Bromide Formation

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Bromide Formation
Stratigraphic range: early Sandbian 461–458 Myo
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Homotelus bromidensis fossil trilobites (Bromide Formation, Middle Ordovician; Criner Hills, southeastern Carter County, southern Oklahoma, USA) 4 (15402497771).jpg
Type Geological formation
Unit of Simpson Group
Sub-unitsMountain Lake Member, Pooleville Member
UnderliesViola Formation [1]
OverliesTulip Creek Formation [2]
Thickness71 meters (233 ft) Pooleville Member at type location. [3]
Lithology
Primary limestone
Otherlimestone interbedded with shale, and sandstone
Location
Coordinates 34°00′N97°00′W / 34.000°N 97.000°W / 34.000; -97.000
RegionCentral-South Oklahoma: Carter County, Johnston County, Murray County and Pontotoc County
Country United States of America
Extentfrom Blount to Decorah [4]
Type section
Named byUlrich, 1911

The Bromide Formation is a geological formation in Oklahoma, USA. It is well known for its diverse echinoderm and trilobite fossil fauna. [1]

Contents

Location

The Bromide Formation crops out in the Arbuckle and Wichita Mountains and in the Criner Hills of Southern Oklahoma. [4] It appears at the surface in particular within Carter, Johnston, Murray and Pontotoc counties (34.0° N, 97.0° W). [5]

Stratigraphy

The Bromide Formation is the uppermost part of the Simpson Group, and originates from the Upper Ordovician (early Sandbian). This mostly carbonate succession is divided into the Mountain Lake and overlying Pooleville members. [1] Although it primarily consists of limestone, limestone interbedded with shale, and sandstone, also occur. [6] The Bromide Formation is a shallow water marine sediment. [7]

Much of the Mountain Lake Member comprises meter-scale, deep ramp cycles that overlie a lowstand systems tract of sandstones and sandy crinoidal grainstones. Cycle tops are starved surfaces with irregular, mineralized hardgrounds. The Pooleville Member consists of an early highstand interval of shallow subtidal carbonates and late highstand peritidal carbonates (Corbin Ranch Submember). Down-ramp, the Pooleville is represented largely by centimeter-thick shales and interbedded lime mudstones. [1]

Economic use

The Bromide Formation has been a source of oil and gas, with exploration slightly north of the area where the formation is exposed.

4x2 1/2 cm of fossil sea floor, from the Bromide Formation. The dark brownish thallus to the left is the green algae Ischadites iowensis, on top of it and to the top of the picture is the pygidium and back part of the thorax of the Corynexochid trilobite Nanillaenus punctatus, to the right is the cephalon of the Harpetid trilobite Dolichoharpes reticulata Bromide Formation panorama.jpg
4×2½ cm of fossil sea floor, from the Bromide Formation. The dark brownish thallus to the left is the green algae Ischadites iowensis, on top of it and to the top of the picture is the pygidium and back part of the thorax of the Corynexochid trilobite Nanillaenus punctatus, to the right is the cephalon of the Harpetid trilobite Dolichoharpes reticulata

Origin

The Bromide Formation was deposited in a shallow, storm-dominated epeiric sea that extended over part of the Laurentia continent, in what is today Southern Oklahoma. The sea spread into an area that sunk into a rift, that ultimately did not endure, a so-called aulacogen. Lying approximately at 30° Southern latitude, a low-land desert bordered much of the shallow sea from where well-rounded quartz sand blew in. This now represents the sandstone at the base of the Bromide Formation. Eventually, sea level rise caused by subsidence drowned the borderlands cutting off the supply of sand, and now the shales and limestones of the Middle Bromide (upper Mountain Lake Member) accumulated on a broad ramp. Gradually – primarily echinoderm – skeletons build up a carbonate shelf. Further eustatic sea level rise (transgression) cut off the supply of virtually all sediments from land, and remains of carbonate-producing organisms began filling the basin. This now forms the limestone of the upper Bromide (Pooleville Member). Finally, a drop in sea level (regression) exposed the entire platform, and became a broad, nearly featureless, hot, semi-arid sabkha. [8]

Fossils

Fossils have been found in the Bromide Formation of green algae, sponges, corals, graptolites, lampshells, moss animals, trilobites, clam shrimps, molluscs, several groups of echinoderms, and teeth of jawless fish.

Green algae

Sponges

Corals

Graptolites

Lampshells

Chaulistomella magna is also known as Dinorthis subquadrata and Valcourea magna Chaulistomella magna brachial valve.jpg
Chaulistomella magna is also known as Dinorthis subquadrata and Valcourea magna
Hesperorthis sulcata Hesperorthis sulcata brachial.jpg
Hesperorthis sulcata
an Oxoplecia gouldi lampshell Oxoplecia gouldi lateral.jpg
an Oxoplecia gouldi lampshell
Schizambon perspinosum, 8 mm, used to be covered in hairthin long spines Schizambon perspinosum.jpg
Schizambon perspinosum, 8 mm, used to be covered in hairthin long spines
a Spirifer perlamellosus lampshell Spirifer perlamellosus 2 brachial valve.jpg
a Spirifer perlamellosus lampshell
Looking at the brachial valve of a Strophomena costellata Strophomena costellata brachial.jpg
Looking at the brachial valve of a Strophomena costellata

Moss animals

Arthropods

Trilobites

Clam shrimps

  • Bromidella reticulata [9]
  • Bythocypris cylindrica [9]
  • Cryptophyllus oboloides [9]
  • Dicranella bicornis [9]
  • Eridoconcha magna [9]
  • Eridoconcha simpsoni [9]
  • Eurychilina reticulata [9]
  • Eurychilina ventrosa [9]
  • Halliella labiosa [9]
  • Krausella arcuata [9]
  • Leperditella cf. deckeri [9]
  • Leperditella inflata [9]
  • Primitiopsis bassleri [9]
  • Schmidtella umbonata [9]
  • Ulrichia initialis [9]

