We present a newly compiled geologic map of the Pine Mountain window based on available 1:24,000 (and smaller) scale geologic maps; this map provides an improved basis to reconcile long-standing issues regarding tectonic evolution. We integrate sensitive high-resolution ion microprobe (SHRIMP) single-grain U-Pb ages of igneous, metamorphic, and detrital zircons from Grenville basement rocks, associated metasedimentary units, and cover rocks to help clarify the pre-Appalachian history and to better delimit the distribution of Laurentian versus peri-Gondwanan and Gondwanan units along the southeast flank of the window. U-Pb results indicate that some units, which earlier had been correlated with Neoproterozoic to Early Cambrian Laurentian rift deposits of the Ocoee Supergroup (i.e., Sparks-Halawaka Schist), actually are supracrustal rocks deposited prior to ~1100 Ma that were intruded and metamorphosed during the Ottawan phase of the Grenville orogeny. Zircons from the Phelps Creek Gneiss are 425 ± 7 Ma and overlap in time with plutons that intruded rocks of the Carolina superterrane during the Silurian (i.e., the Concord-Salisbury suite). The host units to the Phelps Creek Gneiss had also previously been interpreted as Sparks-Halawaka Schist, but field relations combine with the Silurian intrusive age to suggest that they rather belong to the peri-Gondwanan Carolina superterrane, helping to refine the position of the Central Piedmont suture in its most southern exposures. Results suggest that the Pine Mountain window is not framed by a single fault, but by Alleghanian faults of different timing, rheology, and kinematics, some of which were reactivated while others were not. The new map and U-Pb dates reveal that the southwesternmost exposures of the Central Piedmont suture are located farther northwest, so the width of the Pine Mountain window narrows from 22 km wide in central Georgia to only 5 km in Alabama. At its narrowest, the flanks of the Pine Mountain window are marked by two relatively thin normal faults (the Towaliga and Shiloh faults, northwest and southeast, respectively) that have excised the wider, earlier-formed mylonite zones. All of the Alleghanian faults are cut by later high-angle, normal and left- and right-slip brittle faults (Mesozoic?), which also influenced the present configuration of the window.

In the Appalachian orogen, the Neoproterozoic(?)–Lower Cambrian Chilhowee Group represents the initial drift-facies deposits along and across the eastern Laurentian continental margin following rifting. In the Southern Appalachians, this group forms thrust sheets along the west flank of the Talladega–Blue Ridge belt. Where the base is unfaulted, it lies depositionally above Ocoee Supergroup rift-facies rocks or Grenville basement. Regionally, the Chilhowee grades up into the Lower Cambrian Shady Dolomite, the initial deposits of the marginwide Cambrian–Ordovician carbonate bank. Sequences more interior to the orogen, including the Kahatchee Mountain Group (Talladega belt), the Nantahala and Brasstown Formations (western Blue Ridge), and the Hollis Quartzite (Pine Mountain belt), are considered to be correlative with the Chilhowee based upon similarities in lithostratigraphic sequence, sequence stratigraphy, sandstone provenance, and paleocurrent studies. Assuming an autochthonous Pine Mountain window, palinspastic restorations of foreland thrusts suggest that the Chilhowee Group restores essentially astride that window, and Chilhowee-equivalent units in the Talladega–Blue Ridge belts, in turn, restore farther southeast. This places the respective sequences southeastward in the order of increasing thickness and depth to basement from the base of the carbonate bank facies, with units restored farthest southeast having the most distal marine characteristics. Retro-deformation of thrust belt structures and the Pine Mountain cover sequence restores the Kahatchee Mountain Group at least to the subsurface position of the Wiggins-Suwannee suture, the southeastern limit of Laurentian continental crust, indicating that this group's basement was subducted beneath Gondwanan or peri-Gondwanan crust, and that the basement of even more outboard Laurentian sequences (e.g., eastern Blue Ridge) was overridden even farther.

