DOCSLIB.ORG

The Genesis Model of Carbonate Cementation in the Tight Oil Reservoir

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Genesis Model of Carbonate Cementation in the Tight Oil Reservoir Open Geosciences 2020; 12: 1105–1115 Research Article Shutong Li*, Shixiang Li, Xinping Zhou, Xiaofeng Ma, Ruiliang Guo*, Jiaqiang Zhang, and Junlin Chen The genesis model of carbonate cementation in the tight oil reservoir: A case of Chang 6 oil layers of the Upper Triassic Yanchang Formation in the western Jiyuan area, Ordos Basin, China https://doi.org/10.1515/geo-2020-0123 The development degree of carbonate cementation affects received April 17, 2020; accepted September 21, 2020 the physical properties of reservoir. Abstract: Carbonate cementation is one of the significant Keywords: carbonate cementation, Yanchang formation, tightness factors in Chang 6 reservoir of the western genesis model, Ordos Basin, tight oil reservoir Jiyuan (WJY) area. Based on the observation of core and thin sections, connecting-well profile analysis as well as carbon and oxygen isotope analysis, it is found that fer- rocalcite is the main carbonate cements in the Chang 6 1 Introduction reservoir of the WJY area. The single sand body controls fi the development of carbonate cements macroscopically. Carbonate cementation is a signi cant diagenesis type in [ – ] - Both carbonate cements and calcite veins hold similar the clastic reservoir 1 3 . It is the product of the interac fl diagenetic conditions: the dissolution of plagioclase is tion between rock and geological uid in the diagenesis - the main calcium source and the de-acidification of or- process under the changes of physical and chemical con [ – ] - ganic acids is the main carbon source. The diagenetic ditions such as temperature and pressure 1,4 6 . The con stage is identified as the mesogenetic A stage. The sedi- tent, source, and occurrence state of carbonate cements mentary environment is of low salinity. Accordingly, the have a great impact on the migration and accumulation development model of carbonate cementation in Chang 6 of oil and gas, as well as the reservoir physical properties [ – ] reservoir is summarized into three types: “eggshell pat- 7 9 . In previous studies, it has been found that the - tern,”“cutting pattern,” and “favorable reservoir pattern.” carbonate cementation is generally intense in thin sand stone layers which are adjacent to mudstones, and in the sandstone reservoir near the sandstone/mudstone con- tacts, which is interpreted that mudstone and/or source * Corresponding author: Shutong Li, Key Laboratory of Petroleum rock interlayers as carbon and ion sources transporting Resources, Gansu Province. Northwest Institute of Eco-Environment Ca2+,Mg2+, and Fe2+ to the adjacent sandstone reservoir and Resources, Chinese Academy of Sciences, Lanzhou 730000, under the condition of compaction and hydrocarbon gen- - Gansu, China, e mail: [email protected] [ – ] * Corresponding author: Ruiliang Guo, Shaanxi Key Laboratory of eration overpressure 5,6,10 13 . However, the genetic Petroleum Accumulation Geology, Xi’an Shiyou University, Xi’an model of carbonate cementation in the tight sandstone 710065, China; School of Earth Sciences and Engineering, Xi’an reservoir behind this phenomenon is rarely studied and Shiyou University, Xi’an 710065, China; University of Chinese discussed thoroughly and deeply. Carbonate cementation Academy of Sciences, Beijing 100049, China, is widely developed in Chang 6 tight oil reservoir in the e-mail: [email protected] western Jiyuan area (WJY area hereafter), Ordos Basin, Shixiang Li, Xinping Zhou: PetroChina Changqing Oil Field Company, Xi’an 710018, China China, which is one of the important factors leading to Xiaofeng Ma: Key Laboratory of Petroleum Resources, Gansu the reservoir tightness [14–16]. Meanwhile, the high con- Province. Northwest Institute of Eco-Environment and Resources, tent of carbonate cements is also found in the sandstone Chinese Academy of Sciences, Lanzhou 730000, Gansu, China layer near the boundary of sandstone and mudstone [17]. Jiaqiang Zhang, Junlin Chen: Key Laboratory of Petroleum Previous relevant studies mainly focused on the distribu- Resources, Gansu Province. Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, tion and source of carbonate cements in tight sandstone Gansu, China; University of Chinese Academy of Sciences, Beijing reservoirs, but there is a deficiency in the genesis pattern 100049, China of carbonate cements and development model of a Open Access. © 2020 Shutong Li et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License. 1106 Shutong Li et al. favorable reservoir [5,6,11–13]. Also, the related studies 2 Geological setting mainly focused on the impact of diagenesis on the carbo- nate cementation, while the research on the influence of Ordos Basin is a typical multi-cycle craton basin with a sedimentation factors on the forming and development long-term stable sedimentation process located in central pattern of carbonate cements is insufficient. Hence, based and western China [21–23](Figure 1a). The inner struc- on the characteristics of sand body development, the ture of the basin is relatively simple, while faults and microscopic observation of carbonate cementation, the folds are relatively developed in the margin [20].TheWJY analysis of carbon and calcium source [18,19], the ana- area is located in the northwestern Ordos Basin, spanning lysis of paleo-temperature and paleo-salinity [14,20], the three first-level tectonic units of West margin thrust belt, exploratory studies have been conducted about the ge- Tianhuan Depression, and Shanbei Slop (Figure 1b).The netic model of carbonate cements in the WJY area to Upper Triassic Yanchang formation is a set of terrigenous provide a scientific basis for the next step exploration clastic rock depositional systems with fluvial and lacustrine work and reference for the relevant study with similar facies formed in the process of basin subsidence [24,25].It geological features. can be divided into ten reservoir groups, and Chang 6 is the Figure 1: (a) Location of the Ordos Basin in China. (b) Structural division of the Ordos Basin. (c) Lithology section of the Upper Triassic Yanchang Formation in the Ordos Basin, Ch-Chang. Modified after Guo et al. (2020). The genesis model of carbonate cementation in the tight oil reservoir 1107 first lacustrine recession period after Chang 7 reaches 4 Results the maximum lacustrine flooding period [26](Figure 1c). The sediments of Chang 6 in the WJY area are mainly 4.1 Characteristics of Chang 6 sand body interbedded deposition of fine sandstone, siltstone, pelitic siltstone, and mudstone, which belongs to the delta front sub-facies [14]. The sedimentary characteristics of sand body control the physical properties and diagenetic features of the reser- voir macroscopically. In this study, four connecting-well profiles perpendicular to the source supply direction and 3 Samples and methods three profiles parallel to the source supply direction were established to analyze the distribution characteristics of First, based on the observation of 115 cores and compre- Chang 6 sand body in the WJY area. The profiles show hensive interpretation of 78 single well logging curves, we that delta front subfacies are mainly developed in Chang have established four connecting-well profiles perpendi- 6 tight reservoir of the WJY area, and the delta plain fi - cular to the source supply direction and three pro les par subfacies can be partly found in the northwest of the - allel to the source supply direction to analyze the sedimen study area. The underwater distributary channel sand tary characteristics of Chang 6 sand body. The well logging body and the river distributary channel sand body are curves of Gamma ray and spontaneous potential were mainly developed in the delta front sub-facies and delta used in the profiles to identify reservoir lithology. plain sub-facies, respectively (Figure 2a and b). The river Second, utilizing the axioskop 40 polarizing micro- mouth bar is barely developed because of the near-source scope manufactured by Zeiss and the Quanta FEG 450 sedimentary environment [24], where the river carrier is scanning electron microscope (SEM), 62 samples from 43 regarded as the “hyper-pycnal flow” relative to lake water wells were collected for microscopic identification in the and continues to advance toward the lake surface with Key Laboratory of Petroleum Resources Research, Institute ff of Geology and Geophysics, Chinese Academy of Sciences. little lateral di usion. At the same time, the lake surface - By observing 152 thin sections, which were impregnated is prone to oscillation because of the strong hydrody [ ] with