Stable isotope(δ~(13)C_(ker),δ~(13)C_(carb),δ~(18)O_(carb)) distribution along a Cambrian outcrop section in the eastern Tarim Basin,NW China and its geochemical significance     

Hu Liu  Zewen Liao  Haizu Zhang  Yankuan Tian  Bin Cheng  Shan Yang 《地学前缘(英文版)》2017,8(1):163-170

This study investigated the geochemical features of the lower Paleozoic strata of Yaerdang Mountain outcrop along with the core samples from well TD2∈ in the eastern Tarim Basin,NW China.The total organic carbon abundance,hydrocarbon-generating precursor biospecies,and stable isotope ratios of organics and carbonate(δ~(13)C_(ker),δ~(13)C_(carb) and δ~(18)O_(carb)) were comprehensively studied for their possible correlative constraints during sedimentary evolution.The results revealed that the δ~(13)C_(ker)(VPDB) of Cambrian kerogens along the outcrop section varied from-34.6‰ to-28.4‰,indicating an increasing tendency from the lower Cambrian to the upper Cambrian.This was on the whole accompanied by the variation in the δ~(13)C_(carb) and δ~(18)O_(carb) along the profile,which might be associated with the changes in the sea level and also in the compositional variation of benthic and planktonic biomass.The large variation in the stable carbon isotope ratios up to 6‰ along the outcrop section reflected the heterogeneity of the Cambrian source rocks from the eastern Tarim Basin.Hence,the ~(13)C-enriched crude oils from well TD2∈might have been derived from a localized stratum of Cambrian source rocks.The results from this study showed the possibility of multiple source kitchens in the Cambrian-lower Ordovician portion of Tarim Basin.  相似文献   

京西北盆岭构造区现代构造应力场的非均匀特征   总被引：8，自引：0，他引：8       下载免费PDF全文

张红艳  谢富仁  荆振杰 《地球物理学报》2009,52(12):3061-3071

京西北盆岭构造区包括延矾、怀涿、蔚广、阳原、灵丘、怀安及张家口多个活动断陷盆地.通过对该区大量活动断层擦痕的测量,利用由断层滑动资料反演构造应力张量的计算方法,获得研究区24个测点的构造应力张量数据;同时利用格点尝试法对研究区两个不同应力分区的中小地震震源机制解进行了分析.依据断层滑动与震源机制解两类资料的分析计算结果,初步给出了研究区现代构造应力场的非均匀特征：延矾盆地区域（B区）断层滑动反演的构造应力张量与震源机制解类型均表现为走滑型,表明该区受控于NEE-SWW向挤压、NNW-SSE向拉张的区域构造应力作用.怀涿、蔚广等盆地所在的山西断陷带北部尾端区域（A区）断层滑动反演的构造应力张量与震源机制解类型以正断型为主,表明怀涿、蔚广等盆地所在的山西断陷带北部尾端区域（A区）受近NNW-SSE向拉张的局部构造作用相对于延矾盆地更为显著.现代构造应力场的非均匀分布反映了京西北盆岭构造的差异特征.  相似文献   

新疆艾比湖周边白刺沙堆形态特征空间异质性研究   总被引：8，自引：1，他引：7  

刘金伟  李志忠  武胜利  李万娟  王少朴  曹向东  凌智永 《中国沙漠》2009,29(4):628-635

在实地调查和形态测量的基础上,应用统计学原理和方法,对新疆艾比湖周边白刺沙堆的实测形态参数进行数理统计分析,以分析艾比湖周边白刺沙堆的空间异质性。结果表明,艾比湖周边白刺沙堆的长轴平均长度介于4.5~7 m之间,短轴平均长度介于3~5.5 m之间,沙堆平均高度介于0.5~1 m之间;沙堆长轴、短轴、迎风坡坡长和背风坡坡长之间均具有显著相关性,尤其是长轴长度和背风坡坡长,短轴长度和迎风坡坡长具有高度相关性,沙堆的高度与短轴的相关程度最高。从白刺沙堆各发育阶段形态特征分析,艾比湖东部和东北部桑德库木和鸭子湾北部白刺沙堆处于生长阶段,艾比湖西部阿拉山口附近的白刺沙堆处于发育的衰退阶段。  相似文献   

