ABSTRACT

Volumetric analysis of the sedimentary-stratigraphic cycles demonstrable by surface and subsurface study of the onshore and offshore post-Pennsylvanian deposits surrounding the Southern Appalachians leads to recognition of economically significant geological factors. Known and potential economic resources have close relations with: 1) cycles of uplift and planation in the sourcelands; 2) depth of erosion, type and duration of weathering, and paleoclimatology of the sourcelands; 3) marine transgressions and regressions; 4) paleo-oceanography; 5) volcanism; and 6) Pleistocene eustatic sea level changes. To date, no clear evidence exists that continental migrations or collisions relate to known post-Pennsylvanian economic resources in the Southeast; however, much evidence exists that indicates strong (to several km.) vertical movements, of uplift and subsidence, have helped develop, control, or localized known and potential deposits.

The major known petroleum accumulations of the northeast Gulf Coast mostly relate to: 1) deltaic and littoral source beds, whose depositional facies were associated with pulses of sourcelands uplift; 2) reservoirs whose nature, volume, and extent depended on complex interplay between depositional facies, migrating sites of depocenters, and shifting coastlines; and 3) effects of evaporite tectonics. While other factors characteristic of the northeast Gulf Coast are similar in time and magnitude along the South Atlantic coast of the United States, the apparent lack of evaporite tectonics there may somewhat simplify onshore and offshore petroleum search. Regarding other mineral fuels, post-Pennsylvanian conditions in the Southeast have not favored the formation of significant coal deposits, although notable uranium concentrations occur with Mio-Pliocene phosphatic deposits and thorium with Pleistocene beach and heavy mineral concentrations.

Known non-metallic mineral resources consequent upon post-Pennsylvanian geological processes in the Southeast include kaolins, phosphates, bauxites, glass sands, specialty clays, and heavy mineral and black sand concentrates. Additional potential deposits likely occur associated with unconformities, former strand lines, and, in particular, near exposed high-rank metamorphic and igneous complexes.