DOCSLIB.ORG

Ferrous Carbonate Concretions Below Bleached Sandstone

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Ferrous Carbonate Concretions Below Bleached Sandstone Concretions, bleaching, and CO2-driven fl ow The footprints of ancient CO2-driven fl ow systems: Ferrous carbonate concretions below bleached sandstone David B. Loope* and Richard M. Kettler Department of Earth and Atmospheric Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA ABSTRACT the vadose zone. Absolute dating of differ- In this paper, we present a conceptual model ent portions of these widespread concretions for bleaching of the sandstone and the down- Iron-rich carbonates and the oxidized could thus reveal uplift rates for a large por- ward transport of iron from the source rock remains of former carbonates (iron-oxide tion of the Plateau. Iron-rich masses in other to the geochemical trap where concretions concretions) underlie bleached Navajo Sand- sedimentary rocks may reveal fl ow systems nucleated and grew. First, we will describe stone over large portions of southern Utah. with similar histories. and interpret a variety of iron-rich concre- Iron in the carbonates came from hematite tions. Some still contain carbonate minerals rims on sand grains in the upper Navajo INTRODUCTION and some do not, but we argue below that all that were dissolved when small quantities originated as reduced-iron carbonates. The of methane accumulated beneath the seal- Over a broad portion of the Colorado Pla- bleached rocks are striking evidence for a ing Carmel Formation. As a second buoyant teau of southwestern United States, the Jurassic large-scale fl ow system (Beitler et al., 2005; gas (CO2 derived from Oligocene–Miocene Navajo Sandstone contains a wide variety of Chan et al., 2005). We claim that the concre- magmas ) reached the seal and migrated up iron-oxide–cemented masses. Here we explain tions reveal the changing composition, source, dip, it dissolved in the underlying water, why these structures are found down section oxidation state, and migration direction of the enhancing the solution’s density. This water and down dip from bleached sandstone. When fl uids in that system. carried the released ferrous iron and the carbon dioxide dissolves in an aqueous solu- In the Ladbroke Grove Gas Field (Otway methane downward. Carbonates precipi- tion, the density of that solution increases. This Basin, South Australia), the Cretaceous sand- tated when the descending, reducing water fact has huge implications for subsurface car- stone reservoir contains high levels of CO2 that degassed along fractures. The distribution of bon sequestration (Lindeberg and Wessel-Burg, was derived from a magmatic source (Watson a broad array of iron-rich features made rec- 1997; Ennis-King and Paterson, 2005; Mac- et al., 2004). In a nearby gas fi eld, the same ognition of the extent of the ancient fl ow sys- Minn and Juanes, 2013), and here we show that sandstone is not exposed to CO2-enhanced pore tems possible. Although siderite is not pre- it is essential to understanding iron diagenesis in waters. Analysis of cores shows that iron-rich served, dense, rhombic, mm-scale, iron-oxide the Navajo Sandstone. carbonate minerals are much more abundant pseudomorphs after ferrous carbonates are North of the Grand Canyon, in southern in the former reservoir than in the latter. These common. Distinctive patterns of iron oxide Utah’s Grand Staircase, the upper part of the pore-fi lling carbonates occur mostly as con- were also produced when large (cm-scale), Navajo Sandstone forms the White Cliffs and cretions 2–10 cm in diameter. The Ladbroke poikilotopic carbonate crystals with multi- the lower Navajo forms the upper part of the Grove Field is an excellent analog for geologi- ple iron-rich zones dissolved in oxidizing Vermillion Cliffs (Fig. 1). Mudrocks and evapo- cal storage of CO2 (Watson et al., 