PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY AND CORRELATION OF THE
AQUIA FORMATION IN THE TYPE AREA, ALONG THE POTOMAC RIVER, VIRGINIA
by
Craig Duncan Faris
Thesis submitted to the Faculty of the
Virginia Polytechnic Institute and State University
in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
in
Geological Sciences
APPROVED:
Dr. R. K. Bambach, Chairman
Dr. D. M. McLean Dr. G. C. Grender
November, 1S82 Blacksburg, Virginia
ACKNOWLEDGEMENTS
I would first like to acknowledge the tremendous
contribution of the late Dr. C. G. Tillman, who served as
committee chairman until his death in April, 1982. It was
at his suggestion that this study was initiated. Dr.
Tillman gave freely of his time and efforts with the sole
intent of helping his students be the best geologists they
could be. He was an asset to the teaching profession and
will be sorely missed.
Many thanks are due Dr. Richard Bambach for assuming
chairmanship of my committee after Dr. Tillman's death. Dr.
Bambach made many useful suggestions and was a great help in
the final synthesis of this thesis.
Dr. Dewey M. McLean and Dr. Gordon C. Grender served on
my committee and made many helpful suggestions and comments.
The Department of Geological Sciences made financial
resources available through a Graduate Teaching
Assistantship,
funding.
the Core Research Grant, and computer
Dr. Richard Cifelli, of the National Museum of Natural
History, kindly made the Cushman collections available to me
and served as a reader.
Doug Murrow and Tony Benger assisted in the field work.
~hanks go to Bill Seaton for his invaluable discussions
ii
of the Aquia Formation and tremendous encouragement.
Colleagues Mike Huggins and John Firth served as
soundingboards and also s~pplied well-needed diversions.
Lynn Sharp assisted in the dark room.
My parents and family cannot be thanked enough for
their continual support and encouragement.
large part in the completion of this thesis.
They played a
Many thanks go to Nancy Cox for assistance on the SEM,
typing, and drafting, as well as needed encouragement.
The final, but greatest, thanks go to my Lord Jesus
Christ. He has given me a new and abundant life and opened
my eyes to the beauty of His creation.
"He is the image of the invisible God, the firstborn over all creation. For by Hirn all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things were created by Him and for Him. He is before all things, and in Him all things hold together."
Colossians 1:15-17
iii
TABLE OF CONTENTS
TITLE PAGE ... i
ACKNOWLEDGEMENTS .................... ii
TABLE OF CONTENTS .................... iv
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . vi
INTRODUCTION . . . . . . . . . . . 1
Geologic Setting of the Aquia Formation ......... 4
Previous work .... 5
Objectives . • . • . 6
STRATIGRAPHY
Stratigraphic Relations ................. 7
Lithology ................... 8
General Paleontology . . . . . • . . . . . . 9
SAMPLE COLLECTION AND PREPARATION 9
BIOSTRATIGRAPHIC ZONATION ................ 11
BIOSTRATIGRAPHY ..................... 29
Physical Stratigraphy . . . . . . . . . . . . . 38
iv
V
Correlations . . . . . . . . . . . . . . . . . . . . . . 40
Regional Overview .................... 44
SUMMARY ......................... 46
SYSTEMATIC PALEONTOLOGY ................. 49
REFERENCES CITED .................... 62
PLATES ..... 70
APPENDIX: Sample Locations 84
VITA . . . . . . . . . . . . . . . . . . . . . . . . . . 85
LIST OF FIGURES
Figure 1: Location map showing sample localities of
the present study. . . . . . . . . . . . .. 2
Figure 2: Planktonic foraminiferal zonal schemes of
various authors ................ 13
Figure 3: Planktonic foraminiferal zones of
Stainforth, et al ( 1975). . . . . . . . . . . . 24
Figure 4: Range chart of planktonic Foraminifera
recovered in samples CDFS and CDF7 ....... 30
Figure 5: Sampled sections CDFS and CDF7 ......... 32
Figure 6: Sampled sections CDFl and CDFS ......... 36
Figure 7: Biostratigraphic correlation of three
foraminiferal studies of the Aquia Formation
in Virginia .
