STRATIGRAPHIC AND PALEOENVIRONMENTAL SUMMARY OF THE SOUTH-EAST GEORGIA EMBAYMENT - A CORRELATION OF EXPLORATORY WELLS

A Continental Offshore Stratigraphic Test (COST) well and six explorat ory wells have been drilled in the south-east Georgia embayment. The o ldest rocks penetrated are weakly metamorphosed Lower Ordovician quart z arenites and Silurian shales and argillites in the Transco 1005-1 we ll and Upper Devonian argillites in the COST GE-1 well. These marine s trata, which are equivalent to the Tippecanoe sequence in Florida, und erlie the post-rift unconformity and represent part of a disjunct frag ment of Gondwana that was sutured to the North American craton during the late Palaeozoic Alleghanian orogeny. The Palaeozoic strata are unc onformably overlain by interbedded non-marine Jurassic (Bajocian and y ounger) sandstones and shales and marginal marine Lower Cretaceous san dstones, calcareous shales and carbonates, which contain scattered bed s of coal and evaporite. Together, these rocks are stratigraphically e quivalent to the onshore Fort Pierce and Cotton Valley(?) Formations a nd rocks of the Lower Cretaceous Comanchean Provincial Series. The abu ndance of carbonates and evaporites in this interval, which reflects m arine influences within the embayment, increases upwards, eastwards an d southwards. The Upper Cretaceous part of the section is composed mai nly of neritic calcareous shales and shaley limestones stratigraphical ly equivalent to the primarily marginal marine facies of the onshore A tkinson, Cape Fear and Middendorf Formations and Black Creek Group, an d to limestones and shales of the Lawson Limestone and Peedee Formatio ns. Cenozoic strata are primarily semiconsolidated marine carbonates. Palaeocene to middle Eocene strata are commonly cherty; middle Miocene to Pliocene strata are massive and locally phosphatic and glauconitic ; Quaternary sediments are dominated by unconsolidated carbonate sands . The effects of eustatic changes and shifts in the palaeocirculation are recorded in the Upper Cretaceous and Tertiary strata.