2004), and we waters. Rhombic pseudomorphs are found rites of the Middle Jurassic Carmel Formation argue here that—before it was exhumed during in the central cores of small spheroids and form an effective seal at the top of the Navajo. the Neogene—the Navajo Sandstone contained large (meter-scale), irregular concretions Previous workers have shown that the upper CO2, methane, and abundant, iron-rich carbon- that are defi ned by thick, tightly cemented Navajo was originally red and that the iron in ate concretions. rinds of iron-oxide–cemented sandstone. the concretions came from iron liberated dur- Ferrous iron, carbon dioxide, methane, The internal structure and distribution of ing the bleaching of the overlying rocks (Beitler and siderite have been widespread in the pore these features reveal their origins as iron- et al., 2005; Chan et al., 2005). We agree with waters of Earth’s sediments and sedimentary carbonate concretions that formed within a these conclusions, but they raise two previ- rocks for billions of years, but iron oxides have large-scale fl ow system that was altered dra- ously un answered questions: How, if the iron- been widespread on Earth only since the Early matically during Neogene uplift of the Colo- oxide concretions came from the bleached rocks Protero zoic. Recognition that iron-oxide masses rado Plateau. With rise of the Plateau, the above, was the iron moved down section and in the Navajo Sandstone had ferrous carbon- iron-carbonate concretions passed upward down dip? And, if the concretions formed as pri- ate precursors (Loope et al., 2010, 2011, 2012; from reducing formation water to shallow, mary precipitates from the mixing of reducing Kettler et al., 2011; Weber et al., 2012) and that oxidizing groundwater fl owing parallel to and oxidizing waters (Beitler et al., 2005; Chan those carbonates were emplaced by CO2-driven modern drainages. Finally they passed into et al., 2005), how was oxidizing water intro- fl ow systems should aid interpretation of other duced and maintained below the widespread iron-oxide accumulations on Earth and on *Corresponding author email: [email protected] reducing waters? other planets. Geosphere; June 2015; v. 11; no. 3; p. 1–15; doi:10.1130/GES01094.1; 12 fi gures; 1 table. Received 26 June 2014 ♦ Revision received 20 January 2015 ♦ Accepted 25 March 2015 ♦ Published online ___ Month 2015 For permissionGeosphere, to copy, contact June [email protected] 2015 1 © 2015 Geological Society of America Loope and Kettler ′ Tmv Miocene volcanics 30 miles N 38° 28 50 km Jna Jc N Tov Oligocene volcanics Tov Te Eocene lake beds 24 Jc Jurassic Carmel Fm pre-J Jna Jurassic Navajo SS A DF* qu study site ar ius 12 with former Pla ′ teau 12 road or preserved carbonates Tmv Circle Cliffs Uplift Escalante Anticline Proposed,Jna subsurface paleoflow paths of: 2 89 W 110° 54 mantle-derived CO2 (buoyant; up dip) * t CC Te l u water3 carrying CO2 (aq) a – 2+ F HCO CH 4 and Fe t 3 n 12 (high density; down dip) u Tov g u t l a s u a n F u 12 E * e a P n e a Jna c n i i - l r r mJ-K c u o H n Te * o DF White M mJ-K b Cliffs a b i Cliffs Jna a White K RG Sevier Fault Vermillion * Jc ″ 9 MN* WY Cliffs ZNP * 30 ′ ZT White Cliffs UT NV study WC area * Vermillion Jna BG CO W 113° 12 Vermillion Cliffs 59 89 * PC pre-J Cliffs * N 37° 00′ AZ Figure 1. Simplifi ed geologic map of southwestern Utah showing distribution of Mesozoic and Cenozoic rocks, major structures, locations of study sites, and postulated, subsurface paleofl ow paths of buoyant, supercritical CO2 and, in the eastern part of study area, paths of dense water carrying ferrous iron and aqueous CO2 (alter- native explanation for the eastern paths [black arrows] is hydrodynamic fl ow; Loope et al., 2010). Flow paths of dense waters in the western area are unknown. SH—Sand Hollow; RG—Russell Gulch; ZT—Zion Tunnel; 3LC—Three Lakes Canyon; MN—Mollie’s Nipple; BG—Buckskin