DOCSLIB.ORG

Depositional Environments, Diagenesis, and Reservoir Delineation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Depositional Environments, Diagenesis, and Reservoir Delineation DEPOSITIONAL ENVIRONMENTS, DIAGENESIS, AND RESERVOIR DELINEATION OF THE FCU 1947 UPPER CLEAR FORK CORED INTERVAL – AN SEM IMAGE ANALYSIS APPROACH TO PORE SYSTEM CHARACTERIZATION by TORE RAY WIKSVEEN Presented to the Faculty of the Graduate School of The University of Texas at Arlington in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN GEOLOGY THE UNIVERSITY OF TEXAS AT ARLINGTON DECEMBER 2013 Acknowledgements I would first like to thank XTO Energy for granting me the resources, both tangible and intangible, to conduct and complete this study. My time at XTO Energy has brought me a wealth of knowledge and experience. I am indebted to the company and my mentors for all they have provided me with. Particularly, I’d like to thank Wayne R. Gibson and Jason P. Slayden, who have both been close by my side, providing assistance and guidance throughout this study. I would like to thank John Wickham, Merlynd Nestell, and Qinhong Hu at the University of Texas at Arlington, for providing me counsel and direction over the course of my graduate studies. Several students at University of Texas at Arlington are also to be thanked for their support and ability to keep me moderately sane. Jillian Rowley, Paul Monahan, Johnathon Bogacz, and Shariva Darmaoen have been instrumental in keeping me motivated during defeating times. Most importantly, I would like to thank my mom, dad, sister Karissa Plusko, brother Randy Hosey, and Rene Finical. The emotional support, love, and selflessness they have provided has allowed me to thrive in any endeavor I have pursued. I could not have finished this study without them. st November 21 , 2013 ii Abstract DEPOSITIONAL ENVIRONMENTS, DIAGENESIS, AND RESERVOIR DELINEATION OF THE FCU 1947 UPPER CLEAR FORK CORED INTERVAL – AN SEM IMAGE ANALYSIS APPROACH TO PORE SYSTEM CHARACTERIZATION Tore Ray Wiksveen, M.S. The University of Texas at Arlington, 2013 Supervising Professor: John Wickham Delineating reservoir facies in heterogeneous tidal-flat carbonates is a challenge which requires analysis at greater resolutions than wireline logs can provide. Such depositional environments are documented in the upper Clear Fork deposits of Fullerton Field in West Texas. This study examined lithofacies and depositional facies of core to gain understanding of the best reservoir facies. Whole-core examination, Core Laboratories and wireline log analysis, thin section microscopy and SEM image analysis were used to delineate reservoirs. Subtidal facies were deemed the poorest of reservoirs because compaction, anhydrite plugging, and burial diagenesis obliterated pore space. Intertidal facies were determined as the best reservoirs, particularly those directly beneath shallowing-upwards cycle tops. Grainier fabric and fabric selective dissolution of these facies increased porosity. Supratidal facies were determined as the second best reservoirs because eogenetic dolomitization protected them from compaction. Furthermore, these depositional facies can be correlated to nearby wells via distinct wireline signatures. iii Table of Contents Acknowledgements ............................................................................................................. ii Abstract ...............................................................................................................................iii Table of Figures .................................................................................................................vii Chapter 1 Introduction......................................................................................................... 1 Purpose .......................................................................................................................... 1 Nomenclature Disclaimer ............................................................................................... 2 Previous studies ............................................................................................................. 2 Methods .......................................................................................................................... 4 Core and Thin Sections .............................................................................................. 5 Pore Classification ...................................................................................................... 6 Pore Quantification and Analysis ............................................................................... 6 Borehole Logs and the Segregation of Cored Interval. ............................................ 10 Chapter 2 Geological Setting ............................................................................................ 12 Paleogeography ............................................................................................................ 12 Tectonic Evolution and Basin Filling ............................................................................. 13 Stratigraphy .................................................................................................................. 16 Depositional Environment ............................................................................................. 21 Study Location .............................................................................................................. 24 Chapter 3 Analysis of Fullerton 1947 Core ....................................................................... 28 Core Interpretation ........................................................................................................ 