blue epoxy resin to highlight the pore spaces and namic force 24 , and the bottom of the lake basin in some of them were stained with Alizarin Red S and the WJY area is relatively gentle [14]. Therefore, the K-ferricyanide for carbonate mineral identification, we sand body is vertically discontinuous and is separated analyzed the reservoir mineral type and content, the by a large number of clay interlayers (Figure 2a and b). degree of sorting and roundness, pore types and diagen- The deposit thickness of the single-layer sand body is esis characteristics. The specific content of diagenetic relatively thin and heterogeneous (mainly 2–15 m).In minerals and cements was quantified by counting at least addition, the sand body has good plane continuity and 350 points of each thin section using an optical collection obvious progradation process characteristics (Figure 2a system. Also, the porosity and
Load more

Recommended publications
  • Calcite Cementation of Sixty-Five-Year-Old Aragonite Sand Dredge Pile
    University of Mississippi eGrove Electronic Theses and Dissertations Graduate School 2011 Calcite Cementation of Sixty-Five-Year-Old Aragonite Sand Dredge Pile Nathan M. Snyder Follow this and additional works at: https://egrove.olemiss.edu/etd Part of the Geology Commons Recommended Citation Snyder, Nathan M., "Calcite Cementation of Sixty-Five-Year-Old Aragonite Sand Dredge Pile" (2011). Electronic Theses and Dissertations. 269. https://egrove.olemiss.edu/etd/269 This Dissertation is brought to you for free and open access by the Graduate School at eGrove. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of eGrove. For more information, please contact [email protected]. CALCITE CEMENTATION OF SIXTY-FIVE-YEAR-OLD ARAGONITE SAND DREDGE PILE A Thesis presented in partial fulfillment of requirements for the degree of Master of Science in the Department of Geology and Geological Engineering The University of Mississippi by NATHANIAL M. SNYDER May 2011 Copyright Nathanial M. Snyder ALL RIGHTS RESERVED ABSTRACT Dredging of the harbor at Stocking Island, Bahamas (23°31’45”N, 75°49’41”W) in 1942 produced four dredge piles of cross-bedded aragonite skeletal sand. The spoils piles are on the leeward (western) shore of the island, where they are subject to minimal wave energy. Collectively they are 350 x 50 m in plan view and 2 m high. The surface is very well cemented, which requires a hammer and chisel for sampling. Samples were collected from six sites at various locations of the dredge pile. Samples were analyzed for both chemical and physical properties using thin-section examination, X-ray diffraction, X-ray fluorescence, bulk density measurements, isotopic analyses, and scanning electron microscopy.
    [Show full text]
  • Hydrogeology of Wales
    Hydrogeology of Wales N S Robins and J Davies Contributors D A Jones, Natural Resources Wales and G Farr, British Geological Survey This report was compiled from articles published in Earthwise on 11 February 2016 http://earthwise.bgs.ac.uk/index.php/Category:Hydrogeology_of_Wales BRITISH GEOLOGICAL SURVEY The National Grid and other Ordnance Survey data © Crown Copyright and database rights 2015. Hydrogeology of Wales Ordnance Survey Licence No. 100021290 EUL. N S Robins and J Davies Bibliographical reference Contributors ROBINS N S, DAVIES, J. 2015. D A Jones, Natural Rsources Wales and Hydrogeology of Wales. British G Farr, British Geological Survey Geological Survey Copyright in materials derived from the British Geological Survey’s work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail [email protected]. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract. Maps and diagrams in this book use topography based on Ordnance Survey mapping. Cover photo: Llandberis Slate Quarry, P802416 © NERC 2015. All rights reserved KEYWORTH, NOTTINGHAM BRITISH GEOLOGICAL SURVEY 2015 BRITISH GEOLOGICAL SURVEY The full range of our publications is available from BGS British Geological Survey offices shops at Nottingham, Edinburgh, London and Cardiff (Welsh publications only) see contact details below or BGS Central Enquiries Desk shop online at www.geologyshop.com Tel 0115 936 3143 Fax 0115 936 3276 email [email protected] The London Information Office also maintains a reference collection of BGS publications, including Environmental Science Centre, Keyworth, maps, for consultation.