Influence of bed heterogeneity and habitat type on macroinvertebrate uptake in peri-urban streams     

REID  H.E.  BRIERLEY  G.J.  BOOTHROYD  I.K.G. 《国际泥沙研究》2010,25(3):203-220

The role of geomorphic structure, referred to as physical heterogeneity, and its influence upon the colonization of habitat by macroinvertebrates was analysed in the peri-urban, Twin Streams Catchment, in West Auckland, New Zealand. Using a cross-scalar approach, 4 riffle-run assemblages were analysed in each of 2 River Styles (a confined, low sinuosity, gravel bed river and a partly confined, low sinuosity, bedrock, cobble, and gravel bed river). Each of these 8 locations comprised 2 distinct sampling areas; the upstream zone had a more heterogeneous river bed with a high diversity of physical features and flow, whilst the downstream area had a more homogeneous structure. Microhabitat features sampled at each site included streambed material, bank margins, fine grained organic debris, wood, and boulders. Habitat mosaics and their associated macroinvertebrate relationships followed a semi-predictable but interrupted pattern, supporting the view that river systems are a patchy discontinuum. Homogeneous zones were more frequently characterised by higher proportions of Trichoptera than heterogeneous zones, whilst heterogeneous zones were frequently characterised by Plecoptera and Ephemeroptera. Diversity was maximised when the species pools from heterogeneous and homogeneous sites were combined for any given site. Functional habitats influenced macroinvertebrate assemblages in non-linear and complex ways. Wood and organic debris habitats were associated with high diversity, abundance, and sensitive species whereas streambed habitat was usually associated with low diversity. A diverse range of physical zones that approximates the 'natural range of behaviour' for the given type of stream was considered to provide a more effective platform for rehabilitation planning than emphasising heterogeneity of physical structure in its own right.  相似文献   

Experimental Study of the Main Influencing Factors in Mechanical Properties of Conglomerate     

ZHOU Bo  GE Hongkui  ZHOU Wei  WANG Jianbo  HAO Hongyong  WANG Xiaoqiong  LIU Pengyu 《中国地震研究》2020,34(3):430-451

In recent years, with the success of exploration and development of conglomerate reservoirs in Mahu Depression, Junggar Basin, China, it is urgent to study the mechanical properties and its influencing factors of conglomerate which is considered as a new oil and gas reservoir. Based on the investigations of petrologic characteristics, heterogeneity and mechanical properties of conglomerate in Baikouquan formation, the content and geometric characteristics of gravel in conglomerate, the main factors in heterogeneity and the mechanical behavior in the triaxial compression experiment of conglomerate are analyzed in this paper. The results show that the size and content of gravel in conglomerate varies greatly, and conglomerate has strong heterogeneity under the influence of gravel content and size. An analysis of mechanical properties of conglomerate shows that conglomerate is characterized by plasticity. Besides, the sphericity is negatively correlated to the gravel content, while the heterogeneity increases with the increase of conglomerate plasticity. Due to the existence of heterogeneous gravel, local stress may concentrate in conglomerate when the stress is loaded. Consequently, a large number of micro-cracks appear at the edge of gravel, demonstrating the strong plasticity of conglomerate. This paper is of referential significance to the study of rock mechanical properties and the evaluation of engineering properties in conglomerate development.  相似文献   

Solute dilution under imbibition and drainage conditions in a heterogeneous structure: Modeling of a sand tank experiment     

M. Rossi  O. Ippisch  H. Flühler 《Advances in water resources》2008

This study aims at modeling the transport of a conservative tracer in two dimensions, as experimentally observed in a strongly heterogeneous medium under conditions of variable water saturation during drainage and imbibition. Solute transport experiments were conducted in a sand tank containing an artificial packing of three quartz sands of different particle sizes. The packing was characterized by the presence of numerous homogeneous layers (0.5 × 5 × 5 cm) inclined at 45° and randomly distributed in a tank. Six different stationary flow conditions were sequentially established during imbibition and drainage. When a stationary flow regime was reached, several solute pulses were applied at different positions at the upper surface of the sand structure. The transport regime was studied by monitoring the tracer plumes injected as point-like pulses at the surface, as they travelled through the sand bedding.  相似文献   

Reaction rates and effective parameters in stratified aquifers     

Daniel Fernàndez-Garcia  Xavier Sánchez-Vila  Alberto Guadagnini 《Advances in water resources》2008

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Point-to-point connectivity,an abstract concept or a key issue for risk assessment studies?     

