Chemical speciation of redox sensitive elements during hydrocarbon leaching in the Junggar Basin,Northwest China     

《Journal of Asian Earth Sciences》2011,40(6):713-723

Bleaching related to seepage of petroleum fluids and subsurface migration of crude oil and natural gas can alter the chemical and mineralogical properties of rocks, while concurrently depleting hydrocarbon reservoirs. Mud volcanoes constitute one type of petroleum seepage present in several areas on the southern margin of the Junggar Basin in the Xinjiang Uygur Autonomous Region, NW China. The results of XRD, XRF, XANES, and Mössbauer spectroscopy on rock samples collected from areas affected by these mud volcanoes revealed an enrichment of certain minerals and elements, as well changes in mineralogical, molecular, or ionic carrier (“species”). After bleaching, reddish sedimentary rocks showed depletion in silica and enrichment of calcium, magnesium, manganese, and iron. Other elements, including aluminum, potassium, sodium, and titanium, were largely unchanged. Reduced iron and sulfur compounds predominated in the bleached rocks, producing changes in color from the original reddish into green, deep gray, and black. Iron and calcium were associated with carbonates, indicating carbonation of these elements during the bleaching processes. Manganese also appeared to be associated with carbonate, though not with sulfate even though sulfate was present in the bleached rocks. Alkaline conditions were apparently the dominant because reduced manganese would have been absent under acidic condition. The alteration of certain minerals, clay minerals in particular, was also observed in bleached rocks, the alteration of smectite-group minerals to chlorite and muscovite, for example. Mineralogical and geochemical changes in rocks bleached by hydrocarbon fluids could provide a better overall understanding of bleaching processes, and may have applications in surface geochemical exploitation and remote imaging.  相似文献   

Estimation of land surface evapotranspiration over the Heihe River basin based on the revised three‐temperature model     

Xinping Luo  Keli Wang  Hao Jiang  Jia Sun  Qingliang Zhu 《水文研究》2012,26(8):1263-1269

  相似文献   

Effect of land‐use changes on nonpoint source pollution in the Xizhi River watershed,Guangdong, China     

Kai Xu  Yunpeng Wang  Hua Su  Jingxue Yang  Lili Li  Cang Liu 《水文研究》2013,27(18):2557-2566

The Annualized Agricultural Non‐point Source (AnnAGNPS) pollution model has been widely used to assess and predict runoff, soil erosion, sediment and nutrient loading with a geographic information system. This article presents a case study of the effect of land‐use changes on nonpoint source (NPS) pollution using the AnnAGNPS model in the Xizhi River watershed, eastern Pearl River Delta of Guangdong province, China. The land‐use changes in the Xizhi River watershed between 1998 and 2003 were examined using the multitemporal remote sensing data. The runoff, soil erosion, sediment transport and nutrient loading 1998 and 2003 were assessed using AnnAGNPS. The effects of land‐use changes on NPS were studied by comparing the simulation results of each year. Our results showed that (i) the NPS loadings increased when forest and grass land converted into paddy, orchard and farmland land, and population size and gross domestic product size as well as the usage amounts of fertilizer and pesticide in the entire watershed were firmly correlated with the NPS loadings; (ii) the land‐use change during fast urbanization in particular when other land types were converted into the development land and buildup land led to increasing of NPS pollution; and (iii) urban land expansion showed more important effects on total organic carbon (TOC) loading compared with nitrogen and phosphorus loadings. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Relationships between altitudinal gradient and plant carbon isotope composition of grassland communities on the Qinghai-Tibet Plateau,China   总被引：3，自引：0，他引：3  

ZHOU YongChun  FAN JiangWen  ZHONG HuaPing  ZHANG WenYan 《中国科学:地球科学(英文版)》2013,(2):311-320

Foliar and root carbon isotope composition(δ13C) of grassland communities on the Qinghai-Tibet Plateau,China,was obtained by the biomass weighting method and direct measurement.We investigated the characteristics and altitudinal patterns of foliar and root δ13C and determined which environmental factors influenced foliar δ13 C most.Foliar δ13 C of alpine steppe was significantly higher than that of alpine meadow and temperate steppe.For alpine meadow,root δ13C was significantly higher than of foliar δ13C.Foliar δ13C increased with altitude at an average rate of 0.60‰ km 1 for the whole grassland ecosystem.This rate was lower than that at species level.However,there were no significant relationships between root δ13C and altitude.Atmospheric pressure was a more important factor than temperature and precipitation in its influence on the altitudinal pattern of foliar δ13C at the community level.  相似文献   

