DOCSLIB.ORG

GEOL 332 Lab 5 Sedimentary Rock Identification II Sedimentary Rocks

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
GEOL 332 Lab 5 Sedimentary Rock Identification II Sedimentary Rocks GEOL 332 Lab 5 Sedimentary Rock Identification II Name: _____________________________________________ Date: _______________ Sedimentary Rocks: Carbonates, et al. Lab Equipment List: hand lens, ruler, pencil, and eraser. Objectives 1) to become familiar with the properties important in recognizing and classifying sedimentary rocks 2) to become familiar with the textures characteristic of sedimentary rocks; Carbonate Sedimentary Rock Classification In a simple model for the evolution of sedimentary rocks we find that if weathering, transportation, and sorting go to completion all that remains are three end member rock compositions. Siliciclastic Rocks: Quartz Arenite / Shale Carbonate Rocks: Limestone / Dolomite Limestones are not single composition rocks but a group of related rocks all composed of CaCO3 and reacting with dilute HCl acid. Limestone [CaCO3] is also chemically related to Dolomite [CaMg (CO3)2]. Because all these rocks have CO3 in common they are called the Carbonates. The composition of most Carbonates is derived from a combination of biological and chemical components. Two Carbonate classification systems are used today, one by R.L. Folk and the second by R.J. Dunham. The Dunham system is based on depositional texture (that is, the amount of matrix surrounding the grains at the time of deposition). It uses such names as Mudstone, wackestone, packstone, grainstone, and boundstone. Carbonate rock names (Limestones and Dolomites) consist of a conjunction of two names, one describing the ALLOCHEMS, the large pieces, the other describing the INTERSTITIAL MATERIAL. Allochems are equivalent to gravel, sand, lithics or feldspars in the siliciclastics. Interstitial material is equivalent to Clay or cements in clastics. There are four kinds of allochems: 1. Fossils ‐ may be whole fossils, or broken and abraded fossils; all are called "bio" fragments 2. Oolites ‐ small spheres 3. Pellets ‐ fecal Pellets produced by invertebrate animals; look superficially like Oolites but are dull 4. Intraclasts ‐ chunks of eroded Limestone deposited as a Conglomerate 1 | Page GEOL 332 Lab 5 Sedimentary Rock Identification II Interstitial Material Micrite is "lime mud", the dense, dull‐looking sediment made of Clay sized crystals of CaCO3. Micrite forms from the breakdown of calcareous algae skeletons. It is not clear if all ancient Micrites formed in the same way. Many Carbonates are composed of nearly 100% Micrite. Such rocks are simply called Micrites. With Carbonates containing allochems the question is whether Micrite is present or absent as an interstitial material, and if present, by how much. If Micrite is present during deposition then it fills the spaces between the allochems and the rock will be given a name which describes the allochems in a Micrite matrix. For example, a rock with fossil fragments embedded in Micrite is called a "Biomicrite". If the depositional environment has strong currents, only allochems may be deposited. If we could see the sediment during deposition and all the allochems would be loose, like a pure sand or gravel. This is analogous to a 100% siliciclastic sand on a beach with no silt or Clay. In this case, Micrite would be clay‐ sized and would be washed away. The rock formed is then composed only of allochems, held together by clear to translucent Calcite crystals with rhombohedral cleavage (called SPAR or SPARITE) acting as a cement. The spar is precipitated from fresh or marine water percolating through the sediment after deposition, but before final cementation. Classification of Carbonates The classification of Carbonates using the allochem/interstitial material system (the Folk System) is very systematic and straight forward. The allochem name is combined with the interstitial name (Micrite or spar). The table below shows the major categories of Carbonate rocks based on their allochems and interstitial material. But what happens if there is more than one allochem in the rock, or there is a mixture of Micrite and spar? You can easily build your own descriptive rock names. The name is built up by stringing together 2 | Page GEOL 332 Lab 5 Sedimentary Rock Identification II all the allochem names in order from least to most abundant, and then adding the interstitial material name ("matrix" below for short). For example, a rock like this: Oolites + Fossils + Spar matrix = Oo bio sparite o The name is written as one word, Oobiosparite. Another example (again allochems from least to most abundant): Pellets + Oolites + Fossils + Micrite matrix = pel oo bio Micrite o The name is written as one word, Peloobiomicrite. But what if there is both Micrite and spar matrix? The system is the same; just list them from least to most abundant. Fossils + Spar matrix + Micrite matrix = bio spar Micrite This system goes through other levels of refinement, such as in the table below where the abundance of allochems is indicated. Other modifiers may deal with different sizes of allochems. A