    [Show full text]
  • Strength Developed from Carbonate Cementation in Silica-Carbonate Base Course Materials
    24 TRANSPORTATION RESEARCH RECORD 1190 Strength Developed from Carbonate Cementation in Silica-Carbonate Base Course Materials ROBIN E. GRAVES, JAMES L. EADES, AND LARRY L. SMITH Strength increases resulting Crom carbonate cementalion in are depleted, new sources must be found to accommodate compacted sands and cemented coquina highway base course the transportation needs of the state's rapidly expanding materials or variable quartz-calcite composition were investi­ population. Materials obtained from the newer quarries gated lhrough the use of limerock-bearing-ratio (LBR) le ting. often have a different mineralogical composition because Q uart~ and calcite sands were mixed in various proportion , of the great variability of geologic conditions affecting their compacted into LBR mold , oaked for time periods from 2 deposition. days up to 60 days, and tested to determine stt·ength increase with time. For comparison, cemented coquina highway base This has been the case with cemented coquina base course course materials of variable quartz-calcite composition were materials in Florida (3). Currently mined cemented coquina also compacted soaked, and tested. Jn addition duplicate sets contains abundant quartz sand, often resulting in carbon­ or specimens were te tcd that had 1 percent Ca(OH}i, (hydrated ate compositions below the 50 percent required by FDOT. lime) mixed with the dry materials before compacting and The quartz occurs in two forms. Some is incorporated into soaking. This was done to provide a om·ce of' CaH ions for cemented limestone rock, but most exists as unconsoli­ formation of additional calcium carbonate cement. Re ul~ of the LBR testing program showed that more strength developed dated quartz sand.
    [Show full text]
  • Geometry of Calcite Cemented Zones in Shallow Marine Sandstones
    '’W 4 PROFIT RF-^/w 1990-1994 PROJECT SUMMARY REPORTS RESERVOIR CHARACTERIZATION NEAR WELL FLOW Program for Research On Field Oriented Improved Recovery Technology oismsunoN of ihb documeot is iwumiteo % Edited by: Jem Olsen, Snorre Olaussen, Trond B. Jensen, Geir Helge Landa, Leif Hinderaker Norwegian Petroleum Directorate Stavanger 1995 DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document PROFIT - RESERVOIR CHARACTERIZATION Geometry of calcite cemented zones in shallow marine sandstones Olav Walderhaug, Edward Prestholm and Ingrid E.L0xnevad Rogaland Research, Stavanger Abstract thought to belong to concretions. The difference between the geometry of calcite Calcite cementation in the Jurassic shallow cementation in the Ula Formation and in the marine sandstones of the Bearreraig Formation, Bridport Sands is thought to be due to a the Valtos Formation, the Bridport Sands and relatively uniform rate of siliciclastic deposition the Bencliff Grit occurs as continuously for the Ula Formation having led to a more cemented layers, as stratabound concretions and uniform distribution of biogenic carbonate as scattered concretions. All three geometrical compared to the Bridport Sands where laterally forms of calcite cementaton may occur within extensive layers of biogenic carbonate formed the same formation, whereas in other cases a during periods of very low siliciclastic formation may be dominated by only one or deposition. Based on the results of the core and two of these modes of calcite cementation. outcrop studies, a tentative identification key Calcite cemented layers and layers of for calcite cemented zones encountered in cores stratabound concretions in the studied is suggested.
    [Show full text]
  • A) Conglomerate B) Dolostone C) Siltstone D) Shale 1. Which
    1. Which sedimentary rock would be composed of 7. Which process could lead most directly to the particles ranging in size from 0.0004 centimeter to formation of a sedimentary rock? 0.006 centimeter? A) metamorphism of unmelted material A) conglomerate B) dolostone B) slow solidification of molten material C) siltstone D) shale C) sudden upwelling of lava at a mid-ocean ridge 2. Which sedimentary rock could form as a result of D) precipitation of minerals from evaporating evaporation? water A) conglomerate B) sandstone 8. Base your answer to the following question on the C) shale D) limestone diagram below. 3. Limestone is a sedimentary rock which may form as a result of A) melting B) recrystallization C) metamorphism D) biologic processes 4. The dot below is a true scale drawing of the smallest particle found in a sample of cemented sedimentary rock. Which sedimentary rock is shown in the diagram? What is this sedimentary rock? A) conglomerate B) sandstone C) siltstone D) shale A) conglomerate B) sandstone C) siltstone D) shale 9. Which statement about the formation of a rock is best supported by the rock cycle? 5. Which sequence of events occurs in the formation of a sedimentary rock? A) Magma must be weathered before it can change to metamorphic rock. A) B) Sediment must be compacted and cemented before it can change to sedimentary rock. B) C) Sedimentary rock must melt before it can change to metamorphic rock. C) D) Metamorphic rock must melt before it can change to sedimentary rock. D) 6. Which sedimentary rock formed from the compaction and cementation of fragments of the skeletons and shells of sea organisms? A) shale B) gypsum C) limestone D) conglomerate Base your answers to questions 10 and 11 on the diagram below, which is a geologic cross section of an area where a river has exposed a 300-meter cliff of sedimentary rock layers.
