Geology of the Southeast Durham and Southwest Durham 7.5-minute quadrangles, North Carolina

              GEOLOGY OF THE SOUTHEAST DURHAM AND SOUTHWEST
DURHAM 7.5-MINUTE QUADRANGLES,
NORTH CAROLINA
By
N.C. DOCUMENTS
Charles W. Hoffman and Patricia E. Gallagher CLEARINGHOUSE
BULLETIN 92
MAR 23 1990
N.C, STATE LIBRARY
RALEIGH
•n«** >$j»v
NORTH CAROLINA GEOLOGICAL SURVEY
DIVISION OF LAND RESOURCES
DEPARTMENT OF NATURAL RESOURCES
AND COMMUNITY DEVELOPMENT
GEOLOGICAL SURVEY SECTION
The Geological Survey Section examines, surveys, and maps the geology, mineral resources,
and topography ofthe state to encourage the wise conservation and use ofthese resources by industry,
commerce, agriculture, and government agencies for the general welfare of the citizens of North
Carolina.
The Section conducts basic and applied research projects in environmental geology, mineral
resource exploration, and systematic geologic mapping. Services include identifying rock and
mineral samples submitted by citizens and providing consulting services and specially prepared
reports to agencies that need geological information.
The Geological Survey Section publishes Bulletins, Economic Papers, Information Circu-lars,
Educational Series, Geologic Maps and Special Publications. For a list of publications or more
information about the Section please contact the Geological Survey Section at P.O. Box 27687,
Raleigh, North Carolina 2761 1-7687, or call (919) 733-2423.
Jeffrey C. Reid
Chief Geologist
GEOLOGY OF THE SOUTHEAST DURHAM AND SOUTHWEST
DURHAM 7.5-MINUTE QUADRANGLES,
NORTH CAROLINA
By
Charles W. Hoffman and Patricia E. Gallagher
BULLETIN 92
NORTH CAROLINA GEOLOGICAL SURVEY
DIVISION OF LAND RESOURCES
RALEIGH
1989
STATE OF NORTH CAROLINA DEPARTMENT OF NATURAL RESOURCES
AND
TAA/nrcr mad™ rnvi?DMnp COMMUNITY DEVELOPMENT
JAMES G. MARTIN, GOVERNOR WILLIAM W. COBEY, JR., SECRETARY
CONTENTS
Page
Abstract 1
Introduction 1
Location 1
Objectives, Scope, and Methods 1
Conventions 3
Geologic Setting 3
Previous Work 4
Geology 6
Igneous and Metamorphic Rocks 6
Carolina Slate Belt Rocks 6
Diabase 6
Sedimentary rocks 8
Lithofacies Association I 8
Trcs/sij - Sandstone With Inter-bedded
Siltstone 8
Description 8
Localities 10
Interpretation 10
Lithofacies Association II 10
Trcs/si
2
- Sandstone With Inter-bedded
Siltstone 13
Description 13
Localities 13
Interpretation 13
Trcsi/s -Siltstone With Interbed-ded
Sandstone 14
Description 14
Localities 16
Interpretation 16
Lithofacies Association III 16
Page
Trcs - Sandstone 17
Description 17
Localities 17
Interpretation 18
Trcsc - Pebbly Sandstone 18
Description 18
Localities 19
Interpretation 19
Trcs/c - Sandstone With Interbed-ded
Conglomerate 19
Description 19
Localities 19
Interpretation 21
Tree - Conglomerate 21
Description 21
Localities 21
Interpretation 21
Structure 24
Discussion 24
Depositional model 24
Paleoclimate 26
Conclusions 26
Acknowledgements 27
References Cited 27
Appendices
A. Mineralogical Composition of
Sandstones 30
B. Locality Register 31
C. Geochemical Data For Diabase 34
ILLUSTRATIONS
Plates (in pocket)
1. Geologic map of Southeast Durham
7.5-minute Quadrangle
2. Geologic map of Southwest Durham
7.5-minute Quadrangle
Figure Page
1. Location map 2
2. Newark rift system basins of eastern
North America 4
3. Weight percent Ti02
versus Mafic
Index (Fe
2 3
*/(Fe
2 3
*+MgO)) for
representative diabase samples 7
ILLUSTRATIONS (continued)
Figure Page
4. Generalized distribution of lithofacies
and major diabase bodies 9
5. Outcrop of Trcs/sij fades exposed at
Locality 1 11
6. Outcrop of Trcs/sij facies exposed at
Locality 2 12
7. Section of Trcs/si
2
facies exposed at
Locality 7 14
8. Composite section of Trcs/si
2
facies ex-posed
in Borden Brick and Tile
Hoover Road Quarry (Locality 8).... 15
9. Ternary plot of sandstone
composition 16
10. Tics facies exposed in excavation
east of Page Road (SR 1973) at 1-40
(Locality 14) 17
11. Excavated block of bioturbated Trcs
sandstone at Locality 15, Southern
Parkway west of U.S. 70 17
Figure Page
12. Section of Trcs facies exposed at
Locality 16, west side of Miami
Boulevard (SR 1959) north of
1-40 18
13. Outcrop of Trcsc facies on Kemp
Road (SR 1902) east of junction
with Virgil Road(SR 1903)
(Locality 20) 20
14. Interbedded sandstone and conglom-erate
of Trcs/c facies at Raleigh-
Durham International Airport 21
15. Jonesboro fault at Locality 26 in
Leesville Industrial Park 22
16. Ditch excavation on north side of
Trusswood lot, Leesville Industrial
Park (Locality 27) 23
17. Sketch diagrams of proposed
depositional models 25
u
GEOLOGY OF THE SOUTHEAST DURHAM AND SOUTHWEST
DURHAM 7.5-MINUTE QUADRANGLES,
NORTH CAROLINA
Bulletin 92
By Charles W. Hoffman and Patricia E. Gallagher
ABSTRACT INTRODUCTION
The Southeast Durham and Southwest Durham 7.5-
minute Quadrangles include a 26 kilometer transect of the
Durham Triassic basin from the Jonesboro fault on the south-eastern
side of this half-graben structure to a bounding un-conformity
on the northwestern side. The basin is filled with
non-marine, primarily fluvial, clastic deposits of the Late
Triassic Chatham Group. The Chatham Group rocks are
intruded by Early Jurassic diabase as dikes and sheets.
Bordering rocks are pre-Mesozoic intrusive, metavolcanic
and metasedimentary rocks of the Carolina slate belt.
Within the Triassic sedimentary rocks, three litho-facies
associations comprised of seven distinct lithofacies
form three belts that generally conform to the trend of the
basin. The western association is comprised of a single
lithofacies consisting ofsandstone with interbedded siltstone.
The central association is comprised of two lithofacies, sand-stone
with interbedded siltstone and siltstone with interbed-ded
sandstone. The eastern association is comprised of four
lithofacies; sandstone, pebbly sandstone, sandstone with
interbedded conglomerate, and conglomerate. The western
lithofacies association consists of mud-clast-rich, trough
crossbedded, arkosic sandstone interspersed with locally
thick siltstone beds. The unit is interpreted to represent sandy
braided streams flowing within fine-grained interstream areas.
The central lithofacies association consists ofarkosic, fining-upward,
meandering stream deposits in the northern part of
its area. To the south, in the upper part of its section, this
lithofacies association grades to a muddy system dominated
by fine-grained overbank fluvial and lacustrine deposits with
intercalated sandstone. The eastern lithofacies association
consists of conglomerates along the border fault and grades
basinward through interbedded sandstone and conglomerate
to pebbly sandstone and then to muddy sandstone. Adjacent
facies exhibit both intertonguing and gradational relation-ships.
This set oflithofacies is interpreted to represent basin-margin
alluvial fan deposits that prograded from a southeast-ern
highland.
LOCATION
The Southeast Durham and Southwest
Durham 7.5-minute Quadrangles encompass an
area of approximately 300 square kilometers. The
quadrangles include a large part ofthe Durham Tri-assic
basin and small areas of the adjacent Pied-mont
region (figure 1). A significant amount of the
study area is urban and suburban. Large portions of
Durham, Research Triangle Park, and Raleigh-
Durham International Airport are located within
the study area as are developing sections ofRaleigh
and Chapel Hill.
OBJECTIVES, SCOPE, AND METHODS
Adequate land use planning and resource
management require, among many other things,
sound baseline information on a variety of proper-ties
that are directly related to geology. Such
information includes soil types and their ability to
bear weight, maintain a slope, or transmit fluid;
groundwater quality and quantity; mineral resource
potential (especially aggregates for highway and
building construction); and potential geologic
hazards such as landslides or radon gas. In the
rapidly urbanizing Research Triangle area, where
proper planning is basic to maintaining a desirable
quality of life, the need for accurate geologic maps
at a suitable scale is vital.
This study was undertaken to meet these
— 36°
„<y / Sanf
v ' Wadesboro I
Durham basin
ord basin
>asin >
80°
1
Durham
J*
STUDY AREA
Raleigh ^
78°
1
76°
1
lOOmi -34°
100km
Figure 1. Map of North Carolina showing location of study area within the Durham Triassic basin.
needs. The specific objective was to provide de-tailed
surface geologic mapping of the study area.
Toward this end, lithofacies within the Triassic
sedimentary rocks of the two quadrangles were
identified and mapped. The lithofacies are defined
chiefly by field criteria including mineralogical
composition and sedimentary textures and struc-tures.
Binocular and petrographic examination of
selected samples was conducted to support and
refine the field descriptions. Thin-section point
count data are tabulated in Appendix A.
Additionally, Jurassic diabase bodies and
the contact between Triassic sedimentary rocks
and pre-Mesozoic crystalline rocks were mapped.
The distribution of pre-Mesozoic crystalline rock
lithologies was compiled from existing sources
(Parker, 1979; Wilson and Carpenter, 1981; North
Carolina Geological Survey, 1985). Other than to
delineate the contact between these rocks and the
Triassic sedimentary rocks, the crystalline rocks
were not investigated. The distribution ofalluvium
was interpreted from topographic and soils maps.
The quadrangle maps included in this re-port
(Plates 1 and 2, in pocket) have been reduced
in scale for publication. Full size ( 1 :24,000 scale)
diazo prints of the quadrangle maps (with topogra-phy)
are available separately as North Carolina
Geological Survey Open-File Reports 89- 1 (South-east
Durham Quadrangle) and 89-2 (Southwest
Durham Quadrangle).