vi
. 42
INTRODUCTION
Correlation of strata has long been one of the primary
goals of geologic studies. The utilization of planktonic
Foraminifera as guide fossils has significantly added to the
achievement of this goal. The zonal schemes of Balli
(1957), Stainforth, et al. (1975), and Berggren (1978) have
enabled further refinement of correlations and understanding
of the time/ space relationships of Tertiary strata.
In this study, the Paleocene Aquia Formation was
sampled in outcrop in the type area along the Potomac River,
Virginia (Figure 1). The object was to ascertain, through
planktonic foraminiferal data, the exact time stratigraphic
position of the section in relation to the zonal scheme of
Stainforth, et al., ( 1975). Such placement has enabled a
detailed correlation of this section with that of Gibson, et
al. (1980) and Seaton (1982). It is hoped these
correlations will significantly add to the understanding of
the geometry and depositional history of the Salisbury
Embayment.
Field reconnaissance in this study has shown an outcrop
to be Nanjemoy that was previously considered Aquia (Ruhle,
1962). The Cretaceous/Aquia contact is reported in this
study. This has enabled an accurate placement of the upper
and lower formation boundaries.
1
2
Figure 1 : Location map showing sample localities of the present study. Locations of the Oak Grove Core (1980) and Seaton (1982) are also shown.
3
MD
'SEIT STUDY FREDRICKSBUR6
195
VIRGINIA
POTOMAC
' RIVER ·soa .....
NORTH
1 /
_604 1 1 1 mile
4
Geologic Setting of the Aquia Formation
The Atlantic Coastal Plain is an easterly thickening
wedge of Cretaceous and Tertiary marine and non-marine
sediments that range from O feet in the west (along the Fall
Line) to roughly 3000 feet in the east ( of £shore) . The
Coastal Plain strata rest unconformably on Precambrian,
Paleozoic and Mesozoic basement rocks. In the area of
study, the Aquia Formation di sconf ormably overlies Lower
Cretaceous rocks.
The Aquia Formation was deposited in a west-northwest
trending basin, known as the Salisbury Embayment, that
extends from New Jersey to southern Virginia and west to the
Fal 1 Line (Sabet, 1977). The depocenter of the embayment
migrated with time, but during Aquia time deposition was
centered in northern Maryland and southern Delaware (Brown,
Miller and Swain, 1972; Teifke, 1973). The Aquia Formation
thins to the south and west.
Aquia deposition occurred slowly in relatively shallow
water (Nogan, 1964; Drobnyk, 1965; Youseffnia, 1978;
Reinhardt, Newell and Mixon, 1980). The formation
represents the initial phase of the early Tertiary marine
transgressions.
5
Previous Work
The sediments of the Aquia Formation were first
described by Darton (1891), and later by Clark and Martin
(1901). Further studies were by Drobnyk (1965), Daniels and
Onuschak (1974), and Weems (1974).
Cushman (1944) initiated study of the Foraminifera of
the Aquia Formation and gave an Eocene age for the
formation. Shifflett's (1948a,b) work on Aquia Foraminifera
supported
described
an Eocene age.
Foraminifera from
Loeblich and
the Aquia
Tappan (1957b)
Formation and
suggested a late Paleocene age (Landenian). This late
Paleocene age was supported by Page ( 1959), Nogan ( 1964),
Gibson, et al. (1980), and Seaton (1982) by their studies of
Aquia Formation Foraminifera. (Nogan' s suggested age of
Early Eocene for the uppermost Aquia was based on a zone
that has recently been reassigned to the Paleocene.) McLean
(1969), Witmer (1975), and Gibson, et al. (1980) further
documented a Paleocene age based on sporomorphs,
dinoflagellates and calcareous nannoplankton.
