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Characteristics of the mantle source region of sodium lamprophyres and petrogenetic tectonic setting in northeastern Hunan,China

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Science China Earth sciences 2004年第6期47卷 559-569页

作者： JIA Dacheng HU Ruizhong LU Yan XIE Guiqing QIU Xuelin Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang China College of Geo-Exploration Science and Technology Jilin University Changchun China South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China

A set of unique sodium lamprophyres is devel)0.1(oped in the Cenozoic intraconti)]nental extensional zone of northeastern Hunan. These lamprophyres are significantly different in major [(and trace elements and Sr, Nd isotopes from ordinary potassic lamprophyr\ es. )0(The rocks)0( )(are)( )]characterized as being enriched in Na2O and high in TiO2 and weakly enriched in Nb, Ta, Nd and LREE with no negative Eu anomaly. The trace elements and Sr, Nd isotopic compositions are typical of the mantle source region of oceanic island basalts (OIB). The average initial 87Sr/86Sr ratio is 0.705332, and the average initial 143Nd/144Nd ratio is 0.512650, with εNd(t) being[( )45.4(+3.5)(--)(+3.9, )]marking a mantle source region of unique sodium lamprophyres. The lamprophyres were formed by metasomatism of the primitive mantle at the bottom of lithosphere by vola[(tile)(-)(containing )68.2(f)(l)(u-)]ids/melts from the asthenosphere. The measured Rb-Sr isochron age of sodium lamprophyre is 136.61 Ma, representing a period in which the tectonic setting changed from compressive to extensional. [(Sodium lamprophyres were formed in a mantle plume tectonic set)0(ting characterized by mantle )]upwelling from the asthenosphere within the continent. Asthenospheric mantle upwelling is the principal geodynamic factor leading to the formation of sodium lamprophyres and constraining the [(Yanshanian i)0(n)(tracontinental extensional activity in northeast)0(ern Hunan, China.)]

关键词： sodium lamprophyre, mantle source region, tectonic setting,genesis,northeastern Hunan.

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Spatial Pattern of Rural Settlements in the Upper Reaches of the Minjiang River——a case Study in Maoxian County, Sichuan

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Journal of Mountain Science 2007年第2期4卷 146-154页

作者： FENG Werdan LI Ainong ZHOU Wancun Chengdu Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041SichuanChina Graduate School of chinese academy of sciences Beijing 100039 China Chengdu Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041Sichuan China

A quantitative analysis of the spatial pattern of rural settlements in the upper reaches of the Minjiang River was made with the major data sources being the relevant ETM image and the national geographical database of China (including contour line, river and road) at the scale of 1:250 000, and using image interpretation and field investigation to obtain spatial information on rural settlements. The results of the spatial analysis technique of GIS and correlation analysis showed that most settlements (78.2 %) were located in the mountain area at 1500 ∼ 2700 m altitude, and almost half in the arid valley area. More than 80.0 % of settlements had their slopes above 15°. Most settlements had good access to water resources, roads and communications, and tended to cluster close to the road network rather than the river. About half of the rural settlements in the study area were relatively concentrated, while the others were decentralized. Those with higher altitude usually had land with steep slope, inconvenient water and road accesses, and were located far apart from each other. In view of such a situation, further research should be done to make reasonable countermeasures on these settlements for better living conditions and ecosystem stability.

关键词：农村聚落空间模式 GIS 中国

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Deduction and application of generalized Euler formula in topological relation of geographic information system (GIS)

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Science China Earth sciences 2004年第8期47卷 749-759页

作者： ZHANG Shuqing1, ZHANG Junyan1,2 & ZHANG Bai1 Northeast Institute of Geography and Agricultural Ecology, chinese academy of sciences, Changchun 130012, China Northeast Design Institute of China City Planning and Engineering, Changchun 130012, China Northeast Institute of Geography and Agricultural Ecology Chinese Academy of Sciences Changchun China Northeast Design Institute of China City Planning and Engineering Changchun China

By combining geographic information system (GIS), a new conception of 揼roup?in which covers the complex connected region is introduced in the paper. Based on the concep-tion of group, a generalized Euler formula and its properties are deduced and proved. The paper also describes the mathematical principles of generating topological information of polygon in GIS maps and the methods for checking up the veracity of topological relations of the map with Euler formula and general Euler formula. We have also obtained the quantitative relations among real nodes, chains, islands and groups with the formulas. At the same time, the paper introduces Whole Sphere Stereographic (WSS) projection into the GIS, and defines a new conception of 搒ea? The deduction of general Euler formula and the introduction of WSS projection to GIS have developed new ways of delineating GIS topological models from plane to sphere and even con-structing three dimensional (3-D) topological models.