Gulch; PC—Paria Canyon; CC—Calf Creek; E—Egypt; DF—Dry Fork. ZNP near southwest corner is Zion National Park. For generalized cross section of the Grand Staircase: http:// en .wikipedia .org /wiki /Grand _Staircase -Escalante _National _Monument #mediaviewer /File: Grand _Staircase -big .jpg. Previous Work primary precipitates formed during the mixing Study Area and Geologic Setting of iron-bearing, reducing waters and oxygen- Chan et al. (2000, 2005), Beitler et al. ated meteoric waters. This hypothesis guided This paper is based on fi eld observations and (2005), and Nielsen et al. (2009) carried out fi eld-based work (Potter and Chan, 2011), analyses of four different types of samples from extensive studies on both the bleaching of the bench experiments (Chan et al., 2007; Barge the Navajo Sandstone at ten localities (Fig. 1): Navajo Sandstone and the iron-oxide concre- et al., 2011), and iron isotope studies (Chan (1) rinded, iron-oxide–cemented concretions; tions within it. Nielsen et al. (2009) showed et al., 2006; Busigny and Dauphas, 2007). (2) sandstone with poikilotopic, iron-zoned that although the upper Navajo Sandstone is Loope et al. (2010, 2011, 2012) and Kettler ferroan calcite cement; (3) calcite concretions bleached in the southern part of Zion National et al. (2011) reinterpreted the concretions as the containing large, rhombic, iron-oxide pseudo- Park (and continuously for 100 km eastward; altered (oxidized) remains of precursor concre- morphs or iron-oxide accumulations along Fig. 1), bleaching does not extend to the north- tions cemented by ferrous carbonate minerals. cleavage planes; and (4) iron-oxide patterns western portion of Zion, where the Navajo Weber et al. (2012) presented evidence that preserved in non-calcareous sandstone. Three retains its early diagenetic, red color. Although iron-oxidizing microbes mediated the oxida- of our sites (Fig. 1) are down dip from the this color-transition zone is only ~2 km wide, tion of the carbonates.
Load more

Recommended publications
  • PRELUDE to SEVEN SLOTS: FILLING and SUBSEQUENT MODIFICATION of SEVEN BROAD CANYONS in the NAVAJO SANDSTONE, SOUTH-CENTRAL UTAH by David B
    PRELUDE TO SEVEN SLOTS: FILLING AND SUBSEQUENT MODIFICATION OF SEVEN BROAD CANYONS IN THE NAVAJO SANDSTONE, SOUTH-CENTRAL UTAH by David B. Loope1, Ronald J. Goble1, and Joel P. L. Johnson2 ABSTRACT Within a four square kilometer portion of Grand Staircase-Escalante National Monument, seven distinct slot canyons cut the Jurassic Navajo Sandstone. Four of the slots developed along separate reaches of a trunk stream (Dry Fork of Coyote Gulch), and three (including canyons locally known as “Peekaboo” and “Spooky”) are at the distal ends of south-flowing tributary drainages. All these slot canyons are examples of epigenetic gorges—bedrock channel reaches shifted laterally from previous reach locations. The previous channels became filled with alluvium, allowing active channels to shift laterally in places and to subsequently re-incise through bedrock elsewhere. New evidence, based on optically stimulated luminescence (OSL) ages, indicates that this thick alluvium started to fill broad, pre-existing, bedrock canyons before 55,000 years ago, and that filling continued until at least 48,000 years ago. Streams start to fill their channels when sediment supply increases relative to stream power. The following conditions favored alluviation in the study area: (1) a cooler, wetter climate increased the rate of mass wasting along the Straight Cliffs (the headwaters of Dry Fork) and the rate of weathering of the broad outcrops of Navajo and Entrada Sandstone; (2) windier conditions increased the amount of eolian sand transport, perhaps destabilizing dunes and moving their stored sediment into stream channels; and (3) southward migration of the jet stream dimin- ished the frequency and severity of convective storms.
