Defining the Timing, Extent, and Conditions of Paleozoic Metamorphism in the Southern Appalachian Blue Ridge Terranes of Tennessee, North Carolina, and Northern Georgia

Abstract

The crystalline core of the southern Appalachian (Figure 1) orogen preserves a complex record of four collisional tectonic events from the Late Mesoproterozoic to Permian that variably modified the margin of Laurentia (Hatcher, 1987). Despite 60 years of radiometric dating efforts (e.g., Davis et al., 1962;Long et al., 1959) there remain entire 30 × 60-min quadrangles (>4,970 km 2 ) in the southern Appalachian orogen without a single metamorphic age determination, let alone the extensive high precision geo-and thermochronology needed to unravel the complex spatio-temporal history of crustal thickening, exhumation, and erosion along the length of the orogen. By comparison, the New England segment of the northern Appalachians has a rich geo-and thermochronologic data set (e.g., Robinson et al., 1998). Although initially considered to be dominantly Taconian and Acadian (Robinson et al., 1979;Thompson et al., 1968), modern high precision geo-and thermochronology across New England revealed profound Neoacadian (late Devonian to early Carboniferous) and Alleghanian (Permo-Carboniferous) reworking of the older metamorphic infrastructure via processes such as tectonic wedging, transpression, and syn-to post-orogenic extensional collapse (e.g.,

First‐Order Transition in Appalachian Orogenic Processes Revealed by Along‐Strike Variation of the Moho Geometry

“…The Taconic orogeny is recognized throughout the Appalachian orogen, but its timing and style are thought to have varied. Tectonic models of the Taconic orogeny in other parts of the orogen typically invoke east-dipping subduction of the Laurentian margin under arcs or accreted terranes for the Canadian Appalachians ( van Staal & Barr, 2012;van Staal et al, 2007), for the central Appalachians (Hughes et al, 2014;Wise & Ganis, 2009) and for the southern Appalachians (Hatcher, 2010;Thigpen et al, 2022). However, Tull et al (2014Tull et al ( , 2018 suggested a northwest-dipping subduction polarity throughout the Taconic orogeny in the Appalachians of Georgia and Alabama (Figure 6d).…”