Geology Reference
In-Depth Information
mid-Florida Platform semi-enclosed sub-basins, and
neither are fi lled in with siliciclastic sediments. As
a result, the 'dimpling' by coalescing karst basins
in the mid Florida Platform setting provides a pre-
viously unrecognized mechanism for the creation
of accommodation space sometimes resulting in
the apparent 'drowning' of a carbonate platform
by siliciclastics even though a signifi cant hiatus
occurs between the two depositional units.
sub-basins provides a previously unrecognized
mechanism for the creation of accommodation
that can result in the 'drowning' of a carbonate
platform by siliciclastics.
ACKNOWLEDGEMENTS
The Tampa Bay component of the study was
funded by the US Geological Survey (USGS)
Florida Integrated Science Center - Center for
Coastal and Watershed Studies in St Petersburg,
FL as part of the Tampa Bay Project; Dr Kim
Yates programme manager. We also thank Mark
Hansen, and Dana Wiese of the USGS for their
advice during this phase of the project. The
Charlotte Harbor component of the study was
supported by the USGS (Tampa Sub-district),
Florida Department of Environmental Regulation
and the South Florida Water Management District.
The Caloosahatchee River component of the study
was supported by the USGS through the South
Florida Water Management District. Dr C. Kerans,
UT-Austin, provided important insight concern-
ing ancient analogues. We thank Drs Don McNeill,
Tom Scott and Len Vacher for reviews and com-
ments. We thank an anonymous reviewer for his/
her meticulous comments, which were very help-
ful. We acknowledge NASA for use of its Blue
Marble imagery (used in Fig. 1), which is available
at: http://earthobservatory.nasa.gov/Newsroom/
BlueMarble/. We thank the USGS for providing
the terrain model used in Figure 6.
CONCLUSIONS
1
Multiple, spatially restricted, partially enclosed
karst sub-basins with as much as 100 m of
relief in a mid-carbonate platform setting lie
beneath the modern estuaries of Tampa Bay
and Charlotte Harbor located along the Florida
Gulf of Mexico coastline.
Seismic basement consists of the carbonate,
2
upper Oligocene to middle Miocene Arcadia
Formation, which has been signifi cantly
deformed into folds, sags, warps and sinkholes.
This deformation is interpreted to have been
caused by deep-seated dissolution of carbonates
at depth allowing the overlying stratigraphy to
collapse thus creating a surfi cial depression.
Sub-basin formation occurred during the mid-
to late Miocene sea-level lowstand.
Approximately 90% of the accommodation
3
space of these surfi cial sub-basins has been fi lled
by sequences dominated by prograding clino-
forms. Adjacent borehole data indicate that the
sediment infi ll is dominantly siliciclastic depos-
ited in a deltaic depositional setting. The infi ll
of the Tampa Bay and Charlotte Harbor basins
consists mostly of the Peace River Formation of
very late Miocene to Pliocene age. This sediment
fi ll represents a small component of a large and
extensive (>1000 km long) siliciclastic Cenozoic
invasion of peninsular Florida.
The sedimentary fi ll of the sub-basins was part
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4
of a signifi cant remobilization of quartz-rich
sediments through enhanced sediment dis-
charge in local, short-length rivers. Enhanced
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5
backfi lled basins, Tampa Bay and Charlotte
Harbor represent spatially restricted, mid-
platform, fi lled-in karst features. The 'dimpling'
of a carbonate platform by coalescing karst
