Origin of middle Silurian Keefer sandstone, east-central Appalachian basin

Conference · Mon Aug 01 04:00:00 EDT 1988 · AAPG Bull.; (United States)

OSTI ID:5791090

Meyer, S C; Textoris, D A; Dennison, J M

The Keefer Sandstone of northeastern West Virginia and western Maryland was deposited in back-barrier, barrier-island, and marine shelf environments along a prograding, storm-dominated, mesotidal coastline of probable low wave energy. Back-barrier sediments were deposited in tidal-flat and lagoonal environments. Barrier-island sediments are dominated by cross-bedded sandstones deposited in deep, laterally migrating tidal inlets. Erosion accompanying the passage of a migrating tidal inlet usually resulted in the removal of underyling shoreface and shelf sands, so that tidal-inlet sandstones commonly lie with a markedly erosive contact on subtidal shales of the underlying Rose Hill Formation. Sand was transported to the shelf from the coastline by downwelling, storm-generated currents. Chamosite ooids formed in gently agitated waters immediately below fair-weather wave base. Outcrops to the east, which preserve back-barrier and barrier-island lithofacies, record a single basinward progradation of the shoreline. However, outcrops farther west, which preserve finer grained sandstone, shale, and limestone shelf lithofacies, document four progradational events in stacked coarsening-upward sequences. Each is typically capped by transgressive sandstones, commonly hematite ooid-bearing, which mark episodes of coastal retreat. Retreat occurred through shoreface and nearshore erosion. Chamosite ooids were transported basinward during coastal retreat and altered to hematite prior to burial. Transgressive shelf sands contain abundant coarse sand eroded from tidal-inlet deposits. Deposition of the Keefer was a response to a decrease in rate of eustatic sea level rise, or a decrease in basin subsidence rate. This was followed by deposition of the transgressive basin facies of the Rochester Shale.

• Research Organization: Univ. of North Carolina, Chapel Hill (USA)
• OSTI ID: 5791090
• Report Number(s): CONF-8809345-
• Conference Information: Journal Name: AAPG Bull.; (United States) Journal Volume: 72:8
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
APPALACHIAN BASIN
DEPOSITION
FEDERAL REGION III
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
LEVELS
MARYLAND
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NORTH AMERICA
PALEOZOIC ERA
PETROLEUM DEPOSITS
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEA LEVEL
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SILURIAN PERIOD
USA
WEST VIRGINIA