Silurian and Lower Devonian of southwestern Virginia
Thermal maturity of the Silurian and Lower Devonian rocks in Virginia west of New River decreases southwestward. Oil and gas shows are reported. The total thickness of Lower Devonian plus Silurian strata ranges from 52 to 1000 ft (16 to 305 m), with a maximum in Buchanan County. Sandstones were derived from sources southeast of the central Appalachian basin, some from lands southeast of the outcrop belt, and some formed by reworking of sandstones within the outcrop areas. Sandstones change northwestward to shales in the Clinch and Rose Hill Formations. In the Middle Silurian and Helderberg Group, sandstones grade northwestward to limestones. Limestones in the Hancock Formation change westward to dolomite. The Onesquethaw Stage is represented by sandstone, chert, and limestone assigned to the Wildcat Valley and Huntersville Formations. In the Middle Silurian (Keefer or Big Six sandstone) and Early Devonian (Wildcat Valley Sandstone), longshore currents carried sand across the southwest end of the basin toward Kentucky. Several regional unconformities are present. These unconformities are mostly related to sea level changes, but some are probably tectonic in origin. Five unconformities are significant: 1) at base of Silurian, 2) at base of upper Helderberg over much of the area, 3) at base of Oriskany Sandstone, 4) at base of Huntersville Formation, and 5) at base of Upper Devonian black shales in extreme western Virginia, where Chattanooga Shale overlies middle Devonian to Middle Silurian strata.
- Research Organization:
- Univ. of North Carolina, Chapel Hill
- OSTI ID:
- 5551021
- Report Number(s):
- CONF-8410269-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 68:12; Conference: AAPG Eastern Section meeting, Pittsburgh, PA, USA, 10 Oct 1984
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
02 PETROLEUM
03 NATURAL GAS
SEDIMENTARY ROCKS
GEOLOGIC HISTORY
STRATIGRAPHY
VIRGINIA
DEPOSITION
DEVONIAN PERIOD
GEOLOGIC FORMATIONS
LITHOLOGY
MATURATION
NATURAL GAS
PETROLEUM
SILURIAN PERIOD
ENERGY SOURCES
FEDERAL REGION III
FLUIDS
FOSSIL FUELS
FUEL GAS
FUELS
GAS FUELS
GASES
GEOLOGIC AGES
GEOLOGY
NORTH AMERICA
PALEOZOIC ERA
ROCKS
USA
580100* - Geology & Hydrology- (-1989)
020200 - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration