Publication Details

Bream:2004
Field Value
Title: Detrital zircon ages and Nd isotopic data from the southern Appalachian crystalline core, GA‐SC‐NC‐TN: New provenance constraints for Laurentian margin paragneisses
Authors: B.R. Bream, R.D. Hatcher Jr., C.F. Miller, and P.D. Fullagar
Publication: Geol. Soc. Am. Mem., v. 197, p. 459‐475.
Publish Date: Jan 2004
DOI: 10.1130/0-8137-1197-5.459
PDF: pdf
BibTEX Citation: Bream:2004.bib

Abstract:

Sedimentary and metasedimentary rocks within the southern Appalachian Blue Ridge and Inner Piedmont contain a valuable record of Late Proterozoic Laurentian margin evolution following the breakup of Rodinia. Paleogeographic reconstructions and increasing amounts of geochronologic and isotopic data limit the derivation of these paragneisses to the Laurentian and/or west Gondwanan craton(s). Southern Appalachian crystalline core paragneiss samples have εNd values between ‐8.5 and ‐2.0 at the time of deposition and contain abundant 1.1‐1.25 Ga zircon cores with Grenville 1.0‐1.1 Ga metamorphic rims. Less abundant detrital zircons are pre‐Grenvillian: Middle Proterozoic 1.25‐1.6 Ga, Early Proterozoic 1.6‐2.1 Ga, and Late Archean 2.7‐2.9 Ga. Blue Ridge Grenvillian basement has almost identical εNd values and displays the same dominant magmatic core and metamorphic rim zircon ages. Based on our data, nonconformable basement−cover relationships, and crustal ages in eastern North America, we contend that the extensive sedimentary packages in the southern Appalachian Blue Ridge and western Inner Piedmont are derived from Laurentia. εNd values from Carolina terrane volcanic, plutonic, and volcaniclastic rocks are isotopically less evolved than southern Appalachian paragneisses and Blue Ridge Grenvillian basement, easily separating this composite terrane from the mostly Laurentian terranes to the west. Neoproterozoic and Ordovician, as well as Grenvillian and pre‐Grenvillian, zircons in eastern Inner Piedmont paragneisses indicate that these samples were deposited much later and could have been derived entirely from a Panafrican source or possibly a mixture of Panafrican and recycled Laurentian margin assemblages