Impact of sea level rise on the sedimentology and stratigraphy of estuarine systems

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5953401

Ward, R F; Kearney, M S

Drowned-river valley estuaries are characteristic features of trailing-edge continental margins, as exemplified by the United States Atlantic Coast. During marine transgressions, the classic cycle of estuarine development is one of initial submergence and subsequent infilling, with the latter stages marked by extensive accumulations of fine-grained sediments in expanding marshes, deltas, and floodplains. Seismic surveys, vibracoring, and radiocarbon dating in the estuarine tributaries in middle Chesapeake Bay (The largest estuary along the Atlantic Coast), indicate that thick accumulations (>25 m) of organic-rich fine-grained sediments have been deposited since the middle Holocene. However, studies of recent accretion rate (based on pollen and radionuclide analyses) suggest the marshes, which represent a near-end member of the estuarine depositional sequence, may no longer be accumulating significant volumes of sediment. Relatively rapid crustal subsidence plus eustatic sea level rise produces a local submergence of approx. 4 mm/yr. Although marsh accretion rates in the upper estuarine tributaries approach 1 cm/yr, marsh accretion rates in the middle and lower reaches are significantly less (<2 mm/yr) than submergence. Here, numerous marshes are converting to open water as they become increasingly flooded by the tides. This change in depositional regime is also reflected in the carbon content (decreasing) and grain size (coarsening) of the marsh sediments and tidal channel migrations. In the coming decades, the rate of the world sea level rise is projected to increase significantly. This acceleration in the global eustatic trend together with lower sediment inputs from surrounding watersheds may reverse the historic trend of estuarine infilling.

• OSTI ID: 5953401
• Report Number(s): CONF-880301-
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
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03 NATURAL GAS
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AGE ESTIMATION
ATLANTIC OCEAN
BAYS
CHESAPEAKE BAY
COASTAL REGIONS
CONTINENTAL MARGIN
DEPOSITION
ESTUARIES
EXPLORATION
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGY
ISOTOPE DATING
LEVELS
MINERAL RESOURCES
NATURAL GAS DEPOSITS
OCEANOGRAPHY
PALYNOLOGY
PETROLEUM DEPOSITS
PETROLEUM GEOLOGY
RESOURCES
RIVER DELTAS
SEA LEVEL
SEAS
SEDIMENTATION
STRATIGRAPHY
SURFACE WATERS
TIDE