Outcrop within the two quadrangles is
limited and generally poor because of deep weath-ering
and extensive soil development. Total out-crop
area is estimated to be less than two percent.
Except in the upper reaches of tributary streams,
alluvium masks outcrop within most portions of
the drainage system. These streambed outcrops
usually provide little vertical exposure but do yield
representative samples for grain size and textural
observations. Roadside ditches and road cuts also
expose some bedrock, however primary deposi-tional
features such as bedding orientation and
sedimentary structures are obscured by weathering
in most of these outcrops. Three quarries operated
by Borden Brick and Tile Company (a division of
Cherokee Sanford Group) are within the study area
and provided some of the better sections during the
study. Key exposures examined for the project are
listed in the Locality Register (Appendix B).
Additionally, information was provided by
temporary exposures created by construction ac-tivity.
Construction in progress during this project
included excavation for the Southern Parkway (no
Wake County Secondary Route (SR) number as-signed
to date) from Alexander Drive (SR 2028) at
Miami Boulevard (SR 1959) to U.S. 70, major
expansion of Burroughs-Wellcome and Glaxo
pharmaceutical companies in Research Triangle
Park, excavation for a sewer line along Stirrup Iron
Creek from Chin Page Road (SR 1969) to Page
Road (SR 1973), initial development ofACC park
north of U.S. 70 between Mt. Herman Road (SR
1646) and Sycamore Creek, and numerous smaller
scale activities. Excavation for the 10,000 foot
runway (5R - 23L) at Raleigh-Durham Interna-tional
Airport and for Interstate 40 from the Dur-ham
Freeway (N.C. 147) to U.S. 15-501 pre-dated
this project but engineering data and interviews
with personnel associated with those activities
were utilized.
CONVENTIONS
Several conventions used in this report may
not be familiar or evident to some readers. One is
the terminology and symbols used to identify the
sedimentary lithofacies. These are based on a
system used by the U.S. Geological Survey for
Newark Supergroup rocks of the eastern United
States early Mesozoic basins (Smoot, Froelich, and
Luttrell, 1988). The standardized symbols and
terms facilitate interbasin and intrabasinal com-parisons
ofdepositional units. In this report the age
(Tr = Triassic) and group (c = Chatham Group) are
common to all of the Triassic lithofacies. Trc is
followed by a symbol for the major or characteris-tic
lithology (c = conglomerate, sc = pebbly sand-stone,
s = sandstone, and si = siltstone) to further
designate the lithofacies. Subscript numerals dif-ferentiate
similar lithologies of different facies and
interbedded lithologies are separated by a slash (/)
with the dominant lithology being given first. For
example, "s/si" denotes sandstone with interbed-ded
siltstone.
This report does not apply formal nomen-clature
below group rank. Until additional detailed
facies mapping is completed over a wider area and
until subsurface relationships are better under-stood,
it is inappropriate to apply formal nomencla-ture
below group rank to rocks of the Durham
basin.
Many of the rock descriptions, mainly in
the figured geologic sections, include standard
color names based on the Rock-Color Chart pre-pared
by The Rock Color Chart Committee (1948)
and distributed by the Geological Society ofAmer-ica.
Both English and metric units are used.
Distances that are likely to be measured with a
motor vehicle's odometer are given as miles; oth-erwise
metric units are used.
Another convention is in the identification
of streets, roads, and highways. Generally, the
street or road name is given first and followed in
parentheses by the state route number. This is
because much of this area is urban or becoming
urban and signs and local recognition are generally
based on street or road names rather than route
numbers (although the quadrangle maps generally
show only the route numbers). In some cases,
streets within private developments are not state
maintained and Secondary Route (SR) numbers do
not apply.
GEOLOGIC SETTING
The Durham basin is part of a series of
extensional basins in eastern North America that
developed during rifting in the early Mesozoic.
This rifting event resulted in the separation of the
North American and African plates. Approxi-mately
20 "synrift" basins, collectively identified
as the Newark rift system, are exposed along the
North American continental margin from South
Carolina to Nova Scotia (figure 2). Many other,
presumably coeval, basins have been interpreted to
lie beneath the late Mesozoic and Cenozoic sedi-ments
of the Atlantic Coastal Plain and adjacent
continental shelf (for example Benson, 1984).
Newark rift system basins contain Late
Triassic and Early Jurassic non-marine clastic
100
100
-h-
200
200 300 MILES
I
300 400 KILOMETERS
EXPLANATION
1. Wadesboro(N.C.-S.C)
2. Sanford (N.C.)
3. Durham (N.C.)
4. Davie County (N.C.)
5. Dan River and
Danville (N.C. -Va.)
6. Scottsburg (Va.)
7. Basins north of
Scottsburg (Va.)
8. Farmville (Va.)
9. Richmond (Va.)
10. Taylorsville (Va.)
11. Scottsville (Va.)
12. Barboursville (Va.)
13. Culpeper(Va.-Md.)
14. Gettysburg (Md. - Pa.)
15. Newark (N.J.- Pa. -N.Y.)
16. Pomperaug (Conn.)
17. Hartford (Conn. - Mass.)
18. Deerfield (Mass.)
19. Fundy or Minas
(Nova Scotia -Canada)
20. Chedabucto (Nova
Scotia -Canada)
<igure 2. Newark rift system basins of eastern
North America (from Froelich and Olsen,
1984).
deposits of fluvial and lacustrine origin with inter-bedded
evaporites and basaltic flows. These rocks
form the Newark Supergroup (Froelich and Olsen,
1984). Interbedded basalt flows belonging to the
Newark Supergroup are limited to basins from
Virginia northward. A second Early Jurassic epi-sode
of intrusion by diabase dikes, sheets, and sills
occurred. These intrusions are concentrated mainly
in the Carolinas and are sparse to absent in the more
northern basins (ManspeizerandCousminer, 1988).
Due to their cross-cutting relationships and post-depositional
emplacement, these rocks are not
included in the Newark Supergroup.
The Durham basin, and the Sanford and
Wadesboro basins to the south, form a 240-kilome-ter-
long by up to 26-kilometer-wide structureknown
as the Deep River basin (figure 1). The individual
basins are separated by cross-trending structural
highs named the Colon cross structure (between
Durham and Sanford basins) and the Pekin cross
structure (between Sanford and Wadesboro ba-sins).
Sedimentary rocks of the Deep River basin
of Chatham County were named the Chatham
series by Emmons (1857). Subsequently, the term
Chatham Group has been used to include all the
Late Triassic (Carnian) rocks of the Deep River
basin (Froelich and Olsen, 1984; North Carolina
Geological Survey, 1985).
The Durham basin is a half-graben struc-ture
within crystalline rocks of the Piedmont re-gion.
It is down-faulted on the southeastern margin
and bounded on the west mainly by an uncon-formity.
Locally, the western border is formed by
minor southeast dipping high-angle normal faults
.
The eastern border fault was named the Jonesboro
fault (Campbell and Kimball, 1923) for an expo-sure
in Lee County . It dips northwestward at a high
angle.
PREVIOUS WORK
Very little detailed geologic work has been
published on the Durham basin. Harrington (1951)
mapped the basin's western border at a scale of
approximately 1:125,000. The 1977 Carolina
Geological Society Field Trip Guidebook (Bain
and Harvey, 1977) contains a reconnaissance geo-logic
map of the Durham basin at a scale of
1:250,000 which has been extensively referenced
by subsequent investigators. Bain and Harvey's
map was used in the compilation of the Geologic
Map ofNorth Carolina (North Carolina Geological
Survey, 1985).
Wheeler and Textoris (1978) described
several occurrences of chert and limestone within
the Durham basin. They concluded that the chert
and limestone were precipitated under semi-arid to
arid conditions in and along the margins of playa
lakes that formed during wet climatic periods and
evaporated during subsequent dry periods. Their
study constitutes the only published detailed petro-graphic
analysis of Durham basin chert and car-bonate.
In his reporton the geology ofWake County,
Parker (1979) mapped a portion of the Durham
basin along with the crystalline rocks ofthe county.
He recognized three belts or facies within the
Triassic sedimentary rocks: a fanglomerate belt
adjacent to the eastern border fault, a sandstone-mudstone
belt basinward of the fanglomerate, and
a limestone-chert belt basinward of the sandstone-mudstone.
Heregarded these belts as lateral equiva-lents
that persisted vertically through the sedimen-tary
section. The metavolcanic and metasedimen-tary
rocks immediately adjacent to the Durham
basin on its southeast side was termed the Cary se-quence.
Bain and Brown (1980) characterized the
structure and sedimentation of the "Durham Trias-sic
basin" (Deep River basin of current usage)
using a variety of geophysical tools including seis-mic
reflection and refraction, gravity, resistivity,
and aeromagnetic surveys. Their study is the most
extensive work on the structural aspects of the
Deep River basin. Most of their work specific to
the Durham basin, however, was conducted south
of the Southeast and Southwest Durham Quad-rangles.
One key finding was that the basin's
eastern border is a step-faulted zone several kilo-meters
wide. From this observation Bain and
Brown (1980) inferred that, contrary to conven-tional
thinking, some of the border conglomerates
may be older than more basinward strata. They
also inferred that the basin was faulted longitudi-nally
and transversely to create individual horsts
and grabens as small as 1 kilometer wide by 3 kilo-meters
long and that most of these are rotated east
to southeast by post-depositional faulting. Dis-placement
of at least 300 to 600 meters was in-ferred
along the largest inrrabasin fault, the Bonsal-
Morrisville fault, which trends northeast- south-west
and terminates at approximately the Durham-
Chatham County line about 2 miles south of Nel-son.
Wilson and Carpenter (1981) compiled the
work ofHarrington (1951) and Parker ( 1 979) along
with unpublished mapping of the Durham basin as
part of a five-county report. In their report, the
name Sanford Formation was applied to all Trias-sic
strata of the Durham basin. Bain and Harvey
(1977) had previously argued that the stratigraphic
nomenclature of the Sanford basin (Sanford,
Cumnock, and Pekin Formations) proposed by
Reinemund (1955) was not applicable to the rocks
of the Durham basin. The bulk of Wilson and
Carpenter's (1981) report dealt with crystalline
rocks of the Piedmont that surround the Durham
basin.
