Bromide Formation
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| Bromide Formation | |
|---|---|
| Stratigraphic range: early Sandbian 461–458 | |
_4_(15402497771).jpg) | |
| 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]
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.
