DOCSLIB.ORG

Petrography and Geochemistry of Dolomites

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Petrography and Geochemistry of Dolomites PETROGRAPHY AND GEOCHEMISTRY OF DOLOMITES IN THE LOWER CRETACEOUS EDWARDS FORMATION, TAYLOR COUNTY, TEXAS by CYNTHIA LYNN WELCH, B.S. A THESIS IN GEOSCIENCE Submitted to the Graduate Faculty of Texas Tech University m Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Approved May, 2001 ACKNOWLEDGEMENTS I extend my gratitude to both the National and the Southwest Section chapters of AAPG and to Texaco Exploration and Production for theu assistance in fimding my graduate work. I would also like to thank the Department of Geosciences at Texas Tech University for the innumerable education opportunities I have received. I would like to thank my advisor, George B. Asquith for his guidance, constant enthusiasm, and most of all his love of Geology that has inspired me from the first day I sat in his classroom. Thank you to Dr. Calvin G. Barnes for his advice and guidance during both my undergraduate and graduate careers. Teachers, in the true sense of the word, are rare. Thank you to my graduate committee: Dr. George B. Asquith, Dr. Calvin G. Barnes, Dr. Moira K. Ridley, and Dr. Haraldur Karlsson for all of their comments and support in developing this thesis. I would like to thank Mike Gower for the preparation of my thin sections and his overall ability to do anything asked of him. Thank you to Rusty Winn for his invaluable tutorials in the isotope lab, James Browning for his assistance in the isotope lab, and to Melanie Barnes for her assistance with the trace element analysis. Thank you to the Department of Biological Sciences Electron Microscopy Laboratory at Texas Tech University for providing facilities for SEM analysis and to Dr. Mark Grimson for assistance in the SEM lab. 1 would like to thank my family for their constant role as my support system. My parents, Tom and Sharon Welch have always supported me without hesitation and 11 encouraged me to achieve my goals without limitation. Thank you to my sister, Kathleen Welch for her amazing strength and constant belief in my fiiture. I would like to thank Jana Moore for her encouragement, inexhaustible patience, and enduring love. Finally, I dedicate this thesis to the memory of my Grandmother, Margaret Welch who would have been dancmg at my graduation if she were able. HI TABLE OF CONTENTS ACKNOWLEDGEMENTS ii ABSTRACT vi LIST OF TABLES ix LIST OF FIGURES x CHAPTER I. INTRODUCTION 1 Purpose of Study 1 Previous Work 3 Dolomitization 4 Methods of Study 9 II. STRATIGRAPHY AND REGIONAL DEPOSITIONAL SETTING 11 Regional Stratigraphy 11 Regional Depositional Setting 11 III. PETROGRAPHY 17 General Information 17 Detailed Descriptions and Photomicrographs 20 IV. SCANNING ELECTRON MICROSCOPY ANALYSIS 33 Purpose of Analysis 33 Detailed Descriptions and SEM Photos 33 IV V. MULBERRY CANYON AREA DEPOSITIONAL HISTORY 42 VI. ISOTOPE, MAJOR ELEMENT, AND TRACE ELEMENT GEOCHEMISTRY 55 Analytical Methods 55 Models of Dolomitization 68 Results 76 Interpretation of Geochemistry 80 VII. DL\GENETIC HISTORY AND CONCLUSIONS 92 Penecontemporaneous Dolomitization Event 92 Subtidal Dolomitization Event 94 Leaching Event 96 Porosity-filling Dolomite Event 97 Diagenetic Model 99 VIII. SUMMARY 100 REFERENCES 102 APPENDIX A. X-RAY DIFFRACTION ANALYSIS CALIBRATION CURVES 107 B. ISOTOPE, MAJOR ELEMENT, AND TRACE ELEMENT DATA 109 ABSTRACT The Lower Cretaceous (Edwards) Mulberry Canyon Section is located in Taylor County, Texas and consists of two tidal flat-capped parasequences that contain three stages of dolomite. Of the three stages of dolomite present, previous work has established the probable environment and conditions for the formation of the first stage of dolomite, however, the