Juergen Reinhardt

Evidence for Cenozoic tectonism in the southwest Georgia Piedmont

Paleocene nonmarine sediment in the Georgia Piedmont has been isolated from correlative Coastal Plain deposits by high-angle reverse faults and subsequent erosion. The reverse faults also offset surficial deposits of probable Pliocene age. The sediments, preserved north of Pine Mountain, in the vicinity of Warm Spring9s, Georgia, consist of (1) a lower sedimentary sequence, herein called the “Republic Mine beds,” composed mainly of massive, locally bauxitic, kaolinitic clay and well-bedded, coarse to fine quartz sand; and (2) an upper sequence, herein called “surficial deposits,” composed predominantly of clayey quartz sand and quartzite gravel. The compositional and textural dissimilarities between the two sequences indicate differences in provenance, depositional environment, and tectonic setting. The orientation of the faults and the sense of fault movement near Warm Springs indicate that this area of the western Georgia Piedmont is unlike that of the tectonic regimes previously documented in the Atlantic and Gulf Coastal Plains. The orientation of some structures and the amount and rate of fault deformation are more similar to features in the Gulf Coastal tectonic province, whereas the involvement of basement rocks in fault zones and the compressional style of deformation are comparable to tectonic features described elsewhere in the eastern United States, especially in Coastal Plain sediments along the Fall Line of the Atlantic Coastal Plain.

The Stratigraphic and structural significance of Paleocene pollen from warm springs, Georgia

Abstract Twenty pollen species recovered from auger samples of an isolated pod of sediment within the Piedmont Province of Meriwether County, Georgia, indicate a late Paleocene (early Sabinian) age for the deposit. The age assignment is based on the concurrent ranges of the species as they occur in the Gulf and Atlantic Coastal Plains. No dinoflagellate cysts or acritarchs were observed in the samples examined, and their absence supports stratigraphic and sedimentologic evidence for a nonmarine origin of the sediments. The sediments have been protected from erosion by faulting along the southern margin of the basin containing them. The structural relationships and the Paleocene age for the deposit provide evidence of Cenozoic tectonic activity within the Piedmont Province of Georgia. Regional stratigraphic and sedimentologic evidence suggests that the deposit was probably a northward extension of the bauxite districts of Andersonville, Georgia, and Eufaula, Alabama. Illustrations of the twenty biostratigr...

Tomstown Dolomite (Lower Cambrian), central Appalachian Mountains, and the habitat of Salterella conulata

Measured sections in the Tomstown Dolomite, Washington County, Maryland, indicate a considerably thinner section of carbonate rocks than in Virginia. Salterella conulata Clark, found at three previously undescribed localities, is confined to a narrow stratigraphic interval and may have biostratigraphic value. S. conulata is a faunal component in the lagoon-bay portion of an Early Cambrian tidal flat complex.

Load structures at the sediment-saprolite boundary, Fall Line, Maryland

The field relationship of Lower Cretaceous sedimentary rocks to saprolite along the Fall Line provides new information about sedimentation and saprolite burial in Howard County, Maryland. The response that the saprolite, which was formed from a felsic gneiss, has made to the overlying sediment suggests that (1) the crystalline rock had weathered to saprolite before sediment emplacement, (2) the sediment was deposited by a highly erosive agent, (3) the saprolite was water saturated and deformed plastically during sedimentation, and (4) later reorientation of the sediment-saprolite deformation structures took place, probably during sediment compaction. Sedimentary petrology, sediment-saprolite contacts, and reverse density and injection structures along the sediment-saprolite boundary seem to rule out a Quaternary periglacial origin (congeliturbations) or any other origin involving saprolitization later than sedimentation. The field relationships and sedimentological analysis indicate synsedimentary deformation of the saprolite during Early Cretaceous time.