Molluscs

Echinoderms

Sea urchins and sand dollars

  • Bromidechinus rimaporus (Pooleville Member) [14]

Edrioasteroids

Cystoids

Anthracocrinus primitivus Anthracocrinus primitivus.jpg
Anthracocrinus primitivus
  • Amygdalocystites tribranchiatus [9]
  • Anthracocrinus primitivus [9]
  • Cheirocrinus ardmorensis [9]
  • Cheirocrinus cf. loeblichi [9]
  • Echinoencrinites cf. ornatus [9]
  • Enoploura cf. papillata [9]
  • Eumorphocystus multiporata [9]
  • Glyptocytites loeblichae [9]
  • Glyptocytites logani [9]
  • Hesperocystus deckeri [9]
  • Myeinocytites natus [9]
    a Oklahomacystis tribrachiatus cystoid Oklahomacystis tribrachiatus normalized.jpg
    a Oklahomacystis tribrachiatus cystoid
  • Oklahomacystus tribranchiatus [12]
  • Pararchaeocrinus decoratus [9]
  • Platycystites bassleri [9]
  • Platycystites bromidensis [9]
  • Platycystites cristatus [9]
  • Platycystites fimbratus [9]
  • Platycystites levatus [9]
  • Pleurocystites watkinsi [9]
  • Quadrocystis graffhami [12]
  • Synclairocytis angulatus [9]
  • Synclairocytis sulphurensis [9]
  • Tanaocystis watkinsi [16]
  • Traskocrinus sp. [12]

Sea lilies

  • Annulocrinus ramifer [17]
  • Archaeocrinus subovalis [9]
  • Calceocrinus longifrons [17]
  • Carabocrinus treadwelli [9]
  • Euptychocrinus skopaios [12]
  • Hybocrinus crinerensis [9]
  • Hybocrinus nitidus [9]
  • Hybocrinus pyxidatus [9]
  • Palaeocrinus hudsoni [9]
  • Paracremacrinus laticardinalis [17]

Chordates

Teeth of jawless fish (conodonts)

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References

  1. 1 2 3 4 Carlucci J.R. and S.R. Westrop. Sequence Stratigraphy and Facies Architecture of the Bromide Formation (Upper Ordovician; Sandbian) of Oklahoma. 2009 Portland Geological Society of America Annual Meeting. Paper No. 36-5.
  2. ↑ Jones, R.H. The Middle-Upper Ordovician Simpson Group of the Permian Basin: Deposition, Diagenesis, and Reservoir Development
  3. 1 2 3 4 5 Fay, O. and A.A. Graffham. Biostratigraphic and paleontological studies. Echinoderm faunas from the Bromide Formation (Middle Ordovician) of Oklahoma: Lawrence, Kansas, University of Kansas Paleontological Institute Monograph 11 30-33 (1982)
  4. 1 2 Loeblich, A.R. jr. Bryozoa from the Ordovician Bromide Formation Oklahoma. Journal of Paleontology, 16-4 (1942)
  5. ↑ Amsden, T.W. Upper Bromide Formation and Viola Group (Middle and Upper Ordovician in Eastern Oklahoma). Part I – Welling-Fite-Corbin-Ranch-Strata. Oklahoma Geological Survey. Bulletin 132 (1983)
  6. ↑ Viola Limestone and Bromide Formation. Mineral Resources On-Line Spatial Data. U.S. Geological Survey
  7. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Bauer, J.A. Conodonts from the Bromide Formation (Middle Ordovician), South-Central Oklahoma. Journal of Paleontology 68-2 (1994).
  8. ↑ Longman, M.W. Deposition of the Bromide Formation, Arbuckle Mountains, Oklahoma: Ontogeny of an Ancient Carbonate Shelf. Oklahoma City Geological Society Volume, pp. 268-285 (1982).
  9. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 Amsden, T.W. Catalogue of Fossils from the Middle and Upper Ordovician of Oklahoma. Oklahoma Geological Survey, Circular 43. 1957
  10. ↑ Byrnes, J.G. Notes on the Nature and Environmental Significance of the Receptaculitaceae. Lethaia, Vol. 1, pp. 368-381 (1968)
  11. ↑ Rigby, J.K. and R.C. Gutschick. Two new Lower Paleozoic Hexactinellid Sponges from Utah and Oklahoma. Journal of Paleontology, 50-1, pp. 79-85 (1976)
  12. 1 2 3 4 5 6 7 8 9 10 Fossil collection of Geological Enterprises, Ardmore, OK, USA
  13. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Shaw, F.C. Simpson Group (Middle Ordovician) Trilobites of Oklahoma. Journal of Paleontology 48-5, Memoir 6, Part II (1974)
  14. ↑ Smith, A.B. and J.J. Savill. Bromidechinus, a new Ordovician echinozoan (Echinodermata), and its bearing on the early history of echinoids. Transactions of the Royal Society of Edinburgh: Earth Sciences 92, pp. 137-147 (2001)
  15. ↑ Fay, R.O.; Graffham, A.A.; Sprinkle, J. (1982). "Previous studies of Bromide echinoderms. Echinoderm faunas from the Bromide Formation (Middle Ordovician) of Oklahoma". University of Kansas Paleontological Institute Monograph. 11: 34–44.
  16. ↑ Klimetz, M.P. The Regents Earth Science and Regents Physics Web Resource for Students and Teachers
  17. 1 2 3 Brower, J.C. Calceocrinoids from the Bromide Formation (Middle Ordovician) of Southern Oklahoma. Oklahoma Geological Survey, Circular 78 (1977)
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