Shady Dolomite
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| Shady Dolomite | |
|---|---|
| Stratigraphic range: Cambrian Series 2: | |
| Type | Geological formation |
| Sub-units | Austinville, Patterson, and Ivanhoe Members |
| Underlies | Rome Formation, Elbrook Formation |
| Overlies | Weisner Quartzite, Chilhowee Group |
| Lithology | |
| Primary | Dolomite |
| Other | Limestone and Shale |
| Location | |
| Region | Appalachia and Southeastern United States |
| Type section | |
| Named for | Shady Valley, Tennessee, USA |
| Named by | Arthur Keith - 1903 |
| Country | United States |
The Shady Dolomite is a geologic formation composed of marine sedimentary rocks of early Cambrian age (Cambrian Series 2: 521-509 million years ago). It outcrops along the eastern margin of the Blue Ridge province in the southeastern United States and can be found in outcrops in the states of Alabama, Georgia, Tennessee, North Carolina, and Virginia. It can also be found in the subsurface of Kentucky, Ohio, and West Virginia. The Shady is predominantly composed of dolomite and limestone with lesser amounts of mudrock. It contains fossils of trilobites, archaeocyathids, algae, brachiopods, and echinoderms, along with the enigmatic fossil Salterella.[1][2][3][4][5][6] The Shady Dolomite was first described by Arthur Keith in 1903[7] and was named for exposures in the Shady Valley of Johnson County in the state of Tennessee. Near Austinville, Virginia, the Shady hosts ore deposits that have been mined extensively for lead and zinc ore.[8]
The Shady Dolomite was deposited on the margin of the paleocontinent of Laurentia. The rocks that make up the Shady represent sediment deposition on and around an ancient carbonate platform.[9][10][11]
The initial carbonate sedimentation of the Shady began on the southern shelf of Laurentia and formed on top of the siliciclastic sequence that now make up the rocks of the Chilhowee Group.[12] These carbonate sediments formed a carbonate ramp that over time developed into a rimmed carbonate shelf.[10][11]
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