Model for carbonate deposition in an Epicontinental Bay
By mapping the distribution of correlative sediments across the north-central region of the Appalachian basin, a paleogeographic model has been generated for part of the Mississippian period. During the Chesterian, the upper Greenbrier Limestone was deposited in an embayment that extended northward into parts of West Virginia, Ohio, Pennsylvanian, and Maryland. The bay, only a few hundred kilometers wide, was surrounded by lowlands to the west and north, and deltaic sediments shed from nearby highlands diluted the easternmost facies. In the bay, several different shallow-water carbonate environments are distinguished. Muddy skeletal sand was deposited in the central part, which was characterized by normal marine circulation and salinity. This open-bay facies supported a moderately diverse fauna of forams, brachiopods, and mollusks. From the central facies to the bay margins, water depth decreased, circulation became more restricted, and salinity was slightly higher. A restricted-bay facies developed closer to shore, with sediment consisting of pelletal mud and scattered skeletal grains. Diversity was lower, and the fauna was composed primarily of forams and ostracodes. A tidal mud flat surrounded the embayment on all three sides where partly to totally dolomitized mud containing cryptalgal structures formed. Oolite shoals, present on the eastern side of the bay near its mouth, mark areas where tidal currents were concentrated. Eventually, the epicontinental sea flooded the small enclosed bay, replacing the shallow-water facies with an open-marine facies. The new environment supported a highly diverse fauna including crinoids, brachiopods, mollusks, forams, and ostracods.
- Research Organization:
- West Virginia Univ., Morgantown
- OSTI ID:
- 5377657
- Report Number(s):
- CONF-860624-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 70:5; Conference: American Association of Petroleum Geologists annual meeting, Atlanta, GA, USA, 15 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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