Regional analysis of the Lower Mississippian Maccrady Formation of the Central Appalachians: New evidence for Mississippian unconformity and tectonism

Conference · Fri Mar 01 00:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:7171069

Warne, A G ^[1]

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1. Univ. of North Carolina, Chapel Hill (United States)

The Lower Mississippian Maccrady Formation was the first salt and gypsum deposit to be commercially exploited in the United States. These thick commercial deposits are found in a limited area of southwestern Virginia, although thinner gypsum and anhydrites occur in the Maccrady Formation throughout much of southwestern Virginia and southern West Virginia. Thick Maccrady salt and gypsum deposits are the result of local, syndepositional subsidence, a change from humid to arid climate as the North American Plate drifted northward, and a eustatic sea level rise. Regional mapping of the Maccrady Formation and adjacent strata, which incorporated biostratigraphic information, more clearly demonstrates the presence of a regional unconformity at the top of the Maccrady Formation, and establishes the amount of missing strata at the hiatus. Topography on this unconformity is considered to control hydrocarbon accumulation in the overlying Big Lime. Important Appalachian hydrocarbon reservoirs occur immediately above (Big Lime) and below (Big Injun and Weir sands) the Maccrady Formation. Regional mapping indicates that intra-Mississippian tectonics were active before, during, and after Maccrady deposition, resulting in several local to intraregional uplifts in southwestern Virginia, eastern Kentucky, and central West Virginia. The uplifts are thought to be near vertical and basement controlled. Hydrocarbon production and potential exploration areas can be related to these uplifts. A major Mississippian uplifted are along Pine Mountain and as far east as Norton, Virginia, is thought to have been a barrier or sill that restricted normal seawater flow to the east, resulting in Maccrady evaporite deposition.

• OSTI ID: 7171069
• Report Number(s): CONF-910403-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 75:3; Conference: Annual meeting of the American Association of Petroleum Geologists (AAPG), Dallas, TX (United States), 7-10 Apr 1991; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
58 GEOSCIENCES
KENTUCKY
SALT DEPOSITS
PETROLEUM GEOLOGY
VIRGINIA
WEST VIRGINIA
CARBONIFEROUS PERIOD
EVAPORITES
EXPLORATION
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GYPSUM
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
MINERAL RESOURCES
MINERALS
NORTH AMERICA
PALEOZOIC ERA
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SULFATE MINERALS
USA
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration
580000 - Geosciences