A new tectonic map of the southern and central Appalachians incorporates modern field and structural-stratigraphic, geochronologic (mostly sensitive high-resolution ion microprobe–reverse geometry, SHRIMP–RG, and Sm-Nd), geochemical, and geophysical data to identify crustal boundaries and blocks. Major tectonic units include the ∼735 Ma Laurentian failed rift, ∼565 Ma rifted margin sedimentary-volcanic assemblage deposited on Grenvillian and pre-Grenvillian crust, the Laurentian platform, and a series of distal Laurentian terranes (Cowrock, Cartoogechaye, Tugaloo-Chopawamsic-Potomac) accreted to Laurentia during the Taconian (Ordovician) or Neoacadian (Late Devonian–early Mississippian) orogenies. The Dahlonega gold belt consists of more proximal metasandstone and pelitic schist; it also contains Ordovician arc volcanic rocks, and a mixed detrital zircon suite of Laurentian and Gondwanan, or Penokean, affinity. The newly recognized Cat Square terrane contains Laurentian, Avalonian, and 430 Ma detrital zircons, and is considered a remnant ocean basin that closed during Acadian-Neoacadian accretion of the Carolina superterrane. The Pine Mountain terrane (southernmost exposed Appalachians) consists of Grenvillian basement and a cover sequence bearing Gondwanan or Penokean detrital zircons. The Carolina superterrane contains numerous peri-Gondwanan terranes that were deformed, metamorphosed, and amalgamated prior to 530 Ma, then accreted to Laurentia during the Neoacadian along the central Piedmont suture. The Raleigh-Goochland terrane contains blocks of Laurentian basement and cover that moved SW (dextrally) out of the collision zone to the north as the Theic ocean closed north to south during the early Alleghanian orogeny. This event also produced the Kiokee-Raleigh belt high-grade metamorphic core in the eastern Piedmont, and includes faults of the Pine Mountain window. The latter is framed by Alleghanian thrust and dextral faults formed at different crustal depths (times?). Subsurface components of the southern and central Appalachians are recognized in potential field and limited drill data. The Carolina superterrane extends beneath the Coastal Plain—possibly eastward to the East Coast magnetic anomaly. South of the Carolina superterrane and north of the Wiggins suture is the Brunswick (Charleston) terrane, another peri-Gondwanan terrane. The east–west Alleghanian Wiggins suture with the Suwannee terrane is recognizable to the south beneath Georgia and Alabama in potential field data, truncating all Appalachian structures and older crustal blocks west of the Appalachians. South of the suture, African basement and cover lie in the eastern Florida subsurface, while to the west are other Gondwanan or peri-Gondwanan components that may have originally connected with Yucatan.

A late Paleozoic fault duplex forms a structural culmination in the Blue Ridge-Piedmont thrust plate near Cartersville, Georgia. The duplex contains at least three major lens-shaped horses, stacked vertically and bounded by faults that branch from the sole of the Blue Ridge-Piedmont plate. The duplex telescopes older Paleozoic structures and metamorphic fabrics that are related to Taconic thrusting of the Blue Ridge over the North American shelf. The duplex, embedded in the sole of the Blue Ridge-Piedmont plate, may have been detached from the area of the Pine Mountain window in the central Georgia Piedmont, and horizontally displaced 130 km during formation of the Valley and Ridge fold and thrust belt.

Thrusts in the crystalline core of the southern Appalachians formed by both ductile and brittle mechanisms during three or more major Paleozoic deformational-thermal events (Taconic, Acadian, Alleghanian), in contrast to thrusts in the foreland which formed primarily as brittle faults during the Alleghanian. Early prethermal peak thrusts formed in the crystalline core, then were subsequently thermally overprinted and annealed. Thrusts that formed late in a metamorphic-deformational sequence have maintained a planar geometry. Many of these thrusts, such as the Brevard and Towaliga faults, were later reactivated in either the ductile or brittle or both realms, possibly involving both dip-slip and strike-slip motion. The thrusts framing the Pine Mountain and Sauratown Mountains windows formed both pre- and post-thermal peak. The pre-thermal peak Box Ankle thrust in the Pine Mountain window is a structurally lower fault, whereas the window is flanked externally by the post-thermal peak Towaliga (northwest) and Goat Rock (southeast) faults. Conversely, in the Sauratown Mountains the brittle Hanging Rock thrust frames an inner window beneath the older Forbush thrust. Here a downward and outward propagating sequence is suggested for the development of thrusts. North American basement rocks are involved in both the Pine Mountain and Sauratown Mountains windows, and basement and cover behave as a homogeneously coupled mass with respect to strain. Consequently, the only factor that controlled the siting of early thrusts may have been the depth to the ductile-brittle transition zone. The frontal Blue Ridge thrust was the last formed in the Blue Ridge-Piedmont thrust sheet although the Cartersville-Miller Cove thrust is a slightly older Alleghanian thrust than the Great Smoky fault.