environment and conditions for the other two stages has not been conclusively established. The first stage is fine-grained (<10}am), matrix-selective, often- laminated dolomite that has replaced the micrite in unfossiliferous mudstones (tidal flats). The second stage is fine-grained (<10nm), matrix-selective dolomite that has replaced the micrite in fossiliferous subtidal wackestones/packstones. The third stage is coarse­ grained (10-240}am) dolomite that is filling or partially filling fossil-moidic porosity along with equant calcite in the fossiliferous subtidal wackestones/packstones. The purpose of this study is to use petrographic (petrography, scanning electron microscopy, and x-ray diffraction) and geochemical (major element, trace element, and isotopic) analyses to: (1) establish the depositional history of the Mulberry Canyon Section, (2) document the three stages of dolomite present in the section, and (3) establish the environment and conditions of dolomitization for each stage present in the Mulberry Canyon Section. A hypersaline penecontemporaneous origin for the dolomitized tidal flats is suggested by the presence of mudcracks, tepee structures, possible algal laminations, modified cubic pyrite crystals, and by their association with the Kirschberg Evaporite. VI The geochemical data supports a hypersaline penecontemporaneous origin for the tidal flat dolomite. Values for 6^^0 of both tidal flats (6'^O=-0.9 to -0.25foPDB, 5^^C=0.6 to 1.9%oPDB) have a more hypersaline signature when compared to Lower Cretaceous marine (6^^0=-4.4%oPDB, 5^^C=2.4%oPDB) and meteoric (6^^0= -8.8%PPDB, 5^^C=l.l%oPDB) values determined m this study. Values for 6^^C of both tidal flats 1 ^ (5 C=0.6 to 1.9%oPDB) vary in a possible mixing fi^ctionation trend suggesting (along with the presence of modified pyrite) bacterial processes such as methanogenesis and/or sulfate reduction in the tidal flats. Na/Ca versus Mg/Ca, and Sr/Ca values of the tidal flat dolomitized mudstones exhibit a slight positive correlation, which suggests an evaporative association and supports the isotopic data. The tidal flat hypersaline brines sank, moved seaward (seepage reflux), and mixed with marine water. This mixed hypersaline and marine fluid was responsible for selective dolomitization of the underlying subtidal wackestones/packstones matrix. The similarity in isotope and trace element geochemistry between the dolomitized mudstones (tidal flats) and subtidal dolomitized matrix indicates similar dolomitizing fluids were responsible in both stages of dolomitization. Oxygen isotope values (6'^0=-3.7 to -0.996oPDB) of the dolomitized subtidal wackestone/packstone matrix below the upper tidal flat have a marine signature, suggesting a marine influence in this stage of dolomite. A slight positive correlation in Na/Ca versus Mg/Ca, and Sr/Ca values of the subtidal dolomitized matrix suggests evaporite association and, therefore, an association with the hypersaline brines responsible for the dolomitization of the tidal flats. Vll Coarse-grained dolomite filling or partially filling moldic porosity exhibits marine to meteoric isotopic values (6'*0=-7.2 to -4.7%,PDB, 8^^C=-0.3 to +0.5%<,PDB). hi addition to isotopic evidence, the coarse-grained dolomite exhibits similar concentrations of Mn, Fe, and Sr (Mn=124ppm, Fe=1098ppm, and Sr=276ppm) to the meteoric values (Mn=l 17ppm, Fe=863ppm, and Sr=192ppm) suggestmg that mixed waters (marine and meteoric; Dorag dolomitization) were responsible for this last stage of dolomite. Vlll LIST OF TABLES 3.1 Percentage Dolomite in Mulberry Canyon Section Samples 17 6.1 Isotopic Results from Alizarin Red-S Treated and Untreated Calcite Standard 60 6.2 Major and Trace Element Results from Alizarin Red-S Treated and Untreated Calcite Standard 62 