classification such as this one works well if you want to construct rock names from observations. The system, however, does not lend itself well to constructing keys for classification. A key requires the establishment of arbitrary categories of rocks, and a system like the one above deals with all the myriad combinations that are possible. Most limestones are classified by Folk allochemical rocks if they contain over l0% allochems (transported carbonate grains). Based on the percentage of interstitial material, the rocks may be further subdivided into two groups: sparry allochemical limestones (containing a sparry calcite cement of clear coarsely crystalline mosaic calcite crystals) and microcrystalline allochemical limestone (containing microcrystalline calcite mud, micrite, which is subtranslucent grayish or brownish particles less than about 5 microns in size). Further subdivision is based on the allochem ratios of Folk (1962) are shown in Scholle & Ulmer‐Scholle (2003). Thus Folk's classification is most suited for thin section study. Remember that he terms rocks with appreciable matrix as micrites while matrix‐free rocks that contain sparry calcite cement are termed sparites. As you can see sparites and micrites are further subdivided by means of their most common grains. 3 | Page GEOL 332 Lab 5 Sedimentary Rock Identification II In contrast, Dunham's classification (figures above) and its modification by Embry and Klovan (1971) and James (1984) deals with depositional texture. For this reason, his scheme may be better suited for rock descriptions that employ a hand lens or binocular microscope. For example, if the grains of a limestone are touching one another and the sediment contains no mud, then the sediment is called a grainstone. If the carbonate is grain supported but contains a small percentage of mud, then it is known as a packstone. If the sediment is mud supported but contains more than 10 percent grains, then it is known as a wackestone, and if it contains less than 10 percent grains and is mud supported, it is known as a mudstone. If one compares the two classifications, a rock rich in carbonate mud is termed a micrite by Folk and a mudstone or wackestone by Dunham. Moreover, a rock containing little matrix is termed a sparite by Folk and a grainstone or packstone by Dunham. The wide range of percentage of mud matrix that a carbonate may have and still be termed a packstone by Dunham sometimes reduces the utility of this classification. Embry has modified Dunham's classification and Klovan (1971) to include coarse grained carbonates (above figure). In their revised scheme, a wackestone in which the grains are greater than 2mm in size is termed a floatstone and a coarse grainstone is called a rudstone. Both terms are extremely useful in description of limestones. Embry and Klovan to more graphically reflect the role that the organisms performed during deposition also modified the boundstone classification of Dunham. Terms such as bafflestone, bindstone, and framestone are useful in concept but are extremely difficult to apply to ancient limestones where diagenesis and sample size limit one’s ability to assess an organism’s function. The last two pages of this lab includes a key to identify rocks based on their allochems and interstitial material. Just be aware that its main weakness is that there are always rocks that do not fit easily into its simple categories. There is also a chemical and biochemical rock identification key. 4 | Page GEOL 332 Lab 5 Sedimentary Rock Identification II Folk Sedimentary Rock Classification: Folk’s (1959, 1962) classification of limestones, which uses prefixes to indicate the framework grains present (bio‐ for fossils, pel‐ for peloids, oo‐ for Ooids, and intra‐ for intraclasts) and stems to indicate whether the interstitial calcite is micritic or sparry. If the rock is originally bound together (as in a reef rock), it is a biolithite. 5 | Page GEOL 332 Lab 5 Sedimentary Rock Identification II Textural maturity classification of limestones proposed by Folk (1962). Textural maturity classes are based on the percentage of allochems present, their degree of sorting, and the extent of rounding (a function of abrasion history). (Folk, 1965) The Dunham classification of carbonate sedimentary rocks (Dunham 1962) with modifications by Embry & Klovan (1971). This scheme is the most commonly used for description of limestones in the field and in hand specimen. Rock Identification Step 1, fill out the table for the known sedimentary rock samples. (15 pts) Step 3, fill out the table for the unknown sedimentary rock samples. (15 pts) 6 | Page GEOL 332 Lab 5 Sedimentary Rock Identification II (Dunham, 1962) 7 | Page GEOL 332 Lab 5 Sedimentary Rock Identification II 8 | Page GEOL 332 Lab 5 Sedimentary Rock Identification II References: Dunham, R. J., 1962, Classification of carbonate rocks according to depositional texture. In: Ham, W. E. (ed.), Classification of carbonate rocks: American Association of Petroleum Geologists Memoir, p. 108‐ 121. Embry, AF, and Klovan, JE, 1971, A Late Devonian reef tract on Northeastern Banks Island, NWT: Canadian Petroleum Geology Bulletin, v.