    [Show full text]
  • Lite Geology 14
    Winter 1995 L I T E NewMexico Bureau ~.~, .~,..,.~ "~ ~,,~..~,~.~.,..~,~ of .............. ¯ Mines and Mineral .’..:. .i .,.."".. Resources (NMBM&MR) A quarterly publication for educators arid the public- contemporary geological topics~ issues and events EadhBriefs "Concretions, Bombs, and Ground Water Peter S. Mozley Departmentof Earth and EnVironmental Science, NewMexico Tech Concretions are hard masses of sedimentary and, more rarely, volcanic rock that form by the preferential precipitation of minerals (cementation) in localized portions of the rock. They are commonlysubspherical, but frequently form a variety of other shapes, including disks, grape-like aggregates, and complex shapes that defy description (Figs. 1, 2, and 3). Concretions are usually very noticeable features, because they have a strikingly. different color and/or hardness than the rest of the rock. In someareas this is unfortunate, as the concretions have attracted the unwanted attention of local graffiti artists. Commonly, when you break open concretions you will find that they have formed around a nucleus, such as a fossil fragment or piece of organic matter. For a variety of reasons, this nucleus created a more favorable site for cement precipitation than other sites in therock. ~erhapsthe mostunusual concretion "[ spent too much time in thesame place in the back swamp .nucleiarefound in a modemcoastal’ and the clanged concretion went and nucleated on me." saltmarsh in England.Siderite (FeCOa) concretionsin the marshformed aroundWorld-War-II era military shells,bombs, and associated shrapnel, ThisIssue: includingsome large unexploded shells(AI-Agha et al.,1995). A British Earth Briefs--how does Nature conceal Reptiles’onthe Rocks--someunique geologiststudying these concretions bombs and record ancient water-flow photosof homedlizards in New realizedthis only after striking a large pathways? Mexico unexplodedshell repeatedly with his rockhammer (yes, he livedto tellabout Have you ever wondered..
    [Show full text]
  • Hydrogeological Properties of Fault Zones in a Karstified Carbonate Aquifer (Northern Calcareous Alps, Austria)
    Hydrogeol J DOI 10.1007/s10040-016-1388-9 PAPER Hydrogeological properties of fault zones in a karstified carbonate aquifer (Northern Calcareous Alps, Austria) H. Bauer1 & T. C. Schröckenfuchs 1 & K. Decker1 Received: 17 July 2015 /Accepted: 14 February 2016 # The Author(s) 2016. This article is published with open access at Springerlink.com Abstract This study presents a comparative, field-based impermeable fault cores only very locally have the potential hydrogeological characterization of exhumed, inactive fault to create barriers. zones in low-porosity Triassic dolostones and limestones of the Hochschwab massif, a carbonate unit of high economic Keywords Fractured rocks . Carbonate rocks . Fault zones . importance supplying 60 % of the drinking water of Austria’s Hydrogeological properties . Austria capital, Vienna. Cataclastic rocks and sheared, strongly cemented breccias form low-permeability (<1 mD) domains along faults. Fractured rocks with fracture densities varying by Introduction a factor of 10 and fracture porosities varying by a factor of 3, and dilation breccias with average porosities >3 % and per- Fault zones in the upper crust produce permeability heteroge- meabilities >1,000 mD form high-permeability domains. With neities that have a large impact on subsurface fluid migration respect to fault-zone architecture and rock content, which is and storage patterns (e.g. Agosta et al. 2010, 2012; Caine et al. demonstrated to be different for dolostone and limestone, four 1996;Faulkneretal.2010;Jourdeetal.2002; Mitchell and types of faults are presented. Faults with single-stranded mi- Faulkner 2012; Shipton and Cowie 2003; Shipton et al. 2006; nor fault cores, faults with single-stranded permeable fault Wibberley and Shimamoto 2003; Wibberley et al.
