Mineral resources of the Bradwell Bay Wilderness and the Sopchoppy River study area, Wakulla County, Florida

Abstract

The Bradweli Bay Wilderness and Sopchoppy River Study Area comprise 23,000 acres (93 km 2 ) in the Apalachicola National Forest in the Florida panhandle. The area is a swamp-covered, almost flat surface of a terrace in which the Sopchoppy River is entrenched. Deposits directly underlying the terrace surface generally consist of as much as 30 feet (9 m) of sand, clay, muck, and peat of Pliocene to Holocene age overlying limestone and marl of Miocene age. The limestone and marl are on the east flank of the gulf trough, and are underlain by a thick sequence of older Tertiary and Cretaceous sedimentary rocks. Older formations of probable Jurassic, Triassic, Paleozoic, and Precambrian ages are known from scattered holes drilled for oil in surrounding areas. The Hawthorn Formation of middle Miocene age, from which phosphate and fuller's earth are chiefly produced in Florida, is not found in the Study Area therefore, the potential for resources of phosphate is low. Phosphate pellets, however, were found in auger holes in sand above the St. Marks and Jackson Bluff Formations of early and late Miocene age, respectively. The pellets are mostly in sands deposited in an estuary during Pliocene or early Pleistocene time; they were derived from older rocks, presumably the Hawthorn Formation. Approximately 136,000 tons (123,000 tonnes) of air-dried peat are available from bay swamps in the Study Area, but the deposits are too shallow and widespread to make mining economically feasible. Large quantities of quartz sand are available in abandoned beach ridges and in deposits of shallow nearshore marine origin, but sieve tests show that the sand is generally too fine for mortar and masonry use, and it is not suitable as moulding or glass sand because it lacks the required size grades and purity. The northern Florida, southern Alabama, and Georgia region produces oil, phosphate, fuller's earth, sand, and peat. The Study Area is about 175 miles (280 km) east-southeast of the Jay oil field in the western panhandle of Florida. Part of the production is from the Smackover Formation of Jurassic age, which is also the target formation for drilling in the vicinity of the Study Area. Four oil test wells have been drilled in the vicinity of the Study Area but all proved to be unsuccessful. Phillips Petroleum Company completed a well in Leon County at a depth of 10,466 feet (3,190 m). Placid Oil Company drilled a well in Wakulla County to 12,116 feet (3,693 m) and two in Liberty County, one to 12,131 feet (3,698 m) and the second to 12,400 feet (3,780 m). These three test wells are alined along a northeast trend immediately northwest of the Bradwell Bay area. The oil and gas potential of the Bradwell Bay-Sopchoppy area is low.