Diabase of the eastern United States early
Mesozoic basins has been the object of many
studies on many scales (see summary in Froelich
and Gottfried, 1985). Investigations by Ragland
and others (1968) andWeigand and Ragland( 1970)
contain data on the petrography and geochemistry
of some Durham basin diabase dikes. Several of
the dikes examined in those reports are located in
the project area.
Gore (1986) compiled a field trip guide-book
for the Durham and Sanford basins which
includes contributions by several other authors.
That publication reviews much of the previous
work and presents new data as well.
GEOLOGY
IGNEOUS AND METAMORPHIC ROCKS
Carolina Slate Belt Rocks
The Durham basin is bordered on both
sides by metavolcanic and metasedimentary rocks
of the Carolina slate belt (North Carolina Geologi-cal
Survey, 1985). Parker (1979) described crys-talline
rocks of a 1.5- to 3.0-kilometer-wide belt
adjacent to the Jonesboro fault as "dacitic and an-desitic
metatuffs and flows with phyllite, meta-siltstone,
pebbly arkose, and ilmenite-magnetite
quartzite." Several small adamellite bodies are
interspersed within the mixed lithology unit. The
term "Cary sequence" was used by Parker (1979)
for these rocks.
To the west of the Durham basin, within the
northwest corner of the study area, Wilson and
Carpenter (1981) mapped two units. They named
one " felsic igneous complex" and the other "felsic
crystal tuffs and felsic tuffs."
Diabase
Early Jurassic diabase dikes and sheets
intrude the Triassic strata of the Durham basin.
The diabase is dark gray to black, fine to medium
crystalline, and composed mainly of an interlock-ing
mosaic of equigranular plagioclase feldspar,
clinopyroxene (commonly augite), and olivine
(Froelich, written communication, 1988). Aphanitic
"chill margins" were observed in a few outcrops.
Coarse crystalline textures occur in some of the
thicker diabase bodies. A distinctive "knobby"
weathering texture caused by very large (1 to 2
centimeters) clinopyroxene oikocrysts is notice-able
in some outcrops of a large diabase body in the
Oak Grove area. Diabase commonly weathers into
spheroidal boulders with a dark-yellowish orange
(10YR 6/6) surface stain and yields a characteris-tic
yellow-orange soil.
Weigand and Ragland (1970) classified
Mesozoic dolerite dikes of eastern North America.
They recognized both quartz-normative and oli-vine-
normative bodies and subdivided the quartz-normative
type into high-Ti0
2, low-TiO
z, and high
Fe^*1 sub-types. They observed that quartz-nor-mative
dikes are the dominant variety from Nova
Scotia to Maryland, olivine-normative dikes are
dominant in the Carolinas, and both types occur in
approximately equal proportions in Virginia and
Georgia. Figure 3 shows weight percent Ti0
2
versus mafic index (Fe
2 3
*/(Fe
2 3*+MgO)) for
representative eastern North American diabase
dikes reported elsewhere (Ragland and others, 1968
;
Weigand and Ragland, 1970) along with new val-ues
for two diabase bodies from the Southeast and
Southwest Durham Quadrangles. Two of the plot-ted
values, DDH- 1 and DDH-2, are from drill core
from the Oak Grove diabase sheet. These fall
within the typical compositional range for olivine-normative
dikes (samples provided by Nello Teer
Company; analyses performed by J. D. Arthur,
Florida State University, and provided by A. J.
Froelich). Another plotted value, JY(2), is from
the large north-south trending dike in the south-central
portion of the Southwest Durham Quad-rangle.
This dike plots as a high-Ti0
2
quartz-nor-mative
type (samples collected as part ofthis study;
analyses performed by J. Taggart, A. Bartel, and D.
Siems, U.S. Geological Survey, and provided by
A. J. Froelich).
Contact metamorphic aureoles of hornfels
or "baked" sedimentary rocks occur in strata in-truded
by diabase. These blackened and hardened
zones are commonly about half as wide as the dike
and typically exhibit closely spaced parallel frac-tures.
Such fracture patterns locally continue
straight across the sedimentary-igneous contact
without interruption and are interpreted as cooling
features. Where diabase intruded lithologies of
varying porosity, for example a unit of interbedded
sandstone and mudstone, the thickness and inten-sity
of alteration within the contact aureole is
highly irregular. Coarse-grained arkose is espe-cially
distinctive where thermally metamorphosed.
Superficially, the baked arkose resembles granite.
1 Fe
2 3
* = Fe
2 3
+ FeO
o
OX)
+
a*
fa
fa
a»
a
76 —
72 —
*? 68 —
64 —
60 —
56 —
u
48 —
44
0.2
high Fe.O * quartz-nomiative
low TiO.quartz-noimative
high Ti02
quartz-normative
olivine-normative
i—
i
1—
r
0.4 0.6
1—i—i—i—
r
0.8 1.0 1.2 1.4
Weight Percent Ti0
2
Figure 3. Plot of weight percent TiO versus Mafic Index (weight percent Fe,0 */(Fe2
'2~3* + MgO)) for
representative diabase dikes reported by Weigand and Ragland (1970) and Ragland and others
(1968) (•) and for newly analyzed samples (). Four major diabase chemical types are shown. See
Appendix C for table of analyses and key to samples.
Diabase dikes occur throughout the two
quadrangles. The dikes are generally linear; how-ever,
detailed mapping shows that some are sinu-ous.
Thickness is highly variable, both within indi-vidual
dikes and from one dike to another. Ob-served
dikes were as thin as 5 centimeters and as
thick as over 100 meters. Dikes are usually steeply
dipping to vertical.
The Durham and Sanford basins contain
the southernmost known occurrences of sheet- like
diabase bodies within the eastern U.S. early Meso-zoic
basins (Froelich and Gottfried, 1985). Fro-elich
and Gottfried (1985) define the term "sheet"
(as applied to Newark Supergroup diabase bodies)
to "embrace all ofa great variety offorms displayed
by the intrusive diabase other than vertical or
steeply inclined dikes ...." The term "sill" has been
used by some workers (Wilson and Carpenter,
1981; North Carolina Geological Survey, 1985) to
describe the larger diabase bodies of the Durham
basin. Structural observations and drill data,
however, indicate that these bodies are discordant
to the sedimentary strata. For example, the Oak
Grove diabase sheet dips northward at a moderate
angle of 25°-40° (Nello Teer Company, unpub-lished
data). Thus, the term "sheet" is more appro-priate.
Our mapping in the Southwest Durham
Quadrangle has significantly enlarged the mapped
outcrop area of the BP dike of Ragland and others
(1968). They studied the body in the vicinity of its
outcrop inthelargeroadcutonU.S. 15-501 Bypass
just south of the Cornwallis Road interchange.
This body lies along the trend of a prominent aero-magnetic
anomaly (U.S. Geological Survey, 1974)
that continues eastward and aligns with the Oak
Grove diabase sheet. The aeromagnetic anomaly
passes through urban area; therefore, it is difficult
to confirm the continuity of diabase outcrop. It
seems reasonable to infer diabase as the underlying
cause of this anomaly, but some sort of structure or
lithologic variation within basement rocks can not
be ruled out.
Soil maps were of limited use for delineat-ing
the occurrence and extent of diabase. Iredell
and Mecklenburg soil types are generally recog-nized
as indicating mafic parent material. Map-ping
for this project, however, found significantly
more diabase than is suggested by the distribution
of Iredell and Mecklenburg soils on the Durham
and Wake County soils maps (U. S. Department of
Agriculture, 1976; U.S. Department of Agricul-ture,
1970.
SEDIMENTARY ROCKS
Mapping of Triassic sedimentary rocks
delineated seven lithofacies that are grouped into
three lithofacies associations (figure 4). The three
associations form three belts that generally con-form
to the trend of the basin. The western associa-tion
(Lithofacies Association I) is comprised of a
single lithofacies consisting of sandstone with in-terbedded
siltstone (Trcs/sij). The central associa-tion
(Lithofacies Association II) is comprised of
two lithofacies, sandstone with interbedded siltstone
(Trcs/si
2
) and siltstone with interbedded sandstone
(Trcsi/s). The eastern association (Lithofacies As-sociation
III) is comprised of four lithofacies,
sandstone (Trcs), pebbly sandstone (Trcsc), sand-stone
with interbedded conglomerate (Trcs/c), and
conglomerate (Tree).
Floodplain alluvium (Qal) is also shown on
the geologic maps although specific investigation
of this material was beyond the project's scope.
The mapped distribution of alluvium is largely
interpretive and is based on a combination of topo-graphic
and soils information. Relatively flat,
locally broad, surfaces are evident along most
streams and tributary drainages of the study area.
These areas approximately coincide with the Chew-acla-
Wehadkee-Congaree or the Altavista soil
associations (U. S. Department of Agriculture,
1976). With modification, alluvium is mapped
where both the topography and soils maps suggest
alluvial deposits.
Lithofacies Association I
Trcs/si, - Sandstone With Interbedded Siltstone
Description. Lithofacies Association I consists of
a single facies identified as the Trcs/sij facies. This
unit consists of fine- to medium-grained, pinkish-gray
(5YR 8/1) to light-olive-gray (5Y 6/1), feld-spathic
sandstone and reddish-brown bioturbated
siltstone and mudstone. Fine- to very fine-grained
biotite is a common accessory that helps to distin-guish
the sandstones of this facies from sandstones
of the other lithofacies. Muscovite is also com-mon,
though it is not distinctive to this lithofacies.
Widespread red clayey soils, abundant and large
mud clasts in sandstone channel deposits, and
some exposures which contain thick siltstone beds
indicate that siltstone is, volumetrically, a signifi-cant
component of this facies.
Sandstone preferentially outcrops and thus
is the dominant lithology exposed through the area
underlain by this facies. Overall, outcrops of this
facies are less abundant but usually larger than
those of the other lithofacies associations. The
outcrops of Lithofacies Association I also exhibit
more large-scale sedimentary structures than out-crops
of the other lithofacies associations.
