Pre-Mesozoic Basement Rocks of the Alabama Coastal Plain

ABSTRACT On the basis of lithologic and structural characteristics, pre-Mesozoic rocks of the Alabama coastal plain can be divided into four provinces: (1) folded and thrust-faulted Paleozoic sedimentary rocks in a succession similar to that of the Alabama outcrop; (2) Talladega slate belt consisting of slate, quartzite, phyllite, marble, and fine-grained schist that resemble rocks exposed in the Alabama Piedmont; (3) Piedmont metamorphic and igneous belt consisting of a wide variety of rock types dominated by aluminous schist and gneiss of kyanite and sillimanite grade, into which felsic and mafic igneous rocks are intruded; and (4) Suwannee basin containing lower Paleozoic shale and sandstone. Overlying and partly obscuring provinces 3 and 4 are Mesozoic volcanic rocks that, in part, resemble felsic and mafic rocks of province 3. Rocks of province 3 resemble rocks of the northern Alabama Piedmont, except for a pink, potash feldspar granitic rock that does not crop out. Rocks of the inner and southern parts of the Alabama Piedmont are not recognized, and northern Alabama Piedmont rocks appear to form the pre-Mesozoic basement of most of the Alabama coastal plain.