Temporal and spatial distribution of Paleozoic metamorphism in the southern Appalachian Blue Ridge and Inner Piedmont delimited by ion microprobe U-Pb ages of metamorphic zircon

Kinematic, Deformational, and Thermochronologic Conditions Along the Gossan Lead and Fries Shear Zones: Constraining the Western‐Eastern Blue Ridge Boundary in Northwestern North Carolina

“…Deformation during the Taconic orogeny is characterized by well‐developed foliation and folding coincident with peak metamorphic conditions (Absher & McSween, ; Eckert et al, ). Metamorphic zircon rims from the WBR and EBR suggest that Taconic metamorphism ranged from 462 to 448 Ma (Merschat et al, ). U‐Pb dating of zircons from leucosomes in granulite facies gneisses gives the age of peak metamorphism and partial melting as 458 ± 1 Ma (Moecher et al, ) and eclogite from the EBR yielded metamorphic zircon ages of 459 ± 1 Ma (Miller et al, ).…”

“…There is less evidence for the Acadian orogeny in the southern Appalachians than in the northern Appalachians, and because deformation occurs later in the southern Appalachians herein it is referred to as the Neoacadian orogeny (Hatcher et al, ; Merschat et al, , ). The Neoacadian orogeny is generally characterized by dextral strike‐slip kinematics that may be associated with major terrane transport of a few hundred kilometers (Hatcher et al, ; Merschat et al, ; Trupe et al, ).…”

“…The Neoacadian orogeny is generally characterized by dextral strike‐slip kinematics that may be associated with major terrane transport of a few hundred kilometers (Hatcher et al, ; Merschat et al, ; Trupe et al, ). The Inner Piedmont is the Acadian and Neoacadian orogenic core (Hatcher & Merschat, ; Merschat et al, , ); however, plutonic rocks across the Blue Ridge have Acadian ages, suggesting that the effects of Acadian tectonism were felt along the Blue Ridge, but the only definitively Acadian‐aged structure in the region is the Burnsville fault (Adams et al, ; Goldberg & Dallmeyer, ; Miller et al, ; Trupe et al, ). However, hornblende 40 Ar/ 39 Ar dates from amphibolites from both the Virginia and North Carolina Blue Ridge record ages of 360–400 Ma (Goldberg & Dallmeyer, ; Jenkins et al, ) and the associated deformation is interpreted as occurring under amphibolite facies conditions (Trupe et al, ; Waters‐Tormey & Stewart, ).…”

“…Alleghanian orogenesis in the southern Appalachians consists of an early phase of transpression followed by head‐on collision of Gondwana with Laurentia (Becker et al, ; Gates et al, ; Hatcher, ). Evidence for Alleghanian deformation is distributed throughout the orogen: the Valley and Ridge foreland fold‐and‐thrust belt developed in unmetamorphosed Paleozoic rocks, and the Blue Ridge and Piedmont are the crystalline core that exposes Alleghanian ductile deformation, metamorphism, and magmatic/plutonic arcs, as well as variable domains or pieces of the crystalline terranes that preserve older deformational events described above (Hatcher, , ; Hatcher et al, ; Merschat et al, ). The Alleghanian orogeny in the Blue Ridge is characterized as dominantly low‐grade, thrust‐related, westward transport, of the entire Blue Ridge thrust sheet during collision (Hatcher, , ).…”

“…In the southern Appalachians the Blue Ridge Province is part of an allochthonous crystalline core consisting of low‐ to high‐grade metamorphic and plutonic rocks. From southern Virginia southward, the Blue Ridge is commonly divided into a western belt (WBR), which formed on the Laurentian margin, and an eastern belt (EBR), which was accreted onto North America likely during the Taconic orogeny (462–448 Ma; Hatcher et al, ; Miller et al, ; Merschat et al, ). The WBR‐EBR boundary extends for ~1,100 km from Virginia to Alabama and is a major NE striking structure marked by several faults (Figure ).…”