Loeblich and Tappan ( 1957b) were the first to employ
planktonic foraminiferal zones in subdividing the Aquia
Formation. Nogan (1964) also employed
foraminiferal zones to the Aquia Formation.
planktonic
However,
6
neither study provided adequate stratigraphic data in order
to relate these zones to the rocks as seen in outcrop.
Gibson, et al. (1980) employed planktonic foraminiferal
zones in the biostratigraphy of a core which penetrated the
Aquia Formation two miles south of Oak Grove Virginia.
Seaton (1982) recently applied an updated planktonic
foraminiferal zonal scheme to outcrops of the Aquia
Formation south of Fredricksburg, Virginia.
Objectives
The objectives of this research are 1) to identify and
illustrate the planktonic Foraminifera occurring in the
Aquia Formation at the type area along the Potomac River,
Virginia; 2) to present an accurate zonal correlation based
on planktonic Foraminifera which can be related directly to
the formation as seen in outcrop; 3) to enhance
understanding of the areal distribution and nature of the
Aquia Formation.
STRATIGRAPHY
Stratigraphic Relations
In the study area the Aquia Formation unconformably
overlies non-marine sediments of the Lower Cretaceous Upper
contact is marked by a Potomac Group. The
lithology in which coarse-grained, mottled,
change of
limonitic
sandstone and micaceous, clayey sand of the upper Potomac
Group are overlain by the medium-grained, glauconite-quartz
sand of the Aquia Formation. The contact is marked by a
boulder conglomerate near Chester and Potomac, Virginia and
along the James River (Clark and Miller, 1912), and along
the Pamunkey River near Fredricksburg, Virginia (Seaton,
1982). No boulder bed was found in this study.
Overlying the Aquia Formation are the variously colored
clays of the 12-20 foot thick Marlboro Clay, of late
Paleocene and early Eocene age. The glauconi tic sands of
the Aquia Formation grade upward into alternating sand and
clay laminae to typical Marlboro clays over a 3-8 inch
interval (Gibson, et al. 1980). The Marlboro Clay is
unconformably overlain by the clay-rich, glauconitic sands
of the Nanjemoy Formation.
The Aquia Formation displays two distinct regional
strikes and dips: 1) north of Stafford, Virginia, and
extending into Maryland, a northeast strike and
7
8
southeasterly dip. 2) south of Stafford, Virginia, a north-
south strike and easterly dip. The study area is in the
transition region where the two orientations grade into one
another.
Lithology
The Aquia Formation is a medium-fine grained
glauconite-quartz sand. The glauconite content varies from
20-70 percent with the quartz content being approximately
inversely proportional (Drobnyk, 1965). Mica content is
variable, but generally less than 10 percent, although
Drobnyk (1965) reports percentages as high as 22. Feldspars
constitute less than 5 percent of the formation. Calcium
carbonate in the form of mollusc shells, Foraminifera tests,
and cement is locally a major constituent.
Calcium-carbonate cemented layers known as "indurated
beds" occur throughout the formation. They vary in
thickness between six inches and one and one-half feet.
Extensive shell beds are also common and range from six
inches to several feet thick. Their major constituents are
Turritella and bivalve shells.
The formation is predominantly dark to olive green.
Leached and weathered bands of brown to yellow color occur
9
in the upper portions of the outcrops.
common and appear as grey blotches.
General Paleontology
Shell ghosts are
The Aquia Formation contains a varied fauna dominated
by turri tel lid gastropods, bi valves, and oysters. Densely
packed mollusc shell beds range from 6 inches to 8 feet in
thickness, although scattered individual shells are also
common. The shells are randomly oriented and often
articulated. Vertebrate remains including shark and ray
teeth, whale bones, and even alligator teeth are common.
Coelenterates are rare. Microfossils include Foraminifera,
ostracodes, palynomorphs, and scolecodonts.