    [Show full text]
  • Ron Blakey, Publications (Does Not Include Abstracts)
    Ron Blakey, Publications (does not include abstracts) The publications listed below were mainly produced during my tenure as a member of the Geology Department at Northern Arizona University. Those after 2009 represent ongoing research as Professor Emeritus. (PDF) – A PDF is available for this paper. Send me an email and I'll attach to return email Blakey, R.C., 1973, Stratigraphy and origin of the Moenkopi Formation of southeastern Utah: Mountain Geologist, vol. 10, no. 1, p. 1 17. Blakey, R.C., 1974, Stratigraphic and depositional analysis of the Moenkopi Formation, Southeastern Utah: Utah Geological Survey Bulletin 104, 81 p. Blakey, R.C., 1977, Petroliferous lithosomes in the Moenkopi Formation, Southern Utah: Utah Geology, vol. 4, no. 2, p. 67 84. Blakey, R.C., 1979, Oil impregnated carbonate rocks of the Timpoweap Member Moenkopi Formation, Hurricane Cliffs area, Utah and Arizona: Utah Geology, vol. 6, no. 1, p. 45 54. Blakey, R.C., 1979, Stratigraphy of the Supai Group (Pennsylvanian Permian), Mogollon Rim, Arizona: in Carboniferous Stratigraphy of the Grand Canyon Country, northern Arizona and southern Nevada, Field Trip No. 13, Ninth International Congress of Carboniferous Stratigraphy and Geology, p. 89 109. Blakey, R.C., 1979, Lower Permian stratigraphy of the southern Colorado Plateau: in Four Corners Geological Society, Guidebook to the Permian of the Colorado Plateau, p. 115 129. (PDF) Blakey, R.C., 1980, Pennsylvanian and Early Permian paleogeography, southern Colorado Plateau and vicinity: in Paleozoic Paleogeography of west central United States, Rocky Mountain Section, Society of Economic Paleontologists and Mineralogists, p. 239 258. Blakey, R.C., Peterson, F., Caputo, M.V., Geesaman, R., and Voorhees, B., 1983, Paleogeography of Middle Jurassic continental, shoreline, and shallow marine sedimentation, southern Utah: Mesozoic PaleogeogÂraphy of west central United States, Rocky Mountain Section of Society of Economic Paleontologists and Mineralogists (Symposium), p.
    [Show full text]
  • Cyclicity, Dune Migration, and Wind Velocity in Lower Permian Eolian Strata, Manitou Springs, CO
    Cyclicity, Dune Migration, and Wind Velocity in Lower Permian Eolian Strata, Manitou Springs, CO by James Daniel Pike, B.S. A Thesis In Geology Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCES Approved Dustin E. Sweet Chair of Committee Tom M. Lehman Jeffery A. Lee Mark Sheridan Dean of the Graduate School August, 2017 Copyright 2017, James D. Pike Texas Tech University, James Daniel Pike, August 2017 ACKNOWLEDGMENTS I would like to extend my greatest thanks to my advisor Dr. Dustin Sweet, who was an excellent advisor during this research. Dr. Sweet was vital throughout the whole process, be it answering questions, giving feedback on figures, and imparting his extensive knowledge of the ancestral Rocky Mountains on me; for this I am extremely grateful. Dr. Sweet allowed me to conduct my own research without looking over my shoulder, but was always available when needed. When I needed a push, Dr. Sweet provided it. I would like to thank my committee memebers, Dr. Lee and Dr. Lehman for providing feedback and for their unique perspectives. I would like to thank Jenna Hessert, Trent Jackson, and Khaled Chowdhury for acting as my field assistants. Their help in taking measurements, collecting samples, recording GPS coordinates, and providing unique perspectives was invaluable. Thank you to Melanie Barnes for allowing me to use her lab, and putting up with the mess I made. This research was made possible by a grant provided by the Colorado Scientific Society, and a scholarship provided by East Texas Geological Society.
