Orphans are exotic, internally complex, detached duplexes within windows of far-traveled thrust sheets. They were amalgamated to the base of the overriding sheet as allochthonous structures. Internal stratigraphy differs significantly from both super- and subjacent rocks of the enveloping thrust, thus indicating that they originated from a distal ramp location where the stratigraphy was intermediate between that of super- and subjacent rocks. They characteristically occur in windows elongated perpendicular to direction of thrust transport. These complex, antiformal stack types of duplexes include a bounding window-roof fault within the overriding thrust sheet that is antiformal and commonly overturned forelandward, whereas the basal fault of orphans is the smoothly curved primary thrust of the overriding sheet in which they are encapsulated. Within an orphan, structurally higher elements are typically part of an inverted sequence of strata that were duplexed after being overturned and may now be antiformal, thus conforming with the antiformal roof fault. Structurally lower elements are typically part of an upright sequence of the same orphan strata and may be anticlinal. The presence of the same strata in the lower upright and higher inverted elements of an orphan suggests derivation from the overturned footwall syncline of a distal ramp that was detached from the footwall and amalgamated to the overriding thrust sheet. Orphans, which individually contain internally different stratigraphic sequences, may be stacked together. Orphans with older strata lie toward the hinterland and those with progressively younger strata lie successively toward the foreland, suggesting their derivation from successive dismembered footwall ramps separated by intervening flats as the thrust climbed upward. Recognition of orphans has serious implications for balancing cross sections and modeling original fold-fault geometry. Orphans result from structural modification of footwall ramps with overturned footwall synclines, the modification of which changes the structure to apparent fault-bend folds through ramp-smoothing processes that involve reducing ramp angle through dismemberment and removal of the footwall syncline.

Basement rocks of the Lovingston massif in the central Blue Ridge anticlinorium include jotunite, anorthosite, charnockitic rocks, and related Fe-Ti oxide- and apatite-rich rocks that display strong similarities to lithologic assemblages elsewhere in the Grenville orogen. The rock units preserve evidence of a protracted history of granulite-facies metamorphism and plutonism from ca. 1.15 to ca. 1.0 Ga, followed by multiple episodes of lower-grade Paleozoic metamorphism. New whole-rock major-and trace-element data indicate systematic chemical trends, incompatible element enrichments relative to the lower crust, and overall uniformity among Lovingston rocks. Quantitative geochemical models and field associations support interpretation of the Grenvilleage Archer Mountain Suite and Turkey Mountain Suite plutonic series as being derived from lower crustal sources. Archer Mountain Suite biotite granitoids and leucocratic granitoids and younger Roseland Anorthosite (with the associated Roses Mill pluton) and charnockitic plutons contain a substantial amount of lower crustal chemical component that is equivalent to the average Stage Road Suite. We propose that all of the Grenvilleage rocks in the Lovingston massif are related to a broad igneous protolith, represented by the Stage Road Suite, from which remobilized magmatic bodies were derived during orogenesis. Chemical data further indicate that Neoproterozoic intrusions and/or mylonitization along the Rockfish Valley fault had only minor local effects on highly mobile elements near their contacts or localized in shear zones.

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Within the southern and central Appalachians, Grenville-age basement rocks are found in major massifs in the Blue Ridge and Sauratown Mountains anticlinoria and in the vicinity of the Grandfather Mountain window. These massifs are, respectively, Pedlar and Lovingston Massifs in the Blue Ridge anticlinorium, Sauras Massif in the Sauratown Mountains anticlinorium, and Watauga, Globe, and Elk River Massifs near the Grandfather Mountain window. In central Virginia the Lovingston Massif is juxtaposed against the Pedlar Massif, and in northwestern North Carolina-southwestern Virginia, the Elk River Massif is thrust over the Globe and Watauga Massifs, all along faults of the Fries fault system, which includes the Rockfish Valley, Fork Ridge, Devil’s Fork, and Linville Falls faults, as well as the Fries fault per se . The Pedlar Massif is a deeper granulite facies country-rock terrane intruded by charnockite plutonic suites. The Lovingston Massif primarily is a shallower granulite/amphibolite facies terrane intruded by biotite dioritoid plutonic suites containing bodies of charnockite. Country rocks of the Watauga Massif were subjected to metamorphic conditions similar to those of the Lovingston Massif, but were intruded by a plutonic suite of biotite dioritoid, biotite granitoid, and granitoid. The Elk River, Globe, and Sauras Massifs all are terranes metamorphosed to amphibolite facies and intruded by granitoid/dioritoid suites containing some porphyritic biotite dioritoid phases. A suite of late Precambrian (post-Grenville) peralkaline granitoid plutons intruded all of the massifs except the Pedlar. These plutons presumably are related to upper Precambrian volcanic rocks that were associated with a rifting environment and that were later metamorphosed and deformed along with overlying sedimentary rocks to form part of the Appalachian orogenic belt.