Sample Collection and Preparation
Samples were taken at one-foot intervals on outcrops
along the Potomac River from Aquia Creek to Fairview Beach,
Virginia. The outcrop was cleared of all weathered material
prior to sampling. Each sample was sealed in a plastic bag
and labeled. Sampling tools were cleaned prior to
collecting to avoid contamination. Due to the estuarine
10
nature of the Potomac River at these localities,
consideration was given to maintaining a standard elevation
for the initial sampling level. For this reason, sampling
was begun at the mean low tide level at each locality.
During sample preparation 300-500 grams of sediment
from each sample were boiled in sodium bicarbonate to
defloculate the clay portion. The sediments were sieved
through 45 mesh, 120 mesh, 170 mesh and 230 mesh screens,
consecutively, and washed in water; the sorted sediment was
thoroughly dried in an oven at low temperature. Soap
floating was done on each mesh size to concentrate the
Foraminifera. The concentrate was picked for planktonic
Foraminifera. Selected specimens were photographed using
the Virginia Tech Veterinary Science JEOL35 Scanning
Electron Microscope.
Of the four outcrops sampled, two were chosen for
biostratigraphic analysis. The others were severely leached
or weathered and unsuitable for evaluation. Section CDF7
(Figure 1) generally yielded many (200 or more) planktonic
Foraminifera (although very low diversity) in each sample.
The samples in section CDF5 (Figure 1) were low in
Foraminifera, often with fewer than fifteen specimens.
Preservation was generally good. Two genera and twenty-two
species of planktonic Foraminifera were recognized.
BIOSTRATIGRAPHIC ZONATION
Benthic Foraminifera have been used for correlation
since the late 1800's and early 1900's (Bagg, 1898; Cushman,
1926, 1939, 1946; Dorreen, 1948). They allow precise
correlations for relatively localized areas. Benthic forms
are geographically restricted by the occurrences of the
environments to which they are adapted. The distribution of
specific benthic forms is environmentally controlled. Thus,
zonations based on benthic Foraminifera may have rather
limited applications.
Planktonic Foraminifera are not as restricted in their
distribution as benthic forms. Loeblich and Tappan (1957a)
note their biostratigraphic utility:
Because of their independence of the sea bottom, rapid dispersal by ocean currents, and their ability to select the depth and therefore to some extent the temperature they pref er whi 1~ living, their relatively rapid evolutionary development, and their bouyancy which allows further dispersal even after the death of the organisms, certain planktonic forms supply the best available evidence for worldwide correlations. (p. 1109)
Correlation using planktonic Foraminifera was suggested
as early as 1940 (Cushman & Dorsey, 1940; Thalman, 1942;
Finlay, 1947; Stainforth, 1948; Le Roy, 1948; Grimsdale,
1951), but a comprehensive zcnal scheme did not come into
full use until around 1957. Two significant zonal schemes
11
12
were published at this time (Bolli, 1957; Loeblich and
Tappan, 1957a). Loeblich and Tappan ( 1957a) demonstrated
the practicality of correlation via planktonics and brought
attention to many of the problems inherent in such
correlations, such as provincialism of faunas and the
relationship of planktonic zones to type sections.
Belli' s ( 1957) zones have proven accurate and useful,
and have served as the basis for at least two important
zonal works by Berrgren ( 1971c) and Stainforth, et al ..