关键词： Euler formula,general Euler formula,geographic information system,topological relation.

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Existence of Qiongnan suture zone on the north margin of South China Sea

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chinese Science Bulletin 2006年第B12期51卷 107-120页

作者： LIU Hailing YAN Pin LIU Yingchun DENG Hui Key Laboratory of Marginal Sea Geology South China Sea Institute of Oceanology and Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 501301 China Sinopec International Petroleum Exploration & Production Corporation Beijing 100083 China

This paper aims to explore whether paleo-suture zone exists in the pre-Cenozoic basement of South China Sea (SCS). By taking advantage of integrated geophysical surveying data, including multi-channel reflection seismicity, oceanic bottom seismicity, gravity and magnetic data as well as paleomagnetism and drilling information, a comprehensive analysis on sedimentary stratigraphy, seismic stratigraphy, magmatic and metamorphic petrology, geochemistry, gravity study, magnetics, paleogeomagnetics as well as geotectonics was carried out, and the results clearly indicate that a pre-Cenozoic suture zone, i.e. “Qiongnan (south Hainan Island) suture zone”, does exist on the north margin of SCS. This suture zone starts in the west from the Jiusuo-Lingshui fault zone in the south of Hainan Island, extends eastward across the continental slope to the north of SCS, and links with Shoufeng fault in Taiwan. It is inferred that the Qiongnan suture zone was sutured approximately in Indosinian (Triassic) Epoch and is actually the vestige of “Qiongnan ocean basin”, the extension of the main paleo-Tethys ocean basin in SCS. The formation of Qiongnan suture zone marked the collision-accretion of the Qiongnan Block toward the Qiongzhong Block. The Qiongnan suture zone is linked to the west with the southward extension of the principal suture zone of the Paleo-Tethys at Bitu-Changning-Menglian-Bentong-Raub, across the southern segment of the Red River-East Vietnam-Wanna strike-slip fault zone, and connected to the east with the suture zone emplaced into the south margin of the Oki-Hida Pre-Jurassic terranes in southwest Japan, across the northerni2 e segment of the Manila trench fault zone in the northeast side of Taiwan Island. The discovery of this suture zone is believed to be potentially significant toward study of the pre-Cenozoic geotectonic pattern of SCS, the temporal and spatial distribution of the east paleo-Tethys structural domain in SCS and the relationship of recombination

关键词：海南岛琼南缝合带南海北缘琼南海盆琼南板块地质构造古特提斯

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Investigation and Assessment of Landslides and Debris Flows in Sichuan Province of China by Remote Sensing Technique

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chinese Geographical Science 2006年第3期16卷 223-228页

作者： ZHANG Baolei ZHANG Shumin ZHOU Wancun Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Graduate University of chinese academy of sciences Beijing 100049 China Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Bering 100101 China Shandong Economic University Jinan 250014 China

Taking TM images, ETM images, SPOT images, aerial photos and other remote sensing data as fundamental sources, this research makes a thorough investigation on landslides and debris flows in Sichuan Province, China, using the method of manual interpretation and taking topography maps as references after the processes of terrain correction, spectral matching, and image mosaic. And then, the spatial characteristics of landslides and debris flows in the year of 2005 are assessed and made into figures. The environmental factors which induce landslides and debris flows such as slope, vegetation coverage, lithology, rainfall and so on are obtained by GIS spatial analysis method. Finally, the rela- tionships of landslides or debris flows with some environmental factors are analyzed based on the grade of each envi- ronmental factor. The results indicate: 1) The landslides and debris flows are mainly in the eastern and southern area of Sichuan Province, however, there are few landslides and debris flows in the western particularly the northwestern Si- chuan. 2) The landslides and debris flows of Sichuan Province are mostly located in the regions with small slope degree. The occurring rate of debris flow reduces with the increase of the vegetation coverage degree, but the vegetation cov- erage degree has little to do with the occurrence of landslide. The more rainfall a place has, the easier the landslides and debris flows take place.