6.3 Diagnostic Geologic, Petrographic, and Geochemical Characteristics of Different Dolomitization Models 74 6.4 Geologic, Petrographic, and Geochemical Results for the Three Types of Dolomites Present in the Mulberry Canyon Section 90 B. 1 Marine and Meteoric Calcite Fraction Isotope Values for Samples from Fluvanna Quarry 110 B.2 Marine and Meteoric Trace Element Values for samples from Fluvaima Quarry 110 B.3 Dolomite Fraction Oxygen and Carbon Isotope Values for the Mulberry Canyon Section Samples 111 B.4 Calcite Fraction Oxygen and Carbon Isotope Values for the Mulberry Canyon Section Samples 112 B.5 Concentrations of Ca, Mg, Na, and Sr for Samples in the Mulberry Canyon Section 113 B.6 Concentrations of Fe, Mn, Ba, and Zn for Samples in the Mulberry Canyon Section 114 B.7 Concentrations of Al and K for Samples in the Mulberry Canyon Section 115 IX LIST OF FIGURES 1.1 Map Illustrating General Location of Mulberry Canyon Section 2 1.2 Seepage Reflux, Evaporative Pumping, and Mixing Zone (Dorag) Models for Dolomitization 7 2.1 General Stratigraphic Nomenclature of the northem Edwards Plateau 12 2.2 Location of Study Area, the Lower Cretaceous Shelf Edge, and the Concho Arch 13 2.3 Paleoenvironmental Map of Texas During Lower Cretaceous Time 15 3.1 Stratigraphic Column of Mulberry Canyon Section 18 3.2 Photomicrographs of Units 1 through 3 21 3.3 Photomicrographsof Units 3 through 7 23 3.4 Photomicrograph of Unit 8 and Outcrop Photographs of Units 8 and 9 26 3.5 Photomicrographs of Units 9 through 12 28 3.6 Photomicrographs of Units 13 and 14 31 4.1 SEM Photographs of Units 1 through 3 34 4.2 SEM Photographs of Units 4 through 8 36 4.3 SEM Photographs of Units 8 through 11 38 4.4 SEM Photographs of Units 11 through 14 40 5.1 Mulberry Canyon Section Stratigraphic Column with Depositional Environments 43 5.2 Lithofacies Distribution During Deposition of Unit 1 45 5.3 Lithofacies Distribution During Deposition of Units 2 through 4 45 5.4 Lithofacies Distribution During Deposition ofUnits 6 through 10 46 X 5.5 Lithofacies Distribution During Deposition of Unit 11 46
Load more

Recommended publications
  • Dolomitization
    2/25/2009 Dolomitization A Short Course VU March, 2009 Peter Swart University of Miami www.aoqz76.dsl.pipex.com/ Landscapes.htm Dieudonné Sylvain Guy Tancrede de Gratet de Dolomieu usually known as Déodat de Dolomieu (Dolomieu June 23, 1750 - Chateuneuf November 28, 1801) a French geologist; the rock Dolomite was named after him. During one of his field trips to the Alps of South Tyrol (today part of northeastern Italy) he discovered a calcareous rock which, unlike limestone, did not effervesce in weak acid. He published these observations in 1791 in the Journal de Physique. The following year, in the same journal, the rock was named dolomie (or dolomite, in English) by Nicolas-Théodore de Saussure. Today both the rock and its major mineral constituent bear the name of Dolomieu, as do the Dolomites, the mountain range in northwestern Italy, where he first identified the rock. http://en.wikipedia.org/wiki/Dolomieu 1 2/25/2009 1980 1994 "Dolomite is a complicated mineral. It exhibits a wide range in the concentration of major elements and is as complex as Feldspar" (Land, 1980) 2 2/25/2009 CaMg(CO3)2 Dolomites appear to be OXYGEN between 3 to 4 per mille heavier (more O-18) than co-occuring carbonates. +3 Dolomite CARBON Calcite +1 Dolomites are about 1 per mille heavier in carbon Stable Isotopes Natural Variations UNDA 18 Oo/oo - - - - 6 2 4 0 4 8 2 12345 6 200 Bulk Dolomites 400 o 3 /oo 600 (fbmp) Depth 800 1000 1200 1400 3 2/25/2009 Experimental CaMgCO3+H3PO4=CO2+H2O+CaMgHPO4 1/2 1/4 = [CO2] [H2O][CaMgHPO4] /[CaMgCO3][H3PO4] 4 2/25/2009
    [Show full text]
  • 9 Carboniferous: Extensional Basins, Advancing Deltas and Coal Swamps