(1975) (Figure 2). His zones are presented here as
published in his original paper (Belli, 1957). The zonal
definitions are taken from his range chart and remarks and
are consistent with the explanation for his zones:
The distribution chart of the species of Globigerina and Globorotalia clearly shows the short ranges of most of the species within this age period. This short range pattern led to the present subdivision of the Lizard Springs formation [ Paleocene-Eocene J into eight zones based on the stratigraphic distribution of characteristic single species or groups of species. (p. 62) -brackets added-
Globorotalia trinidadensis zone
Type locality: Lower Lizard Springs Formation, south
Trinidad, BWI - subsurface
Remarks: Begins with the first appearance of calcareous
Foraminifera. Characterized by the concurrent
13
Figure 2 : Planktonic foraminiferal zonal schemes of various authors.)
authors. (Taken from referenced
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15
appearances
Globorotalia
of Globigerina
trinidadensis,
daubjergensis,
Globorotalia
compressa, and Globorotalia pseudobulloides. The
zone coincides with the total range of Globigerina
daubjergensis. The ranges of the others extend
into following zones.
Globorotalia uncinata zone
Type locality: Lower Lizard Springs Formation,
Trinidad, BWI - outcrop (slipmass)
Remarks: The zone is characterized by Globorotalia
uncinata and Globigerina spiralis, which first
appear at the base of the zone. The fauna of the
Globorotalia trinidadensis zone (excluding
Globigerina daubjergensis) is also common to this
zone. The zone coincides with the total range of
Globigerina spiralis.
Globorotalia pusilla pusilla zone
Type locality: Lower Lizard
Trinidad, BWI - subsurface
Springs Formation,
Remarks: Globorotalia pusilla pusilla first appears at
the base of of this zone, in addition to
Globigerina triangularis, Globorotalia anmilata
16
abundocamerata, and Globorotalia ehrenbergi.
Globorotalia angulata is also typical of the zone.
Globototalia pseudomenardii zone
Type locality: Lower Lizard Springs Formation,
Trinidad, BWI - outcrop (slipmass)
Remarks: This zone is defined by the total range of
Globorotalia Globigerina
velascoensis,
pseudomenardii.
Globigerina linaperta, and
Globorotalia aequa are also common to this zone.
Globorotalia velascoensis zone
Type locality: Lower Lizard Springs Formation,
Trinidad, BWI - outcrop
Remarks: Globigerina soldadoensis appears for the first
time at the base of this zone. Globorotalia
velascoensis and Globigerina velascoensis appear
for the last time at the top of the zone. Typical
forms include Globigerina linaperta, Globigerina
primitiva, and Globorotalia aeaua.
Globorotalia rex zone
Type locality: Upper Lizard
Trinidad, BWI - outcrop
Springs Formation,
17
Remarks: Eight species, including Globorotalia rex, and
Globorotalia wilcoxensis appear for the first time
at the base of the zone. The long-ranging
Globorotalia aeaua becomes extinct at the end of
the zone. The zone coincides with the total range
Globorotalia wilcoxensis.
These zones are widely accepted and have been adopted
by Berrgren (1969a,b, 1971a,b,c, 1972, 1978) for his
subdivision
the JOIDES
1971b).
of the Paleocene-Lower Eocene, and applied in
Deep Sea Drilling Project (Berggren 1969e,
Bolli's (1966a) minor revisions of his zones are the
basis for the current zonation Stainforth, et al. (1975).
The most prolific use of Bolli's (1957) zones was by W.
A. Berggren (1965a,b, 1969a,b,c,d,e, 197la,b,c,
1978). Berggren' s original modification of Bolli
1972,
(1957),
al though presented in 1967, was published in 1971 ( Figure
2). Berggren further modified the zonal scheme prior to
publication. This modification was presented in the
addendum of the 1971c paper and is the scheme shown below.
Berggren did not publish range charts or zonal
definitions. The following definitions are inferred from
his text figures and relations to his other published
papers. Below are the zone types used by Berggen.
18
T-R-Z = Total Range Zone, defined by the total range of
index form.
C-R-Z = Concurrent Range Zone, defined by the concurrence of
all or part of the ranges of two or more index
forms.
P-R-Z = Partial Range Zone, defined by a portion of the
range of the index form.
