Gasport Formation
Geologic formation in the United States and Canada
From Wikipedia, the free encyclopedia
The Gasport Formation is a geologic formation in the Appalachian Basin and Michigan Basin.[1] This is one of the reef formations separating the Appalachian Basin from the Michigan Basin and the Ohio Basin. It is a part of the Lockport Group of carbonates. It is the lowest and oldest formation within the Lockport. The Gasport is found in Michigan, New York, Ohio, and Pennsylvania. Outcrops are limited to the area around the Great Lakes. It is part of a large reef structure dating back to the Silurian period. Being part of the Lockport Group it is a feature of the Niagara Escarpment.[2]
- Pekin Member
- Gothic Hill Member
| Gasport Formation | |
|---|---|
| Stratigraphic range: Sheinwoodian ~ | |
| Type | Formation |
| Unit of | Lockport Group |
| Sub-units |
|
| Underlies | Goat Island Formation |
| Overlies | Clinton Group |
| Lithology | |
| Primary | Limestone, Dolomite |
| Other | Chert |
| Location | |
| Region | New York, Ohio, Pennsylvania, West Virginia, Ontario |
| Country | United States, Canada |
| Type section | |
| Named for | Gasport, New York |
| Named by | Brett C.E. |
Description
The Gasport represents a period of reef building with the upper Pekin Member containing large stromatolite structures.[3] The lower Gothic Hill Member contains bryozoans, corals, and crinoids. The upper Pekin Member is a dark grey argillaceous limestone. The texture of the member tends to be grainstone to wackestone.[4] Bioherms are common throughout this member. Many large structures can be observed in outcrops and quarries up to 25 feet tall and 100 eet in length. At its base there is an erosional disconformity contact with the underlying Clinton Group.