    [Show full text]
  • Integrated Geological, Geophysical, and Hydrological Study of Field-Scale Fault-Zone Cementation and Permeability, Loma Blanca Fault Central New Mexico
    Integrated geological, geophysical, and hydrological study of field-scale fault-zone cementation and permeability, Loma Blanca Fault Central New Mexico By Johnny Ray Hinojosa, Geology MSC Candidate Peter Mozley, Professor of Sedimentology TECHNICAL PROGRESS REPORT Sub Award Q01864 June 2017 Funded by: New Mexico Water Resources Research Institute National Science Foundation DISCLAIMER The New Mexico Water Resource Research Institute and affiliated institutions make no warranties, express or implied, as to the use of the information obtained from this data product. All information included with this product is provided without warranty or any representation of accuracy and timeliness of completeness. Users should be aware that changes may have occurred since this data set was collected and that some parts of these data may no longer represent actual conditions. This information may be updated without notification. Users should not use these data for critical applications without a full awareness of its limitations. This product is for informational purposes only and may not be suitable for legal, engineering, or surveying purposes. The New Mexico Water Resource Research Institute and affiliated institutions shall not be liable for any activity involving these data, installation, fitness of the data for a particular purpose, its use, or analyses results. i ABSTRACT The Loma Blanca fault is a Pliestocene age normal fault located within the Sevilleta National Wildlife Refuge in central New Mexico. The normal fault is an extensional feature of the Rio Grande Rift. It is believed that the fault is a barrier to subsurface fluid flow moving down-gradient towards the Rio Grande River. Previous work under a National Science Foundation grant conducted geophysical measurements in an attempt to visualize groundwater impoundment on the footwall (up-gradient) side of the fault.
    [Show full text]
  • Investigating the Variations in Depositional Facies by Investigating the Accuracy of the Neural Network Model Within the St
    INVESTIGATING THE VARIATIONS IN DEPOSITIONAL FACIES BY INVESTIGATING THE ACCURACY OF THE NEURAL NETWORK MODEL WITHIN THE ST. LOUIS LIMESTONE, KEARNY COUNTY, KANSAS By CHANCE REECE B.S., Kansas State University, 2014 A THESIS Submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Geology College of Arts and Sciences KANSAS STATE UNIVERSITY Manhattan, Kansas 2016 Approved by: Major Professor Dr. Matt Totten Copyright CHANCE REECE 2016 Abstract The Mississippian-aged St. Louis Limestone has been a major producer of oil, and natural gas for years in Kearny County, Kansas. Since 1966 two major fields in the County, the Lakin, and Lakin South fields, have produced over 4,405,800 bbls of oil. The St. Louis can be subdivided into six different depositional facies, all with varying lithologies and porosities. Only one of these facies is productive, and the challenge of exploration in this area is the prediction of the productive facies distribution. A previous study by Martin (2015) used a neural network model using well log data, calibrated with established facies distributed within a cored well, to predict the presence of these facies in adjacent wells without core. It was assumed that the model’s prediction accuracy would be strongest near the cored wells, with increasing inaccuracy as you move further from the cored wells used for the neural network model. The aim of this study was to investigate the accuracy of the neural network model predictions. Additionally, is the greater accuracy closest to the cored wells used to calibrate the model, with a corresponding decrease in predictive accuracy as you move further away? Most importantly, how well did the model predict the primary producing unit (porous ooid grainstone) within the St.
