Hydrochemical and isotopic investigation of a sandstone aquifer groundwater in a semi arid region,El Ma El Abiod,Algeria     

A. Rouabhia  F. Baali  Ch. Fehdi  N. Kherici  L. Djabri 《Environmental Geology》2009,57(8):1699-1705

This work present results of the hydrochemical and isotopic studies on groundwater samples from the study area. Chemical and environmental isotope data are presented and discussed in terms of the origin of dissolved species and of groundwater. All of the investigated groundwater are categorized into two chemical types: low and relatively high mineralized waters type. Interpretation of chemical data, based on both thermodynamic calculations and stability diagrams, suggests that the chemical evolution of groundwater is primarily controlled by water-rock interactions. Interpretation of ¹⁸O and ²H suggests that the recharge of the investigated groundwater may result from differents mechanisms  相似文献   

海量录井层序“砂地比”的自动计算     

李斌  朱筱敏  李洋 《高校地质学报》2012,18(1):189-192

       在陆相层序地层研究中,多条录井地层“砂地比”的对比分析是判断物源方向、揭示沉积环境、辅助层序地层划分 及岩相古地理研究中的一项重要指标,为地学研究中最基本的方法。本文使用Access 数据库技术以层序为单位实现了海量 录井地层“砂地比”的快速计算,与传统的方法相比,提高了工作效率,增强了数据的准确性和可靠性。实践证明,该方 法是一种切实可行的科学计算方法,可以在地学研究中推广使用。  相似文献   

An experiment on temperature variations in sandstone during biaxial loading     

《Physics and Chemistry of the Earth》2015

The temperature response to stress–strain variations in rock is useful in developing an understanding of the thermodynamic property of crust. In this study, the temperature of sandstone during loading was investigated using laboratory biaxial testing. By changing the loading patterns, the deformation of a specimen was controlled to produce two distinct modes of strain: volume strain only and shear strain only. These strain modes were produced separately such that the temperature variation associated with the different deformation modes could be analysed. Experimental results indicate that temperature, as a scalar quantity, is notably sensitive to rock deformation. In the case of the volume strain, the temperature variation is positively correlated with the variation in the bulk stress. The temperature rises with the increase in hydrostatic pressure, and vice versa. In the case of the shear strain, experimental results repeatedly show two characteristics: firstly, there appears obvious increase in temperature in the area of pure shear strain, which is most likely related to local plastic deformation; secondly, the temperature drops in the area of tension during loading, whereas the temperature rises within the area of compression. This is to say, the state of crustal stress–strain should be obtained through the measurement of rock temperature.  相似文献   

Origin and significance of soft-sediment deformation in the Old Red Sandstone of central South Wales,UK     

《Proceedings of the Geologists' Association. Geologists' Association》2017,128(3):422-430

Vertically oriented water-escape cusps are the most common type of soft-sediment deformation structure in sandstone-rich intervals of the fluvial Brownstones and Senni Formations (Cosheston Subgroup, Daugleddau Group) of the Lower Old Red Sandstone in the central Brecon Beacons and eastern Black Mountains, South Wales. The structures are widely distributed and occur at several stratigraphical levels. They can be divided into two styles. (1) Small-scale (height less than a single bed), isolated water-escape cusps formed when loosely packed sediment deposited rapidly in flood events liquefied in advance of subsequent flood events or pulses, causing localised fluidization due to the escape of excess pore water. Inclined cusps higher in some beds confirm the relationship of this deformation style to active flood events. (2) Horizons of larger-scale (occupying the entire bed thickness), laterally continuous water-escape cusps and fold trains can be traced for hundreds of metres to kilometres and result from widespread liquefaction in response to earthquakes. A lack of overturning indicates that their formation did not coincide with active flow conditions. Further detailed mapping is needed to clarify the continuity and extent of such structures and their relationship to faults that may have been active during sedimentation. The occurrence of triggers capable of causing liquefaction in granular materials provides a greater control on the occurrence of soft-sediment deformation than do lithological controls such as grain size or interbedding of sandstone and mudstone. The findings are broadly consistent with interpretations of soft-sediment deformation in the Cosheston Subgroup in Pembrokeshire, SW Wales.  相似文献   