A conduit-related genesis of the Lengshuiqing intrusive assemblage (Sichuan,SW China)     

Marian Munteanu  Allan H. Wilson  Yong Yao  Shao-Yong Jiang  Gordon Chunnett  Yaonan Luo  Leonard Mafurutu  Rofhiwa Phadagi 《Journal of Volcanology and Geothermal Research》2010,189(1-2):118-130

Lengshuiqing is part of the late Proterozoic igneous province from the western margin of the Yangtze craton. The Lengshuiqing area comprises five ultramafic–mafic intrusions, emplaced in the late Proterozoic Yanbian Group. The intrusions from Lengshuiqing contain cumulate ultramafic zones (peridotite + olivine pyroxenite), with cumulus olivine and Cr-spinel, and intercumulus pyroxenes, hornblende, phlogopite and plagioclase. Ni–Cu ore (pyrrhotite + pentlandite + chalcopyrite) is hosted in the ultramafic zones. Olivine-free diorite–quartz diorite ± gabbro and granite zones commonly occur above the ultramafic rocks. The genesis of the intrusions (conduit-related accumulation or differentiation from stagnant magma) was investigated. The amount of sulphides in the intrusions from Lengshuiqing is one order of magnitude bigger than the sulphides that can be dissolved by a volume of mafic magma similar with the volume of the intrusions. Most intrusions from Lengshuiqing have bulk composition (peridotite ± diorite ± granite) more magnesian (MgO = 21–22%; Mg# > 78) than the deduced composition of their parental magma (MgO = 9–11%; Mg# = 64–67). This indicates the accumulation of sulphide and mafic silicates from a volume of magma much bigger than the volume of the intrusions, which can be explained by the fractionation from magma ascending through the intrusions to shallower depths. A continuous supply and vent of magma is consistent with the lack of chilled margins, the melting of the wall rocks and the generation of high-temperature mineral assemblages (K-feldspar, diopside, and sillimanite) in the Yanbian Group. The intrusions from Lengshuiqing are seen as microchambers on conduits draining olivine-, Cr-spinel-, and sulphide-bearing mafic magma from a larger staging chamber.  相似文献   

热液条件下CO2和H2反应产烃研究进展     

季福武  周怀阳  杨群慧 《地球科学进展》2007,22(1):41-48

热液条件下CO2和H2形成烷烃的反应，提供了自然条件下CO2转化为有机质的一条非生物途径。研究这一过程，对于油气费托非生物成因研究和海底热液生命起源的讨论具有重要意义。已有研究表明，热力学有利的温度、压强条件和合适的催化剂，是热液条件下CO2和H2发生反应形成烷烃的必需条件。在热力学有利的条件下，铬铁矿能够催化反应形成CH4、C2H6和C3H8，但还不清楚是否存在能够促使反应产生C4H10等长链烷烃的天然矿物催化剂。含一种或多种过渡金属元素的磁铁矿，可能是值得考察的对象。另外，研究热液条件下CO2和H2反应形成烷烃的过程和机理，建立反应所形成烷烃的C、H同位素综合判识指标，是今后值得探索的研究课题。  相似文献   

A partial least-squares regression approach to land use studies in the Suzhou-Wuxi-Changzhou region     

ZHANG Yang  ZHOU Chenghu 《地理学报》2007,17(2):234-244

In several LUCC studies, statistical methods are being used to analyze land use data. A problem using conventional statistical methods in land use analysis is that these methods assume the data to be statistically independent. But in fact, they have the tendency to be dependent, a phenomenon known as multicollinearity, especially in the cases of few observations. In this paper, a Partial Least-Squares (PLS) regression approach is developed to study relationships between land use and its influencing factors through a case study of the Suzhou-Wuxi-Changzhou region in China. Multicollinearity exists in the dataset and the number of variables is high compared to the number of observations. Four PLS factors are selected through a preliminary analysis. The correlation analyses between land use and in-fluencing factors demonstrate the land use character of rural industrialization and urbaniza-tion in the Suzhou-Wuxi-Changzhou region, meanwhile illustrate that the first PLS factor has enough ability to best describe land use patterns quantitatively, and most of the statistical relations derived from it accord with the fact. By the decreasing capacity of the PLS factors, the reliability of model outcome decreases correspondingly.  相似文献   