    Carboniferous: extensional 9 basins, advancing deltas and coal swamps C. N. WATERS & S. J. DAVIES The structural evolution of England and Wales during the Trough and Widmerpool Gulf of the East Midlands (Fig. 9.4), Carboniferous was primarily a consequence of an oblique the Craven Basin of Lancashire and Harrogate Basin of (dextral) collision between Gondwana and Laurussia (Warr Yorkshire, formed connected narrow embayments. The inter- 2000). Several phases can be recognized. The Rhenohercynian vening platforms include the linked East Midlands Shelf and Ocean opened during Early–Mid Devonian regional back-arc Derbyshire High, the Holme High, Hathern Shelf and the transtension between Avalonia and Armorica (Fig. 9.1), possi- North Wales Shelf (Fig. 9.2). These platform areas represent the bly associated with northward-directed subduction along the northern margin of the Wales–Brabant High, which formed a southern margin of Armorica. A narrow seaway floored by persistent topographical feature throughout the Carboniferous. oceanic crust developed, extending across southwest England, Along the southern margin of the Wales–Brabant High there northern France and Germany. Cessation of the subduction, is a gradual change southward from a shelf in the South Wales associated with the Ligerian orogenic phase of central Europe, and Bristol region into a deep marine back-arc seaway of the resulted from the collision of the Iberian and Armorican Culm Basin of Cornwall and Devon (Fig. 9.2), that developed microplates (Fig. 9.1). During the Late Devonian, transpressive from the Late Devonian to Silesian times (see Chapter 10). closure of this restricted ocean, associated with the Bretonian By late Dinantian time the magnitude of regional N–S exten- orogenic phase, may have occurred in response to short-lived sion had greatly reduced.
    [Show full text]
  • Dolomitization of the Upper Jurassic Carbonate Rocks in the Geneva Basin, Switzerland and France
    Swiss Journal of Geosciences (2018) 111:475–500 https://doi.org/10.1007/s00015-018-0311-x (012 3456789().,- volV)(0123456789().,-volV) Dolomitization of the Upper Jurassic carbonate rocks in the Geneva Basin, Switzerland and France 1 1 1 1 2 1 Yasin Makhloufi • Elme Rusillon • Maud Brentini • Andrea Moscariello • Michel Meyer • Elias Samankassou Received: 1 September 2017 / Accepted: 1 May 2018 / Published online: 30 May 2018 Ó Swiss Geological Society 2018 Abstract The Upper Jurassic carbonates represent important potential targeted reservoirs for geothermal energy in the Geneva Basin (Switzerland and France). Horizons affected by dolomitization, the focus of the present study, are of particular interest because they proved to be productive in time-equivalent deposits currently exploited in Southern Germany. The study is based on sub-surface samples and outcrops in the Geneva Basin. Petrographic analyses allowed to constrain the parage- nesis of the Upper Jurassic units prior to discussing the cause(s) and effect(s) of dolomitization. Data reveal that the facies are affected by early and late diagenesis. All samples show at least two stages of burial blocky calcite cementation with the exception of those from the sub-surface, which display an incomplete burial blocky cementation preserving primary intercrystalline porosity. Dolomitization affected all units. The results point to an early dolomitization event, under the form of replacement dolomite. Dedolomitization, through calcitization and/or dissolution, is an important process, creating secondary pore space. Results of the present study favor a reflux model for dolomitization rather than the mixing-zone model suggested in earlier work. However, considering the geodynamic context, other dolomitization models cannot be excluded for the subsurface.