The Old Red Sandstone of Britain and Ireland — a review     

《Proceedings of the Geologists' Association. Geologists' Association》2017,128(3):409-421

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砂岩储层中原生孔隙的破坏与保存机制研究进展   总被引：2，自引：1，他引：1  

胡作维  李云  黄思静  吕杰  朱炳光 《地球科学进展》2012,27(1):14-25

埋藏条件下原生孔隙的破坏与保存机制是含油气盆地砂岩储层质量研究的一个核心领域,其在油气地质学研究中的意义不言而喻。与次生孔隙的形成与保存机制相比,影响原生孔隙破坏与保存的因素有着其特殊的复杂性和多样性。在总结国内外研究进展的基础上,试图深入理解不同成岩机制在砂岩储层原生孔隙破坏与保存中的意义和作用,包括破坏机制（如机械压实、胶结作用等）和保存机制（如地层超压、颗粒包膜、盐体侵位和烃类占位等）。目前难以实现砂岩储层质量钻前准确预测的一个困难在于无法明确原生孔隙演化的动力和过程,将来成岩作用、流体作用、沉积过程和盆地演化的更紧密结合可能是解决砂岩储层原生孔隙破坏与保存机制研究中最有希望的发展方向之一。  相似文献   

Petrography and major element geochemistry of the Permo-Triassic sandstones, central India: Implications for provenance in an intracratonic pull-apart basin     

Sampa GhoshSoumen Sarkar  Parthasarathi Ghosh 《Journal of Asian Earth Sciences》2012,43(1):207-240

Detrital mode, composition of feldspars and heavy minerals, and major element chemistry of sandstones from the Permo-Triassic succession in the intracratonic Satpura Gondwana basin, central India have been used to investigate provenance. The Talchir Formation, the lowermost unit of the succession, comprises glacio-marine and glacio-fluvial deposits. The rest of the succession (base to top) comprising the Barakar, Motur, Bijori, Pachmarhi and Denwa formations, largely represent variety of fluvial depositional systems with minor fluvio-deltaic and fluvio-lacustrine sedimentation under a variety of climatic conditions including cold, warm, arid, sub-humid and semi-arid. QFL compositions of the sandstones indicate a predominantly continental block provenance and stable cratonic to fault-bounded basement uplift tectonic setting. Compositional maturity of sandstones gradually increases upwards from the Early Permian Talchir to the Middle Triassic Denwa but is punctuated by a sharp peak of increased maturity in the Barakar sandstones. This temporal change in maturity was primarily controlled by temporal variation in fault-induced basement uplift in the craton and was also influenced by climatic factors. Plots of different quartz types suggest plutonic source rocks for the Talchir sandstones and medium-to high-rank metamorphic plus plutonic source rocks for the younger sandstones. Composition of alkali feldspars in the Permo-Triassic sandstones and in different Precambrian rocks suggests sediment derivation from felsic igneous and metasedimentary rocks. Compositions of plagioclase in the Talchir and Bijori sandstones are comparable with those of granite, acid volcanic and metasedimentary rocks of the Precambrian basement suggesting the latter as possible source. Rare presence of high-K plagioclase in the Talchir sandstones, however, indicates minor contribution from volcanic source rock. Exclusively plagioclase-bearing metasedimentary rock, tonalite gneiss and mafic rocks are the probable sources of plagioclase in the Upper Denwa sandstones. Quartz-rich nature of the sandstones, predominance of K-feldspar over plagioclase and albite rich character of plagioclase in the sandstones is consistent with deposition in an intracratonic, pull-apart basin like the Satpura Gondwana basin. Composition of garnet and its comparison with that from the Precambrian basement rocks suggests mica-schist and amphibolite as possible sources. Predominance of dravite variety of tourmaline in the Permian sandstones suggests sediment supply from metasedimentary rocks. Presence of both dravite and schorl variety of tourmaline in subequal amount in the Triassic sandstones indicates sediment derivation from granitic and metasedimentary rocks. However, schorl-bearing rocks are absent in the basement complex of the study area. A-CN-K plot suggests granites, acid volcanic rock and meta-sediments of the basement as possible sources of the Talchir sandstones and metasedimentary rocks for the Barakar to Pachmarhi sandstones. The Denwa sandstones were possibly derived from K-feldspar-free, plagioclase-bearing metasediments, mafic rocks and tonalite gneiss. Chemical Index of Alteration (CIA) values suggest low intensity source rock weathering for the Talchir sandstones and higher intensity source rock weathering for the others. Various bivariate plots of major oxides composition of the sandstones suggest passive to active continental margin setting and even arc tectonic setting for a few samples.  相似文献   