28 Results ...................................................................................................................... 30 Discussion ................................................................................................................ 33 Depositional Model ................................................................................................... 52 Core Laboratories Analysis of Reservoir Properties .................................................... 54 iv Porosity Analysis Results ......................................................................................... 54 Porosity Analysis Discussion .................................................................................... 55 Permeability Analysis Results .................................................................................. 57 Permeability Analysis Discussion ............................................................................. 58 Grain Density Analysis Results ................................................................................ 59 Grain Density Analysis Discussion ........................................................................... 59 Chapter 4 Microscopic Examination ................................................................................. 61 Thin Section Examination ............................................................................................. 61 Results ...................................................................................................................... 61 Discussion ................................................................................................................ 63 Diagenetic History of FCU 1947 Core .......................................................................... 72 Results ...................................................................................................................... 72 Discussion ................................................................................................................ 75 Chapter 5 Porosity ............................................................................................................ 81 Pore Types ................................................................................................................... 81 Results ...................................................................................................................... 81 Discussion- Major Pore Types ................................................................................. 81 SEM Image Analysis..................................................................................................... 91 Results ...................................................................................................................... 91 Discussion .............................................................................................................. 102 Limitations and Considerations .............................................................................. 109 Chapter 6 Reservoir Exploitation .................................................................................... 114 Wireline Log Responses ............................................................................................. 114 Results .................................................................................................................... 114 Discussion .............................................................................................................. 117 v Perforation Targets and Completions Practices ......................................................... 118 Results .................................................................................................................... 118 Discussion .............................................................................................................. 119 Chapter 7 Conclusions ...................................................................................................
Load more

Recommended publications
  • 1 Running Head: SEQUENCE STRATIGRAPHY of TEXAS
    Running Head: SEQUENCE STRATIGRAPHY OF TEXAS MIDDLE PERMIAN PLATFORM CARBONATES OUTCROP-BASED CHARACTERiZATION OF LEONARDIAN PLATFORM CARBONATE IN WEST TEXAS: IMPLICATIONS FOR SEQUENCE STRATIGRAPHIC STYLES IN TRANSITIONAL ICEHOUSE-GREENHOUSE SETTINGS Stephen C. Ruppel, W. Bruce Ward1, and Eduardo E. Ariza Bureau of Economic Geology The University of Texas at Austin 1 Current address: Earthworks LLC, P.O. Box 178, Newtown, CT 06470-0178 1 ABSTRACT The Sierra Diablo Mountains of West Texas contain world class exposures of lower and middle Permian platform carbonates. As such these outcrops offer key insights into the products of carbonate deposition in the transitional icehouse/greenhouse setting of the early-mid Permian that are available in few other places in the world. They also afford an excellent basis for examing how styles of facies and sequence development vary between platform tops and platform margins. Using outcrop data and observations from over 2 mi (3 km) of continuous exposure, we collected detailed data on the facies composition and architecture of high frequency (cycle-scale) and intermediate frequency (high frequency sequence scale) successions within the Leonardian. We used these data to define facies stacking patterns along depositional dip across the platform in both low and high accommodation settings and to document how these patterns vary systematically between and within sequences . These data not only provide a basis for interpreting similar Leonardian platform successions from less well constrained outcrop and subsurface data sets but also point out some important caveats that should be considered serve as an important model for understanding depositional processes during the is part of the Permian worldwide.