    [Show full text]
  • Dolomitization of Holocene Mg-Calcite Supratidal Deposits, Ambergris Cay, Belize
    Dolomitization of Holocene Mg-calcite supratidal deposits, Ambergris Cay, Belize ^ Geological Consultants, Midland, Texas 79701 A. M. REID J J. M. GREGG St Joe Minerals Corp., Viburnum, Missouri 65566 ABSTRACT Skinner, 1957; Von der Borch and Lock, 1979; slow rates and over-all limited amounts of do- Von der Borch and others, 1964; Muir and oth- lomite found in most recent supratidal deposits Dolomitized crusts and associated sedi- ers, 1980), and the arid Persian Gulf sabkhas (Machel and Mountjoy, 1986) seemingly are in- ments 845-2925 yr old on Ambergris Cay, (Curtis and others, 1963; Illing and others, 1965; compatible with the formation of many thick Belize, Central America, compose a signifi- McKenzie and others, 1980). These dolomites sequences of ancient bedded peritidal dolomites. cant portion of the Holocene sediment section characteristically are microcrystalline, poorly An addition to the inventory of Holocene do- on many supratidal flats. The dolomitic sec- ordered and calcium-rich, and compose from a lomites described above are those crusts and as- tions are as thick as 0.7 m and contain an trace to, rarely, as much as 95%-100% of some sociated dolomitic sediments found on the average of 70% calcic dolomite. Dolomite oc- indurated supratidal crusts (Shinn and others, humid, supratidal carbonate flats on Ambergris curs as a replacement of high-Mg calcite mic- 1965; Deffeyes and others, 1965; Illing and oth- Cay in Belize, Central America (Fig. 1). Recent rite matrix and allochems, and as pas- ers, 1965), or they occur as poorly consolidated mapping has shown that supratidal dolomitiza- sively precipitated cements.
    [Show full text]
  • Origins and Geochemistry of Dolomites and Their Dissolution in the Middle Triassic Leikoupo Formation, Western Sichuan Basin, China
    minerals Article Origins and Geochemistry of Dolomites and Their Dissolution in the Middle Triassic Leikoupo Formation, Western Sichuan Basin, China Shunli Zhang 1,2, Zhengxiang Lv 1,2,*, Yi Wen 1,2 and Sibing Liu 1,2 1 State Key Laboratory of Oil-Gas Reservoirs Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; [email protected] (S.Z.); [email protected] (Y.W.); [email protected] (S.L.) 2 College of Energy Resources, Chengdu University of Technology, Chengdu 610059, China * Correspondence: [email protected] Received: 18 May 2018; Accepted: 30 June 2018; Published: 6 July 2018 Abstract: Triassic dolomites occur pervasively in the Western Sichuan Basin. Although these strata have been deeply buried and affected by multiple phases of dolomitization and dissolution, some intervals in the upper part of the Leikoupo Formation have developed high porosity. Based on their petrographic and geochemical features, three major types of dolomite fabrics are recognized, namely, dolomicrite, fabric-retentive dolomite, and fabric-destructive dolomite. Geochemical evidence indicates that the dolomicrite formed following the Sabkha model in a low-temperature hypersaline environment, as these rocks exhibit abnormally high Sr and Na contents, lower Fe and Mn contents, δ18O values generally ranging from −1.70 to −1.67 (with an average value of −1.69 ), and higher Mg/Ca ratios. The fabric-retentiveh dolomiteh formed following the seepage-refluxh model in a shallow burial environment, and these rocks exhibit the highest 87Sr/86Sr ratios, δ18O values generally ranging from −6.10 to −2.50 (with an average value of −3.98 ), and a wide range of Fe and Mn contents, indicatingh that theyh may have been altered by meteorich water.