Pl Globoconusca daubjergensis - Globorotalia pseudobulloides
zone
Concurrent range zone
The total zone is defined by the concurrence of the
ranges of Globoconusca daubjergensis and
Globorotalia oseudobulloides before the first
appearance of Globorotalia uncinata and
Globorotalia spiralis. This zone is divided into
three subzones. The limits of these subzones are
indeterminate from Bolli's (1957) range chart but
can be interpolated from the range chart of
Stainforth, et al. ( 1975).
a) Globorotalia pseudobulloides subzone
Defined by the portion of the range of
Globorotalia oseudobulloides between its
19
first appearance and the first appearance of
Globorotalia cornpressa (or possibly
Globorotalia inconstans).
b) Globigerina triloculinoides subzone
Defined ~ the portion of the range of
Globigerina triloculinoides between the first
appearance of Globorotalia comoressa (or
possibly Globorotalia inconstans) and the
first appearance of Globorotalia
trinidadensis.
C) Globorotalia trinidadensis / Gr. inconstans /
Gr. compressa subzone
Defined by the concurrence of the ranges of
all three of the index forms before the
first appearance of Globorotalia uncinata.
P2 Globorotalia uncinata - Globigerina spiralis zone
Concurrent range zone
Defined by the concurrence of the ranges of
Globorotalia uncinata and Globigerina soiralis.
Coincides with the total range of Globigerina
soiralis (as shown by Bolli, 1957).
P3 Globorotalia ousilla - Globorotalia angulata zone
20
Concurrent range zone
Begins at the first appearance of Globorotalia angulata
and, except for the lower portion, is
characterized by the concurrent ranges of the two
index forms. Globorotalia pusilla pusilla appears
after Globorotalia angulata so the bottom of the
zone is not truly a concurrent range zone.
P4 Globorotalia pseudomenardii zone
Total range zone
This zone is defined by the total range of Globorotalia
pseudomenardii.
PS Globorotalia velascoensis zone
Partial range zone
Defined by the portion of the range of Globorotalia
velascoensis between the extinction of
Globorotalia pseudomenardii and the first
appearance of Globorotalia subbotinae.
P6
This zone is divided into two subzones:
a) Globorotalia velascoensis I Globorotalia
subbotinae subzone
21
Concurrent range zone
Characterized by the concurrence of the
ranges of the two index forms between
the first appearance of Globorotalia
subbotinae and the final occurrence of
Globorotalia velascoensis.
b) Globorotalia subbotinae
wilcoxensis subzone
Concurrent range zone
Characterized by the
Pseudohastigerina
concurrence of the
ranges of the index forms between the
final occurrence of Globorotalia
velascoensis and the first appearance of
Globorotalia aragonensis.
The modifications of Berggren (1972) were made in the
Pl and P6 zones ( Figure 2) . Pl was extended to include a
lower subzone, Globorotali a eobulloides, thereby beginning
at the lowermost Paleocene. The Pl zone was changed from
Globoconusca daubjergensis - Globorotalia pseudobulloides C-
R-Z to Globigerina daubjergensis P-R-Z (Globigerina
daubjergensis is a senior synonym of Globoconusca
daubjergensis). The Pl zone is more clearly defined as to
its ending, ie. the final appearance of Gb. daubjergensis.
The Pl Gr. triloculinoides and Gr. pseudobullcides subzones
22
have been reversed in this later publication. The reason
for this reversal is unclear (probably editorial error).
Subzone P6a has been shortened so its ending coincides
with the Pseudohastigerina datum. Subzone P6b has been
changed from Globorotalia subbotinae Pseudohastigerina
wilcoxensis C-R-Z to Globorotalia subbotinae / Acarinina
wilcoxensis P-R-Z. This is a change of index form.
In 1978 Berrgren published another revision (Figure 2).