Farmers＇ vulnerability to flood risk： A case study in the Poyang Lake Region   总被引：2，自引：0，他引：2  

MA Dingguo CHEN Jie ZHANG Wenjiang ZHENG Lin LIU Ying 《地理学报(英文版)》2007,17(3):269-284

This paper quantitatively explores farmers＇ vulnerability to flood in the Poyang Lake Region （PLR） with the supports of GIS spatial functions. The analysis consists of three major steps, which is based on the spatial unit of township. Firstly, the spatial extent and characteristics of flood risk areas were determined using a digital elevation model （DEM） derived from the 1：50,000 topographic map. Secondly, for each of the township, six indices indicating the economic activities of local farmers were calculated. These indices are： rural population proportion, cultivated land proportion, GDP per unit area, employment proportion of primary industry, net rural income per capita and agricultural income proportion. These six indices were then normalized and used for later vulnerability assessment. Thirdly, the normalized indices （as GIS data layers） were overlaid with the flood risk areas to produce the risk coefficient for each township and to calculate the overall vulnerability for each township. The analysis results show that in the PLR there are high flood risk areas where the farmers＇ livings are seriously influenced or threatened. About 55.56% of the total 180 townships in the flood risk areas have a high degree of flood vulnerability. The townships under flood risk are mainly distributed in the areas around the Poyang Lake and the areas along the ＂five rivers＂.  相似文献   

青藏高原东缘晚新生代大邑砾岩的 物源分析与水系变迁^*   总被引：2，自引：4，他引：2  

黎兵  李勇  张开均  张玉修  张毅  魏庆国  汪洋 《第四纪研究》2007,27(1):64-73

成都盆地晚新生代碎屑沉积物的快速堆积是青藏高原东缘强烈隆升的产物,同时为青藏高原东缘晚新生代的隆升提供了强有力的证据。文章以盆地底部的大邑砾岩作为研究切入点,详细研究了它的物源区,以深化对青藏高原东缘晚新生代隆升过程的理解。通过砾石成分统计、砂岩薄片鉴定、重矿物分析以及古流向恢复等方面的研究表明,成都盆地北部和南部的大邑砾岩分别受不同的物源区和河流所控制。其中北部的大邑砾岩受控于出口在都江堰南约4km处向南流的河流所控制,其物源区为玉堂镇以西、汶川-茂汶断裂以东的流域范围内。而南部的大邑砾岩则主要受向东流的古青衣江的控制,其物源区即为现代青衣江流域。大邑砾岩的物源分析表明晚新生代期间岷江和青衣江都曾发生河流改道。  相似文献   

西藏羌塘盆地东部中-上侏罗统沉积特征及沉积相划分   总被引：1，自引：2，他引：1  

张玉修  张开均  李勇  李亚林  谢尧武  黎兵 《大地构造与成矿学》2007,31(1):52-62

详细野外剖面测量基础上,对羌塘盆地东部中-上侏罗统剖面主要岩类的宏观特征(颜色和构造)、物质组分、结构及磁化率等特征进行系统研究,研究区碎屑岩主要为砾岩、砂岩、粉砂岩和泥岩等岩类,磁化率值呈现低→高→低→高→低(雀莫错组→布曲组→夏里组→索瓦组→雪山组)的规律性变化。综合沉积特征显示雀莫错组和雪山组主要为河流相-河控三角洲相沉积,布曲组为碳酸盐缓坡相沉积为主,夏里组主要为潮坪-泻湖相沉积,索瓦组主要为混积陆棚-泻湖-潮坪相沉积,中-晚侏罗世羌塘盆地古水深在下降的总趋势中呈现浅→深→浅→深→浅的升降旋回,盆地沉积中心由东向西迁移,区域构造演化和全球海平面变化共同控制了盆地沉积面貌。  相似文献