    [Show full text]
  • Distribution of Elements in Sedimentary Rocks of the Colorado Plateau a Preliminary Report
    Distribution of Elements in Sedimentary Rocks of the Colorado Plateau A Preliminary Report GEOLOGICAL SURVEY BULLETIN 1107-F Prepared on behalf of the U.S. Atomic Energy Commission Distribution of Elements in Sedimentary Rocks of the Colorado Plateau A Preliminary Report By WILLIAM L. NEWMAN CONTRIBUTIONS TO THE GEOLOGY OF URANIUM GEOLOGICAL SURVEY BULLETIN 1107-F Prepared on behalf of the U.S. Atomic Energy Commission UNITED STATES GOVERNMENT PRINTING OFFICE. WASHINGTON : 1962 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, 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____________________________-__-__-_---_-___-___ 337 Introduction ______________________________________________________ 339 Physical features of sedimentary rocks------_--__----_------------__- 339 Precambrian sedimentary rocks.________________________________ 341 Cambrian system____________________________________________ 342 Ordovician system..___________________________________________ 344 Devonian system._____________________________________________ 344 Mississippian system.._________________________________________ 346 Pennsylvanian system________________________________________ 346 Permian system _______________________________________________ 349 Triassic system______________________________________________ 352 Moenkopi formation _______________________________________ 352 Chinle formation..._______________________________________
    [Show full text]
  • Geology and Stratigraphy Column
    Capitol Reef National Park National Park Service U.S. Department of the Interior Geology “Geology knows no such word as forever.” —Wallace Stegner Capitol Reef National Park’s geologic story reveals a nearly complete set of Mesozoic-era sedimentary layers. For 200 million years, rock layers formed at or near sea level. About 75-35 million years ago tectonic forces uplifted them, forming the Waterpocket Fold. Forces of erosion have been sculpting this spectacular landscape ever since. Deposition If you could travel in time and visit Capitol Visiting Capitol Reef 180 million years ago, Reef 245 million years ago, you would not when the Navajo Sandstone was deposited, recognize the landscape. Imagine a coastal you would have been surrounded by a giant park, with beaches and tidal flats; the water sand sea, the largest in Earth’s history. In this moves in and out gently, shaping ripple marks hot, dry climate, wind blew over sand dunes, in the wet sand. This is the environment creating large, sweeping crossbeds now in which the sediments of the Moenkopi preserved in the sandstone of Capitol Dome Formation were deposited. and Fern’s Nipple. Now jump ahead 20 million years, to 225 All the sedimentary rock layers were laid million years ago. The tidal flats are gone and down at or near sea level. Younger layers were the climate supports a tropical jungle, filled deposited on top of older layers. The Moenkopi with swamps, primitive trees, and giant ferns. is the oldest layer visible from the visitor center, The water is stagnant and a humid breeze with the younger Chinle Formation above it.
    [Show full text]
  • Schmitz, M. D. 2000. Appendix 2: Radioisotopic Ages Used In
    Appendix 2 Radioisotopic ages used in GTS2020 M.D. SCHMITZ 1285 1286 Appendix 2 GTS GTS Sample Locality Lat-Long Lithostratigraphy Age 6 2s 6 2s Age Type 2020 2012 (Ma) analytical total ID ID Period Epoch Age Quaternary À not compiled Neogene À not compiled Pliocene Miocene Paleogene Oligocene Chattian Pg36 biotite-rich layer; PAC- Pieve d’Accinelli section, 43 35040.41vN, Scaglia Cinerea Fm, 42.3 m above base of 26.57 0.02 0.04 206Pb/238U B2 northeastern Apennines, Italy 12 29034.16vE section Rupelian Pg35 Pg20 biotite-rich layer; MCA- Monte Cagnero section (Chattian 43 38047.81vN, Scaglia Cinerea Fm, 145.8 m above base 31.41 0.03 0.04 206Pb/238U 145.8, equivalent to GSSP), northeastern Apennines, Italy 12 28003.83vE of section MCA/84-3 Pg34 biotite-rich layer; MCA- Monte Cagnero section (Chattian 43 38047.81vN, Scaglia Cinerea Fm, 142.8 m above base 31.72 