Holocene sequence stratigraphy and sea level rise, south Florida margin

Conference · Mon Mar 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6119181

Locker, S D; Hine, A C; Toscano, M A ^[1]; Shinn, E A ^[2]

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1. Univ. of South Florida, St. Petersburg, FL (United States)
2. Geological Survey, St. Petersburg, FL (United States)

Fluctuation of late Quaternary sea level has been an important factor controlling erosional and depositional patterns on portions of the outer shelf and slope seaward of the lower-most Florida Keys. Studies in this area using high-resolution seismic, side scan sonar, bottom grab sampling, and submersible dives document a Holocene succession of lowstand wedge, transgressive, and highstand systems tract facies which have formed in response to sea level flooding the margin. The last lowstand of sea level is recorded by widespread scallop-like erosion along the slope front, occurring as deep as 150 m. Upslope from the erosional cuts, the transgressive systems tract includes a series of drowned shoreline (and reef) accumulations in the depth range 60--110 meters. Rocks recovered form paleoshorelines near 100 m water depth were submarine-cemented grainstones composed of early Holocene shallow-water carbonates. This transgressive section is partially buried by weakly laminated to reflection free fined-grained deposits of the highstand systems tract. These recent muddy silts reflect a sediment source initiated by flooding of the inner shelf platform and subsequent alongslope transport of fines exported offbank. Two very continuous, linear, and thin (< 5 m thick) paleoshorelines at 60--62 m and 66--68 m reflect a response to a change in rate of sea-level rise across a low gradient surface. The deeper shoreline deposits, ranging from 75--110 m below sea level are isolated features and occur on steeper slopes. The character of preserved transgressive deposits suggests the Holocene rate of rise is punctuated. The lowest stand of sea level produced distinctive erosional features. Accretional transgressive deposits formed during the sea-level rise. Interactions between antecedent topography, bottom currents, and changes in sediment supply, slope gradients, and rate of sea-level rise are key factors controlling facies patterns, accumulation rates, and depositional geometries.

• OSTI ID: 6119181
• Report Number(s): CONF-9304188-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:4; Conference: 42. annual Geological Society of America (GSA) Southeastern Section meeting, Tallahassee, FL (United States), 1-2 Apr 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONTINENTAL SHELF
STRATIGRAPHY
FLORIDA
QUATERNARY PERIOD
SEA LEVEL
ALLUVIAL DEPOSITS
EROSION
FLUCTUATIONS
GEOMORPHOLOGY
SAMPLING
SEISMIC SURVEYS
SONAR
CENOZOIC ERA
CONTINENTAL MARGIN
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
GEOPHYSICAL SURVEYS
LEVELS
MEASURING INSTRUMENTS
NORTH AMERICA
RANGE FINDERS
SURVEYS
USA
VARIATIONS
580000* - Geosciences