检索结果-南通市图书馆

Magma underplating and Hannuoba present crust-mantle transitional zone composition: Xenolith petrological and geochemical evidence

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2005年第8期48卷 1089-1105页

作者： FAN Qicheng1,2, ZHANG Hongfu1, SUI Jianli1, ZHAI Mingguo1, SUN Qian2 & LI Ni2 1. institute of geology and geophysics, chinese academy of sciences, beijing 100029, China 2. institute of geology, China Seismological Bureau, beijing 100029, China 1. institute of geology and geophysics Chinese Academy of Sciences 100029 Beijing China 2. institute of geology China Seismological Bureau 100029 Beijing China

On the basis of mineral assemblage, mineralogy, petrology, and major, trace ele-mental and isotopic geochemistry of the underplated granulite- and eclogite-facies accumulate, peridotite and pyroxenite xenoliths entrained in Hannuoba Cenozoic basalts, this work con-strained the petrological constituents for the crust-mantle transitional zone, which is supported by the results of high-temperature and pressure velocity experiments on rocks and geophysics deep survey. Present lower part of lower crust is mainly composed of granulite-facies mafic accumu-lates (dominantly plagioclase websterite) and crust-mantle transitional zone dominantly com-posed of eclogite-facies pyroxenites with or without garnet and spinel lherzolites; Archaean ter-rain granulite is only nominally early lower crust. Magma underplating in the crust-mantle boundary led to the crustal vertical accretion and the formation of the crust-mantle transitional zone, which is a significant mechanism for the chemical adjustment of the crust-mantle boundary since the Phanerozoic.

关键词： magma underplating, xenolith petrology, geochemistry, cust-mantle boundary constituent, Hannuoba.

在线全文

学校读者我要写书评

暂无评论

东濮凹陷油气资源评价问题探讨

石油学报 2003年第4期24卷 17-20,25页

作者：肖斌中国科学院地质与地球物理研究所北京100029

东濮凹陷是一个典型的盐湖沉积盆地 ,特殊的沉积特征决定了其油气资源评价方法的特殊性。根据东濮凹陷生油岩的高温、高压模拟试验资料 ,在一定的温压条件下 ,生油岩的液态窗可能会延长 ,使深部地层的油气资源 ,尤其是液态石油的资源供... 详细信息

东濮凹陷是一个典型的盐湖沉积盆地 ,特殊的沉积特征决定了其油气资源评价方法的特殊性。根据东濮凹陷生油岩的高温、高压模拟试验资料 ,在一定的温压条件下 ,生油岩的液态窗可能会延长 ,使深部地层的油气资源 ,尤其是液态石油的资源供给量增加。模拟试验资料还表明 ,在高温、高压条件下 ,生油岩的总生烃量会增加 ,其有机碳的转化率最高可达 41%。因此 ,用常规方法计算的资源量偏低 ,应重新测试在高温、高压条件下生油岩的产烃资源 ,准确计算东濮凹陷的资源量。

关键词：东濮凹陷盐湖沉积盆地烃源岩油气资源评价模型

Deep- Seated Tectonic Activation of Tancheng-Lujiang Fault Zone and Its Control over Jiaodong Gold Concentrated Region, China

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 1999年第1期18卷 55-57页

作者： Cai Xinping Zhang Baolin institute of geology, chinese academy of sciences, beijing 100029

A comprehensive discussion on the deep seated genesis of gold metallogenic materials and the tectono magmatic controls over gold deposits is given in this paper, which is based on the crustal and upper mantle structural characteristics of the Jiaodong massif, the property, activation history and styles of the Tancheng Lujiang fault zone, as well as a series of accompanying tectono magmatic events. Prediction for further prospecting gold deposits in the area is also made.

关键词： deep seated tectonic activation Tancheng Lujiang fault zone Jiaodong gold concentrated region.

Crustal structure of Gondwana-and Yangtze-typed blocks:An example by wide-angle seismic profile from Menglian to Malong in western Yunnan

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2005年第11期48卷 1828-1836页

作者： ZHANG Zhongjie1, BAI Zhiming1, WANG Chunyong2, TENG Jiwen1, Lü Qingtian3, LI Jiliang1, SUN Shanxue1 & WANG Xinzheng1 1. institute of geology and geophysics, chinese academy of sciences, beijing 100029, China 2. institute of geophysics, chinese Seismological Bureau, beijing 100081, China 3. institute of Deposition Resource, chinese academy of Geological sciences, beijing 100037, China 1. institute of geology and geophysics Chinese Academy of Sciences 100029 Beijing China 2. institute of geophysics Chinese Seismological Bureau 100081 Beijing China 3. institute of Deposition Resource Chinese Academy of Geological Sciences 100037 Beijing China