0.02 0.04 206Pb/238U 142.8 GSSP), northeastern Apennines, Italy 12 28003.83vE of section Eocene Priabonian Pg33 Pg19 biotite-rich layer; MASS- Massignano (Oligocene GSSP), near 43.5328 N, Scaglia Cinerea Fm, 14.7 m above base of 34.50 0.04 0.05 206Pb/238U 14.7, equivalent to Ancona, northeastern Apennines, 13.6011 E section MAS/86-14.7 Italy Pg32 biotite-rich layer; MASS- Massignano (Oligocene GSSP), near 43.5328 N, Scaglia Cinerea Fm, 12.9 m above base of 34.68 0.04 0.06 206Pb/238U 12.9 Ancona, northeastern Apennines, 13.6011 E section Italy Pg31 Pg18 biotite-rich layer; MASS- Massignano (Oligocene GSSP), near 43.5328 N, Scaglia Cinerea Fm, 12.7 m above base of 34.72 0.02 0.04 206Pb/238U
    [Show full text]
  • Lexique Stratigraphique Canadien - Volume V-B - Region Des Appalaches, Des Basses-Terres Du Saint-Laurent Et Des Iles De La Madeleine Lexique Stratigraphique
    DV 91-23 LEXIQUE STRATIGRAPHIQUE CANADIEN - VOLUME V-B - REGION DES APPALACHES, DES BASSES-TERRES DU SAINT-LAURENT ET DES ILES DE LA MADELEINE LEXIQUE STRATIGRAPHIQUE CANADIEN Volume Fa Région des Appalaches, des Basses-Terres du Saint-Laurent et des îles de la Madeleine par Yvon Globensky et collaborateurs 1993 Québec ©© LEXIQUE STRATIGRAPHIQUE CANADIEN Volume r-8 Région des Appalaches, des Basses-Terres du Saint-Laurent et des Îles de la Madeleine par Yvon Globensky et collaborateurs DV 91-23 1993 Quebec ®® DIRECTION GÉNÉRALE DE L'EXPLORATION GÉOLOGIQUE ET MINÉRALE Sous-ministre adjoint: R.Y. Lamarche DIRECTION DE LA RECHERCHE GÉOLOGIQUE Directeur: A. Simard, par intérim SERVICE GÉOLOGIQUE DE QUÉBEC Chef: J.-M. Charbonneau Manuscrit soumis le: 30-01-91 Accepté pour publication le: 14-06-91 Lecteur critique J. Béland Édition Géomines / F. Dompierre Préparé par la Division de l'édition (Service de la géoinformation, DGEGM) Couvert 1: 1) Paucicrura rogata et Platystrophia amoena. Membre de Rosemont. Au SW de Saint-Jean-sur-Richelieu. Photo: tirée de Globensky, 1981b, page 39 2) Formation de Solomon's Corner. Saint-Armand-Station. Photo: tirée de Globensky, 1981b, page 126 3) Faciès de Terrebonne, formation de Tétreauville. Rivière L'Assomption. Photo: Y. Globensky 4) Formation de Covey Hill. Coupe à l'extrémité NW du lac Gulf, à l'ouest de Covey Hill. Photo: tirée de Globensky, 1986, page 9 Couvert 4: 1) Formation d'Indian Point. Péninsule de Forillon. Photo: D. Brisebois 2) Coupe type de la Formation de Wallace Creek. Étang Streit, près de Philipsburg. Photo: tirée de Globensky, 1981b, page 101 3) Euomphalopsis sp.
    [Show full text]
  • Stratigraphic Correlation Chart for Western Colorado and Northwestern New Mexico
    New Mexico Geological Society Guidebook, 32nd Field Conference, Western Slope Colorado, 1981 75 STRATIGRAPHIC CORRELATION CHART FOR WESTERN COLORADO AND NORTHWESTERN NEW MEXICO M. E. MacLACHLAN U.S. Geological Survey Denver, Colorado 80225 INTRODUCTION De Chelly Sandstone (or De Chelly Sandstone Member of the The stratigraphic nomenclature applied in various parts of west- Cutler Formation) of the west side of the basin is thought to ern Colorado, northwestern New Mexico, and a small part of east- correlate with the Glorieta Sandstone of the south side of the central Utah is summarized in the accompanying chart (fig. 1). The basin. locations of the areas, indicated by letters, are shown on the index map (fig. 2). Sources of information used in compiling the chart are Cols. B.-C. shown by numbers in brackets beneath the headings for the col- Age determinations on the Hinsdale Formation in parts of the umns. The numbers are keyed to references in an accompanying volcanic field range from 4.7 to 23.4 m.y. on basalts and 4.8 to list. Ages where known are shown by numbers in parentheses in 22.4 m.y. on rhyolites (Lipman, 1975, p. 6, p. 90-100). millions of years after the rock name or in parentheses on the line The early intermediate-composition volcanics and related rocks separating two chronostratigraphic units. include several named units of limited areal extent, but of simi- No Quaternary rocks nor small igneous bodies, such as dikes, lar age and petrology—the West Elk Breccia at Powderhorn; the have been included on this chart.