    [Show full text]
  • Theuniversityoftexasbul
    THEUNIVERSITYOFTEXASBULLETIN No. 3027: July 15, 1930 THE GEOLOGY OF STONEWALL COUNTY, TEXAS By L. T. PATTON Bureau of Economic Geology J. A. Udden, Director £. H. Sellards, Associate Director PUBLISHED BY TOE UNIVERSITY OF TEXAS AUSTIN Publications of The University of Texas Publications Committees GENERAL: Frederic Duncalf Mrs.F. A. Perry J. F.Dobie C. H. Slover J. L.Henderson G. W. Stumberg H. J.Muller A.P. Winston official E. J. Mathews Killis Campbell C. F. Arrowood C.D.Simmons E. C.H.Bantel Bryant Smith The University publishes bulletins four times a month, so numbered that the first two digits of the number show the year of issue and the last two the position in the yearly series. (For example, No. 3001is the first bulletin of the year 1930.) These bulletins comprise the official publica- tions of the University, publications on humanistic and scientific subjects, and bulletins issued from time to time by various divisions of the University. The following bureaus and divisions distribute bulletins issued by them; communications concerning bulletins in these fields should be addressed to TheUniversity of Texas,Austin,Texas,care of the bureau or division issuing the bulletin: Bureau of Business Research, Bureau of Economic Geology, Bureau of Engineering Research, Interscholastic League Bureau, andDivision of Extension. Communications concerning all other publications of the University should be addressed to University Publications,TheUniversity of Texas,Austin. Additionalcopies of this publicationmaybeprocuredfrom the Bureau of Economic Geology, The University of Texas, Austin, Texas THE UNIVERSITY OFTEXAS PREM, AUSTUI THEUNIVERSITYOF TEXASBULLETIN No. 3027: July 15, 1930 THE GEOLOGY OF STONEWALL COUNTY, TEXAS By L.
    [Show full text]
  • A Juvenile Skeleton of the Nectridean Amphibian
    Lucas, S.G. and Zeigler, K.E., eds., 2005, The Nonmarine Permian, New Mexico Museum of Natural Histoiy and Science Bulletin No. 30. 39 A JUVENILE SKELETON OF THE NECTRIDEAN AMPHIBIAN DIPLOCAULUS AND ASSOCIATED FLORA AND FAUNA FROM THE MITCHELL CREEK FLATS LOCALITY (UPPER WAGGONER RANCH FORMATION; EARLY PERMIAN), BAYLOR COUNTY, NORTH- CENTRAL TEXAS, USA DAN S. CHANEY, HANS-DIETER SUES AND WILLIAM A. DIMICHELE Department of Paleobiology MRC-121, National Museum of Natural History, PC Box 37012, Washington, D.C. 20013-7021 Abstract—A well-preserved skeleton of a tiny individual of the nectridean amphibian Diplocaulus was found in association with other Early Permian animal remains and a flora in a gray mudstone at a site called Mitchell Creek Flats in Baylor County, north-central Texas. The locality has the sedimentological attributes of a pond deposit. The skeleton of Diplocaulus sp. is noteworthy for its completeness and small size, and appears to represent a juvenile individual. The associated plant material is beautifully preserved and comprises the sphe- nopsids Annularia and Calamites, the conifer IBrachyphyllum, possible cycads represented by one or possibly two forms of Taeniopteris, three gigantopterids - Delnortea, Cathaysiopteris, and Gigantopteridium — and three unidentified callipterids. Several unidentified narrow trunks were found at the base of the deposit, appar- ently washed up against the northern margin of the pond. Other faunal material from the deposit comprises myalinid bivalves, conchostracans, a tooth of a xenacanthid shark, and a palaeonisciform fish. INTRODUCTION Wchita Rver T ^ Coinage i ^ 1 t Complete skeletons of Early Permian vertebrates are rare in north- FwmatJon Grcyp c central Texas, where much collecting has been done for about 150 years c c (Fig.