In aggregate, sandstone sequences are
usually thick (5 meters or more) and are composed
of individual depositional units that are character-ized
by rapid vertical and lateral changes. The
smaller scale sequences are typically 1 .5 to 2.0 me-ters
thick and exhibit poorly defined, fining-up-ward
trends from erosional or channel-form basal
contacts. Sandstone immediately overlying the
basal scours is very coarse grained to pebbly and
contains abundant mudstone clasts. Mudstone
clasts range up to 50 centimeters in diameter and
are commonly scattered along scour surfaces. The
8
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upper portions of fining-upward sequences, where
they are not truncated or removed by another de-positional
sequence, consist ofbioturbated siltstone
and mudstone.
Trough crossbedding is abundant in the
sandstones of this facies. Individual sets decrease
in thickness from between 30 and 40 centimeters
near the base of a sequence to between 10 and 15
centimeters in the upper portions. Tabular foresets
are less abundant, but individual sets up to 1.5
meters thick occur near the tops of fining-upward
sequences in a few outcrops.
Paleocurrent determination by trough cross-bed
orientations from a limited number of locali-ties
show a broad scatter with a strong southerly
component. Within a single outcrop the trough
crossbeds generally show little variability in direc-tion.
Tabular foresets, where preserved, have ori-entations
that vary considerably (up to 90 degrees)
from the trough crossbed orientation of the same
outcrop.
Bioturbation is extensive in the finer grained
portions and within the thinner sandy beds of this
facies. Both root structures and burrows (Scoyenia)
were observed. Rooted zones usually exhibit light-green
to whitish reduction haloes along root traces.
Locally, thin zones of nodular carbonate also occur
in the muddy to silty beds of the Trcs/sij facies.
Voids within the basal portions of some sandstones
are interpreted as weathered-out carbonate and/or
mud clasts that were reworked from underlying
mudstone.
Localities. Representative outcrops of the Trcs/sij
facies occur at Localities 1 and 2 on the Southwest
Durham Quadrangle. Locality 1 (figure 5) is a
construction and road cut at the j unction of Pearson
Drive (SR 1221) and Mimosa Drive approximately
0.3 miles west of Fayetteville Road (SR 1118).
Locality 2 (figure 6), a cut along the abandoned
Norfolk Southern Railroad right-of-way at the
Fayetteville Road overpass about 1.4 miles south
of Interstate 40, was described by Textoris and
Holden (1986). This outcrop is one of the localities
within this facies in which nodular carbonate hori-zons
occur. Supplemental localities for the Trcs/si
1
facies are numbers 3, 4, and 5.
Interpretation. Sandstone sequences within this
facies resemble those of sandy braided rivers de-scribed
by Cant (1978) in that 1) large scale, poorly
defined mud-clast-rich trough crossbeds grade
vertically to smaller scale trough crossbeds, 2)
fining-upward sequences are poorly developed, 3)
intercalated sets of tabular crossbeds have pale-ocurrent
directions at high angles to the directions
indicated by the trough crossbeds, and 4) ripple
cross-laminated, fine-grained sandstone and
siltstone beds are thin to absent at the tops offining-upward
sequences. By this model the tabular
foresets represent mid-channel sand sheets and
bars deposited in waning flow conditions over the
trough crossbeds formed by dunes during high
flow stages.
Unlike Cant's model, however, the Trcs/sij
facies sandstones are surrounded by apparently
thick sequences of heavily bioturbated siltstone
and mudstone. The sparse but well-developed
character of sandstone outcrops suggests that onset
and termination of braid channel sedimentation
happened suddenly and not by lateral migration.
This might be explained by channel avulsion on a
muddy floodplain in a manner similar to that de-scribed
by Smith and Smith (1980) for anastomos-ing
streams.
Lithofacies Association n
Lithofacies Association II is comprised of
twolithofacies, a dominantly sandstone facies (Trcs/
si
2
) and a dominantly mudstone facies (Trcsi/s).
The Trcs/si
2
facies is the more widespread facies.
In the south-central portion of the map area, the
Trcs/si
2
facies grades upward into the Trcsi/s fa-cies.
The contact between Lithofacies Associa-tion
I and Lithofacies Association II appears to be
gradational. This change occurs through a zone
wherein the lithologic and sedimentary character-
10
SOIL
mud-clast-rich
mud-clast conglomerate
trough crossbeds
Figure 5. Outcrop of Trcs/sij facies exposed at Locality 1 . Paleoflow is into the page and toward the left.
11
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istics of both associations occur. Some outcrops or
individual beds within this zone are more distinctly
like one facies or the other, but there is no apparent
systematic vertical change.
Trcs/si
2
- Sandstone With Interbedded Siltstone
Description. The dominantly sandstone facies
(Trcs/si
2) consists of medium- to coarse-grained,
typically grayish-pink (5R 8/2) to pale-red (10R 6/
2), very feldspathic sandstone that grades upward
through finer-grained sandstone into reddish-brown,
bioturbated siltstone and mudstone. Mus-covite
mica is a very common accessory mineral.
Sandstones ofthis facies are distinguished from the
Trcs/sij sandstones by their generally coarser grain
size, noticeably abundant pink potassium feldspar
which gives these sandstones a slighdy different
hue (more red), and relatively less biotite. A better
developed and more consistent rhythmic character
of fining-upward sequences also helps distinguish
the Trcs/si
2
facies from the Trcs/sij and other facies
of the study area.
Depositional sequences in this facies are
typically 2 to 5 meters thick. Coarse- to very
coarse-grained pebbly sandstone with very coarse-grained
muscovite generally marks the base of
cycles. Both flattened and rounded mud clasts
commonly overlie scour surfaces. Typically, these
clasts are only 1 to 2 centimeters in diameter as
compared to the much larger clasts of the Trcs/sij
sandstones. Sequences normally fine upward
through medium- and fine-grained sandstone into
siltstone or mudstone.
Sedimentary structures are commonly
absent or difficult to see due to weathering. Where
crossbedding is obvious, it grades upward from
trough to planar form and decreases in size. Fine-grained
sandstone and siltstone with ripple cross-lamination
and bioturbation gradationally overlie
crossbedded sandstone within fining-upward se-quences.
The few exposures where trough cross-beds
provide paleocurrent data indicate a south-west
flow direction.
Bioturbation is very common within the
muddier beds of this facies and in the thinner sandy
zones between muddier beds. Root structures and
burrows are both present. Thin, discontinuous
lenses of laminated to thin-bedded shale contain-ing
the fossil branchiopod conchostracan (Cyzicus)
occur locally within the Trcs/si
2
unit.
In many outcrops ofthis facies, nodular and
"bedded" limestone zones occur in the thicker
mudstone and siltstone horizons. Limestone nod-ules
are commonly associated with root structures.
The "bedded" limestone occurs as discontinuous
stringers up to several centimeters thick, is usually
dense, and has a laminated structure. Although
these stringers appear to be primary features within
massive mudstone, they rarely yield a strike and
dip conformable with those obtained for enclosing
sedimentary strata. It would thus seem that they are
possibly diagenetic features.
Chert occurs locally within the Trcs/si
2
facies. This is as a replacement of nodular lime-stone;
as float in soil; and, rarely, as pebbles in
channel lag deposits.
Localities. Two key outcrops for this facies are
Locality 7, a roadcut on the west side of Van Road
(SR 2052) approximately 0.3 miles north of its
intersection with Holden Road (SR 1911) (figure
7); and Locality 8, the abandoned Hoover Road
quarry ofBorden Brick and Tile Company which is
reached via an unnamed dirt road that runs west
from East End Avenue opposite Rowena Avenue
(figure 8). Supplementary localities are numbers
9, 10, and 11. Locality 1 1 is the Borden Brick and
Tile Company (a division of Cherokee Sanford
Group) Stone Road Quarry. A significant amount
of stratigraphic section (over 100 meters) was
exposed in the various parts of this quarry. Part of
this section was described by Gore (1986).
Interpretation. Within the Trcs/si
2
facies, well de-veloped,
cyclical, fining-upward sequences con-sist
of pebbly, trough crossbedded bases which
grade upward through finer- grained, ripple- to
parallel-laminated sands into rooted and burrowed,
13
t—m—
r
M VFSFS MSCS
Covered
Pale-reddish-brown (10R 5/4), coarse-grained, micaceous, feldspathic sandstone
grading upward through medium- to fine-grained sandstone to dark-reddish-
brown (10R 3/4) siltstone.
Pale-reddish-brown (10R 5/4), coarse-grained, feldspathic sandstone fining
upward to medium-grained sandstone. Pebble lag at base; lenses of coarse- to
very coarse-grained sandstone occur near top of interval.
Pale-red (5R 6/2), coarse- to very coarse-grained, micaceous, feldspathic
sandstone. Pebbles, granules, and siltstone rip-up clasts at base. Largest clast is
a 4 cm pebble of felsic intrusive rock. Lower 1 m is crossbedded and biorurbated.
Dark-reddish-brown (10R 3/4), medium-grained, micaceous, feldspathic
sandstone fining upward to siltstone. Lower half of interval contains lenses of
coarse - to very coarse-grained sandstone with pebbles.
Pale-reddish-brown (10R 5/4), coarse- to very coarse-grained, micaceous,
feldspathic sandstone fining upward to dark-reddish-brown (10R 3/4),
fine-grained sandstone. Base of interval consists of a 10 cm muddy zone
(weathered rip-up clasts?) overlain by pebbles and granules.
Pale-reddish-brown (10R 5/4), coarse- to very coarse-grained, micaceous,
feldspathic sandstone grading upward to dark-reddish-brown (10R 3/4),
fine-grained sandstone. Upper sandstone coarsens laterally. Sand-filled vertical
and horizontal burrows occur at top of interval.
Figure 7. Section of Trcs/si facies exposed along Van Road (SR 2052) (Locality 7).
sometimes calcareous, siltstone and mudstone.
These characteristics are consistent with lateral
point bar aggradation within a meandering fluvial
system surrounded by a vegetated floodplain
(Cant, 1982; Walker and Cant, 1984). The carbon-ates
appear to be pedogenic and are partially re-placed
by chert. The abundant potassium feldspar
and mica, along with the coarse to very coarse grain
size of the Trcs/si
2
facies, especially in the more
northern portion of this facies, suggests a granitic
source area.
Trcsi/s - Siltstone With Interbedded Sandstone
Description. The upper part of the Trcs/s^ facies
grades southward into the Trcsi/s facies that gener-ally
underlies the Research Triangle Park area.
