Evolution of Cambrian-Ordovician carbonate shelf, US Appalachians

Conference · Tue Jan 01 00:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6198192

Read, J F

Newly compiled cross sections and isopach maps of the Cambro-Ordovician continental shelf, U.S. Appalachians shows that thickness and facies trends are controlled by the Adirondack, New Jersey and Virginia and Alabama arches, and depocenters in Tennessee, Pennsylvania and the Rome Trough. Carbonate sedimentation was initiated with drowning of Early Cambrian clastics, deposition of carbonate ramp facies followed by drowning, regional regression and deposition of Early to Middle Cambrian red beds and platform margin rimmed shelf lime sands and reefs. During subsequent regional transgression the Conasauga intrashelf shale basin formed, bounded toward the shelf edge and along depositional strike by Middle to Upper Cambrian oolitic ramp facies and cyclic peritidal carbonates. During Middle Cambrian rifting, the Rome Trough was filled by thick clastics and carbonates. Intrashelf basin filling and regional regression caused progradation of Late Cambrian cyclic carbonates and clastics across the shelf. By this time, the margin had a relief of 2.5 kms. During the Early Ordovician, incipient drowning of the shelf formed subtidal carbonates and bioherms that passed up into cyclic carbonates which grade seaward into lime sands and reefs. Numerous unconformities interrupt this sequence in the Northern Appalachians. Early dolomitization patterns were controlled by regional highs. Subsidence rates on the margin were low (4 cm/1000 yrs) and typical of a mature passive margin. Shelf sedimentation in the Southern Appalachians ceased with arc-continent collision and development of the Knox unconformity, which dies out into the Pennsylvania depocenter.

• Research Organization: Virginia Tech, Blacksburg (USA)
• OSTI ID: 6198192
• Report Number(s): CONF-8510489-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONTINENTAL SHELF
GEOLOGIC HISTORY
STRATIGRAPHY
TECTONICS
USA
APPALACHIAN MOUNTAINS
CAMBRIAN PERIOD
CARBONATE ROCKS
DEPOSITION
ORDOVICIAN PERIOD
SEDIMENTARY BASINS
CONTINENTAL MARGIN
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
MOUNTAINS
NORTH AMERICA
PALEOZOIC ERA
ROCKS
SEDIMENTARY ROCKS
580201* - Geophysics- Seismology & Tectonics- (1980-1989)
580100 - Geology & Hydrology- (-1989)