The wide-angle seismic profile between Menglian and Malong crosses the Baoshan block (Gondwana-typed), and Simao and southwestern Yangtze blocks (Yangtze-typed). By in-terpreting the wide-angle seismic data, we obtained the seismic crust/upper mantle structure of P-wave velocities together with the seismic reflections of these three blocks, Changning- Menglian and Mojiang suture zones among the mentioned three blocks. Our interpreting results demonstrate that the P-wave crustal velocity of Simao block is slower than that of Baoshan and southwestern Yangtze block and the crustal thickness gradually thickens from the Baoshan block, Simao to southwestern Yangtze block. Crustal reflection patterns of these three blocks have dis-tinct differences too. For the Gondwana-typed blocks, seismic reflections in the upper crust are well developed while in middle-lower crust they are very weak. The crustal reflections in the Yangtze block are very well developed. The crustal reflection patterns in Simao and southwest-ern Yangtze blocks are distinguishable. The average thickness of the crust in the studied area is about 40 km. And we make some discussions on the crustal thickening model of the three blocks in western Yunnan and tectonic setting of seismic developing and interaction of Gondwana and Yangtze blocks.

关键词： Gondwana blocks,Yangtze blocks,wide-angle profile,crustal structure,tectonic setting

LATE QUATERNARY VARIATION OF THE ARIDITY INDEX IN THE BADAIN JARAN DESERT,INNER MONGOLIA,CHINA─A DEDUCTION FROM LANDSCAPE EVOLUTIONS

在线全文

学校读者我要写书评

暂无评论

Scientia Geologica Sinica 2000年第2期 205-214页

作者： YANG Xiaoping (institute of geology and geophysics, chinese academy of sciences beijing 100029)

Palaeoclitalologists have faced for decades the challenge to obtain quantitative palaeoclimatic parameters for the arid and semiarid environrnent The landscape conception in the sense of climatic geomorphology can be used to bridge this gap. In the Badain Jaran Desert, geomorphological studies show that there are clear evidences for the shifting of morphodyndric zones. Comparing the former and present-day formation of landscapes indicates that the precipitation during the less arid periods was much larger than that of previously thought. This is confirmed by lake level changes both in the dune fields and in the marinal regions. Decreased aridity indexes of ca. 30 ka B.P. and 20 ka B.P. signal that the influence of westerlies on the arid region of northwestem China was presumably intensified at these times

关键词： der Wang A DEDUCTION FROM LANDSCAPE EVOLUTIONS LATE QUATERNARY VARIATION OF THE ARIDITY INDEX IN THE BADAIN JARAN DESERT,INNER MONGOLIA,CHINA

Variations of sulfur and carbon isotopes in seawater during the Doushantuo stage in late Neoproterozoic

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 2003年第13期48卷 1375-1380页

作者： ZHANG Tonggang, CHU Xuelei, ZHANG Qirui, FENG Lianjun & HUO Weiguo Key Lab of Mineral Resources Exploration and Research, institute of geology and geophysics, chinese academy of sciences, beijing 100029, China Key Lab of Mineral Resources Exploration and Research Institute of Geology and Geophysics Chinese Academy of Sciences China

Successive analyses of sulfur and carbon isotopic compositions of carbonates strata in the Doushantuo Formation in the Yangtze area were accomplished through a method of extracting trace sulfate from carbonates. Sulfur and carbon isotopic compositions of coeval seawater were estimated from the samples that show the least diagenetic alteration. A high-resolution age curve of sulfur isotopes in seawater sulfates was obtained in the Doushantuo stage, which reflects the trend of variation in seawater sulfur isotopes after the Neoproterozoic snowball Earth event. Similar characteristics of variation in carbon isotopes were observed in the coeval carbonates. A large positive d 34S excursion over +20?occurs in ancient seawater sulfates in the early Doushantuo stage. Simultaneously, the d 13C values in ancient seawater carbonates exhibit a positive excursion up to 10. The maximum d 34S and d 13C values are +46.4 and +6.9? respectively. In the middle Doushantuo stage, the range of variation in d 34S values of seawater is relatively narrow, but d 13C values are quite high. Then, d 34S values of seawater become oscillating, and the same occurs in d 13C values. Negative excursions in d 34S and d 13C values occur simultaneously at the end of the Doushantuo stage, and the minimum d 34S and d 13C values dropped down to -10.1 and -5.7? respectively. The characteristics of variations in the sulfur and carbon isotopes of ancient seawater imply strong changes in oceanic environment that became beneficial to inhabitation and propagation of organism. The organic productivity and burial rate of organic carbon once reached a quite high level during the Doushantuo stage. However, the state of environment became unstable after the global glaciation. The global climate and environment possibly were fluctuating and reiterating. The negative excursions in d 34S and d 13C values occurring at the end of the Doushantuo stage may represent a global event, which might be related to oxidation of dee

关键词：硫碳同位素分馏新元古代成岩作用

Holocene grassland vegetation, climate and human impact in central eastern Inner Mongolia