This revision was contained wholely in the Pl zone:
Pl Globigerina daubjergensis zone
Partial range zone
This zone is divided into three subzones:
a) Globorotalia eobulloides subzone
Interval from the first appearance of
Globorotalia eobulloides to the first
appearance of Globigerina triloculinoides.
b) Globigerina triloculinoides subzone
Interval from the first appearance of
Globigerina triloculinoides to the first
appearance of Globorotalia trinidadensis.
c) Globorotalia cornpressa, Globorotalia inconstans
- Globorotalia praecursoria subzone
Globorotali a praecursori a is thought by
Berrgren to be a senior synonym of
Globorotalia trinidadensis.
23
Subzone is the same as Berrgren (1972).
The modifications at this point were merely
incorporation of the Plc Globorotalia pseudobulloides
subzone into the Plb Globigerina triloculinoides subzone and
a change of nomenclature in the final Pl subzone.
The following zones (Figures 2,3) are a compilation by
Stainforth, et al. (1975). They are taken from Bolli (1957,
1966a). These zones serve as the basis for the zonation
employed in this thesis.
Below are the zone type definitions used by Stainforth,
et al. (1975).
Range zone= zone defined by the total range of index form.
Interval zone = zone defined by the interval between two
arbitrarily chosen end members.
Globigerina eugubina Zone
Category: Range zone Age: Early Paleocene
Author: Luterbacher & Premoli Silva (1964)
Definition: Total range of Globiaerina eugubina.
Globcrotalia pseudobulloides Zone
Category: Interval zone Age: Early Paleocene
Author: Leonov & Alimarina (1961) as Globigerina
pseudobulloides - Globigerina daubjergensis Zone.
24
Figure 3 Planktonic foraminiferal zones of Stainforth, et al. (1975). (Taken from Stainforth, et al., 1975. Only the index fossils recovered in this study are shown.)
25
'-' <.:l PLANKTON IC c ..... FORAMINIFERAL GLOBIGERINA GLOBOROTALIA .... ~ CCC ZONATION ..... <.:l .~ ...
..... >, z ... G1oborota1ia ..... I,,, '-' "' subbotinae C ..... .....
Q)
G1 oborota 1 i a ~ ~ Q)
ve1ascoensis .... 3 . ... ~ "' Q.I lo. .: .... .., ~ ..., ..... ::.. Ii ;:s
~ g-"' 0 C) .... .....
-' ..... ..... ·s .... G1oborota1ia lo. .... oseudomenardii
.....
i 0 z ;:s
G1oborota1ia ;:s <:r' ..... ~ pus i 11 a pus i 11 a 0 0
3 0 ..... C) ;:s
Q.I 0 ..... Q) . ... 0 ... ~ .... ,::
'-' ~ G1oborota1ia Q) l ,:: .: ~ angu1ata 0 ~
-'< C) i 0 - ~ ,:i Q) ~
:::r 0 .... .a ~ ..... :. 0 Globorotalia ..... uncinata }
-' '::!
C(
Gl oborota 1 i a a.. trinidadensis
>, ... I,,, Globorota1ia "' pseudobulloides .....
Globorota1ia eugubina
26
Name shortened by Belli (1966a,b).
Definition: Interval from the first occurrence of
Globorotalia oseudobulloides to the first
appearance of Globorotlia trinidadensis.
Globorotalia trinidadensis Zone
Category: Interval zone
Author: Bolli (1957)
Age: Early Paleocene
Definition: Interval from the first occurrence of
Globorotalia trinidadensis to the first appearance
of Globorotalia uncinata.
Characteristics: Joint occurrence of Globorotalia
trinidadensis,
Globorotalia
Globorotalia pseudobulloides,
Globigerina compressa,
triloculinoides, and Globigerina daubjergensis.
Globorotalia uncinata Zone
Category: Interval Zone Age: Middle Paleocene
Author: Belli (1957), modified Balli (1966a).
Definition: Interval from the first occurrence of
Globorotalia uncinata to the first occurrence of
Globorotalia angulata.
Globorotalia angulata Zone
Category: Interval zone Age: Middle Paleocene
Author: Alimarina ( 1963) as Acarinina angulata Zone.