    [Show full text]
  • Controls on Dolomitization in Extensional Basins: an Example from the Derbyshire Platform, U.K
    Journal of Sedimentary Research, 2020, v. 90, 1156–1174 Research Article DOI: http://dx.doi.org/10.2110/jsr.2020.58 CONTROLS ON DOLOMITIZATION IN EXTENSIONAL BASINS: AN EXAMPLE FROM THE DERBYSHIRE PLATFORM, U.K. 1 2 3 2 3 3 CATHERINE BREISLIN,* STEPHEN CROWLEY, VANESSA J. BANKS, JIM D. MARSHALL, IAN L. MILLAR, JAMES B. RIDING, AND CATHY HOLLIS1 1Department of Earth and Environmental Science, University of Manchester 2Jane Herdman Laboratories, University of LIverpool 3British Geological Survey ABSTRACT: Fault-controlled dolomitization has been documented in Lower Carboniferous (Visean)´ platform carbonates at various localities in the Pennine Basin and North Wales. The largest of these dolomite bodies (approx. 60 km2) occurs on the Derbyshire Platform, on the southern margin of the Pennine Basin. This study tests the hypothesis that dolomitization occurred at this locality during deposition, platform drowning, and the earliest stages of burial, coincident with the transition from a late syn-rift to post-rift regime. It also assesses the importance of syn-rift volcanism on dolomitization. Planar, fabric-retentive dolomite with single-phase (i.e., low temperature) fluid inclusions occurs along NW–SE and E–W oriented faults, and in platform margin facies and in proximity to the Masson Hill Volcanic Complex. Oxygen isotope data are consistent with dolomitization from seawater, but slightly depleted d13C values reflect mixing with magmatic fluids. Volcanic activity is likely to have produced a thermal drive for fluid circulation on the platform margin, and post-depositional alteration of basalts by CO2-rich fluids could have led to alteration of olivine and release of magnesium to convecting seawater.
    [Show full text]
  • Stratigraphy and Sedimentary Facies Or the Madison Limestone and Associated Rocks in Parts Pf Montana, Nebraska, North Dakota, S
    Stratigraphy/"~t * 1 and1 Sedimentaryf~^ "I * FaciesT ^ orf-» the Madison Limestone and Associated Rocks in Parts pf Montana, Nebraska, North Dakota, South Dakota, and Wyoming GEOLOGICAL SURVEY PROFESSIONAL PAPER 1273-A Stratigraphy and Sedimentary Fades of the Madison Limestone and Associated Rocks in Parts of Montana, Nebraska, North Dakota, South Dakota, and Wyoming By JAMES A. PETERSON GEOLOGY AND HYDROLOGY OF THE MADISON LIMESTONE AND ASSOCIATED ROCKS IN PARTS OF MONTANA, NEBRASKA, NORTH DAKOTA, SOUTH DAKOTA, AND WYOMING GEOLOGICAL SURVEY PROFESSIONAL PAPER 1273-A UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1984 DEPARTMENT OF THE INTERIOR WILLIAM P. CLARK, Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging in Publication Data Peterson, James A. Stratigraphy and sedimentary facies of the Madison Umestone and associated rocks in parts of Montana, Nebraska, North Dakota, South Dakota, and Wyoming. (Geological Survey professional paper ; 1273A) Bibliography: p. Supt. of Docs, no.: 119.16:1273-A 1. Limestone Middle West. 2. Geology, Stratigraphic Paleozoic. I. Title. II. Series. QE471.15.L5P47 1981 552'.5 82-600376 For sale by the Distribution Branch, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 CONTENTS Page Page Abstract ._.__.__.._.................._-.__.. Al Stratigraphy and sedimentary facies Continued Introduction.................................. 1 Mississippian rocks Continued Acknowledgments .............................. 2 Madison Limestone Continued Regional paleogeography and paleostructure ........... 3 M-7 to M-8.5 interval (middle Osagean) ..... A18 Stratigraphy and sedimentary facies ................. 6 M-8.5 to M-12 interval (upper Osagean) ...... 19 Precambrian rocks .......................... 6 M-12 to Me interval (approximately Cambrian rocks ....................______._ 6 Meramecian) ....................
