-Garze fold belt of the northeastern Tibetan Plateau:New evidence for lithospheric delamination

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 2010年第9期53卷 1316-1328页

作者： CAI HongMing1,2. ZHANG HongFei1,2. XU WangChun1,2. SHI ZhangLiang1,2.& YUAN HongLin3 1 state key Laboratory of Geological Processes and Mineral Resources, Wuhan 430074,{2. 2.Faculty of Earth Sciences,{2. university of Geosciences, Wuhan 430074,{2. 3 state key Laboratory of continental dynamics, northwest university, xi’an 710069,{2. state key Laboratory of Geological Processes and Mineral Resources Wuhan China Faculty of Earth Sciences China University of Geosciences Wuhan China state key Laboratory of {2. dynamics Northwest University Xi’an China

In the Songpan-Garze fold belt of the northeastern Tibetan Plateau, an Indosinian lithospheric delamination model has been proposed, based on previous investigation of widespread granitoids. However, this model lacks comparable information from volcanism in the area. During the Indosinian delamination in the Songpan-Garze fold belt, whether partial melting of litho- spheric mantle taken place is debated. This paper reports U-Pb zircon LA-ICP-MS ages, geochemical and Sr-Nd-Hf isotopic compositions from the Aba and Wasai calc-alkaline volcanic rocks in the central Songpan-Garze fold belt. Obtained magma crystallization ages are 2.0±3 Ma for the Aba andesite and 2.5±1 Ma for the Wasai andesite. These are consistent with magma crystallization ages of the late Indosinian granitoids in the Songpan-Garze fold belt that formed in a post-collisional tectonic setting. The Aba and Wasai andesites have distinct geochemical singnatures. The former has higher Al2.3, K2., Rb but lower Na2., Ba and Sr contents, suggesting differences in their magmatic evolution. The Aba andesites have ISr values of 0.7070-0.7076 and εNd(t) values of -3.9 to -5.3, and the Wasai andesites have ISr values of 0.7075-0.7077 and εNd(t) values of -3.6 to -3.9. Zircons show εHf(t) values of -3.7 to 0.3 for the Aba andesites and -2.7 to 5.5 for the Wasai andesites. Geochemical and Sr-Nd-Hf isotopic compositions indicate that fractional crystallization and crustal assimilation processes are not key roles for their magma evolution, implying that their chemical compositions are those of primary melts. We suggest that the magma of the Aba andesites originated predominantly from a crustal source, with a minor mantle-derived component. The source region of the magma was likely at the crust-mantle boundary. The magma of the Wasai andesites resulted from partial melting of lithospheric mantle, which was probably metasomatized by fluids so that it was amphibole bearing. The petrogenesis of the Aba and Wasai andesite

关键词： volcanism U-Pb dating geochemistry petrogenesis lithospheric delamination Songpan-Garze fold belt

Thoughts on studies of china continental geology and tectonics

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第10期16卷 1022-1026页

作者： ZHANG Guowei, GUO Anlin and YAO Anping (Ministry of Education key Laboratory of continental {2., Department of Geology, northwest university, xi’an 710069, china) Ministry of Education key Laboratory of continental {2. Department of Geology Northwest University Xi'an 710069 China

As an important part of the global continents, china continent has long been situated in the peculiar tectonic position and experienced extremely complicated activities, which resulted in the regional unique characteristics for china continent on the global common geological background. These characteristics contain abundant information regarding scientific {2. issues of modern geological frontier. Thus, china continent can be a natural laboratory and excellent arena for the modern geosciences. The modern earth sciences have started entering the era featured with earth systematic science and beyond plate tectonics. How to take the regional advantage and exploit the treasure resource to participate the new theoretical and methodological creation is a historic opportunity and great challenge we are facing. This paper generalizes research priorities in four fields on china continental geology and tectonics for discussion. They are: china continental tectonics and dynamics; Mesozoic-Cenozoic crustal deformation and deep-seated processes in china continent and the adjacent regions; deep-seated dynamic background and evolutionary trend of crustal tectonic activities on the time scale of human existence; deep-seated background and processes of conjunction and transformation of different tectonic systems.

关键词： china continental geology and continental tectonics plate tectonics continental dynamics key scientific issues.

