Paleomagnetic evidence for the continuity and independent movement of a distinct major crustal block in the southern Appalachians.
The magnetization of 22 granitic and gneissic S Appalachian rock units, with estimated cooling ages of 415-250Ma has been determined. Included are 842 samples from 114 sites within 19 granites (100 sites) and 3 gneisses (14 sites) located in N Carolina, S Carolina, and Georgia. Samples from 57 of these sites in 14 granites and 3 gneissic bodies yield a remanent magnetism after demagnetization which exhibits good within-site and/or between-site directional consistency. Data for units which cooled to temperatures <300oC between 350-240Ma, a period of apparently only slight N American plate motion, can be divided into two groups. A mean paleopole calculated for the first of these groups, group A (derived from six granites and gneisses 365-325Ma in age), located in the vicinity of Atlanta, Ga, is coincident with well-defined Lower Carboniferous N American paleopoles. Site paleolatitude is estimated to be approx 11oS. Group B granites (six units) range in age from 350-250Ma, are located to the SE of an arc drawn from Columbia, S.C., through Athens, Ga, to Macon, Ga, are apparently anomalous, and lie in a crustal block >20 000km2 in size. The SE extent of this block is unknown due to Coastal Plain onlap.-Author
Publication Source (Journal or Book title)
Journal of Geophysical Research
Ellwood, B. (1982). Paleomagnetic evidence for the continuity and independent movement of a distinct major crustal block in the southern Appalachians.. Journal of Geophysical Research, 87 (B7), 5339-5350. https://doi.org/10.1029/JB087iB07p05339