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2005年第7期48卷 1025-1039页

作者： HUANG Fei1, Kealhofer Lisa2, XIONG Shangfa3 & HUANG Fengbao1 1. Nanjing institute of geology and Paleontology,chinese academy of sciences,Nanjing 210008,China 2. Anthropology and Sociology Department,Santa Clara University,CA 95053,USA 3. institute of geology and geophysics,chinese academy of sciences,beijing 100029,China Nanjing institute of geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China Anthropology and Sociology Department Santa Clara University CA 95053 United States institute of geology and Geoohysics Chinese Academy of Sciences Beijina 100029 China

Phytolith and pollen preserved in the Taipusi Banner paleosol profile, central eastern Inner Mongolia, provide evidence of Holocene grassland vegetation, climate and human impact. The combined phytolith and pollen records reveal a major change in vegetation composition about 5000 a BP. Before 5000 a BP, the vegetation was dominated by Aneurolepidium chinese-Stipa grandis grassland of C4 grasses. After 5000 a BP, C4 grasses rapidly retreated, indicating a shift to colder and more arid conditions. The gradual invasion of Stipa krylovii, Ag-ropyron desertorum, Ephedra, Chenopodiaceae and Caragana reveal the onset of grassland degeneration. Between 10000 and 8720 a BP, the Aneurolepidium chinese-Stipa grandis grassland included a small proportion of Artemisia shrub and Echionopos type plants, implying a strong winter monsoon and very weak summer monsoon. From 8720 to 7000 a BP, C4 grasses were common, indicating a strengthening of the summer monsoon. Between 7000 and 5000 a BP, the Holocene thermal maximum was evident, with a significant expansion of C4 grasses and the presence of some trees (such as Pinus and Betula, and so on) in or near the study site. From 4200?000 a BP, a sandy grassland of Artemisia and Agropyron desertorum together with Aster-type taxa occurred. Precipitation amelioration took place between 3000 and 2170 a BP, with a rapid development of Echinops type plants and a small expansion of C4 grasses. From 2170 a BP to present, human activities accelerated the process of grassland degeneration.

关键词： phytolith and pollen records grassland environment change human impact Holocene central eastern Inner Mongolia.

TIME-IGGCAS model validation:Comparisons with empirical models and observations

在线全文

学校读者我要写书评

暂无评论

Science China Technological sciences 2008年第3期51卷 308-322页

作者： YUE XinAn1,2,3, WAN WeiXing1, LIU LiBo1, NING BaiQi1, ZHAO BiQiang1 & ZHANG ManLian1 1 institute of geology and geophysics, chinese academy of sciences, beijing 100029, China 2 wuhan institute of Physics and Mathematics, chinese academy of sciences, wuhan 430071, China 3 Graduate University, chinese academy of sciences, beijing 100049, China 1. institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China 2. wuhan institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071 China 3. chinese academy of sciences Graduate University Beijing 100049 China

The TIME-IGGCAS (Theoretical Ionospheric Model of the Earth in institute of Ge- ology and geophysics, chinese academy of sciences) has been developed re- cently on the basis of previous works. To test its validity, we have made compari- sons of model results with other typical empirical ionospheric models (IRI, NeQuick-ITUR, and TItheridge temperature models) and multi-observations (GPS, Ionosondes, Topex, DMSP, FORMOSAT, and CHAMP) in this paper. Several conclu- sions are obtained from our comparisons. The modeled electron density and elec- tron and ion temperatures are quantitatively in good agreement with those of em- pirical models and observations. TIME-IGGCAS can model the electron density variations versus several factors such as local time, latitude, and season very well and can reproduce most anomalistic features of ionosphere including equatorial anomaly, winter anomaly, and semiannual anomaly. These results imply a good base for the development of ionospheric data assimilation model in the future. TIME-IGGCAS underestimates electron temperature and overestimates ion tem- perature in comparison with either empirical models or observations. The model results have relatively large deviations near sunrise time and sunset time and at the low altitudes. These results give us a reference to improve the model and enhance its performance in the future.

关键词： ionosphere theoretical model empirical model satellite observation relative deviation

Fluid differentiation and gold mineralization

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S2期44卷 13-15页

作者： QIN Dajun, CAI Xinping and XU Xingwang institute of geology, chinese academy of sciences, beijing 100029, China institute of geology Chinese Academy of Sciences Beijing 100029 China

GOLD mineralization is closely related to ore-forming fluids. During the evolution of fluids, their naturescontinuously change, and the differentiation of the fluids dominates these changes. Fluid differentiationincludes fluid from melt, fluid immiscibility, gasseparating from fluids and so on. We can understand fluids through inclusions, stable isotope andore-forming experiments. Under the poststage reformation, the composition and phases of inclusionsmight be changed, hence, the initial forming conditions of fluids are difficult to be defined onlythrough the observation of these inclusions. Theexistence of solution phase, gas phase and solidphase (fig. 1) indicate that differentiation

关键词： fluid differentiation gold mineralization.