Identification of 3.5 Ga detrital zircons from Yangtze craton in south china and the implication for Archean crust evolution

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 2006年第6期16卷 663-666页

作者： LIU xiaoming, GAO Shan, LING Wenli, YUAN Honglin and HU Zhaochu (National key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Sciences, china {2. of Geosciences, Wuhan 430074, china key Laboratory of continental dynamics, Department of Geology, northwest university, xi' an 710069, china) National key Laboratory of Geological Processes and Mineral Resources Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China key Laboratory of continental {2. Department of Geology Northwest University Xi'an 710069 China

The LA-ICP-MS U-Pb dating of hundreds of detrital zircon grains from the Sinian sandstones of Liantuo formation and tillites of Nantuo formation at Sanxia area in Yichang identified 3319-3508 Ma zircon grains. Their 2.7Pb/2.6Pb and 2.6Pb/2.8U ages show excellent agreement (concordia degree 99%-100% ). Their CL images exhibit well-developed oscillatory zoning and the Th/U ratios are within 0.46-0.76, implying that they are igneous zircons which formed during middle-early Archean. These zircons are the oldest ones discovered in Yangtze craton until now. However, the detrital zircons with ages older than 3. 3 Ga in the metamorphic rocks of Kongling group were not found by further investigation, which suggests the presence of crust older than high-grade metamorphic Kongling terrain in Yangtze craton.

关键词： early Archean detrital zircon zircon dating Yangtze craton.

The microtine distribution and its environmental significance since the Middle Pleistocene in Zhangping Caves of the Qinling Mountains

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 2008年第2期51卷 294-299页

作者： LI Yongxiang1 & XUE xiangXu1,2.1 state key Laboratory of {2. dynamics, Department of Geology, northwest university, Institute of Cenozoic Geology and Environment, xi’an 710069, china 2.Institute of Earth Environment, state key Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences, xi’an 710075, china state key Laboratory of {2. dynamics Department of Geology Northwest University Institute of Cenozoic Geology and Environment Xi’an China Institute of Earth Environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an China

Three microtine species are recovered from the Zhangping Caves of the Qingling Mountains, namely Microtus oeconomus, Caryomys inez and Caryomys eva. They are climate-sensitive ones with different ecological habits, therefore their distribution well corresponds to environmental variations. Statistical comparison of the distribution of fossil microtines and their counterparts nowadays displays that the climate variation of the studied area and its contiguity since the middle Pleistocene are: warm and humid at 493 ka ago, cool and humid at 2.9 ka ago―cold and humid at 2.5 ka ago―cool and humid at 2. ka ago, and warm and dry at present.

关键词： environmental variation since Middle Pleistocene microtine fossils Zhangping Caves of the Qinling Mountains

Paleoenvironments indicated by the fossil mammalian assemblages from red clay-loess sequence in the Chinese Loess Plateau since 8.0 Ma B.P.

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2006年第5期49卷 518-530页

作者： XUE xiangxu1,2. ZHANG Yunxiang1,2.& YUE Leping1,2.1. state key Laboratory of Continent {2. (northwest university), Institute of Cenozoic Geology and Environment, De- partment of Geology, northwest university, xi’an 710069, china 2. Institute of Earth Environment, state key Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences, xi’an 710075, china state key Laboratory of Continent {2. (northwest university) Institute of Cenozoic Geology and Environment Department of Geology Northwest University Xi’an China Institute of Earth Environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an China

Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated. A complete summary profile with projected isotopic ages and fossil-bearing beds has been assembled. The profile is subdivided into 12.stratigraphic units proceeding from the lower (older) to the upper (younger) one. The character of mammalian assemblages contained in each unit was analyzed and the corresponding pa- leo-climatic environments were deduced. The environmental character of each period and the change from the middle of the Late Miocene at about 8.0 Ma B.P. up to the Holocene progressed from the hot semiarid and semi-moist, warmer-moist, warm-moister of the Late Miocene. To slightly less warm moist, cool-dry, slight-warmer-moister of the Pliocene; later the cool to cold dry periods alternated frequently with the mild semiarid and semi-moist periods of the Quaternary. Vegetation progressed from the grasslands with sparse woods, wooded shrub-grasslands and subtropical forest-grasslands of the Late Miocene age to sparse grasslands and dry grasslands of the Pliocene; and to sparse grasslands, dry grasslands and tundras of the Quaternary. The climate changes in the Neogene were of low-amplitute in a generally warm-humid background. Those of the Quaternary were of higher am- plitude with a longer phase. Cool or cold dry and slightly warm semiarid and semi-moist climates al- ternated on a generally cool-dry background. The tendency since the start of the Quaternary was the change to more northern and western shift in the Loess Plateau, with progressively cooler and dryer conditions. The dramatic uplift of the Qinghai-xizang (Tibet) Plateau and the forming and expansion of the Arctic ice sheet might be the main reasons of the more pronounced changes in the Quaternary.

