Paleoenvironmental interpretation of sinkhole sediments on a flat low-lying carbonate platform, a case study from Chassahowitzka River, west-central Florida
Year: 2024
Type: article
Abstract: After rapid increases in ocean volumes during the early Holocene, sea levels rose more slowly from the mid- to late-Holocene. The flat shelf of the eastern Gulf of Mexico meant even small rises in sea level shifted the coastline inland many kilometers. The impact of this transgression on the karst environments of western Florida is not well known. Here we investigate how one Floridian location responded to changing climate from the mid- and late-Holocene. Chassahowitzha River, representing one of many west-central Florida rivers, is spring fed and discharges into the Gulf of Mexico. Sinkholes along this river have the potential to preserve complete and un-disturbed sedimentary records. Three sediment cores were collected from a sinkhole complex just north of the river. All three cores contain their sedimentary record down to the limestone bedrock. Ten radiocarbon dates were used to create the core chronologies. Interpretation of paleoenvironmental changes is based on sediment grain size analysis, microphotography, loss-on-ignition organic carbon contents and identification of microfossils in the sediments. Prior to 6 ka BP, sediments are dominated by quartz sand followed by an organic-rich layer ending at 5 ka BP. We interpret the organic sediments at 6 ka BP as the onset of a marsh environment along the river. Most of the marsh sediments are deposited between 5-6 ka BP when the coastline was 30 kms seaward. Next, there is a 3 kyr gap in deposition as demonstrated by the radiocarbon chronology. A documented regression in the sea level may be a contributing cause to this hiatus. After this interval the sedimentary record is characterized by inorganic deposits which contain an abundance of microfossils. The topmost sediments of each core were interspersed with discrete shell layers which may be indicative of extreme storm events.
Source: Geomorphology
Authors: Philip Edward van Beynen, Ping Wang
Institution: University of South Florida
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: hybrid
Estimated APC paid: $3,300
Funder: University of South Florida
OpenAlex ID: W4405925656