The use of local stone in the buildings of the Isle of Wight     

G.K. Lott 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(5):923-932

The charm of the Isle of Wight, so much appreciated by visitors and the local population alike, is very much a combination of its delightful scenery and unique assemblage of vernacular buildings. These buildings range from isolated farmhouses to elaborate manor houses, castles and churches all constructed using the indigenous stone resources of the island. Today, these stone buildings, many of which date back to medieval times, are increasingly in need of conservation repair to maintain them for future generations. Essential to such conservation work is the safeguarding of the island's indigenous building stone sources as many of the stones used are unique to the island and no longer quarried. Protecting these stone sources could also provide stone for new building projects which would help to further enhance the character of the island's towns and villages.  相似文献   

塔里木盆地上泥盆统一下石炭统东河砂岩沉积相与哈得逊油田的发现          下载免费PDF全文

申银民  贾进华  齐英敏  孙雄伟  周波  马德波  高力 《古地理学报》2011,13(3):279-286

哈得逊油田是塔里木盆地最大的整装油田之一,储量规模超过亿吨.在其发现过程中,东河砂岩的沉积相及其相变规律起了重要的指导作用.东河砂岩为晚泥盆世晚期至早石炭世早期海侵背景下沉积的一套海侵砂(砾)岩,主体为滨岸海滩相砂体,在全盆地范围内是一个明显的穿时沉积体.东河砂岩从古地貌低部位向高部位持续超覆变薄,以陆源碎屑滨岸-浅海...  相似文献   

Defining the concept of stratigraphic grade and applying it to stratal (reservoir) architecture and evolution of the slope-to-basin profile: An outcrop perspective   总被引：1，自引：0，他引：1  

David R. Pyles  James P.M. SyvitskiRoger M. Slatt 《Marine and Petroleum Geology》2011,28(3):675-697

Stratigraphic grade is the similarity of the morphology of successive slope-to-basin profiles in a genetically related depositional system. In this article we use data collected from regional cross-sections of six depositional systems, stratal architecture derived from outcrops of the Lewis Shale (Wyoming, USA), and the Ross Sandstone (Ireland), and supplementary outcrop and subsurface data from other depositional systems to determine how stratigraphic grade relates to stratal (reservoir) architecture in deepwater systems.Four methods are developed that collectively define stratigraphic grade: (1) regional stacking patterns of fourth-order stratigraphic surfaces, (2) the relationship between the trajectory of the shelf edge (T_se) and the trajectory of the depocenter (T_d) for fourth-order stratigraphic units, (3) morphology of the slope-to-basin profiles of fourth-order stratigraphic surfaces, and (4) the similarity of the morphologies of slope-to-basin profiles of fourth-order surfaces in a system (σ_s, σ_r). Several characteristics of stratigraphic (reservoir) architecture of fourth-order stratigraphic cycles are related to stratigraphic grade: (1) longitudinal distribution of sandstone in fourth-order cycles, (2) location of maximum sandstone relative to the depocenter of fourth-order cycles, (3) lengths of fourth-order submarine fans, and (4) longitudinal and vertical distribution of architectural elements. Stratigraphic grade is thus a predictor of reservoir architecture and can thereby be used to reduce the uncertainty in the interpretation of subsurface data.The concept of stratigraphic grade is useful in understanding the stratigraphic evolution of deepwater systems. Most deepwater systems analyzed in this study initiated as out-of-grade and temporally evolved to graded systems over a time span of millions of years. Systems rarely evolve from graded to out-of-grade. First-order controls on stratigraphic grade are determined to be angle of slope, tectonically forced changes in angle of slope during deposition, and sediment supply.  相似文献