Load more

Recommended publications
  • Petrography of Middle Jurassic to Early
    Chaudhuri et al. Journal of Palaeogeography (2018) 7:2 https://doi.org/10.1186/s42501-018-0002-6 Journal of Palaeogeography RESEARCH Open Access Petrography of Middle Jurassic to Early Cretaceous sandstones in the Kutch Basin, western India: Implications on provenance and basin evolution Angana Chaudhuri1, Santanu Banerjee1* and Emilia Le Pera2 Abstract This paper investigates the provenance of Middle Jurassic to Early Cretaceous sediments in the Kutch Basin, western India, on the basis of mineralogical investigations of sandstones composition (Quartz–Feldspar–Lithic (QFL) fragment), Zircon–Tourmaline–Rutile (ZTR) index, and mineral chemistry of heavy detrital minerals of the framework. The study also examines the compositional variation of the sandstone in relation to the evolution of the Kutch Basin, which originated as a rift basin during the Late Triassic and evolved into a passive margin basin by the end Cretaceous. This study analyzes sandstone samples of Jhumara, Jhuran and Bhuj Formations of Middle Jurassic, Upper Jurassic and Lower Cretaceous, respectively, in the Kutch Mainland. Sandstones record a compositional evolution from arkosic to subarkosic as the feldspar content decreases from 68% in the Jhumara Formation to 27% in the Bhuj Formation with intermediate values in the Jhuran Formation. The QFL modal composition indicates basement uplifted and transitional continental settings at source. Heavy mineral content of these sandstones reveals the occurrence of zircon, tourmaline, rutile, garnet, apatite, monazite and opaque minerals. Sub-rounded to well-rounded zircon grains indicate a polycyclic origin. ZTR indices for samples in Jhumara, Jhuran and Bhuj Formations are 25%, 30% and 50% respectively. Chemistry of opaque minerals reveals the occurrence of detrital varieties such as ilmenite, rutile, hematite/magnetite and pyrite, in a decreasing order of abundances.
