Karst Sub‐Basins and Their Relationship to the Transport of Tertiary Siliciclastic Sediments on the Florida Platform

Abstract

Multiple, spatially restricted, partly enclosed karst sub-basins with as much as 100 m of relief occur on a mid-carbonate platform setting beneath the modern estuaries of Tampa Bay and Charlotte Harbor located along the west-central Florida coastline. A relatively high-amplitude seismic basement consists of the mostly carbonate, upper Oligocene to middle Miocene Arcadia Formation, which has been signifi cantly deformed into folds, sags, warps and sinkholes. Presumably, this deformation was caused during a mid-to-late Miocene sea-level lowstand by deep-seated dissolution of carbonates, evaporites or both, resulting in collapse of the overlying stratigraphy, thus creating palaeotopographic depressions.Seismic sequences containing prograding clinoforms fi lled approximately 90% of the accommodation space of these western Florida sub-basins. Borehole data indicate that sediment fi ll is mostly siliciclastic deposited within deltaic depositional systems. The sedimentary fi ll in the Tampa Bay and Charlotte Harbor sub-basins is mostly assigned to the upper Peace River Formation of late Miocene to early Pliocene age. This fi ll is part of a >1000 km long, Tertiary siliciclastic deposit that stretches north-to-south down peninsular Florida. Sediment fi ll of these two sub-basins is linked to erosion and remobilization of pre-existing, middle Miocene quartz-rich sediments via enhanced sediment transport by local, short-length rivers and discharge into coastalmarine depositional environments. Increased sediment discharge possibly resulted from amplifi ed thunderstorm activity and enhanced runoff during a warm period of the Pliocene.Rather than incised valley fi lls or reef-margin, backfi lled basins, Tampa Bay and Charlotte Harbor represent spatially restricted, sediment-fi lled karst palaeotopographic lows. The 'dimpling' of a carbonate platform by karst sub-basins provides a previously unrecognized mechanism for the creation of accommodation that can result in the 'drowning' of a carbonate platform by siliciclastics.

Reconstructing Common Era relative sea-level change on the Gulf Coast of Florida

“…1B) that experiences a humid, sub-tropical climate with an average annual air temperature of~23°C and average precipitation of 1250 mm/yr. The estuary lies near the center of the Jurassic-aged Florida Platform (Hine et al, 2003) overlying an Oligocene-aged karstic sub-basin that collapsed in the mid-Miocene due to deep-dissolution (Brooks and Doyle, 1998;Hine et al, 2009;Morrison and Yates, 2011). Anthropogenic alteration including dredge and fill, removal of wetlands and groundwater withdrawal associated with the urbanization of the communities surrounding Tampa Bay has caused degradation of hydrological and ecological systems within the estuary (Morrison and Yates, 2011).…”

“…The vertical distribution of the samples in our modern training set reflects the geomorphology of salt marshes in the Tampa Bay and Charlotte Harbor estuaries. In this region, salt marshes that formed on remnant karstic features were infilled by siliciclastic material (e.g., Hine et al, 2009). This results in expansive salt-marsh platforms with minimal topographic relief outside of a step change in elevation between the intertidal platform and surrounding shallow sub-tidal settings.…”

“Let Us All Enjoy the Fish”: Alternative Pathways and Contingent Histories of Collective Action and Governance Among Maritime Societies of the Western Peninsular Coast of Florida, USA, 100–1600 CE

“…Once assumed to be a drowned river valley, recent geological findings indicate that the bay is underlain by a number of sinkholes (Brooks and Doyle, 1998;Donahue et al, 2003;Hine et al, 2009). With the melting of ice in the warming that ended the most recent glacial period, the gulf shoreline migrated inland as sea level rose, such that by around 2000 BCE the physiography of the region evolved into something resembling the configuration of modern Tampa Bay (Donahue et al, 2003;Cronin et al, 2007).…”

Provenance of Syn-rift Clastics in the Eastern Gulf of Mexico: Insight from U-Pb Detrital Zircon Geochronology and Thin Sections

“…Rifting along the SGR axis failed and continued to the east until seafloor spreading intiated. The region remained a topographic depression, and during periods of sea level rise in the Cretaceous and Cenozoic, the SGR area was submerged by seawater, forming the Georgia Seaway (also known as the South Georgia Trough, or Georgia Channel System; Warzeski et al, 1996;Hine, 2009). The SGR was originally proposed as a series of separate rift basins within a single larger rift basin by Daniels et al (1983), which is supported by further seismic and aeromagnetic studies (e.g., Kiltgord et al, 1988;Sartin and See, 1997;Heffner, 2013).…”

“…Sediment derived from Yucatan was likely shed into the SFB as it was rifted away from the southern margin of Laurentia and West Florida during the opening of the GOM.Another possible explanation is that at least some sediment derived from southern Laurentia was deposited in the SFB, either by eolian or fluvial input. Similar sediment pathways from the SE Appalachian extended across northern and south Florida during the Oligocene, leaving a thin deposit of sand(Warzeski et al, 1996;Hine, 2009). These deposits are inferredto have been deposited during a marine regression by prograding deltas that extended into southern Florida.…”