Abstract Well and seismic data were combined with existing radiometric data and 1328 new laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb zircon ages from igneous, sedimentary and volcaniclastic rocks in three wells to determine the origin and evolution of key crustal terranes, and the timing of initial rifting and synrift deposition in the southeastern Gulf of Mexico and western Bahamas. These data reveal that several southeastern Gulf of Mexico crustal terranes, distinguished by their zircon age distributions and geochemistries, were amalgamated into a single terrane of mixed Pan-African and Amazonian crustal affinity (the newly named West Florida Terrane) during the formation of Pangaea. Sinistral offset along the Florida Transfer Zone (FTZ) during the Late Triassic–Middle Jurassic was likely to have been facilitated by crustal heterogeneity at the boundary between the West Florida and Suwannee terranes, a prime area for reactivation during the break-up of Pangaea. Initial extension, igneous activity and synrift deposition in the region began during the Middle Triassic in the western Bahamas and offshore North Florida, and rapidly expanded into the South Florida Basin by the Early Jurassic. Peak igneous activity and accommodation in the region was diachronous from north to south, beginning in the north during the Early Jurassic (Sinemurian–Pliensbachian) before ending in the south in the Early–Middle Jurassic (Sinemurian–Aalenian/early Bajocian). Detrital zircons in sedimentary and volcaniclastic rocks were primarily derived from local erosion of pre-existing crustal terranes. Long-distance transport was likely for pre-Neoproterozoic and post-Cambrian Paleozoic zircons. Middle Jurassic detrital zircons in volcaniclastic rocks of the western Bahamas may have been deposited during ash-fall events from hotspot activity in the southeastern Bahamas.

Abstract The Florida Parishes of southeastern Louisiana (Fig. 1) are bounded on the west by the Mississippi River, on the east by the Pearl River, on the north by the Louisiana-Mississippi state line, and on the south by the Mississippi River deltaic plain. Principal cities include Baton Rouge and New Orleans.

T he very productive limestone aquifers of Tertiary and Quaternary age in the Coastal Plain of the Southeastern States contain a water-table circulation system where aquifers are at or near the land surface; the Tertiary limestone unit is a homoclinal artesian system confined beneath younger beds in coastal areas. The Tertiary limestone has a total thickness of several thousand feet and ranges in age from Paleocene to Pliocene. The part of the limestone that represents a hydrologic unit, as much as 1000 feet thick, ranges in age from middle Eocene to middle Miocene. That unit is the principal artesian aquifer in Florida and southeastern Georgia. It is also an aquifer, but of lesser importance, in South Carolina, North Carolina, and Alabama. In southeastern Florida the Quaternary limestone forms a shallow, although highly productive, aquifer. In general, the Tertiary formations dip gently toward the coast, except where the regional dip is interrupted by folds such as the Cape Fear arch, the Ocala uplift, and the Chattahoochee anticline, or by faults such as those on the Ocala uplift. A piezometric map showing the head of water in the principal artesian aquifer in Florida and southeastern Georgia reveals chief areas of recharge where limestone crops out in interstream areas and where sinkholes breach overlying beds; it reveals principal discharge areas in certain stream valleys, springs, and offshore. Lateral movement of the water in the limestone is generally controlled by the hydraulic gradient to the nearest discharge area. The movement may be either controlled by or independent of faults and folds; it may be along joints for short distances. Solution by downward movement of water in the zone of aeration to the water table has formed vertical tubular openings or shafts. Lateral movement of the water from areas of recharge to areas of discharge has formed caves and other solution channels, chiefly in the upper part of the zone of saturation. Since they were formed, some caves have been drowned, and others have been exposed in the zone of aeration as the water rose and fell, chiefly in Pleistocene time. The principal aquifer in Florida probably has caves and solution channels comparable in size and extent to those of Mammoth Cave, Kentucky; however, only a small percentage of these are above the water table at the present time. In a large part of the region the most noticeable change in chemical quality of the water in the limestone resulting from circulation of water is the freshening accompanying removal of salty water from the aquifer. Changes in sea level during Pleistocene time have raised and lowered the water table; thus the position of the upper part of the zone of saturation, in which conditions were most favorable for solution and for the formation of cavities, has changed repeatedly. At the lowest stand of the Pleistocene sea, it is conceivable that the water level in part of the limestone in north-central Florida was a few hundred feet lower than at present. The present pattern of solution openings probably was developed in Pleistocene time.

Abstract Great Bahama Bank (GBB) stands behind many of the models used to illustrate depositional facies variation across flat-topped, isolated carbonate platforms. Such models have long served as subsurface analogs at a variety of scales. We have used Landsat TM and ETM+ imagery, and an extensive set of water depth measurements, to critically evaluate the magnitude and patterns of bathymetry across GBB. The refined bathymetric digital elevation model (DEM) and seafloor sample data were analyzed with eCognition to develop a map of depositional facies that is more robust than previous versions. 60%, or 61,400 km 2 , of GBB lies in 5 m or less of water. This includes carbonate sand accumulations where accommodation space is nearly filled, e.g., Tongue of the Ocean, Schooners, Exumas, Joulters, and the Cat Cay sand bodies, and also includes vast portions of the northern portion of GBB surrounding Andros Island and the New Providence Platform to the west of the Exuma Islands. The 40% of GBB lying in greater than 5 m of water occurs mainly in an east-west trending portion of the southern platform. These bathymetric patterns are important as a potential primary control over flooding history, filling (accommodation) history, and the resultant depositional facies patterns.