    [Show full text]
  • 8. Carbonate and Evaporite Environments
    8. Carbonate and Evaporite Environments Sequence Stratigraphy Institute of Geophysics National Central Univ., Taiwan Prepared by Dr. Andrew T. Lin 8. Carbonate and Evaporite Environments 8.1 Introduction 8.2 Carbonate Shelf (nonreef) Environments • Depositional setting • Sedimentation processes Chemical and biochemical processes Physical processes • Skeletal and sediment characteristics of carbonate deposits • Examples of modern carbonate platforms • Examples of ancient carbonate shelf successions Isolated platforms Rimmed shelves Ramps Epeiric platforms Sequence Stratigraphy Institute of Geophysics National Central Univ., Taiwan Prepared by Dr. Andrew T. Lin 8.3 Slope/Basin Carbonates 8.4 Organic Reef Environments • Modern reefs and reef environments Depositional setting Reef organisms Reef deposits Low-energy reef facies • Ancient Reefs Reef deposits Occurrence of ancient reefs 8.5 Mixed Carbonate-Siliciclastic Systems 8.6 Evaporite Environments • Modern evaporite environment Nonmarine environment Shallow marine environment Deep-water environment • Ancient evaporite environment Nonmarine environment Sequence Stratigraphy Institute of Geophysics Marine environment National Central Univ., Taiwan Prepared by Dr. Andrew T. Lin Carbonate depositional settings • Shelf margin • Shelf – Outer more normal marine – Inner restricted • Margin slope and base of slope • Basin Sequence Stratigraphy Institute of Geophysics National Central Univ., Taiwan Prepared by Dr. Andrew T. Lin Sequence Stratigraphy Institute of Geophysics National Central Univ.,
    [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]
  • Petrography, Modal Composition and Tectonic Provenance of Some
    Open Geosci. 2018; 10:821–833 Research Article Open Access Priscilla Chima*, Christopher Baiyegunhi, Kuiwu Liu, and Oswald Gwavava Petrography, modal composition and tectonic provenance of some selected sandstones from the Molteno, Elliot and Clarens Formations, Karoo Supergroup, in the Eastern Cape Province, South Africa https://doi.org/10.1515/geo-2018-0064 1 Introduction Received November 16, 2017; accepted March 16, 2018 Abstract: The Late Triassic - Early Jurassic non marine clas- Sedimentary rocks, particularly sandstones, are com- tic sediments of the Molteno, Elliot and Clarens Forma- monly used to construe provenance and to identify an- tions were studied to deduce their mineralogy and tectonic cient tectonic settings since clastic detrital components provenance. The study is based on road-cut exposures preserve detailed information on the provenance, sedi- of the formations in the Eastern Cape Province of South ments transportion and the interaction of physical and Africa. Petrographic studies based on quantitative analy- chemical processes [1, 2]. Petrography of sandstones reveal sis of the detrital minerals shows that the clastic sediments more on the provenance of the detritus despite the fact that (mostly sandstones) are predominantly made up of quartz, their original compositions are influenced by processes feldspars, and metamorphic and igneous rock fragments. such as weathering, transportation and diagenesis [3]. [4] Among the main detrital framework grains, quartz con- documented that other factors like source area charac- stitutes about 62-91%, feldspar 6-24% and 3-19% of lithic teristics, orogenesis, multicycling, storage pathways and/ fragments. The sandstones can be classified as both sub- or leaching also contribute to the formation of clastic litharenite and subarkose.
    [Show full text]
  • Petrography and Tectonic Provenance of the Cretaceous Sandstones of the Bredasdorp Basin, Off the South Coast of South Africa: Evidence from Framework Grain Modes
    geosciences Article Petrography and Tectonic Provenance of the Cretaceous Sandstones of the Bredasdorp Basin, off the South Coast of South Africa: Evidence from Framework Grain Modes Temitope Love Baiyegunhi 1,*, Kuiwu Liu 1,*, Oswald Gwavava 1 and Christopher Baiyegunhi 2 1 Department of Geology, University of Fort Hare, Private Bag X1314, Alice 5700, Eastern Cape Province, South Africa; [email protected] 2 Department of Geology and Mining, University of Limpopo, Private Bag X1106, Sovenga 0727, Limpopo Province, South Africa; [email protected] * Correspondence: [email protected] (T.L.B.); [email protected] (K.L.) Received: 8 May 2020; Accepted: 3 June 2020; Published: 28 August 2020 Abstract: The Cretaceous sandstones of the Bredasdorp Basin were investigated to recognize their composition, provenance, and tectonic setting. Ninety-two samples of sandstones from exploration wells E-AH1, E-AJ1, E-BA1, E-BB1, and E-D3 were investigated using both petrographic and X-ray diffraction (XRD) methods. Petrographic studies based on quantitative investigation of the detrital framework grain shows that the Bredasdorp sandstones chiefly consist of quartz (52.2–68.0%), feldspar (10.0–18.0%), and lithic fragments (5.0–10.2%). These sandstones are mostly fine grained, moderately well-sorted, and subrounded to rounded. The modal composition data shows that the sandstones could be classified as subarkosic arenite and lithic arkose. Such a composition of the sandstones perhaps indicates the interplay of pulses of fast uplift of the source area and rapid subsidence of the Bredasdorp Basin, with subsequent periods of calmness within the transgressive-regressive sequence in a rift tectonic regime.
