Graptolite biostratigraphy and depositional history of Middle Ordovician shales, southern Appalachians
Conference
·
· Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:5311140
Graptolite-bearing Middle Ordovician shales extend the length of the southern Appalachians in eastern thrust belts of the Valley and Ridge province. They directly overlie platform carbonates deposited on the continental shelf, and their initial deposition records subsidence of a foreland basin in response to the Taconic orogeny. Recent studies of graptolite biostratigraphy based on extensive collecting from numerous outcrops demonstrate that the base of the shales and, thus, initiation of tectonically induced subsidence are progressively older to the southeast. Oldest ages are recorded in the Coosa belt of Alabama and east-central Georgia, where the Athens Shale and Rockmart Slate extend down into the tentaculatus Zone. Because of similar age and lithology, the position of these outcrops defines depositional strike. To the northeast, this trend projects under the Cartersville thrust, suggesting that similar strata extend beneath the allochthonous Blue Ridge and Piedmont. To the northwest, basal shales from the Helena thrust belt of Alabama and from immediately west of the Blue Ridge thrust in northeast Tennessee and southwest Virginia correlate with the teretiusculus Zone. The outcrops are also interpreted to define depositional strike, which is overridden by the Blue Ridge thrust between Georgia and northeast Tennessee and in central Virginia. Farther northwest across depositional strike, basal graptolite shales correlate with the gracilis Zone. The oldest, easternmost shale outcrops correlate closely with shales in western Newfoundland that also record development of a foreland basin on the cratonic margin. Therefore, implications can be made about the pattern of initiation and progression of the Taconic orogeny.
- Research Organization:
- Oklahoma State Univ., Stillwater
- OSTI ID:
- 5311140
- Report Number(s):
- CONF-860624-
- Conference Information:
- Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:5
- Country of Publication:
- United States
- Language:
- English
Similar Records
Graphic correlation of middle Ordovician graptolite shale, southern Appalachians: An approach for examining the subsidence and migration of a Taconic foreland basin
Subsidence history of the Alabama promontory in response to Late Paleozoic Appalachian-Ouachita thrusting
Significance of integrating conodont, graptolite, and chitinozoan biostratigraphy in Middle Ordovician of southern and central Appalachians
Journal Article
·
Thu Feb 29 23:00:00 EST 1996
· Geological Society of America, Bulletin
·
OSTI ID:420908
Subsidence history of the Alabama promontory in response to Late Paleozoic Appalachian-Ouachita thrusting
Conference
·
Mon Feb 28 23:00:00 EST 1994
· Geological Society of America, Abstracts with Programs; (United States)
·
OSTI ID:7059493
Significance of integrating conodont, graptolite, and chitinozoan biostratigraphy in Middle Ordovician of southern and central Appalachians
Conference
·
Thu May 01 00:00:00 EDT 1986
· Am. Assoc. Pet. Geol., Bull.; (United States)
·
OSTI ID:5443510