    [Show full text]
  • New England Zoological Club
    PROCEEDINGS OF THE NEW ENGLAND ZOOLOGICAL CLUB NEW GENERA AND SPECIES OF PELYCOSAURIAN REPTILES BY ALFRED SHERWOOD ROMER IN the course of recent collecting trips by the Museum of Comparative Zoology and a re-study of pre-existing collections, Ii number of new types of Permo-Carboniferous pelycosaurs have come to light. I hope to discuss these reptiles in a general review of the group, which is approaching completion. This $tudy has been aided by a grant from the Penrose Fund of the Geological Society of America, and the present preliminary cliagnoses of the new types are published with the permission or the Society. Eothyris parkeyi gen. et spec. nov. Genoholotype, M.C.Z., 1161, (figured): a skull and jaws, found about one mile west of the former Woodrum ranch-house, $outh of Dundee, Archer County, Texas; horizon Belle Plains P.N.E.Z.C. ROMER--PELYCOSAURS [ pooember30] 90 Vol. XVI 1937 ROMER--PELYCOSA Formation, Wichita Group. A small primitive pelycosaur, the type skull about 65 mm. in length as preserved. The skull Lupeosaurus kayi gen. et sp' is relatively broad and low, and the face short, (although this appearance is increased by distortion and damage in the type); Genoholotype, M.C.Z., 1455, a preS8 the orbit and temporal region are relatively elongated. The and scapulocoracoid, found near the postorbital has a broad posterior expansion above the small Creek, Archer County, Texas; horizOI temporal vacuity. The parietal is very primitive, in extend­ Formation, Wichita Group. A pelycos ing far back of the pineal. The supra-temporal is relatively sembling Edaphosaurus in caudal verter large.
    [Show full text]
  • Xenacanthus (Chondrichthyes: Xenacanthiformes) from North America
    Acta Geologica Polonica, Vol. 49 (J 999), No.3, pp. 215-266 406 IU S UNES 0 I Dentitions of Late Palaeozoic Orthacanthus species and new species of ?Xenacanthus (Chondrichthyes: Xenacanthiformes) from North America GARY D. JOHNSON Department of Earth Sciences and Physics, University of South Dakota; 414 East Clark Street, Vermillion, SD 57069-2390, USA. E-mail: [email protected] ABSTRACT: JOHNSON, G.D. 1999. Dentitions of Late Palaeozoic Orthacanthus species and new species of ?Xenacanthus (Chondrichthyes: Xenacanthiformes) from North America. Acta Geologica Polonica, 49 (3),215-266. Warszawa. Orthacanthus lateral teeth have paired, variably divergent, smooth, usually carinated labio-lingually compressed principal cusps separated by a central foramen; one or more intermediate cusps; and an api­ cal button on the base isolated from the cusps. Several thousand isolated teeth from Texas Artinskian bulk samples are used to define the heterodont dentitions of O. texensis and O. platypternus. The O. tex­ ensis tooth base has a labio-Iingual width greater than the anteromedial-posterolateral length, the basal tubercle is restricted to the thick labial margin, the principal cusps are serrated to varying degrees, and the posterior cusp is larger. The O. platypternus tooth base is longer than wide, its basal tubercle extends to the center, the labial margin is thin, serrations are absent on the principal cusps, the anterior cusp is larger, and a single intermediate cusp is present. More than two hundred isolated teeth from Nebraska (Gzhelian) and Pennsylvania (Asselian) provide a preliminary description of the heterodont dentition of O. compress us . The principal cusps are similar to O.