    [Show full text]
  • Mesozoic Stratigraphy at Durango, Colorado
    160 New Mexico Geological Society, 56th Field Conference Guidebook, Geology of the Chama Basin, 2005, p. 160-169. LUCAS AND HECKERT MESOZOIC STRATIGRAPHY AT DURANGO, COLORADO SPENCER G. LUCAS AND ANDREW B. HECKERT New Mexico Museum of Natural History and Science, 1801 Mountain Rd. NW, Albuquerque, NM 87104 ABSTRACT.—A nearly 3-km-thick section of Mesozoic sedimentary rocks is exposed at Durango, Colorado. This section con- sists of Upper Triassic, Middle-Upper Jurassic and Cretaceous strata that well record the geological history of southwestern Colorado during much of the Mesozoic. At Durango, Upper Triassic strata of the Chinle Group are ~ 300 m of red beds deposited in mostly fluvial paleoenvironments. Overlying Middle-Upper Jurassic strata of the San Rafael Group are ~ 300 m thick and consist of eolian sandstone, salina limestone and siltstone/sandstone deposited on an arid coastal plain. The Upper Jurassic Morrison Formation is ~ 187 m thick and consists of sandstone and mudstone deposited in fluvial environments. The only Lower Cretaceous strata at Durango are fluvial sandstone and conglomerate of the Burro Canyon Formation. Most of the overlying Upper Cretaceous section (Dakota, Mancos, Mesaverde, Lewis, Fruitland and Kirtland units) represents deposition in and along the western margin of the Western Interior seaway during Cenomanian-Campanian time. Volcaniclastic strata of the overlying McDermott Formation are the youngest Mesozoic strata at Durango. INTRODUCTION Durango, Colorado, sits in the Animas River Valley on the northern flank of the San Juan Basin and in the southern foothills of the San Juan and La Plata Mountains. Beginning at the northern end of the city, and extending to the southern end of town (from north of Animas City Mountain to just south of Smelter Moun- tain), the Animas River cuts in an essentially downdip direction through a homoclinal Mesozoic section of sedimentary rocks about 3 km thick (Figs.
    [Show full text]
  • Jurassic Navajo Sandstone, Glen Canyon National Recreation Area
    JurassicJurassic NavajoNavajo Sandstone,Sandstone, GlenGlen CanyonCanyon NationalNational RecreationRecreation AreaArea –– OutcropOutcrop AnalogAnalog forfor thethe JurassicJurassic NuggetNugget SandstoneSandstone Reservoir,Reservoir, ThrustThrust BeltBelt NAVAJO SANDSTONE OUTCROP CHARACTERISTICS Spectacular contorted bedding in Navajo Sandstone; south side of Antelope Island in Lake Powell. Location of reservoirs that produce oil (green) and gas and condensate (red) from the Jurassic Nugget Sandstone, Utah and Wyoming. The Index map to Glen Canyon National Recreation Area, Utah Nugget Sandstone play area is dotted. and Arizona (modified from Hintze, 1997; topographic relief base map modified with permission, courtesy of Navajo Sandstone beds display pronounced trough Chalk Butte, Inc., Boulder, Wyoming). cross-bedding which indicates the paleowinds NUGGET SANDSTONE RESERVOIR were from the north and northwest. CHARACTERISTICS • Net pay – 70 to 1000 ft (21-300 m) • Depositional environments – eolian dune (straight-crested to sinuous, coalescing, transverse barchanoid ridges), interdune/playa • Lithology – dune deposits = sandstone (fine- to coarse-grained, subangular to subrounded sand or silt grains cemented by calcite), interdune/playa = sandstone and siltstone with some carbonate (limestone and dolomite) and evaporite • Pore types – intergrainular, fractures • Porosity - averages 11-15%, enhanced by natural fracture systems • Permeability – less than 1 md to 50 md, averaging 18 md Typical limestone oasis deposit near the top of the Navajo Sandstone; Forgotten Canyon. Mudcracks in oasis limestone mud above bed Rapid pinch out of thin limestone bed; Moki Canyon. • Framework and matrix grains in sandstone (>1/16 mm and 1/16 to 1/256 containing ripple marks; Forgotten Canyon. mm, respectively) and siltstone are commonly composed of more than 90 percent quartz (usually frosted) with varying amounts of K-feldspar, plagioclase, and rock fragments Photomicrographs (crossed nicols) of Navajo Sandstone oasis deposits.