    [Show full text]
  • Provenance and Sediment Dispersal of Mississippian Sandstones in the Black Warrior Basin, Ne Mississippi
    PROVENANCE AND SEDIMENT DISPERSAL OF MISSISSIPPIAN SANDSTONES IN THE BLACK WARRIOR BASIN, NE MISSISSIPPI By PATRICK MICHAEL O’CONNOR Bachelor of Science, 2012 Ohio University Athens, Ohio Submitted to the Graduate Faculty of The College of Science and Engineering Texas Christian University In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May, 2015 Copyright By Patrick Michael O’Connor 2015 ACKNOWLEDGEMENTS First, I would like to thank the Mississippi Department of Environmental Quality in Jackson, MS for graciously allowing me to sample their core for this project. I also want to thank Mark Pecha and the team at the University of Arizona LaserChron Center for their assistance with the processing of detrital LA-ICPMS. Also, thank you to the University of Texas at Dallas for allowing me to use their rock crushing lab, and Dr. Majie Fan for the use of the mineral separation lab at University of Texas at Arlington. Secondly, I need to recognize Dr. Xiangyang “Cheyenne” Xie for his significant role in my graduate school experience. Cheyenne’s determination to provide all the necessary resources and accommodations for me to complete my thesis was above and beyond what I could have ever expected from a graduate advisor. Cheyenne exhibited an extreme willingness to always be available, not only as a thesis advisor, but also as a friend throughout my graduate experience. I am very grateful to have had Cheyenne as my advisor and to have built a relationship with him. Additionally, I would like to thank Dr. Alsleben and Dr. Holbrook for all their help.
    [Show full text]
  • IN MEMORY of ROBERT LOUIS FOLK 30 September 1925 – 4 June 2018
    IN MEMORY OF ROBERT LOUIS FOLK 30 September 1925 – 4 June 2018 Robert Folk in a marble quarry in Lipari, Italy. IN MEMORY OF ROBERT LOUIS FOLK Compiled by Murray Felsher, Miles Hayes, Lynton Land, Earle McBride, and Kitty Milliken Produced by Joe Holmes, Research Planning, Inc. Murray Felsher, Ph.D. 1971 FOLKLORE – FIRST CONTACT Having never met him, I knew Robert L. Folk only by reputation. I had left Amherst MA and the University of Massachusetts, where I had undertaken my M.S. work. It was August 1961, and I was married two months earlier. I had spent the summer as a Carnegie College Teaching Intern teaching an Introductory Geology class at CCNY, where I had earned my B.S. As a native New Yorker, I rarely traveled west of the Hudson, and had never been west of the Mississippi. Gathering meager funds and overloading our VW Beetle with all our belongings, we were to be strangers in a strange land, wherein lived strange people who spoke a strangely attractive version of English. I had earlier applied to only two schools for my Ph.D. --- the Massachusetts Institute of Technology and the University of Texas at Austin, and was accepted by both. When I approached H.T.U. Smith --- chairman of the UMass Geology Department, for whom I served as a Graduate Teaching Assistant during my years there --- for his advice on where I should pursue my doctorate, he unhesitatingly said “Texas. Bob Folk is there. Without question, Texas.” But I did have a question or two, and H.T.U.