关键词： paleoenvironment, mammalian fossils, eolian red clay-loess sequence, Loess Plateau.

Northernmost paleo-tethyan oceanic basin in Tibet:Geo-chronological evidence from ^(40)Ar/^(39)Ar age dating of Dur'ngoi ophiolite

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第14期46卷 1203-1205页

作者： CHEN Liang, SUN Yong, PEI xianzhi, GAO Ming, FENG Tao, ZHANG Zhongqing & CHEN Wen1. Laboratory of continental dynamics,{2., xi’an 710069, china 2. Department of Geology,{2., xi’an, 710069, china 3. Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, china Laboratory of continental dynamics Northwest University Xi’an China Department of Geology Northwest University Xi’an China Institute of Geology Chinese Academy of Geological Sciences Beijing China

Whole rock 40Ar/39Ar age dating has been conducted on a basalt sample from Dur’ngoi ophiolite, Qinghai Province, which was reported to be the northernmost pa-leo-tethyan oceanic basin in Tibet. A high temperature pla-teau age (345.3±7.9 Ma) with an isochorn age (336.6±7.1 Ma) has been obtained, representing the eruption time of oceanic crust Considering related geological settings, the new age provides constraints on the northernmost pa-leo-tethyan suture zone in Tibet and the tectonic evolution of Paleo-tethys in Northeast Tibet and adjacent areas.

关键词： Dur’ngoi ophlolite 40Ar -39Ar age Paleo-tethys.

Formation of the Permian basalts and implications of geochemical tracing for paleo-tectonic setting and regional tectonic background in the Turpan-Hami and Santanghu basins,xinjiang

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2006年第6期49卷 584-596页

作者： ZHOU Dingwu1,2. LIU Yiqun1,2. xiNG xiujuan1, HAO Jianrong1, DONG Yunpeng1 & OUYANG Zhengjian1 1. key Laboratory of continental {2., Ministry of Education, northwest university Department of Geology, northwest university, xi’an 710069, china 2. Geoinformation Science & Engineering College, SDUST, Qingdao 2.6510, china key Laboratory of continental {2. Ministry of Education Northwest University Xi’an China Geoinformation Science & Engineering College SDUST Qingdao China Department of Geology Northwest University Xi’an China

The Turpan-Hami and Santanghu basins are the late Paleozoic-Mesozoic-Cenozoicreworked intracontinental basins that superposed on the folded basement of the Paleozoic orogenicbelt. ^(40)Ar/^(39)Ar geochronological study of the basalts developed in the basins reveals that theformation period is Permain (2.3—2.6 Ma). From geochemical comparison of the basalts, theSantanghu basalts exhibit a strong depletion in Nb and Ta, and a selective enrichment in HFSE,reflecting that the source region is influenced by the subducted components related to subduction ofthe ancient oceanic crust and characterized with ''lagged arc volcanic rocks''. In contrast, theTurpan-Hami basalts show a slight depletion in Nb and Ta, high Th/Ta ratio, similar to the basaltsformed in an intracontinental ex-tensional zone or in an initial rift. Combined with the formationperiod of the ophiolite and ophiolite melange zones and regional magmatic activities occurring onthe post-orogenic extensional background in northern xinjiang, it can be inferred from thesegeochemical characteristics that the tectonic background for forming the Turpan-Hami and Santanghubasins is closely related to the regional extension after the continent-continent collisionalorogeny. The basalts of the two basins came from different sources on the post-orogenic extensionalbackground of the similar basin-forming {2.. Although the settings are all intracontinentalrift, the source for the Santanghu basalts is obviously subjected to the metasomatism of thesubducted components, implying the existence of the previous subduction.

关键词： xinjiang, Tu-Ha basin, Santanghu basin, basalt, postorogeny, tectonic setting, extensional background.