    [Show full text]
  • Diagenetic Coloration Facies and Alteration History of the Jurassic Navajo Sandstone, Zion National Park and Vicinity, Southwestern Utah
    DIAGENETIC COLORATION FACIES AND ALTERATION HISTORY OF THE JURASSIC NAVAJO SANDSTONE, ZION NATIONAL PARK AND VICINITY, SOUTHWESTERN UTAH Gregory B. Nielsen, Marjorie A. Chan, and Erich U. Petersen Department of Geology and Geophysics University of Utah 115 S. 1460 E., Rm. 383 FASB Salt Lake City, Utah 84112-0102 [email protected] [email protected] [email protected] ABSTRACT Coloration patterns in the Jurassic Navajo Sandstone of Zion National Park and vicinity are examined using a broad variety of geochemical, geospatial, petrographic, and bedform analysis techniques. Six diagenetic coloration facies (including 12 subfacies) are defined and characterized. Results indicate a prolonged and complex diagenetic history with variations in color resulting largely from changes in the concentration and distri- bution of iron oxides. In the northern Kolob Plateau, the Navajo Sandstone has a uniform red pigmentation (red primary facies) that formed during early diagenesis to produce the “primary” sandstone color. In contrast, Navajo Sandstone of main Zion Canyon displays “secondary” alteration features occurring in three distinct vertical coloration facies: brown (lower), pink (middle), and white (upper). The white and pink facies in Zion Canyon are characterized by a combination of prevalent bleaching, areas of remnant “primary” sandstone, and small concretionary iron-enriched lenses. Bleaching is concentrated in the upper Navajo Sandstone where alteration occurred during middle diagenesis (deep burial). Widespread bleaching and alteration in Zion Canyon terminates abruptly in the central park but narrow, well-defined, white bleached bands locally follow high-permeability beds northward for several kilometers into the red-colored Kolob Plateau (red/white facies). The brown facies is characterized by widespread dark iron oxide cement concentrations precipitated beneath a well-defined subhorizontal boundary.
    [Show full text]
  • Earliest Jurassic U-Pb Ages from Carbonate Deposits in the Navajo Sandstone, Southeastern Utah, USA Judith Totman Parrish1*, E
    https://doi.org/10.1130/G46338.1 Manuscript received 3 April 2019 Revised manuscript received 10 July 2019 Manuscript accepted 11 August 2019 © 2019 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Published online 4 September 2019 Earliest Jurassic U-Pb ages from carbonate deposits in the Navajo Sandstone, southeastern Utah, USA Judith Totman Parrish1*, E. Troy Rasbury2, Marjorie A. Chan3 and Stephen T. Hasiotis4 1 Department of Geological Sciences, University of Idaho, P.O. Box 443022, Moscow, Idaho 83844, USA 2 Department of Geosciences, Stony Brook University, Stony Brook, New York 11794, USA 3 Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Room 383, Salt Lake City, Utah 84112-0102, USA 4 Department of Geology, University of Kansas, 115 Lindley Hall, 1475 Jayhawk Boulevard, Lawrence, Kansas 66045-7594, USA ABSTRACT with the lower part of the Navajo Sandstone New uranium-lead (U-Pb) analyses of carbonate deposits in the Navajo Sandstone in across a broad region from southwestern Utah southeastern Utah (USA) yielded dates of 200.5 ± 1.5 Ma (earliest Jurassic, Hettangian Age) to northeastern Arizona (Blakey, 1989; Hassan and 195.0 ± 7.7 Ma (Early Jurassic, Sinemurian Age). These radioisotopic ages—the first re- et al., 2018). The Glen Canyon Group is under- ported from the Navajo erg and the oldest ages reported for this formation—are critical for lain by the Upper Triassic Chinle Formation, understanding Colorado Plateau stratigraphy because they demonstrate that initial Navajo which includes the Black Ledge sandstone (e.g., Sandstone deposition began just after the Triassic and that the base of the unit is strongly Blakey, 2008; Fig.
    [Show full text]