A model for the sequence stratigraphy of carbonate ramp to rimmed-platform transitions developed from study of the Middle Cambrian of the S. Appalachians

Conference · Wed Jan 01 00:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5688887

Walker, K R; Srinivasan, K ^[1]

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1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences

Part of the Cambrian System in the S. Appalachians consists of six alternating limestone and shale formations (Conasauga Group). The shelf margin discussed here faced a shallower intracratonic shale basin to the west and northwest. Analysis of the Maryville Limestone along a depositional transect reveals that the shelf evolved from a carbonate ramp that sloped gently basinward to a flat-topped rimmed-platform fringed with steep slopes. The authors describe here the sequence stratigraphy of the ramp to platform transition. A process oriented approach has allowed them to define the sequences, sequence boundaries, and the stacking pattern of the Maryville Limestone, and also to develop a general model for ramp to a rimmed-platform development. The Maryville consists of a combination of aggradational, retrogradational, and progradational units. The stacking pattern is the result of variations in sedimentation rate, subsidence, and absolute sea-level change. Each of the dominantly carbonate units of the Conasauga represent a gradual transition from a ramp-like, shallow-water-to-basin transition into a rimmed-platform. The transition between the Maryville Limestone (M. Cambrian) and the overlying Nolichucky Shale (U. Cambrian) is a sequence boundary. This boundary is both an exposure surface and a drowning unconformity and represents a distinct shift in the pattern of sedimentation. It marks the termination of shallow-water carbonate deposition because of exposure, followed by drowning with continued subsidence during lag time slow sedimentation, and, finally, onlap of basinal siliciclastics onto the old rimmed-platform edge as the sedimentation surface gradually deepened. The model developed here can serve as a useful process analog to other lower Paleozoic and possibly younger passive-margin sequences.

• OSTI ID: 5688887
• Report Number(s): CONF-921058-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
APPALACHIAN BASIN
GEOLOGIC MODELS
STRATIGRAPHY
BOUNDARY CONDITIONS
CAMBRIAN PERIOD
CARBONATE ROCKS
FLUCTUATIONS
GEOLOGIC HISTORY
GEOLOGIC STRATA
GROUND SUBSIDENCE
ORIGIN
SEA LEVEL
SEDIMENTATION
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
LEVELS
PALEOZOIC ERA
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
VARIATIONS
580000* - Geosciences