    [Show full text]
  • Geology of the Cross Plains Quadrangle, Brown, Callahan Coleman, and Eastland Counties Texas
    Geology of the Cross Plains Quadrangle, Brown, Callahan Coleman, and Eastland Counties Texas GEOLOGICAL SURVEY BULLETIN 1096-B Prepared in cooperation with the Bureau of Economic Geology, The University of Texas Geology of the Cross Plains Quadrangle, Brown, Callahan Coleman, and Eastland Counties Texas By PHILIP T. STAFFORD PENNSYLVANIAN AND LOWER PERMIAN STRATIG­ RAPHY, BETWEEN THE BRAZOS AND COLORADO RIVERS, NORTH-CENTRAL TEXAS GEOLOGICAL SURVEY BULLETIN 1096-B Prepared in cooperation with the Bureau of Economic Geology, The University of Texas UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1960 UNITED STATES DEPARTMENT OF THE INTERIOR FRED A. SEATON, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.G. CONTENTS Page Abstract___ _____________________________________________________ 39 Introduction._____________________________________________________ 40 Location of area_______________________________________________ 40 Purpose ______________________________________________________ 40 Previous geologic studies. ______________________________________ 40 Acknowledgments _____________________________________________ 41 Methods of study____________________________________________ 42 Mapping and fieldwork___________________________________ 42 Descriptive terminology.__-____________-_____-___-_-_-_-___ 43 Stratigraphy. _____________________________________________________ 44 Pennsylvanian and Permian systems.____________________________
    [Show full text]
  • 30-Johnson (Xenacanth)
    Lucas, S.G., et al. eds., 2013, The Carboniferous-Permian Transition. New Mexico Museum of Natural History and Science, Bulletin 60. 161 XENACANTH SHARKS AND OTHER VERTEBRATES FROM THE GERALDINE BONEBED, LOWER PERMIAN OF TEXAS GARY D. JOHNSON Shuler Museum of Paleontology, Institute for the Study of Earth and Man, Southern Methodist University, PO Box 750274, Dallas, Texas 75275-0274; email: [email protected] Abstract—The Geraldine Bonebed occurs in the Nocona Formation (Wichita Group, Sakmarian age) in Texas. It has historically yielded a large number of mostly complete skeletons of four tetrapod taxa, for which it is famous, and also a diverse flora as well as other vertebrates. Bulk samples of matrix were recently screen-washed and sorted to produce a variety of vertebrate microfossils, including sharks, especially xenacanths. The non-xenacanth sharks are rare and include a petalodont tooth (Janassa?), Helodus sp. (4 teeth) and one partial hybodont tooth. These are all considerably more common higher in the Wichita Group. Only the petalodont and possibly the hybodont and Helodus represent a marine component in the fauna, but the marine faunas are more extensive higher in the Wichita. Also new to the fauna are acanthodians, actinopterygians, Cardiocephalus and Ophiacodon. Among the xenacanths are two typically small Xenacanthus sp. occipital spine fragments, two Orthacanthus sp. occipital spine frag- ments (one small, one very small) and hundreds of Orthacanthus teeth. Orthacanthus texensis teeth are much more common than O. platypternus teeth. Teeth of O. texensis and O. platypternus are comparable in size distributions, as determined by statistical analyses of the tooth-base measurements, to those higher in the Wichita Group.
    [Show full text]
  • Catalogueoftypes22brun.Pdf
    UNIVERSITY OF ILLINOIS LIBRARY AT URBANACHAMPAIGN GEOLOGY JUL 7 1995 NOTICE: Return or renew all Library Materials! The Minimum Fee for •adi Lost Book is $50.00. The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Thett, mutilation, and underlining of books are reasons for discipli- nary action and may result in dismissal from the University. To renew call Telephone Center, 333-8400 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN &S.19J6 L161—O-1096 'cuLUuy LIBRARY FIELDIANA Geology NEW SERIES, NO. 22 A Catalogue of Type Specimens of Fossil Vertebrates in the Field Museum of Natural History. Classes Amphibia, Reptilia, Aves, and Ichnites John Clay Bruner October 31, 1991 Publication 1430 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY Information for Contributors to Fieldiana General: Fieldiana is primarily a journal for Field Museum staff members and research associates, althouj. manuscripts from nonaffiliated authors may be considered as space permits. The Journal carries a page charge of $65.00 per printed page or fraction thereof. Payment of at least 50% of pag< charges qualifies a paper for expedited processing, which reduces the publication time. Contributions from staff, researcl associates, and invited authors will be considered for publication regardless of ability to pay page charges, however, the ful charge is mandatory for nonaffiliated authors of unsolicited manuscripts. Three complete copies of the text (including titl< page and abstract) and of the illustrations should be submitted (one original copy plus two review copies which may b machine-copies).