Temporary exposures made during construction of
the Southern Parkway from Miami Boulevard (SR
1959) east to about Page Road (SR 1973) and
subsurface data obtained from the North Carolina
Department of Human Resources (Soil and Mate-rial
Engineers, 1987) were important supplements
to the otherwise sparse outcrop data for this facies.
Siltstone is the dominant lithology of the
Trcsi/s facies. It is typically reddish brown with
light-green to whitish-gray mottling along both
fossil and modern root structures (similar mottling
is also developed along fractures within the soil
zone). Bedding is usually massive; however, this
may be due to either weathering or intense biotur-bation
which has destroyed primary structures.
Scoyenia burrows are very abundant. Laminated to
thin-bedded reddish-brown shale containing con-chostracans
and ostracods occurs at several locali-ties.
Sandstones within this facies are fine- to
medium grained and are usually less than a meter
thick. Sandstone composition is difficult to dis-cern
in the field because of the relatively fine grain
14
t—
m
M VFS FS CS VCS
Grayish-orange-pink (10R 8/2), coarse- to fine-grained, micaceous, feldspathic
sandstone. Individual beds are separated by thin shaly partings. Lower sandstone
contains trough crossbeds up to 30 cm high; smaller planar crossbeds occur
higher in sandstone.
Grayish-orange-pink (10R 8/2), medium-grained, micaceous, feldspathic sand-stone.
Bed pinches out laterally.
Grayish-orange-pink (5YR 7/2), coarse-grained, micaceous, feldspathic sand-stone
grading upward to crossbedded fine- to medium-grained sandstone.
Contains large vertical burrows.
Mottled light-bluish-gray (5B 7/1) to grayish-red (10R 4/2) to brownish-gray (5
YR 6/1), bioturbated, micaceous, very fine-grained feldspathic sandstone with
calcareous nodules. Thin lens of fine-grained calcareous sandstone near top of
interval. Sand-filled burrows occur at upper contact.
Mottled grayish-red (10R 4/2) to light-gray (N7), medium- to fine-grained,
micaceous, feldspathic sandstone. Granule conglomerate with siltstone rip-up
clasts occurs at base and abruptly grades upward to bioturbated fine-grained
sandstone with faint planar crossbeds.
Moderate-brown (5YR 3/4), micaceous siltstone. Intensely burrowed with
horizontal burrows and large vertical burrows; contains calcareous nodules.
Moderate-brown (5YR 3/4), fine-grained, micaceous, bioturbated, feldspathic
sandstone with small planar crossbeds.
Moderate-brown (5YR 3/4), silty, micaceous, fine-grained, feldspathic sandstone
with horizontal burrows.
Figure 8. Composite section of Trcs/si
2
facies exposed in abandoned Hoover Road Quarry of Borden
Brick and Tile Company (Locality 8).
size. In coarser lenses, sandstones are clearly
feldspathic. Two sandstone samples from this
facies that were examined petrographically are
arkose (figure 9).
In a few exposures the sandstones exhibit
small-scale planar crossbedding and ripple cross
lamination. Otherwise, flow structures were not
observed. Fining or coarsening trends within indi-vidual
sandstone beds are usually very subtle or
absent. Subsurface data and surface exposures
suggest that many of the sandstone beds are len-ticular
in cross-section. However, in several in-stances
beds persist laterally within a given out-crop
(for example Locality 12) for tens of meters.
This persistence of such thin beds suggests a sheet-like
geometry.
Nodular and "bedded" carbonate horizons
as described above for the Trcs/si
2
facies are exten-sive
within the Trcsi/s facies. Most outcrops con-tain
some carbonate either in this form or as cement
within siltstone beds. Chert, also more abundant in
this facies than others, is most often found as float;
however, a number of outcrops contain in-place
chert stringers or nodular-like "bedded" masses.
These are nearly always associated with carbonate.
The major difference between the Trcsi/s and Trcs/
si
2
facies with respect to carbonate and chert is the
relative abundance rather than any characteristic
related to depositional setting. Wheeler and Tex-toris
(1978) hypothesized that chert and limestone
of the Research Triangle Park area (Trcsi/s facies
of this report) were deposited in and along the
margins of playa lakes. The fact that chert and
limestone lithologies occur across several facies of
the basin and that these facies are clearly the result
of sustained fluvial deposition argues against this
hypothesis.
Subsurface data (Soil and Material Engi-neers,
1987) from the main IBM facility located
15
Quartz
^V_— Quartzarenite
Subarkose \ Sublitharenite
r ° /" T\
/d n/
•
\ \
/ /
\ \
/ / Lithic
/ Arkose / Arkose
Feldspalhic \ \
Litharenite \ Litharenite \
Feldspar Rock Fragments
O Trcs/si i Trcsi/s Trcsc
n Trcs/si2 Trcs • Trcs/c, Tree
Figure 9. Ternary plot of sandstone composition
from point-count data. Classification after
Folk (1974).
west of Miami Boulevard (SR 1959) and south of
Alexander Drive (SR 2028) is consistent, at least in
a qualitative sense, with what is indicated for this
facies by outcrop. Drill cuttings and core descrip-tions
document a section that is predominantly
mudstone with interbedded, reddish-brown to tan,
pink, or pinkish-brown, fine- to medium-grained
sandstone. Numerous thin carbonate horizons were
reported.
Localities. Representative outcrops of the Trcsi/s
facies are found at Locality 1 2, along N.C. 55 south
ofits intersection with Alexander Drive (SR 2028),
and Locality 13, ditch and roadcut exposures in the
vicinity of the intersection of N.C. 54 and Davis
Drive (SR 1999).
Interpretation. Laminated shale beds in theTrcsi/s
facies indicate deposition in quiet standing water.
In a sewer excavation (now filled) along Stirrup
Iron Creek, northeast of the Miami Boulevard (SR
1959) - Interstate 40 interchange, a few fish scales
were found with conchostracans and ostracods.
These fossils were deposited in a brownish-gray
laminated shale overlying a coarsening-upward
sandstone sequence containing climbing ripples.
This is interpreted as a lake margin deposit. Olsen
( 1977) observed a 1 -meter-thick laminated siltstone
bed south of this study area which contains abun-dant
fossils, including fish scales and bones. That
bed was interpreted as being oflacustrine origin set
within an overall fluvial sequence (Olsen, 1977;
Renwick, 1987).
The Trcsi/s facies is interpreted as repre-senting
mostly fluvial overbank deposits with lo-cally
developed, areally limited, ephemeral, shal-low,
freshwater lakes. Abundant root structures
and carbonate nodules suggest that exposed sur-faces
were vegetated and that soils developed on
them. The Trcsi/s facies may represent a local
lowland away from the main fluvial belt of the
Trcs/si
2
facies or it could represent a change to
muddier conditions in the later part ofdeposition of
Lithofacies Association II. The change could be
due to basin filling or an increased input of fine-grained
sediment from another source area (possi-bly
the east). Another consideration is that the
drainage system of this lithofacies association may
have flowed into a large lake to the south. A
relative rise of that lake's level would tend to
decrease stream gradients within its feeder fluvial
system.
Lithofacies Association III
Lithofacies Association III is comprised of
four lithofacies that are texturally and mineralogi-cally
distinct from the sedimentary rocks of the
first two lithofacies associations. Namely, musco-vite,
which is very common in the rocks of Litho-facies
Associations I and n, is absent from these
rocks. Also, lithic fragments are more common.
Matrix is a more significant component and ma-trix-
supported textures are common. The facies of
this association progress from massive, boulder-dominated
deposits (Tree) adj acent to the Jonesboro
fault through gradually finer grained cobble, pebble,
and sandstone deposits (Trcs/c and Trcsc) to muddy
sandstone (Trcs) toward the central portion of the
basin.
16
Trcs - Sandstone
Description. A dominantly sandstone fades (Trcs)
comprises the most distal and finest grained facies
of Lithofacies Association in. This facies gener-ally
consists of reddish-brown, poorly- to moder-ately
sorted, fine- to medium-grained sandstone
and muddy sandstone. Matrix-supported granules
and coarse sand grains are common. Locally, some
beds and lenses are moderately well sorted and
relatively low in mud content, but siltstone and
mudstone are typically minor constituents. Com-position,
like texture, is highly variable. Quartz is
the dominant constituent. Lithic fragments are
generally present and in places are abundant.
Noticeably absent from this facies is muscovite.
This property serves to distinguish Trcs sandstones
from sometimes otherwise very similar Trcs/si
2
sandstones. The two samples of this facies that
were examined petrographically plotted as arkose
and lithic arkose (figure 9).
Beds are typically 1 to 2 meters thick and
are commonly tabular bodies that display good
lateral continuity (figure 10). Relatively thin (5 to
20 centimeters), sometimes burrowed, muddy
sandstone zones usually cap the beds of this facies.
Gradation from cleaner sandstone to these fine-grained
zones is usually abrupt. A lack of internal
stratification appears to be due to intense bioturba-tion.
The section exposed by the excavation shown
in figure 10 contains a 25-centimeter-thick, heav-ily
burrowed mudstone bed. Another example of
bioturbation within the Trcs unit is illustrated in
figure 11 (Locality 15). Root mottling similar to
that observed in the other lithofacies associations is
common within this facies.
Localities. A representative section for the Trcs
facies is exposed at Locality 16, a road cut on the
west side ofMiami Boulevard (SR 1959) about 300
meters north of Interstate 40 (figure 12). Supple-mental
localities are numbers 17 and 18.
Figure 10. Exposure of Trcs facies in sewer exca-vation
east of Page Road (SR 1973) at Inter-state
40 (Locality 14).
Figure 11. Excavated block of bioturbated sand-stone
from Trcs facies along Southern Park-way
(locality 15). Rock hammer in lower
right for scale.
17
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Moderate-reddish-brown (10R 4/6), very fine- to fine-grained,
moderately sorted, feldspathic sandstone with scattered light colored
reduction spots. Lacks coarser grains seen in lower beds. Overall
grain size slightly finer than underlying beds.
Dark-reddish-brown (10R 3/4), muddy, fine-grained, feldspathic
sandstone with abundant horizontal burrows.
Moderate-reddish-brown (10R 4/6), very fine- to fine-grained,
moderately sorted, feldspathic sandstone with scattered coarse to
very coarse grains. Reduction spots scattered through bed and
concentrated in a narrow zone near the base.
_^ Zone of reduction spots.
