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- Permanent Link:
- http://dpanther.fiu.edu/dpService/dpPurlService/purl/FI15061883/00001
Material Information
- Title:
- Sedimentary Evidence of Coastal Response to Holocene Sea-Level Change, Blackwater Bay, Southwest Florida
- Creator:
- Lowery, Lily E.
- Publication Date:
- 2009
- Language:
- English
Notes
- Abstract:
- Studies of Holocene coastal sedimentary
sequences in southwest Florida have provided
important clues in determining coastal
response to sea-level changes (Parkinson,
1989; Wanless et al., 1994). Much of the
southwest Florida coast is a mangrovedominated
estuarine system with chains of
mangrove-capped oyster bars that provide a
barrier between the bay and open marine
influences. This low energy, low relief system
provides an ideal environment for the
deposition and preservation of sedimentary
sequences that record relative sea-level
fluctuations. The mangrove fringe is a major
control on shoreline facies, as reported by
Davis (1940) and summarized by Parkinson
(1989), sometimes resulting in local shoreline
changes in opposition to regional trends. In an
early study of the southwest Florida coastal
system, Davis (1940) described the
sedimentation processes specific to mangrove
dominated systems: the trapping of sediment
results in rapid aggradation of peat,
progradation of the shoreline, and local marine
regression in a rising regional system
(Parkinson, 1989). Conversely, mangrove
control in these systems can actually allow the
opposite effect, when the destruction of the
vegetation in a storm or period of storm events
causes shoreline retreat and a punctuated rise
in relative sea level (Wanless et al., 1994).
Initial studies of sedimentary sequences in
southwest Florida (Davis, 1940) documented
coastal submergence during relative sea-level
rise. Later studies (Scholl et al., 1967, 1969)
created a submergence curve for southwest
Florida for the last 7000 years that delineated
continual, but decelerating rise in sea level,which was later modified (Wanless et al.,
1994) to assign specific rates of rise and dates
of changes in rate (Figure 1). More recent
work in the Everglades and Ten Thousand
Islands regions presents a two-phase relative
sea-level model within the decelerating
eustatic system, consisting of (1) transgression
with rapid eustatic rise, followed by (2)
regression beginning at approximately 3200
y.b.p. as sea-level rise slowed and biogenic
sedimentation kept pace with or outpaced
eustatic rise (Parkinson,1987,1989).
During June, 2001, a northeast/southwest
transect of four sediment cores was taken,
roughly perpendicular to the shoreline across
Blackwater Bay (Figure 2) using a vibracore mounted on a pontoon boat. Coring recovered
the entire Holocene sequence (units B, C, D in
Figure 3), in addition to upper Pleistocene
sediments (unit A), with negligible loss and
little compaction. Preliminary descriptive
analysis was performed with open cores
during the summer, and subsequent lab
analysis determined percent carbonate, organic
content, and grain size.
Based on these cores from Blackwater Bay,
we believe that this portion of the southwest
Florida shoreline has experienced three major
phases of relative sea-level change during the
Holocene eustatic rise: (1) transgression, (2)
regression with accumulation of thick peat
sequences, and (3) a return to transgression. ( English )
Record Information
- Source Institution:
- Florida International University
- Rights Management:
- Please contact the owning institution for licensing and permissions. It is the user's responsibility to ensure use does not violate any third party rights.
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