    [Show full text]
  • Occurrence, Availability, and Chemical Quality of Ground
    TEXAS DEPARTMENT OF WATER RESOURCES REPORT 269 OCCURRENCE, AVAILABILITY, AND CHEMICAL QUALITY OF GROUND WATER IN THE CRETACEOUS AQUIFERS OF NORTH-CENTRAL TEXAS VOLUME 1 Phillip L. Nordstrom, Geologist April 1982 TEXAS DEPARTMENT OF WATER RESOURCES Harvey Davis, Executive Director TEXAS WATER DEVELOPMENT BOARD Louis A. Beecherl Jr., Chairman John H. Garrett, Vice Chairman George W. McCleskey W. 0. Bankston Glen E. Roney Lonnie A. “Bo” Pilgrim TEXAS WATER COMMISSION Felix McDonald, Chairman Dorsey B. Hardeman, Commissioner Lee B. M. Biggart, Commissioner Authorization for use or reproduction of any original material contained in this publication, i.e., not obtained from other sources, is freely granted. The Department would appreciate acknowledgement. Published and distributed by the Texas Department of Water Resources Post Office Box 13087 Austin, Texas 78711 ii __ TABLE OF CONTENTS Page SUMMARY AND CONCLUSIONS . 1 INTRODUCTION . .. 3 Purpose and Scope . 3 Location and Extent . 3 Physiography . 3 Climate . 4 Population . 4 Economy . 4 Previous Investigations . 4 Acknowledgements . 7 Method of Investigation . 7 Well-Numbering System . 7 Metric Conversion . 8 GEOLOGY AS RELATED TO THE OCCURRENCE OF GROUND WATER . 9 Geologic History . 9 Paleozoic . 9 Cretaceous . 9 Tertiary and Quaternary . 9 General Stratigraphy . 9 Structure . 10 STRATIGRAPHY OF THE WATER-BEARING FORMATIONS . 12 Paleozoic Rocks . 12 Antlers . 13 iii TABLE OF CONTENTS – Continued Page Twin Mountain Formation . 13 Paluxy Formation . 14 Woodbine Group . 14 Blossom Sand . 15 Nacatoch Sand . 15 CHEMICAL QUALITY OF GROUND WATER AS RELATED TO USE . 15 General Chemical Quality of Ground Water . 15 Quality Criteria or Standards . 16 Municipal . 16 Primary Standards . 20 Secondary Standards .
    [Show full text]
  • 2005 Proceedings.Indd
    Proceedings of the South Dakota Academy of Science, Vol. 84 (2005) 215 UNDERDEVELOPED AND UNUSUAL XENACANTH SHARK TEETH FROM THE LOWER PERMIAN OF TEXAS Gary D. Johnson Department of Earth Sciences University of South Dakota Vermillion, SD 57069 ABSTRACT Xenacanth sharks from the Wichita and Clear Fork Groups in north-central Texas are represented by 51,400 isolated teeth, obtained by bulk-sampling sedi- ments at 65 localities, of Orthacanthus texensis (50% of total), O. platypternus (12%), Barbclabornia luedersensis (38%), and Xenacanthus slaughteri (0.01%) in Early Permian (late Sakmarian-Artinskian) strata spanning some 5 million years (285-280 Ma). Discounting deformed teeth (0.06%), which could usually be identified to species, there remain much more common underdeveloped teeth (1-2%?) and unusual teeth that are rare (<<0.1%). Teeth not fully developed, and presumably still within the dental groove when a shark died, lack the outer hypermineralized pallial dentine on the cusps, which display open pulp cavities; tooth bases possess a poorly developed apical button. Most could be assigned to the species of Orthacanthus, the remainder to B. luedersensis. Based on histologi- cal development in modern shark teeth, in which the base is last to develop, it would seem the reverse occurred in xenacanth teeth, but this conclusion is uncer- tain. Unusual teeth were most closely affiliated with Orthacanthus, but they pos- sess characters normally not associated with that genus, exceeding the presumed limits of variation that might be accepted for its heterodont dentition. Examples include teeth with cristated cusps, in which the distribution of cristae is highly asymmetrical; possession of a single cusp or of three equally developed principal cusps (two are normal in xenacanth teeth); and one tooth with a primary inter- mediate cusp that may have been larger than the principal cusps.
