Petrology and Geochemistry of Neoproterozoic Arc Plutons Beneath the Atlantic Coastal Plain, SRS, SC Page: 8 of 47
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Milledgeville and Augusta terranes, and another, unnamed high-grade terrane exposed in a small
window through sediments of the Coastal Plain (figure 2).
Kudzu terrane: The SE margin of the Modoc zone is bordered by high grade metamorphic rocks
traditionally assigned to the Kiokee belt, Uchee belt, and Dreher Shoals subterrane. All three of
these "terranes" are nearly identical lithologically, and had similar if not identical thermal histories.
It seems likely that these "terranes" were originally one unit that was separated by later tectonic
events or by coastal plain onlap. We propose here that these rocks be referred to as the "Kudzu
terrane" (Kiokee-Uchee-Dreher Shoals-Precambrian Z-Unified terrane).
Kiokee belt (aka "Savannah River terrane"): The Kiokee belt consists of upper amphibolite facies
(sillimantite grade) migmatitic gneiss (biotite-amphibole paragneiss), sillimanite schist, amphibolite,
luecocratic paragneiss, quartzite (chert?), and local ultramafic rocks (Maher, 1978, 1987; Maher and
Sacks, 1987; Maher and others, 1991; Secor and others, 1986a, 1986b; Sacks and others, 1989).
The predominance of migmatitic paragneiss and sillimanite schist indicates temperatures >650*C
and minimum pressures > 3 kb.
Uchee belt (aka "Uchee terrane"): The Uchee belt consists of upper amphibolite facies (sillimantite
grade) migmatitic gneiss, schist, and amphibolite (Bentley and Neathery, 1970; Hanley, 1986;
Chalokwu, 1989). Chalokwu (1989) determined a P-T range of =570-780*C at 7.0 to 9.2 kbars
for amphibolites from this belt. It is nearly identical to the Kiokee belt lithologically.
Dreher Shoals "terrane ": The Dreher Shoals terrane consists of upper amphibolite facies (staurolite-
kyanite grade) schist, gneiss, amphibolite, and granitic orthogneiss (Secor and Snoke, 1978; Secor
and others, 1986a; Dallmeyer and others; 1986; Snoke and Frost, 1990). Snoke and Frost (1990)
determined a P-T range of =750"C at 7.2 t o 8.2 kbars - that is, nearly identical to the P-T ranges
calculated by Chalokwu (1989) for the Uchee belt.
Milledgeville terrane: The Milledgeville terrane consists of upper greenschist to lower
amphibolite facies mudstones, siltstones, and quartzites (metachert?), with local intercalations of
metavolcanic rock (Pickering, 1976). Lithologically, it resembles rocks of the Richtex and Asbill
Pond formations (Carolina slate belt). It may be fault bounded, or it may sit unconformably on top
of the high-grade "Kudzu terrane".
Augusta terrane: The Augusta terrane (Maher and others, 1991), more commonly known as the
Belair belt, is a small terrane exposed between the Kiokee belt and the onlap of the coastal plain
(figure 2). The Augusta terrane consists of low-grade (greenschist facies) metavolcanic rocks and
metasedimentary rocks with lithologic similarities to those of the Carolina terrane (Maher, 1978;
Maher and others, 1991; Shervais and others, 1996). The metasedimentary rocks were originally6
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Maryak, M. Petrology and Geochemistry of Neoproterozoic Arc Plutons Beneath the Atlantic Coastal Plain, SRS, SC, article, October 21, 1998; South Carolina. (https://digital.library.unt.edu/ark:/67531/metadc685097/m1/8/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.