    [Show full text]
  • Glossary Cementation Part of Lithification That Involves Minerals Crystallizing in Pore Space and Holding Sediments Together, Hardening the Sediment
    Glossary cementation Part of lithification that involves minerals crystallizing in pore space and holding sediments together, hardening the sediment. This happens when water flows through pores between sediments. Ions in the water will combine to form minerals (crystals) that fill the pores, holding the sediments together. Some sedimentary rocks are "well cemented." making them quite hard. Some sedimentary rocks are "poorly cemented" and may crumble in your hand. Quartz and calcite are the two minerals that most commonly form the cement in sedimentary rocks. chemical sedimentary rock Rocks formed by an accumulation and lithification of minerals that crystallized in water. Because the water must be saturated with ions to form these minerals, these rocks most often form in oceans (ions make seawater taste salty). These rocks include those made of minerals crystallized by organisms, which are sometimes called biochemical or bioclastic sedimentary rocks. Limestone, chert, rock salt, and rock gypsum are all types of chemical sedimentary rocks. chemical weathering Processes that break a rock apart by changing the chemical composition of minerals or dissolving minerals entirely. For example, salt dropped into a glass of water will dissolve, in which case it will change from the mineral (NaCl) to ions (Na+ and Cl-) that float about in the water. Another example is rust, in which oxygen enters an iron-bearing mineral and changes it into a different (oxidized and smaller) mineral. Chemical weathering is responsible for making the oceans salty and creating all of the clay minerals on Earth. Clay minerals form when feldspar (the most common minerals in Earth's crust) chemically weather.
    [Show full text]
  • Diagenetic History of Triassic Sandstone from the Beacon Supergroup in Central Victoria Land, Antarctica
    Diagenetic history of Triassic sandstone from the Beacon Supergroup in central Victoria Land, Antarctica. Matthias Bernet, Reinhard Gaupp To cite this version: Matthias Bernet, Reinhard Gaupp. Diagenetic history of Triassic sandstone from the Beacon Super- group in central Victoria Land, Antarctica.. New Zealand Journal of Geology and Geophysics, Taylor & Francis, 2005, 48, pp.447-458. hal-00097126 HAL Id: hal-00097126 https://hal.archives-ouvertes.fr/hal-00097126 Submitted on 21 Sep 2006 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Running head: Diagenesis of Beacon Sandstone Diagenetic history of Triassic sandstone from the Beacon Supergroup in central Victoria Land, Antarctica MATTHIAS BERNET* and REINHARD GAUPP** Institut für Geowissenschaften, Johannes-Gutenberg Universität Mainz, Germany *Corresponding author, present address: State University of New York, New Paltz, USA Email: [email protected] **Present address: Institut für Geowissenschaften, Friedrich Schiller Universität, Jena, Germany Abstract The diagenetic history of Triassic sandstone from the Beacon Supergroup, Victoria Land, Antarctica, can be divided into three main phases of shallow burial diagenesis, contact diagenesis (temperatures of 200-300ºC), and post-contact diagenesis, on the basis of petrographic and geochemical analyses.
    [Show full text]
  • GENESIS and HARDENING of Laterite in SOILS
    Iii !llt12 2.5 w IIIII~Bill" U~ Iia~ IW 122. '" 1.0 ... Ii£ ~ : w 1W12.0 ......10 M III~ 1.1 - "'" 1.8 111111.25 111,,1.4 111111.6 111111.25 111111.4 111111.6 MICROCOPY RESOLUTION TEST CHART MICROCOPY RESOLUTION TEST CHART NATIONAL SllREAlt Of STAND~RDS·1963-A NATIONAL BUREAU OF SlANDARDS-1963-A Technical .Bulletin No. 1282 ~ GENESIS AND HARDENING OF Laterite IN SOILS Lyle T. M~xander and John G. ~4Y soil scientists Soil Conservation Service Soil Conservation Service UNITED STATES DEPARTMENT OF AGRICULTURE Washington, D.C. losued December 1962 FOREWORD Soils having some form of laterite within the rooting zone are highly important in the world, especially in tropical cOlmtries. Buried relIcs of such formations can be seen in present temperate areas that were tropical long ago. More important, under favorable conditions, the processes that lead to laterite formation influence soil materials in warm-tempernte and subtropical regions, such as the southern part of the United Stat~s and especially Hawaii and Puerto Rico. But to understand the processes most clearly they should be studied in the Tropics. :F,ortunately, the authors have had opportu­ luties to do this in tropi()J,~ :A.frica. .Although most soil scientists regard laterite as a material, not itself n. kind of soil, forms of it are COllllllon in many kinds of soil. These laterite materials influence the behavior 01 the soils under different management systems. Their presence must be taken into account in soil classitication and its interpretation. Perhaps the most dramatic soils with laterite are those having layers of doughy laterite underneath a leached upper soil.
    [Show full text]