关键词：遥感技术滑坡四川动力地质灾害

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Analyzing global trends of different cloud types and their potential impacts on climate by using the ISCCP D2 dataset

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chinese Science Bulletin 2004年第12期49卷 1301-1306页

作者： DINGShouguo SHIGuangyu ZHAOChunsheng LASG InstituteofAtmosphericPhysicsChineseAcademyofSciencesBeijing100029China DepartmentofAtmosphericScience SchoolofPhysicsPekingUniversityBeijing100871China

The International Satellite Cloud Climatology Project (ISCCP) D2 dataset is used to study the global dis- tribution of low, middle and high cloud amounts and their trends of 1983—2001. Evidences have shown that global warming has accelerated over the past 20 a and the 1990s was the warmest decade in the instrumental records since 1861. Trends of various clouds amounts over this period are analyzed by employing the linear regression method. The results show that global mean total cloud amounts, in general, have tended to reduce over the past 20 a. But there are slightly increasing by about 2% before 1987 and decreasing by about 4% since then. Cloudiness trends of both low and high clouds decrease while increase for the middle cloud. And there exist remarkable discrepancies in different regions. The preliminary analyses suggest that it is likely that the cloud change occurring over the past 20 a is a positive feed- back to global warming.

关键词： ISCCP D2数据集全球气候变暖国际卫星云图气候工程线性衰退方法大气环流模型

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Factors controlling the enrichment of natural gas in Kuche depression,Tarim Basin,NW China:Molecular geochemical evidence from sedimentary organic matter

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chinese Science Bulletin 2004年第S1期49卷 66-71页

作者： SUN Yongge XIAO Zhongyao LIU Dehan CHAI Pingxia XU Shiping SKLOG Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640China Tarim Petroleum Exploration and Development Company PetroChinaKuerle 841000China

Using molecular geochemical data from infrared spectrometer and pyrolysis gas chromatography-mass spectrometry, this paper investigates the petroleum generation characteristics of Jurassic coal measures from Kuche depression, Tarim Basin, NW China. The results showed that the Jurassic coaly rocks with medium maturity (R0%: 0.8-1.1) were enriched in gas-prone functionalities (-CH3) and low molecular weight pyrolysates (21), indicating that the coaly rocks from Kuche depression were gas/condensate prone at the stages of middle to high maturation, and it was further supported by the oil/source correlation from well Yinan 2 in this region.

关键词： natural gas Jurassic coal measures Kuche depression infrared spectrometer pyrolysis gas chromatography-mass spec-trometry.

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Paleoclimatic significance of mineral magnetic properties of loess sediments in northeastern Qinghai- Tibetan Plateau

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chinese Science Bulletin 2003年第19期48卷 2126-2133页

作者： WANGXiaoyong LUHuayu LIZhen DENGChenglong TANHongbing StateKeyLaboratoryofLoessandQuaternaryGeology InstituteofEarthEnvironmentChineseAcademyofSciencesXi'an710075China DepartmentofGeography QinghaiNormalUniversityXining810008China PaleomagnetismLaboratory InstituteofGeologyandGeophysicsChineseAcademyofSciencesBeijing100029China InstituteofSalineLake ChineseAcademyofSciencesXining810008China

