The Carolina Zone: overview of Neoproterozoic to early Paleozoic peri-Gondwanan terranes along the eastern flank of the southern Appalachians

The Carolina Zone is an amalgamation of mainly Neoproterozoic--Early Paleozoic metaigneous-dominated terranes that are clustered along the eastern flank of the southern Appalachians. These terranes are distinguished from other divisions of the orogen by a commonality in gross geologic content and by their close spatial association. They are considered exotic relative to Laurentia on the basis of stratigraphic and tectonic evolution, paleontology, and position in the orogen analogous to that of exotic terranes in the northern Appalachians. They are probably peri-Gondwanan in origin. Within this first-order identity, the terranes exhibit remarkable heterogeneity, with respect to deposition, magmatism, and tectonothermal overprint. The depositional--magmatic history of the zone is viewed in three broad stages, including: (I) pre-600 Ma, (II) ca. 590-560 Ma, and (III) younger than ca. 550 Ma. Although each stage records significant felsic volcanism, there are few compelling stratigraphic linkages between terranes. Stage III plutonism may form a link between the two largest terranes in the zone. The isotopic evolution of the zone reflects the stratigraphic heterogeneity; isotopically juvenile magmatism in some terranes is coeval with more crustally evolved magmatism in others. The tectonothermal history of the zone is heterogeneous, producing a patchwork of suprastructural and infrastructural elements of different ages. Major tectonothermal events responsible for this pattern span the Neoproterozoic--earliest Cambrian, the Late Ordovician--Silurian, and the late Paleozoic. Evidence for regionally extensive events in the zone is sparse and such a fundamental concept as its time of accretion to Laurentia is speculative. The central Piedmont shear zone, a late Paleozoic ductile thrust that defines the western limit of the Carolina Zone, marks the final emplacement of the zone against Laurentian elements. Keywords: Carolina zone; Carolina terrane; Southern Appalachians; Neoproterozoic arcs; peri-Gondwanan terranes