Paolo Trinchero  Xavier Snchez-Vila  Daniel Fernndez-Garcia 《Advances in water resources》2008,31(12):1742-1753

Connectivity of high/low-permeability areas has been recognized to significantly impact groundwater flow and solute transport. The task of defining a rigorous quantitative measure of connectivity for continuous variables has failed so far, and thus there exist a suite of connectivity indicators which are dependent on the specific hydrodynamic processes and the interpretation method. Amongst the many existing indicators, we concentrate on those characterizing connectivity between the points involved in a hydraulic or tracer test. The flow connectivity indicator used here is based on the time elapsed for hydraulic response in a pumping test (e.g., the storage coefficient estimated by the Cooper–Jacob method, S_est). Regarding transport, we select the estimated porosity from the breakthrough curve (_est). According to Knudby and Carrera [Knudby C, Carrera J. On the relationship between indicators of geostatistical, flow and transport connectivity. Adv Water Resour 2005;28(4):405–21] these two indicators measure connectivity differently, and are poorly correlated. Here, we use perturbation theory to analytically investigate the intrinsic relationship between S_est and _est. We find that _est can be expressed as a weighted line integral along the particle trajectory involving two parameters: the transmissivity point values, T, and the estimated values of S_est along the particle path. The weighting function is linear with the distance from the pumping well, thus the influence of the weighting function is maximum at the injection area, whereas the hydraulic information close to the pumping well becomes redundant (null weight). The relative importance of these two factors is explored using numerical simulations in a given synthetic aquifer and tested against intermediate-scale laboratory tracer experiments. We conclude that the degree of connectivity between two points of an aquifer (point-to-point connectivity) is a key issue for risk assessment studies aimed at predicting the travel time of a potential contaminant.  相似文献   

Comparison of laboratory-scale solute transport visualization experiments with numerical simulation using cross-bedded sandstone   总被引：1，自引：0，他引：1  

Katherine A. Klise  Vincent C. Tidwell  Sean A. McKenna   《Advances in water resources》2008,31(12):1731-1741

Using a slab of Massillon Sandstone, laboratory-scale solute tracer experiments were carried out to test numerical simulations using the Advection–Dispersion Equation (ADE). While studies of a similar nature exist, our work differs in that we combine: (1) experimentation in naturally complex geologic media, (2) X-ray absorption imaging to visualize and quantify two-dimensional solute transport, (3) high resolution transport property characterization, with (4) numerical simulation. The simulations use permeability, porosity, and solute concentration measured to sub-centimeter resolution. While bulk breakthrough curve characteristics were adequately matched, large discrepancies exist between the experimental and simulated solute concentration fields. Investigation of potential experimental errors suggests that the failure to fit solute concentration fields may lie in loss of intricate connectivity within the cross-bedded sandstone occurring at scales finer than our property characterization measurements (i.e., sub-centimeter).  相似文献   

Lateral variations of coda Q and attenuation of seismic waves in Southwest Anatolia     

Şakir Şahin 《Journal of Seismology》2008,12(3):367-376

The seismic quality factor (Q _c) and the attenuation coefficient (δ) in the earth’s crust in southwest (SW) Anatolia are estimated by using the coda wave method based on the decrease of coda wave amplitude by time on the seismogram. The quality factor Q _o, the value of Q _c at 1 Hz, and its frequency dependency η are determined from this method depending on the attenuation properties of scattered coda waves. δ is determined from the observations of amplitude variations of seismic waves. In applying the coda wave method, firstly, a type curve representing the average pattern of the individual coda decay curves for 0.75, 1.5, 3.0, 6.0, 12.0, and 24.0 Hz values was estimated. Secondly, lateral variation of coda Q and the attenuation coefficients for three main tectonic patterns are estimated. The shape of the type curve is controlled by the scattering and attenuation in the crustal volume sampled by the coda waves. The Q _o and η values vary from 30 to 180 and from 0.55 to 1.25, respectively for SW Anatolia. In SW Anatolia, coda Q–f relation is described by and δ = 0.008 km⁻¹. These results are expected to help in understanding the degree of tectonic complexity of the crust in SW Anatolia.  相似文献