    [Show full text]
  • Bead Lake District
    State of Washington ARTHUR B. LANGLIE, Governor Department of Conservation and Development W. A. GALBRAITH, Director DIVISION OF MINES AND GEOLOGY SHELDON L. GLOVER, Supervisor Bulletin No. 40 GEOLOGY OF THE BEAD LAKE DISTRICT PEND OREILLE COUNTY, WASHINGTON By MELVIN C. SCHROEDER !loTAT£ PRINTING PLANT OLYMPIA. WASH, 1952 f'or sale by Department of Conservation and Development, Olympia, Washington. Price, 75 cents. CONTENTS Page Foreword . ... 4 Introduction . 5 Location . .. 5 Topography . 6 Acknowledgments and field work...................... ..... ..... 6 Summary of earlier work. 6 Scope of the report. 7 Principal geologic features. 8 Sedimentary rocks . 8 General features . 8 Pre-Cambrian sediments-Newport group.......................... 9 Bead Lake formation ... ...................................... 10 Distribution and thickness ....... .. ........ .. ............ 10 Stratigraphic relations . 10 Lithology .... ..... .. ....................... .......... .. 10 No Name argillite ... ........................................ 11 Distribution and thickness. 11 Stratigraphic relations . 12 Lithology . 12 Skookum formation . 13 Distribution and thickness. 13 Stratigraphic relations . 13 Lithology ............................. .............. .... 14 Conditions of sedimentation. 17 Correlation . 18 Tertiary sediments . 20 Tiger formation ....................... .. ........... ..... .... 20 Distribution and thickness. 20 Lithology . 20 Age ..................................................... 20 Quaternary deposits ................... ..............
    [Show full text]
  • The Role of Microorganisms on the Formation of a Stalactite
    EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Open Access Open Access Natural Hazards Natural Hazards and Earth System and Earth System Sciences Sciences Discussions Open Access Open Access Atmospheric Atmospheric Chemistry Chemistry and Physics and Physics Discussions Open Access Open Access Atmospheric Atmospheric Measurement Measurement Techniques Techniques Discussions Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Open Access Biogeosciences Discuss., 10, 6563–6603, 2013 Open Access www.biogeosciences-discuss.net/10/6563/2013/ Biogeosciences Biogeosciences BGD doi:10.5194/bgd-10-6563-2013 Discussions © Author(s) 2013. CC Attribution 3.0 License. 10, 6563–6603, 2013 Open Access Open Access This discussion paper is/has been under review for the journal BiogeosciencesClimate (BG). Climate The role of Please refer to the correspondingof finalthe Past paper in BG if available. of the Past Discussions microorganisms on the formation of a Open Access The role of microorganisms on the Open Access stalactite Earth System Earth System formation of aDynamics stalactite in BotovskayaDynamics M. Pacton et al. Discussions Open Access Cave, Siberia – palaeoenvironmental Open Access Geoscientific Geoscientific Title Page implicationsInstrumentation Instrumentation Methods and Methods and Abstract Introduction Data Systems Data Systems 1 1 1 2 3 M. Pacton , S. F. M. Breitenbach , F. A. Lechleitner , A. Vaks , C. Rollion-BardDiscussions
    [Show full text]
  • The Geology and Genesis of the Chlorite-Carbonate Alteration in the Footwall of the Hellyer Volcanic­ Hosted Massive Sulphide (Vhms) Deposit
    THE GEOLOGY AND GENESIS OF THE CHLORITE-CARBONATE ALTERATION IN THE FOOTWALL OF THE HELLYER VOLCANIC­ HOSTED MASSIVE SULPHIDE (VHMS) DEPOSIT Alison Bradley, B.Sc. A research thesis submitted in partial fulfilment of the requirements of the degree of Bachelor of Science with Honours Centre for Ore Deposit Research, Geology Department, University of Tasmania. November, 1997. ~EOLOGY PEPT.. _ i ABSTRACT The chlorite-carbonate alteration assemblage is an unusual feature in the footwall of the Hellyer volcanic~hosted massive sulphide deposit, Tasmania. Carbonate alteration is common to many VHMS deposits however its origin and characteristics has been rarely studied in detail. Chlorite-carbonate alteration is defined as texturally diverse dolomite in a matrix of fine-grained chlorite. This distinctive alteration is found at the top of the chlorite-alteration zone around the central and northern hydrothermal discharge sites beneath the deposit. On the ore contact ('contact zone'), the chlorite-carbonate assemblage occurs as thin discontinuous lenses. A lower stratiform chlorite-carbonate alteration zone ('lower zone') occurs approximately 40 metres below the contact zone, is more laterally continuous and only occurs on the west side of the east flank of the ore deposit. Carbonate alteration is associated with sericite, chlorite and quartz in the contact zone but is primarily associated with chlorite in the lower zone. Carbonate-chlorite assemblages have not been observed at greater depths in the footwall alteration pipe, or distal to the deposit. The carbonate mineralogy is Fe-dolomite or dolomite. Carbonate textures consist of large and small spheroids, rhombs, massive carbonate and veinlets. These textures appear to be associated with the initial porosity and permeability of the host rock.