Dark-reddish-brown (10R 3/4), muddy, fine-grained, feldspathic
sandstone with horizontal burrows.
Zone of reduction spots.
Moderate-reddish-brown (10R 4/6), fine-grained, moderately sorted,
feldspathic sandstone with scattered coarse- to granule-sized grains.
Reduction spots scattered through bed and concentrated in a narrow
zone.
Figure 12. Section of Trcs facies exposed at Locality 16 along west side of Miami Boulevard ( SR
1959) about 300 meters north of Interstate 40.
Interpretation. The Trcs facies is somewhat en-igmatic.
It has physical characteristics, namely li-thology,
color, and texture, that place it in Lithofa-cies
Association III; yet the unit's fluvial charac-teristics
suggests a close relationship with Lithofa-cies
Association II deposits. An intertonguing
relationship between Lithofacies Association II
and Lithofacies Association III is indicated by
interbedding ofmicaceous, arkosic sandstones and
mudstones of the Trcs/si
2
facies with muddy, ma-trix-
supported, poorly sorted, sandstons of the
Trcs facies. This relation is exhibited at Locality
17, the Borden Brick and Tile Highway 70 quarry,
along the road into the quarry, and in the northeast-trending
drainage east of the quarry. Locally, the
two lithofacies associations also exhibit a mixing
of lithologic and sedimentologic characteristics.
The Trcs facies appears to reflect deposi-tion
in broad shallow channels incised into muddy
flats. The eradication of internal stratification by
bioturbation indicates relatively thin depositional
units or relatively long periods of non-deposition
between sedimentation events or both. Muddy,
matrix-supported sandstones may also represent
distal debris flow deposits or hyperconcentrated
stream flow deposits (Nilsen, 1982; Pierson and
Scott, 1985)
Trcsc - Pebbly Sandstone
Description. Sandstone of the Trcs facies grades
upsection and southeastward to pebbly sandstone
of the Trcsc facies. The Trcsc facies consists of
reddish-brown, poorly sorted sandstone with at
least 5 percent gravel (chiefly granules with subor-dinate
amounts of pebbles and cobbles). Coarse
clasts are generally matrix supported and scattered
throughout sandstone beds. Siltstone and mudstone
are minor components in this facies. Two of the
three point-counted samples from this facies are
feldspathic litharenites; the third is a lithic arkose
(figure 9).
Bedding on the order of 1 to 3 meters thick
is defined by concentrations ofpebbles and cobbles
18
along basal contacts. These contacts are usually
scour surfaces with conglomeratic zones that range
up to 50 centimeters thick. The conglomeratic por-tions
grade rapidly upward into poorly sorted sand-stone.
Such beds are laterally continuous for only
a few meters. Internal stratification is limited to
rare occurrences of pebble and cobble trains,
commonly only one or two clast diameters thick,
which define flat to slightly inclined lenses within
sandstones. Root mottling is common in this
facies.
Localities. A representative section of the Trcsc
facies is exposed at Locality 20, a roadcut on the
north side of Kemp Road (SRI902) j ust east of its
junction with Virgil Road (SR 1903) (figure 13).
Supplementary outcrops are at Localities 19, 21,
and 22. This facies is very poorly exposed through
the southern half of its mapped extent. Here, a few
scattered outcrops and the relative abundance and
size of gravel float were used to infer the distribu-tion
of the unit.
Interpretation. The Trcsc facies appears to have
been deposited in broad, shallow channels. The
poor sorting and general lack of stratification within
the sandstones may indicate deposition by streams
with high sediment concentrations (hyperconcen-trated
flow) or it could be due to bioturbation
disrupting previously better stratified deposits.
Some of the deposits may also have been formed by
low-viscosity debris flows (Nilsen, 1982). The
coarser grain size and paucity of muddy interbeds
suggest higher energy flow conditions for this
facies versus for the Trcs facies.
Trcs/c - Sandstone With Interbedded Conglomer-ate
Description. Pebbly sandstone of the Trcsc facies
grades upsection and southeastward toward the
basin margin into a coarser grained facies consist-ing
of sandstone with interbedded conglomerate
(Trcs/c). The presence of well-defined conglomer-ate
beds, as opposed to basal conglomeratic lags,
distinguishes this facies from the Trcsc facies. An
arbitrary cut-offof less than 50 percent conglomer-ate
was used to distinguish the Trcs/c facies from
the overlying conglomerate facies (Tree). Most
outcrops of Trcs/c facies exhibit considerably less
conglomerate than this 50 percent limit.
Rock fragments are a noticeable compo-nent
of the pebbly sandstone facies. Two samples
that were point counted plot as arkose and lithic
arkose (figure 9). Sorting is poor and matrix-supported
granule and larger size clasts are very
abundant in the sandstone beds. Within the con-glomerate
beds, both matrix- and clast-supported
textures occur. Conglomerate clasts, generally
coarser than in the Trcsc facies, are mostly cobble
size. The average clast size tends to be larger in the
area north of Leesville Road (SR 1906) where the
width of the outcrop belt decreases. Also to the
north, bedding is more regular with distinctly inter-bedded
sandstone and conglomerate. Clasts in the
northern area are chiefly coarse-grained intermedi-ate
to felsic intrusive rock. South of Leesville
Road, clasts primarily reflect metavolcanic and
metasedimentary source materials.
Outcrops of this facies are relatively sparse
and small. Therefore the relative abundance of
cobble- to boulder- size float was used in some
areas to delineate the unit. Outcrop observations in
the adjacent Cary and Bayleaf Quadrangles were
useful in projecting contacts through areas of lim-ited
access or exposure.
Localities. At Locality 23, the Trcs/c facies is ex-posed
along the sides and bottom of Rocky Branch
for a distance of several hundred meters. Here the
facies consists of alternating tabular sandstone and
conglomerate beds that are approximately equal in
thickness (usually 1 to 2 meters). A second refer-ence
locality is number 24, the east bank of Little
Brier Creek approximately 500 meters north of
Globe Road (SR 1644), and a supplemental local-ity
is number 25. At these two outcrops, the con-glomerates
are channel shaped and define scour
surfaces on underlying pebbly sandstone beds.
These gravels fine upward into pebbly sandstone.
Figure 14 illustrates an outcrop (now covered) of
the Trcs/c facies located about 300 meters south of
19
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Figure 14. Interbedded sandstone and conglomer-ate
of Trcs/c facies at Raleigh-Durham Inter-national
Airport (now covered). Rock ham-mer
in lower left of photo for scale.
the Southeast Durham Quadrangle on Raleigh-
Durham International Airport property.
Interpretation. The Trcs/c facies appears to have
been deposited in broad, relatively shallow chan-nels
by streams with high sediment concentrations
or as debris flows or both. Streams that deposited
this facies were apparently larger and deeper than
those that deposited the Trcsc facies.
Tree - Conglomerate
Description. The Trcs/c facies grades upsection
and southeastward toward the border fault into a
dominantly conglomerate facies (Tree). The Tree
facies is composed mainly of cobble- to boulder-size
clasts that occur in thick to massive beds with
a subordinate amount of very coarse-grained to
gravelly sandstone as matrix, beds, and lenses.
Both clast-supported and matrix-supported tex-tures
are found within the conglomerates of this
facies. Clasts are generally rounded and their size
and composition are highly variable.
Localities. The coarsest-grained deposit observed
is at Locality 26 where massive Triassic conglom-erate
is in fault contact with deeply weathered,
foliated crystalline rocks of the pre-Mesozoic
Carolina slate belt (figure 15). Bedding is not
apparent within the conglomerate adjacent to the
fault. Clast orientation is chaotic with material
ranging from boulder to coarse sand size being
thoroughly intermixed. The largest boulders at this
locality (many are over a meter in diameter) are
metamorphosed felsic volcanic rock. Specular
hematite clasts (ranging up to boulder size), quartz-ite,
and foliated metamorphic clasts are common.
About 300 meters southwest of this first
locality is another Tree outcrop (Locality 27) in
which the conglomerate adjacent to the border
fault is again exposed. Here, several crudely de-fined
beds of granule to pebbly sandstone and
conglomerate are exposed in an excavated ditch
behind the Trusswood manufacturing facility load-ing
yard off Running Oak Road (figure 16).
Maximum clast size is about 50 centimeters with
average clast size about 10 centimeters. Clasts are
chiefly foliated metamorphic rocks, metavolcan-ics,
and quartz.
The Tree facies exhibits systematic com-positional
and textural changes along strike. North
of the Leesville road area, felsic intrusive (granitic
to dioritic) clasts predominate. Sandstone inter-beds,
averaging about 0.5 meters thick, are more
distinct in the northern area. Sorting within the
conglomerate beds, which are generally 1 to 2
meters thick, is somewhat better toward the north.
Average clast size in the northern conglomerates is
about 10 to 12 centimeters and these clasts are usu-ally
more spherical than the clasts of the southern
area. A representative outcrop (Locality 28) of the
northern conglomerate occurs in the bank ofRocky
Branch east of Virgil Road (SR 1903) where a
small power line crosses the drainage.
Interpretation. The Tree facies, with its poor
sorting and matrix-supported character, is inter-
21
•>>>>>>>,Weathered
#&/&:, Tree .-.'.'
Figure 15. Jonesboro fault exposed at Locality 26 in Leesville Industrial Park off Westgate Road (SR
1837). Breccia zone is about 1.5 meters wide. View is northeast along trend offault. Gullying along
fault creates illusion of a southeast dip in this photo.
preted as primarily representing debris flow depos-its.
Lenses of grain-supported conglomerate are
interpreted as deposits of small channels. These
channels either were incised into debris flows or
flowed around them. To the north, channel depos-its
are more dominant in this facies.
The Trcsc, Trcs/c, and Tree facies are inter-preted
as the deposits that developed adjacent to
the eastern border fault as alluvial fans extending
northwestward into the basin. Several paleocur-rent
measurements based on imbricated pebble
orientations indicate northwestward flow. This
information, together with the consistent eastern
source or provenance, the gradational fining of the
facies away from the eastern border fault, the
basinward transition from debris-flow-dominated
to fluvial-dominated deposition, and the basin-ward
transition from thicker channel conglomer-ates
to thinner, sheet-like sandstones are all consis-
22
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23
tent with an alluvial fan model (Nilsen, 1982). The
systematic lithologic change of the conglomerate
deposits along strike suggests that there were
multiple feeder systems operating along the border
fault to produce a complex deposit.