    [Show full text]
  • Depositional Environment and Facies Analyses of the Owl Mountain Province, Fort Hood Military Installation, Bell and Coryell Counties, Texas
    Stephen F. Austin State University SFA ScholarWorks Electronic Theses and Dissertations 12-2018 DEPOSITIONAL ENVIRONMENT AND FACIES ANALYSES OF THE OWL MOUNTAIN PROVINCE, FORT HOOD MILITARY INSTALLATION, BELL AND CORYELL COUNTIES, TEXAS Jacob Meinerts [email protected] Follow this and additional works at: https://scholarworks.sfasu.edu/etds Part of the Geology Commons, Geomorphology Commons, Hydrology Commons, and the Sedimentology Commons Tell us how this article helped you. Repository Citation Meinerts, Jacob, "DEPOSITIONAL ENVIRONMENT AND FACIES ANALYSES OF THE OWL MOUNTAIN PROVINCE, FORT HOOD MILITARY INSTALLATION, BELL AND CORYELL COUNTIES, TEXAS" (2018). Electronic Theses and Dissertations. 222. https://scholarworks.sfasu.edu/etds/222 This Thesis is brought to you for free and open access by SFA ScholarWorks. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of SFA ScholarWorks. For more information, please contact [email protected]. DEPOSITIONAL ENVIRONMENT AND FACIES ANALYSES OF THE OWL MOUNTAIN PROVINCE, FORT HOOD MILITARY INSTALLATION, BELL AND CORYELL COUNTIES, TEXAS Creative Commons License This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License. This thesis is available at SFA ScholarWorks: https://scholarworks.sfasu.edu/etds/222 DEPOSITIONAL ENVIRONMENT AND FACIES ANALYSES OF THE OWL MOUNTAIN PROVINCE, FORT HOOD MILITARY INSTALLATION, BELL AND CORYELL COUNTIES, TEXAS By Jacob Allan Meinerts, B.S Presented to the Faculty of the Graduate School of Stephen F. Austin State University In Partial Fulfillment Of the Requirements For the Degree of Masters of Science STEPHEN F. AUSTIN STATE UNIVERSITY December 2018 Depositional Environment and Facies Analyses of the Owl Mountain Province, Fort Hood Military Installation, Bell and Coryell Counties, Texas By JACOB ALLAN MEINERTS, B.S.
    [Show full text]
  • Stratigraphy and Sedimentology of the Hadar Formation Afar, Ethiopia Tesfaye Yemane Iowa State University
    Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1997 Stratigraphy and sedimentology of the Hadar Formation Afar, Ethiopia Tesfaye Yemane Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Geochemistry Commons, and the Geology Commons Recommended Citation Yemane, Tesfaye, "Stratigraphy and sedimentology of the Hadar Formation Afar, Ethiopia " (1997). Retrospective Theses and Dissertations. 11577. https://lib.dr.iastate.edu/rtd/11577 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. XJMI films the text directly fi'om the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter fece, while others may be from any type of computer printer. The quality of this reproductioii is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps.
    [Show full text]
  • Carbonates, Et Al
    GEOL 332 Lab 5 Sedimentary Rock Identification II Name: _____________________________________________ Date: _______________ Sedimentary Rocks: Carbonates, et al. Lab Equipment List: hand lens, ruler, pencil, and eraser. Objectives 1) to become familiar with the properties important in recognizing and classifying sedimentary rocks 2) to become familiar with the textures characteristic of sedimentary rocks; Carbonate Sedimentary Rock Classification In a simple model for the evolution of sedimentary rocks we find that if weathering, transportation, and sorting go to completion all that remains are three end member rock compositions. Siliciclastic Rocks: Quartz Arenite / Shale Carbonate Rocks: Limestone / Dolomite Limestones are not single composition rocks but a group of related rocks all composed of CaCO3 and reacting with dilute HCl acid. Limestone [CaCO3] is also chemically related to Dolomite [CaMg (CO3)2]. Because all these rocks have CO3 in common they are called the Carbonates. The composition of most Carbonates is derived from a combination of biological and chemical components. Two Carbonate classification systems are used today, one by R.L. Folk and the second by R.J. Dunham. The Dunham system is based on depositional texture (that is, the amount of matrix surrounding the grains at the time of deposition). It uses such names as Mudstone, wackestone, packstone, grainstone, and boundstone. Carbonate rock names (Limestones and Dolomites) consist of a conjunction of two names, one describing the ALLOCHEMS, the large pieces, the other describing the INTERSTITIAL MATERIAL. Allochems are equivalent to gravel, sand, lithics or feldspars in the siliciclastics. Interstitial material is equivalent to Clay or cements in clastics. There are four kinds of allochems: 1.