Constraints on the late Mesozoic regional angular unconformity in West Liaoning-North Hebei by LA-ICP-MS dating

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2008年第11期18卷 1395-1402页

作者： Hong Zhang~(a,b,*) Wenmin Guo~a xiaoming Liu~b a College of Mechanical and Energy Engineering,Jiangsu Polytechnic university,Changzhou 2.3016,china b {2. Laboratory of continental dynamics,Department of Geology,northwest university,xi’an 710069,china College of Mechanical and Energy Engineering Jiangsu Polytechnic University Changzhou 213016 China key Laboratory of continental {2. Department of Geology Northwest University Xi’an 710069 China

The angular unconformity between the Tuchengzi Formation and the Zhangjiakou Formation in the Chengde area is commonly regarded as the direct evidence of boundary between Jurassic and Cretaceous systems,and as the evidence of tectonic transformation interfaces in Mesozoic Era in the West Liaoning-North ***,the lower boundary age of the Zhangjiakou Formation in the Chengde was to be thought about 135 Myr in the *** on the detailed study and systematic sampling in Yixian-Beipiao,Lingy- uan,Chengde and Luanping areas in the field,the authors obtained the following isotopic ages by means of LA-ICP-MS dating:In the Lingyuan area,the Zhangjiakou Formation and the Yixian Formation are in angular unconformable contact;the age range of the Zhangjiakou Formation volcanic rock is from 133 to 130 Myr(seven samples),and that of the Yixian Formation volcanic rock is from 12. to 12. Myr(eleven samples).In the Luotuoshan of Chengde,the Tuchengzi Formation and the Zhangjiakou Formation are in angu- lar unconformable contact;the age at the lower Zhangjiakou Formation is about 12. Myr(one sample),which reflects that the age range of the lower Zhangjiakou Formation is from 12. to 12. Myr combined with the previous *** the Luanping basin,there is the larg- est sediment gap in upper Mesozoic,whose lower boundary age is confined in 131 to 130 *** the Yixian-Beipiao area,the second Member of the Yixian Formation,making up more than 3/4 thickness of the Yixian Formation,was formed in 12. to 119 Myr,and the age of the Yixian Formation at the bottom is about 132.***,the upper boundary age of the Tuchengzi Formation is about 136 Myr in the West Liaoning-North Hebei *** on the above isotopic data combined with the geological characteristics in the field in the West Liaoning-North Hebei region,it reflects that there was a widespread tectonic event in the period of 136 to 12. Myr (mainly in 130-12. Myr)in the West Liaoning-North Hebei,and it formed the

关键词： Dating LA-ICP-MS Angular unconformity Interface of tectonic transformation West Liaoning-North Hebei

Multistage evolution of continental collision orogen:A case study for western Dabie orogen

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 2009年第15期54卷 2568-2579页

作者： WU YuanBao state key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Sciences,{2. university of Geosciences, Wuhan 430074,{2. state key Laboratory of continental dynamics, Department of Geology, northwest university, xi’an 710069,{2. state key Laboratory of Geological Processes and Mineral Resources Faculty of Earth Sciences China University of Geosciences Wuhan China state key Laboratory of {2. dynamics Department of Geology Northwest University Xi’an China

The foramtion and evolution of collisional orogen is a prominent feature along convergent plate margins, and is generally a complex process. This article presents an integrated study of zircon genesis, U-Pb age and Lu-Hf isotope composition as well as geological characteristics for the western Dabie orogen to constrain its multi-stage evolution history. The results suggest that the formation of oceanic crust in the Huwan area was constrained at ca. 400―430 Ma, which was slightly later than the collision of the northern Qinling with the North china Block. It formed in a marginal basin in the northern margin of the Yangtze Block. The peak metamorphism of eclogite in the Huwan area occurred at ca. 310 Ma, and the timing of the initial exhumation of oceanic eclogite was about 2.0 Ma. The high to ultrahigh pressure (HP-UHP) metamorphic rocks in the xinxian and the Hong'an metamorphic zones have the same ages and natures as those of the HP-UHP metamorphic rocks in the other Dabie-Sulu terrains, and also have experienced multi-stage exhumation, and thus can be taken as a coherent part of the Dabie-Sulu orogen. Therefore, the Qinling-Dabie-Sulu orogen is a typical multi-stage continental collision orogen, with an amalgamation process extending more than 2.0 Ma.

关键词：大别造山带大陆碰撞西部演变超高压变质岩碰撞造山带苏鲁造山带变质岩区