Variable width of outcrop for the respec-tive
fan facies may be attributed to at least two
causes. First, variable original thicknesses, either
depositional or erosional, may have developed
within the individual fan facies. Second, post-depositional
reactivation of normal faults of the
border fault zone would alter the outcrop width of
the various facies. The rounded nature of the
conglomerate clasts, especially of very large clasts
adjacent to the border fault, suggests reworking
and supports the latter consideration. Both options
are viable and they are not mutually exclusive.
STRUCTURE
Strike and dip measurements were difficult
to obtain from the generally poor and highly weath-ered
exposures. Those strike and dip measure-ments
shown on Plates 1 and 2 include several
which are only approximate. The most reliable
measurements—where bedding orientation was
unequivocal—tended to be measurements that most
consistently agreed with regional strike of about
N40°-50°E with a 7- 10° southeast dip. Intrabasinal
block faults which have been demonstrated else-where
in the basin (Bain and Brown, 1980) can not
reasonably be interpreted from our structural data;
but neither can their likelihood be excluded. Only
minor (outcrop scale) faults such as the fault that
occurs at Locality 2 or the one reported by Gore
(1986) for Locality 1 1 were observed. These are
generally high-angle normal faults with displace-ments
on the order of 1 to 1 meters. None of these
are mappable at 1:24,000 scale.
The western border of the basin is not ex-posed
in the study area. A roadside ditch on the
northeast side of Cornwallis Road (SR 1308) about
0.1 miles northwest of the intersection with Erwin
Road (SR 1306) contains outcropping felsic intru-sive
rocks in close proximity (less than 2 meters) to
typical arkosic sandstone of the Trcs/sij facies but
their contact relationship is not evident. Angular
quartz cobbles, suggestive of conglomeratic de-posits,
are common as float in sandy soil devel-oped
on Trias sic sedimentary rocks in the area
northwest of Erwin Road and east of the Orange-
Durham County Line. An exposure at Nello Teer
Company's Durham Quarry, located about 4.5 to
5.0 kilometers from the area described above,
provides some indication as to the nature of the
basin's western border. In the quarry, up to 10
meters of arkosic sandstone with interspersed beds
of conglomerate unconformably overlie felsic
volcanic rocks of the Carolina slate belt. The
unconformity dips southeastward. Neither the
quarry exposure nor outcrops in the Durham South-west
Quadrangle provide evidence of a western
border fault along this segment of the Durham
basin.
Using a 7°-10° southeast dip, a 26 kilome-ter
width of the basin, and a 65° dip for the eastern
border fault, the projected maximum thickness for
the rocks of the Durham basin is 3.0 to 4.2 kilome-ters.
Given that the eastern border is step-faulted
(Bain and Brown, 1980), the maximum thickness
could be considerably less than this value. Bain
and Brown (1980), on the basis of gravity and
aeromagnetic modeling, estimated the maximum
thickness of the Durham basin to be about 2 kilo-meters.
This is not inconsistent with the observa-tions
of this study.
DISCUSSION
DEPOSITIONAL MODEL
The three lithofacies associations define
three belts of different provenance and deposi-tional
style: a western belt of arkosic anastomosing
braided stream deposits, a central belt of arkosic
meandering stream deposits, and an eastern belt of
conglomeratic alluvial fan deposits. The pale-ogeographic
reconstruction of this portion of the
Durham basin can be interpreted several ways
depending upon how the stratigraphic relation-ships
of these belts are viewed. Figure 17 illus-
24
NW
|_—^-| siltstone
sandstone
\'.*%?j\ conglomerate & pebbly sandstone
p>— <<l| swamp/wetlands
NW ^L'ihof,„,
^oracies
|~—~^-| siltstone
U- .•'-.[ sandstone
f*.»;.y^ conglomerate & pebbly sandstone
[>— CI swamp/wetlands "mm trend of time lines
Figure 17. Sketch diagrams of possible depositional models. Upper sketch represents lateral facies model wherein the three
lithofacies associations are deposited throughout the depositional history of basin. Lower sketch shows Lithofacies
Association I as an early stage depositional unit underlying Lithofacies Association II. Both models presume persistent
alluvial fan deposition (Lithofacies Asssociation III) along southeastern basin margin.
25
trates the two principle interpretations. In one
sketch, each of the belts represent laterally equiva-lent
facies. By this model the central belt fluvial
deposits intertongue with alluvial fan deposits
draining from an eastern highland and with fluvial
deposits draining from a lower relief western high-land.
Small lakes formed in the central lowland in
interchannel areas.
Textoris and Holden (1986), and Traverse (1986).
The first two of these papers concluded that there
were alternating wet and dry climatic cycles during
deposition of these rocks. On the other hand,
Traverse (1986), citing palynological evidence,
interprets a "drying-upwards" trend from four
Sanford basin samples which span from early to
late Carnian.
Alternatively, as shown in the other sketch,
the western and central belts may each represent a
period ofdeposition in the basin. By this model, the
western belt was deposited during an early stage of
basin development and the central belt was depos-ited
subsequently. In this scenario, the western belt
rocks would extend southeastward beneath the
central belt rocks and intertongue with early stage
alluvial fan deposits. The western belt rocks would
also represent, at least in part, an axial fluvial
system in this model.
Resolving between these two models is
difficult with the data presently available. The map
pattern of the lithofacies belts, the gradational
nature of the contact between the western and
central belts, and the intertonguing nature of the
contact between the central and eastern belts are
consistent with both models. The available pale-ocurrent
data are insufficient to constrain either
model. One consideration is that the lateral facies
model requires that the fluvial drainage systems
persist during accumulation of several kilometers
of section within a technically active basin. This
is unlikely, and significant lateral shifts in the
facies would be expected. The degree to which
these shifts would occur is unpredictable. The
impact of such shifts on the model would be to alter
the amplitude and frequency of the intertonguing
between the two facies. In the final analysis, any
model, based solely on outcrop study, will proba-bly
not apply to the full history of the basin.
PALEOCLIMATE
The paleoclimate of the Durham basin
sedimentary rocks has been discussed in several
papers including Wheeler and Textoris (1978),
One striking aspect of the Durham basin
sedimentary rocks is the abundance of primary
sedimentary structures indicative of generally wet
conditions. Mainly these are root casts and bur-rowing.
Virtually every facies except the con-glomerate
is extensively bioturbated. Smoot and
Olsen (1985) classified massive mudstones of the
Newark Supergroup into mudcracked, sand-patch,
root-disrupted, and burrowed types. The first two
types were considered indicative of dry paleocli-matic
conditions while the latter two were consid-ered
indicative of wet conditions. Durham basin
mudstones are almost exclusively the burrowed
and root-disrupted types.
The interpretation of nodular limestone as
caliche is one of the major points cited by propo-nents
an arid or semi-arid paleoclimate (Textoris
and Holden, 1986). Smoot and Olsen (1985)
described small spherical nodules of micritic cal-cite
concentrated in root tubes and surrounding
matrix of their root-disrupted massive mudstones
(wet conditions). The possibility that nodular
limestone may be formed in a humid setting pre-cludes
the need to interpret a dry paleoclimate on
the basis of nodular limestone.
In summary, the evidence pertinent to inter-pretation
of the paleoclimate remains equivocal,
but the field observations of this study appear to
favor the interpretation that the sedimentary rocks
exposed in the Durham basin were deposited under
dominantly wet conditions.
CONCLUSIONS
Trias sic sedimentary rocks exposed in the
26
Southeast Durham and Southwest Durham 7.5-
minute Quadrangles comprise seven distinct litho-facies
that may be grouped into three lithofacies
associations with distinctive lithological and sedi-mentological
characteristics. Adjacent facies are
gradational and intertonguing. These rocks were
intruded during the Early Jurassic by dikes and
sheets of diabase. Either of two main depositional
models may account for the field relationships seen
in outcrop. This mapping of the sedimentary and
igneous rocks of a portion of the Durham basin is
a considerable revision and refinement ofprevious
reconnaissance work. Much additional work and
data are required to reliably characterize the geo-logic
history of this basin.
ACKNOWLEDGEMENTS
This project was proposed and conducted
under the Cooperative Geologic Mapping Program
(COGEOMAP) between the United States Geo-logical
Survey and the North Carolina Geological
Survey (Agreement Number 14-08-0001-A0433).
Work began in February, 1987, and had a duration
of 12 months. A report was submitted by the North
Carolina Geological Survey to the U. S. Geological
Survey in February, 1988, as part of the contract
between the two agencies. This report is a revision
of that contractual report with limited additional
field and laboratory work.
Joe Smoot and Al Froelich of the U.S.
Geological Survey were cooperating investigators
who provided field consultation during the map-ping
and supplied unpublished manuscripts, field
notes and sketches, and geophysical data to aid in
preparation of the contractual report. Vic Cavaroc
of North Carolina State University, as well as
Smoot and Froelich, reviewed the contractual re-port.
Their efforts were significant and greatly
improved this report.
North Carolina Geological Survey col-leagues
Al Carpenter, Jeff Reid, Leonard Wiener,
and Carl Merschat provided helpful review of this
report.
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P-Smoot,
J. P., Froelich, A. J., and Luttrell, G. W.,
1988, Uniform symbols for the Newark Su-pergroup,
in Froelich, A. J., and Robinson, G.
R., Jr., editors, Studies of the early Mesozoic
basins of the eastern United States: U.S.
28
Geological Survey Bulletin 1776, p. 1-6.
Smoot, J. P., and Olsen, P. E., 1985, Massive
mudstones in basin analysis and paleoclimate
interpretation of the Newark Supergroup, in
Robinson, G. R., Jr., and Froelich, A. J., edi-tors,
Proceedings of the Second U.S. Geologi-cal
Survey Workshop on the early Mesozoic
basins of the eastern United States: U.S.
Geological Survey Circular 946, p. 29-33.
Soil and Material Engineers, 1987, Appendix C
—
Geologic Well Records, Post Closure Permit
Application, prepared by International Busi-ness
Machines and Soil and Material Engi-neers,
Cary, North Carolina.
Smith, D. G., and Smith, N. D., 1980, Sedimenta-tion
in anastomosed river systems: examples
from alluvial valleys near Banff, Alberta:
Journal of Sedimentary Petrology, v. 50, p.
