PROVENANCE OF SEDIMENTS IN THE CENTER OF THE
DURHAM SUB-BASIN, NORTH CAROLINA
GILMER, James P. III, TEXTORIS, Daniel A., Department of
Geology, University of North Carolina, Chapel,Hill,
WATSON, Mary E., North Carolina Geological Survey,
Raleigh, NC, 27607
The study area lies within the central portion of the Upper Triassic
Durham sub-basin, a half-graben structure bounded to the southeast
by the syn-depositional Jonesboro fault system (probably step-faulted)
and to the west by nonconformities and post-depositional faults.
Surrounding the sub-basin are metamorphic rocks of the Carolina
Slate Belt to the west and higher grade metamorphic rocks and silicic
intrusives of the Raleigh Metamorphic Belt to the east.
The study was undertaken in order to determine the specific
source terrane of the arkoses and lithic arkoses which were deposited
in a meandering and axial river system which drained to the
The lithic grains within the sandstones and the pebbles consist
of schists, gneisses, slates, phyllites, and metavolcanics in order of
higher to lower abundance. Many of the lithic constituents contain
index minerals, such as garnet, magnetite, myrmekitic feldspar, and
epidote, that provide estimates of source terrane metamorphic grade.
From the metamorphic grade estimates, lithologic character of the
pebbles and sandstone lithic grains, maturity of texture to determine
distance of transportation, paleocurrent data, and general outcrop
information which suggest distal alluvial fan inflow, it is concluded
that the sands and pebbles were derived predominantly from the east
side of the sub-basin.
The present-day terranes of the Raleigh Metamorphic Belt
were the major source. Sandstone point count data indicate a triple
source: 1) a basement uplift of continental crustal granitic rock, 2) a
dissected volcanic arc, and 3) a mixed source of basement rock,
volcanic arc, and recycled orogen rock.
Compatible source rocks are present within the major exposed
terranes of the Raleigh Metamorphic Belt. The Carolina terrane
consists of low metamorphic grade slates and schists of volcanic arc
origin. The Rolesville batholith, the Falls Lake melange, and the
Nutbush Creek fault zone consist of gneisses, granites, and
leucogneiss of continental crust basement and mixed crust and
recycled orogen origin. The Crabtree terrane consists of garnet-
bearing gneisses of crust/recycled orogen origin.
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