Omaha Dome

Location

Northwestern Gallatin County (J-7)

References

Cady et al. 1939, English and Grogan 1948, Pullen 1951, Swann 1951, Clegg and Bradbury 1956, Bradbury 1962, Bristol 1975

Description

Omaha Dorne is a nearly circular, symmetrical uplift that is 3 to 4 miles (4.8-6.4 km) in diameter and centered in Section 4, T8S, R8E, in Gallatin County. Bristol (1975) mapped structural closure of 160 feet (48 m) on the Brereton Limestone Member Just above the Herrin Coal Member), 200 feet (60 m) on the base of the Kinkaid Limestone, and at least 150 feet (45 m) on the base of the Beech Creek ("Barlow") Limestone. Current Beech Creek maps (ISGS open files) indicate about 200 feet (60 m) of closure. Drilling on the structure has shown doming to be caused by a series of igneous sills or laccoliths intruded into shales of the New Albany Group and younger strata. Units below the New Albany are not domed (Stevenson et al. 1981). The igneous rock is peridotite or lamprophyre and probably is related to the Early Permian ultramafic intrusions found around Hicks Dome and in the Cottage Grove Fault System. Nearly 7 million barrels of oil have been produced from Pennsylvanian, Chesterian, and Ste. Genevieve pay zones on the Omaha Dome.

See also DES PLAINES DISTURBANCE, GLASFORD STRUCTURE, and HICKS DOME.