157-164.
Textoris, D. A., and Holden, C. J., 1986, Paleocli-mate
change within a stratigraphic section, in
Gore, P. J. W., Depositional framework of a
Triassic rift basin: the Durham and Sanford
sub-basins of the Deep River Basin, North
Carolina, in Textoris, D. A., editor, Society of
Economic Paleontologists and Mineralogists
Field Guidebook, Third Annual Midyear
Meeting, Raleigh, North Carolina, p. 101-
102.
The Rock-Color Chart Committee, 1948, Rock-color
chart: Geological Society of America, 5
pi.
Traverse, Alfred, 1986, Palynology of the Deep
River Basin, North Carolina, in Gore, P. J. W.,
Depositional frameworkofaTriassicrift basin:
the Durham and Sanford sub-basins of the
Deep River Basin, North Carolina, in Texto-ris,
D. A., editor, Society ofEconomic Paleon-tologists
and Mineralogists Field Guidebook,
Third Annual Midyear Meeting, Raleigh,
North Carolina, p. 66-71
U.S. Department ofAgriculture, 1970, Soil Survey
of Wake County, North Carolina: U.S. De-partment
of Agriculture, Soil Conservation
Service, 118 p., 104 pi.
U.S. Department of Agriculture, 1976, Soil Survey
of Durham County, North Carolina: U.S. De-partment
of Agriculture, Soil Conservation
Service, 74 p., 42 pi.
U.S. Geological Survey, 1974, Aeromagnetic map
of parts of the Greensboro and Raleigh l°x2°
Quadrangles: U.S. Geological Survey Open-
File report 74-29, 16 pi., scale 1:62,500.
Walker, R. G., and Cant, D. J., 1984, Sandy fluvial
systems, in Walker, R. G., editor, Facies
Models: Geological Association of Canada,
Geoscience Canada Reprint Series 1, p. 71-
89.
Weigand, P. W., and Ragland, P. C, 1970, Geo-chemistry
of Mesozoic dolerite dikes from
eastern North America: Contributions to Min-eralogy
and Petrology, v. 29, p. 195-214.
Wheeler, W.H., and Textoris, D. A., 1978, Triassic
limestone and chert of playa origin in North
Carolina: Journal of Sedimentary Petrology,
v. 48, p. 765-776.
Wilson, W. F., and Carpenter, P. A., 1981, Region
J geology: a guide for North Carolina mineral
resource development and land use planning:
North Carolina Geological Survey Section
Regional Geology Series 1, 45 p.
29
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30
APPENDIX A - LOCALITY REGISTER
LOC
NO
MAP
UNIT LOCALITY DESCRIPTION LATITUDE LONGITUDE
355610 785506
355319 785636
355810 785710
355250 785606
355709 785359
355811 784725
1 Trcs/sij S side of Pearson Rd (SR 1221) at
Coral Dr about 0.2 mi Wof
FayettevilleRd(SR1118)
2 Trcs/sij Cut along abandoned Norfolk Southern
RR at Fayetteville Rd (SR 1 1 1 8)
3 Trcs/si Exposure behind Uzzle Cadillac on S
side of U.S. 15-501 - 0.5 mi W of
N.C. 751
4 Trcs/sij Cut along abandoned Norfolk Southern
RR 700m N of Scott King Rd (SR 1 103)
5 Trcs/sij Cut behind houses along Ancroft Rd N
of Riddle Rd (SR 1 171) NE of Keene
6 Trcs/si
2
Small SW trending drainage within an
aborted subdivision - SE of int. of un-maintained
Rondelay Dr and Flanders St
7 Trcs/si
2 W side of Van Rd(SR 2052) just N of
Hutson Rd - about 0.3 mi N of
HoldenRd(SR1911)
8 Trcs/si
2
Borden Brick and Tile Company Hoover
Road Pit - N of East End Ave along dirt
road opposite Rowena Ave
9 Trcs/si
2
Bluff on S bank of Little Lick Creek
about 500m upstream from Durham City
sewage treatment plant
10 Trcs/si
2 NE side of Ellis Rd (SR 1954) N of
So-Hi Dr (SR 1951) - just N and
across from Southern High School
11 Trcs/si
2
Borden Brick and Tile Company Stone
Road Pit - N of Stone Rd (SR 1956)
and E of Wrenn Rd (SR 1955)
12 Trcsi/s Roadcut on east side of N.C. 55
0.2 mi S of Alexander Dr (SR 2028)
355816
355834
355907
355638
355701
355237
784828
785135
784826
785200
785127
785329
31
APPENDIX B - LOCALITY REGISTER (continued)
LOC
NO
MAP
UNIT LOCALITY DESCRIPTION LATITUDE LONGITUDE
13 Trcsi/s Exposures at intersection of 355328 785146
N.C. 54 and Davis Dr (SR 1999)
355502 784747
355337 785054
355642 784837
14 Trcs Excavation for sewer pump station in 355257 785003
Stirrup Iron Creek E of Page Rd
(SR 1973) and 1-40 (back-filled)
15 Trcs Cut on S side of Southern Parkway (SR
# not available) 0.4 mi W of U.S. 70
16 Trcs W side of Miami Blvd (SR 1959)
just N of 1-40 interchange
17 Trcs Borden Brick and Tile Company High-way
70 Pit - N of U.S. 70 at end of dirt
road 0.3 mi W of Leesville Rd (SR 1906)
18 Trcs Bluff at sharp bend in unnamed 355715 784723
tributary to Lick Creek E of Doc
Nichols Rd (1908) - about 700m N of
AT&T cable
19 Trcsc N side of Kemp Rd (SR 1902) 0.15 mi 355753 784552
W of Virgil Rd(SR 1903)
20 Trcsc N side of Kemp Rd(SR 1902) just E 355753 784542
of Virgil Rd(SR 1903)
21 Trcsc Upper reach of Martin Branch E of 355627 784607
Olive Branch Rd (SR 1905)
downstream of AT&T cable
22 Trcsc Bluff on E side of uppermost part 355616 784631
of Martin Branch on W side of
Olive Branch Rd (SR 1905)
23 Trcs/c Approx. 300m of streambed in Rocky 355659 784523
Branch - above NE-SW power line
SE of substation
24 Trcs/c E side of Little Briar Creek about 355320 784742
500m N of Globe Rd (SR 1644) - behind
Sheriffs Dept. pistol range
32
APPENDIX B - LOCALITY REGISTER (continued)
LOC
NO
MAP
UNIT LOCALITY DESCRIPTION LATITUDE LONGITUDE
25 Trcs/c Bank of Little Brier Creek about 100m 355405 784720
NofLumleyRd(SR1645)
26 Trcc High-Tech Fabricators - Midway-West
Dr - construction cut at E corner
of building
27 Trcc Trusswood plant - Running Oak Dr off
Westgate Rd (SR 1837) - ditch
excavation on N side of wood lot
28 Trcc E bank of Rocky Branch - domestic
utility line crosses stream and Virgil
Rd (SR 1903) about 0.75 mi N of
Carpenter Pond Rd (1901)
355429
355422
355621
784526
784535
784520
33
APPENDIX C - GEOCHEMICAL DATA FOR DIABASE
Sample sio2
52.20
A12 3
14.05
Fe
2 3
*
11.55
MgO
7.47
CaO
10.80
Na2
1.94
K2
0.53
Ti02
1.18
MnO
0.17
Total
1 JY(2) 99.88
2 DDH-1(4) 48.48 13.78 12.37 12.22 11.10 1.75 0.16 0.42 0.20 100.48
3 DDH-2(8) 48.47 13.82 12.03 12.44 11.09 1.55 0.18 0.40 0.19 100.16
4 JY(5) 52.50 14.56 10.60 7.63 10.02 2.04 0.58 1.20 0.19 99.32
5 BP(20) 48.36 16.34 11.00 10.16 9.97 2.10 0.27 0.68 0.19 99.07
6 DU-6(4) 47.83 15.93 10.57 11.69 9.67 2.05 0.13 0.60 0.21 98.66
7 D5(4) 48.08 16.55 11.94 9.67 10.09 2.09 0.18 0.69 0.19 99.46
8 W&R,#9 48.20 15.40 11.50 9.95 10.57 2.21 0.39 0.45 0.17 100.16
9 W&R, #12 47.20 15.70 11.90 9.85 11.30 1.87 0.20 0.69 0.19 100.16
10 W&R, #6 52.50 14.10 11.50 7.54 10.59 2.11 0.74 1.07 0.18 98.20
11 W&R, #8 52.60 14.90 11.60 7.27 10.76 2.22 0.53 0.75 0.20 98.20
12 W&R, #7 51.10 15.00 12.00 7.69 10.85 2.25 0.43 0.77 0.22 98.20
13 W&R, #2 51.60 15.10 13.50 5.62 10.42 2.54 0.68 1.27 0.20 98.20
14 W&R, #3 53.10 14.00 14.20 5.59 9.69 2.54 0.68 1.09 0.22 98.20
15 W&R, #4 53.00 13.70 13.70 5.33 9.60 2.42 0.51 1.08 0.22 98.20
Number in parentheses represents number of analyses averaged for value.
1. Durham basin, N.C., this study, JY dike, SW Durham Quad
2. Durham basin, N.C., this study , Oak Grove sheet, SE durham Quad
3. Durham basin, N.C., this study , Oak Grove sheet, SE Durham Quad
4. Durham basin, N.C., Ragland and others (1968, Table 3)
5. Durham basin, N.C., Ragland and others (1968, Table 3)
6. Durham basin, N.C., Ragland and others (1968, Table 3)
7. Sanford basin, N.C. Ragland and others (1968, Table 3)
8. Pennsylvania, Weigand and Ragland (1970, Table 1, sample 9)
9. Georgia-Alabama, Weigand and Ragland (1970, Table 1, sample 12)
10. Virginia, Weigand and Ragland (1970, Table 1, sample 6)
11. Georgia-Alabama, Weigand and Ragland (1970, Table 1, sample 8)
12. Connecticut-Pennsylvania, Weigand and Ragland (1970, Table 1, sample 7)
13. Connecticut, Weigand and Ragland (1970, Table 1, sample 2)
14. Virginia, Weigand and Ragland (1970, Table 1, sample 3)
15. North Carolina, Weigand and Ragland (1970, Table 1, sample 4)
34