    [Show full text]
  • North-Central Texas, USA: Implications for Western Equatorial Pangean Palaeoclimate During Icehouse–Greenhouse Transition
    Sedimentology (2004) 51, 851–884 doi: 10.1111/j.1365-3091.2004.00655.x Morphology and distribution of fossil soils in the Permo-Pennsylvanian Wichita and Bowie Groups, north-central Texas, USA: implications for western equatorial Pangean palaeoclimate during icehouse–greenhouse transition NEIL JOHN TABOR* and ISABEL P. MONTAN˜ EZ *Department of Geological Sciences, Southern Methodist University, Dallas, TX 75275, USA (E-mail: [email protected]) Department of Geology, University of California, Davis, CA 95616, USA ABSTRACT Analysis of stacked Permo-Pennsylvanian palaeosols from north-central Texas documents the influence of palaeolandscape position on pedogenesis in aggradational depositional settings. Palaeosols of the Eastern shelf of the Midland basin exhibit stratigraphic trends in the distribution of soil horizons, structure, rooting density, clay mineralogy and colour that record long-term changes in soil-forming conditions driven by both local processes and regional climate. Palaeosols similar to modern histosols, ultisols, vertisols, inceptisols and entisols, all bearing morphological, mineralogical and chemical characteristics consistent with a tropical, humid climate, represent the Late Pennsylvanian suite of palaeosol orders. Palaeosols similar to modern alfisols, vertisols, inceptisols, aridisols and entisols preserve characteristics indicative of a drier and seasonal tropical climate throughout the Lower Permian strata. The changes in palaeosol morphology are interpreted as being a result of an overall climatic trend from relatively humid and tropical, moist conditions characterized by high rainfall in the Late Pennsylvanian to progressively drier, semi-arid to arid tropical climate characterized by seasonal rainfall in Early Permian time. Based on known Late Palaeozoic palaeogeography and current hypotheses for atmospheric circulation over western equatorial Pangea, the Pennsylvanian palaeosols in this study may be recording a climate that is the result of an orographic control over regional- scale atmospheric circulation.
    [Show full text]
  • Tectonic History of the Palo Duro Basin, Texas Panhandle
    OF-WTWI-1983-1 TECTONIC HISTORY OF THE PALO DURO BASIN, TEXAS PANHANDLE by Roy T. Budn; k Prepared for the U. S. Department of Energy Office of Nuclear Waste Isolation under contract no. DE-AC-97-83WM 46615 Bureau of Economic Geology W. L. Fisher, Director The University of Texas at Austin Un i ve rs i t Y Stat ion, P.O. Box X Austin, Texas 78712 , / ) ~' 3.3.2 TECTONIC HISTORY INTRODUCTION The Palo Duro Basin is one of a dozen or more intracratonic basins formed as a result of large-scale plate motions in the Late Paleozoic (Goldstein, 1981; Kluth and.Coney, 1981). The margins of the basin are defined by a series of uplifts that developed during the Pennsylvanian (fig. 1). The Palo Duro Basin is bounded on the northeast by the Amarillo-WiChita Uplift, on the northwest by the Bravo Dome, and on the west by the Sierra Grande and other smaller uplifts, all of which were imporant sources of sediment. To the south, the Matador Arch served as a sediment barrier and loci of carbonate buildups, as did a number of smaller, generally unnamed, uplifts to the east. The Palo Duro Basin includes sediments deposited in two temporally separate but spatially overlapping basins (Budnik and Smith, 1982). The initial basin, a northwest extension of the Hardeman Basin (fig. 2), formed as a result of the foundering of a Mississippian shelf during the latest Mississippian or early Pennsylvanian (Budnik and Smith, 1982; Dutton and others, 1982). Up to 2,500 ft (750 m) of Pennsylvanian and a similar thickness of Wolfcampian (Lower Permian), primarily marine, sediments were deposited during this phase (Dutton and others, 1982).
    [Show full text]