    [Show full text]
  • Publication 21. Geological Series 17. MINERAL RESOURCES OF
    STATE OF MICHIGAN Trenton Limestone .................................................19 MICHIGAN GEOLOGICAL AND BIOLOGICAL SURVEY "Niagara" Limestone ..............................................20 Engadine Dolomite. ............................................20 Publication 21. Geological Series 17. Manistique Series...............................................21 Fiborn Limestone................................................21 MINERAL RESOURCES OF MICHIGAN Hendricks Series ................................................22 WITH Salina Formation....................................................23 STATISTICAL TABLES OF PRODUCTION Monroe Formation..................................................23 AND VALUE OF MINERAL PRODUCTS Lower Monroe, or Bass Island Series ........................23 FOR Upper Monroe, or Detroit River Series .......................23 Dundee or Onondaga Limestone ...........................24 1915 AND PRIOR YEARS. Traverse (Hamilton and Marcellus) Formation .......24 Bayport (Maxville) Limestone.................................25 WITH A TREATISE ON LIMESTONE RESOURCES R. A. SMITH. CHAPTER V. Distribution, Character, and Development of Limestone Deposits by Counties.25 PREPARED UNDER THE DIRECTION OF Pre-Cambrian Limestones. ........................................26 R. C. ALLEN Dickinson county. ...................................................26 DIRECTOR, MICHIGAN GEOLOGICAL AND Gogebic county. .....................................................26 BIOLOGICAL SURVEY Iron county. ............................................................27
    [Show full text]
  • A 4-Day Geological Field Trip in the Western Dolomites
    Geo.Alp, Vol. 8, S. 76–118, 2011 A 4-DAY GEOLOGICAL FIELD TRIP IN THE WESTERN DOLOMITES Rainer Brandner1 & Lorenz Keim2 With 28 Figures 1 Institut für Geologie & Paläontologie, Universität Innsbruck, Innrain 52, A-6020 Innsbruck; E-mail address: [email protected] 2 Amt für Geologie & Baustoffprüfung/Ufficio Geologia e prove materiali, Autonome Provinz Bozen – Südtirol/Provincia Autonoma di Bolzano-Alto Adige, Eggentalerstr./Via Val d’Ega 48, I-39053 Kardaun/Cardano; E-mail address: [email protected] Introduction and geological setting of the Dolomites The Dolomite Mountains are known for their spectacular seismic scale outcrops showing Triassic carbonate platforms and build-ups preserved with their clinoforms and slope facies in primary transition to adjacent basi- nal areas. The juxtaposition of Middle and Upper Triassic reefs and basins are preserved due to the lack of strong tectonic deformation and is strengthened by erosion to form the extraordinary landscape as seen today. Since the outstanding studies of Richthofen (1860) and Mojsisovics (1879), who correctly recognized the primary geometries of the build-ups (“Überguss-Schichtung”) in transition to the basins, the Dolomites are the type area for heteropic facies developments. Bosellini (1984) presented the first modern synthesis of depositional geometries of the build-ups. Regional sequence stratigraphy was firmly established with the revision of the chronostratigraphic framework by Brack & Rieber (1993), De Zanche et al. (1993) and Mietto & Manfrin (1995). In addition, a better understanding was developed of progradation and retrogradation geometries of carbonate platform development in context with sea level changes (Gianolla et al., 1998, with further references).
    [Show full text]