Abstract

The Talladega belt of Alabama and Georgia is located at the southernmost exposed part of the southern Appalachian orogen and is one of the westernmost metamorphic terranes in this part of the orogen. The presence of the Lower Devonian Jemison Chert of the Talladega Group provides a maximum age for the timing of greenschist facies metamorphism and penetrative slaty cleavage formation in this terrane.

Six slate samples collected from upper Precambrian(?)-Lower Cambrian, and Silurian(?)-Devonian rocks of the Talladega belt have an average K-Ar age of 399 ±17 Ma. This age is interpreted to be the approximate time of regional greenschist facies metamorphism. The timing of metamorphism in the Talladega belt is similar to the age of the Acadian orogeny in the Maritime and northern Appalachians. Unlike the accreted nature of the Acadian terranes in the northern Appalachians, the Talladega belt appears to have been part of the early to middle Paleozoic cratonic margin of North America. The results of this study indicate that Acadian dynamothermal events extended into parts of the Laurentian margin in the southern Appalachians.

Paleozoic igneous activity in the southern Appalachians was less extensive compared with the voluminous Acadian plutonism of the northern Appalachians; however, synkinematic to postkinematic Devonian plutons are present in the central and western parts of the orogen.

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