Loess deposit in the northeastern Qinghai-Tibetan Plateau offers an excellent record of climate and environment changes in this region. We have conducted multiparameter mineral magnetic analyses of samples of loess deposits from the Dongchuan, Lalakou and Panzishan sections. The methods used include magnetic susceptibility, frequency-dependent susceptibility, temperature-dependent susceptibility, isothermal remanent magnetization acquisition, and magnetic hysteresis loops. The results reveal that magnetite is the dominant contributor to magnetic susceptibility. Maghemite and hematite is also present in the loess layers and paleosol horizons. The higher concentration of maghemite in paleosols suggests that the formation of maghemite occurred during in situ pedogenesis, which plays an important role in the enhancement of the magnetic susceptibility. Similar to that in the chinese Loess Plateau lying to the east of the Liupan Mountains, magnetic granulometry in the studied loess and paleosols is predominantly pseudo-single-domain (PSD). However, the mean grain-size of the ferrimagnetic minerals in loess is evidently coarser (larger PSD and multidomain-like) than in paleosols (mainly PSD). The magnetic susceptibility of loess and paleosols is positively correlated with the content of ultrafine magnetite/maghemite grains, and hence with the intensity of in situ pedogenesis. Therefore, the enhanced magnetic susceptibility in the studied loess-paleosol sequences can be interpreted as being due to climatically induced in situ pedogenesis.

关键词：古气候矿石磁性质黄土沉积东北地区青海西藏高原环境变迁

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Terrestrial mollusk evidence for the origin and sedimentary environment of the Late Tertiary Red Clay Formation in the Loess Plateau, China

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chinese Science Bulletin 2004年第10期49卷 1072-1076页

作者： PEIYunpeng WUNaiqin LIFengjiang InstituteofGeologyandGeophysics ChineseAcademyofSciencesBeijing100029China InstituteofGeologyandGeophysics ChineseAcademyofSciencesBeijing100029China

The origin and sedimentary environment of theLate Tertiary (Neogene) Red Clay Formation in northernChina had long been controversial. A new mollusk recordfrom the Xifeng red clay (red-earth) sequence in the centralLoess Plateau provides the biological evidence for addressingquestions of its origin and environmental implication. Thestudy of composition and preservation condition of seventymollusk fossil assemblages reveals the initial ecological con-dition of the red clay formation, avoiding the effect ofpost-deposited alteration. The result shows that all of identi-fiable mollusk species are composed of terrestrial taxa, mostof them are the common species found in the overlying Qua-ternary Ioess-paleosol sequence. Most of fossil individualspreserved in the red clay strata are in living conditions basedon the investigation of fieldwork, indicating the originalpopulation. Thus, the mollusk fossil assemblages can be usedas an indicator of primary environment of the red clay for-mation. The mollusk record from the Xifeng red clay se-quence supports the view that the red clay is an aeolian ori-gin, similar to the overlying Quaternary loess deposits. Ourdata also reveal the history of environmental changes atXifeng from 6.2--2.4 Ma, which is coupled in phase with theformation and development of the Arctic ice sheets and theprocess of the Tibetan Plateau uplift. Both may be the majorcause and forcing mechanisms of the late Tertiaryenvironmental changes in the Loess Plateau.

关键词：陆地软体动物沉积环境黄土高原化石红粘土近第三纪环境变迁起源

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Climatic significance of stable carbon isotope in tree rings of Abies spectabibis in southeastern Tibet

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chinese Science Bulletin 2003年第18期48卷 2000-2004页

作者： LIU Xiaohong Qin Dahe SHAO Xuemei CHEN Tuo REN Jiawen Cold and Arid Regions Environment and Engineering Research Institute Chinese Academy of SciencesLanzhou 730000China Institute of Geographic sciences and Nature Resources Research Chinese Academy of SciencesBeijing 100101China

The annually cross-dated stable carbon isotope of tree-ring a-cellulose of Abies spectabibis collected from the southeastern Tibetan Plateau is used to examine its rela-tionship with climatic parameters. The residual D13C series in treerings is constructed after removing the effects of age trend and rising CO2. We found a close relationship between D13C in tree rings and the relative humidity of September—November of the previous year measured at the nearby Ny-ingchi Meteorological Station, albeit a strong 搇agged effect? Thus we developed a transfer function to reconstruct the autumn relative humidity for the Nyingchi region, which explained 37.9% of the total variance (p 01). Our results suggest a high frequency and moderate amplitude variance of the relative humidity before 1800, and the variance re-versed afterwards.

关键词： Abies spectabibis tree rings stable carbon isotope cli-matic reconstruction.

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