Bromide Formation

Bromide Formation
Stratigraphic range: early Sandbian 461–458 Myo
Type Geological formation
Unit of Simpson Group
Sub-units Mountain Lake Member, Pooleville Member
Underlies Viola Formation[1]
Overlies Tulip Creek Formation[2]
Thickness 71 meters (233 ft) Pooleville Member at type location.[3]
Lithology
Primary limestone
Other limestone interbedded with shale, and sandstone
Location
Coordinates 34°00′N 97°00′W / 34.000°N 97.000°W
Region Central-South Oklahoma: Carter County, Johnston County, Murray County and Pontotoc County
Country United States of America
Extent from Blount to Decorah[4]
Type section
Named by Ulrich, 1911

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

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.

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. The animals we know from the fossil record from many well-known locations (including the Bromide Formation) can be viewed at a website that several paleontological institutions contributed to.[9]

green algae

sponges

corals

graptolites

lampshells

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

moss animals

arthropods

trilobites

clam shrimps

molluscs

echinoderms

sea urchins and sand dollars

edrioasteroids

cystoids

Anthracocrinus primitivus

sea lilies

chordates

teeth of jawless fish (conodonts)

References

  1. 1.0 1.1 1.2 1.3 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. 3.0 3.1 3.2 3.3 3.4 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. 4.0 4.1 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. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12 7.13 7.14 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. 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12 10.13 10.14 10.15 10.16 10.17 10.18 10.19 10.20 10.21 10.22 10.23 10.24 10.25 10.26 10.27 10.28 10.29 10.30 10.31 10.32 10.33 10.34 10.35 10.36 10.37 10.38 10.39 10.40 10.41 10.42 10.43 10.44 10.45 10.46 10.47 10.48 10.49 10.50 10.51 10.52 10.53 10.54 10.55 10.56 10.57 10.58 10.59 10.60 10.61 10.62 10.63 10.64 10.65 10.66 10.67 10.68 10.69 10.70 10.71 10.72 10.73 10.74 10.75 10.76 10.77 10.78 10.79 10.80 10.81 10.82 10.83 10.84 10.85 10.86 10.87 10.88 10.89 10.90 10.91 10.92 10.93 10.94 10.95 10.96 10.97 10.98 10.99 10.100 10.101 10.102 10.103 10.104 10.105 10.106 10.107 10.108 10.109 10.110 10.111 10.112 10.113 10.114 10.115 10.116 10.117 10.118 10.119 10.120 10.121 10.122 10.123 10.124 10.125 10.126 10.127 10.128 10.129 10.130 10.131 10.132 10.133 10.134 10.135 10.136 10.137 10.138 10.139 10.140 10.141 10.142 10.143 10.144 10.145 10.146 10.147 10.148 10.149 10.150 10.151 10.152 10.153 10.154 10.155 10.156 10.157 10.158 10.159 10.160 10.161 10.162 10.163 10.164 10.165 10.166 10.167 10.168 10.169 10.170 10.171 10.172 10.173 10.174 10.175 10.176 10.177 10.178 10.179 10.180 10.181 10.182 10.183 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. 13.0 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9 Fossil collection of Geological Enterprises, Ardmore, OK, USA
  13. 14.0 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 14.9 14.10 14.11 14.12 14.13 14.14 14.15 14.16 14.17 14.18 14.19 14.20 14.21 14.22 14.23 14.24 14.25 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. 18.0 18.1 18.2 Brower, J.C. Calceocrinoids from the Bromide Formation (Middle Ordovician) of Southern Oklahoma. Oklahoma Geological Survey, Circular 78 (1977)