    [Show full text]
  • Carbonate Petrography and Geochemistry of the Eiss Limestone of Kansas
    CARBONATE PETROGRAPHY AND GEOCHEMISTRY OF THE EISS LIMESTONE OF KANSAS by '?? PAUL L. DOWLING, JR. B. S., Old Dominion College, 1965 A MASTER'S THESIS submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Geology and Geography KANSAS STATE UNIVERSITY Manhattan, Kansas 1967 Approved by: Major ^Professor Ml ii CONTENTS Introduction 1 Purpose of the Investigation 1 General Description and Areal Location 2 General Facias Variations 7 Lithology 8 General Discussion 8 Lower Limestone Unit 11 Middle Shale Unit 16 Upper Limestone Unit 16 Method of Investigation 22 Sampling Procedure 22 Laboratory Techniques 22 Acid Etching and Staining 25 Thin-Sections 26 Powdered Sample Preparation 26 X-ray Spectrographs Analyses 26 Oxide Analyses 29 Ferrous Iron and Insoluble Residue Determinations ... 29 Magnesium Analyses by Atomic Absorption 34 Clay Mineral Determinations 35 8 7 86 Sr /Sr Initial Ratio Determinations 37 Petrography 40 General Discussion 40 Lower Eiss Limestone Unit 55 Upper Eiss Limestone Unit 60 Petrographic Environmental Discussion 62 Clay Minerology 67 General Discussion 67 Lower Eiss Limestone Unit 69 Upper Eiss Limestone Unit 72 lii Calcium and Magnesium Geochemistry 73 Aragonite - Calcite Relationships 73 Precipitation Mechanism 74 The Role of Magnesium 75 Calcium/Magnesium Ratios 79 Eiss Limestone Ca/Mg Consideration 82 Strontium Geochemistry 89 Eiss Limestone Sr/Ca Consideration 97 Strontium Isotopic Analyses 103 Iron and Manganese Geochemistry 108 General Discussion 108 Eiss Limestone
    [Show full text]
  • Chapter 5 LIMESTONES
    Chapter 5 LIMESTONES 1. INTRODUCTION 1.1 Something like about one-fifth of all sedimentary rocks are carbonate rocks. The two main kinds of carbonate rocks, limestones and dolostones, together with sandstones and shales, are what might be called the “big four” of sedimentary rock types. I’m reluctant to try to guess what percentage of all sedimentary rocks those “big four” account for, but the figure must be in the upper nineties. Moreover, carbonate rocks are economically important because together with sandstones they constitute reservoirs for most of the world’s petroleum and gas reserves (and let’s not forget that they are the source of all of the world’s portland cement—not a jazzy, exciting resource, but a very important one for our modern civilization). 1.2 Up until about fifty years ago, the petrologic study of carbonate rocks lagged far behind that of siliciclastic rocks. Since that time, however, there has been great progress, as it has become realized that to a great extent carbonate rocks can be treated as clastic deposits analogous to sandstones and shales (the main exception being reef limestones). Great progress has also been made in recent years on the geochemistry of carbonate precipitation, the role of organisms in carbonate deposition, and the diagenesis of carbonate sediments. 1.3 Carbonate sediments are often described as chemically precipitated. In one sense, that’s true: they are formed by precipitation of one or another carbonate mineral in various sedimentary environments. But don’t let the term “chemically precipitated” fool you: they don’t form in the same way that rock candy does from a sugar solution on your windowsill.
    [Show full text]