Present name introduced by Hillebrandt (1965).
27
Definition: Interval from the first appearance of
Globorotalia angulata to the first occurrence of
Globorotalia pusilla pusilla.
Globorotalia pusilla pusilla Zone
Category: Interval zone
Author: Bolli (1957)
Age: Middle Paleocene
Definition: Interval from the first occurrence of
Globorotalia pusilla pusilla to the
occurrence of Globorotalia pseudomenardii.
Globorotalia pseudomenardii Zone
Category: Range zone
Author: Bolli (1957)
Age: Late Paleocene
first
Defintion: Total range of Globorotalia pseudomenardii.
Characteristics: This zone typically contains
Globorotalia pusilla laevigata, Globorotalia
acuta, Globorotalia occlusa, Globorotalia aequa
and others persisting from lower zones.
Globorotalia velascoensis Zone
Category: Interval zone
Author: Bolli (1957)
Definition: Interval from
Age: Late Paleocene
last occurrence of
Globorotalia pseudomenardii to last occurrence of
Globorotalia velascoensis.
28
Globorotalia subbotinae Zone
Category: Interval Zone Age: Early Eocene
Author: This is essentially the Globorotalia rex Zone
of Balli ( 1957, 1966a). ( See Stainforth, et al.
1975, for explanation.)
Definition: Interval from extinction cf Globorotalia
velascoensis to first occurrence of Globorotalia
aragonensis.
Characteristics: This zone typically contains
Globorotalia
marginodentata,
Globorotalia
subbotinae,
Globorotalia
wilcoxensis,
Globorotalia
formosa gracilis,
and others.
Globorotalia aecrua often appears in the lower part
of the zone.
Locality CDF7
This locality
pseudomenardii
characteristic
zone
index
BIOSTRATIGRAPHY
is assigned to
because
fossils
of
(Figure
the
the
3) .
Globorotalia
presence of
Globigerina
triloculinoides is the only zonal foraminifer in the lower
three feet of the section (Figures 4,5). This species has a
relatively long range and by itself can only be used to
limit the section to the Globorotalia pseudobulloides to
middle Globorotalia pseudomenardii zone. Globorotalia
angulata occurs in sample CDF7-9. This species indicates
the sample is no older than the Globorotalia angulata zone,
and no younger than the end of the Globorotalia velascoensis
zone. (The range of Globorotalia angulata has been reported
to extend to the end of the Paleocene. Personal
communication, Seaton, 1982.) The next zonal foraminifer
encountered is Globigerina mckannai, in sample CDF7-10. The
range of this species restricts the sample to the
Globorotalia ousilla pusilla to middle Globorotalia
velascoensis zone. Combined with the concurrence of
Globigerina triloculinoides and Globorotalia angulata this
sample is indicative of the Globorotalia pusilla ousilla to
middle Globorotalia pseudomenardii zone. In sample CDF7-12
29
30
Figure 4 : Range chart of planktonic Foraminifera recovered in samples CDFS and CDF7.
n n n n n n n n n n n n 0 0 0 0 0 0 0 0 0 0 0 0
""" """ """ """ """ """ """ """ """ """ """ """ _, _, _, _, _, _, _, _, _, _, _, _, • . . • . • • . • • • • - N c.., • UI a, m co - - - -C) - N c..,
n n n n n n 0 0 0 Cl 0 0
""" """ """ """ """ """ UI UI UI UI UI UI • • • J. • • - N c.., UI a,
X ~ X X rx X X X X Globigerina aquiensis
~ Globlgerina chascanona
X X X X Globigerina linaperta -~ X IX Globlgerlna mckannai
1x· Globlgerlna cf. G. mckannai
X X ~ Globlgerina spiralis
X IX X IX ~ X X X X X Globigerlna triloculinoides
X X X Globigerlna velascoensis
X X Globorotalia acuta
X IX X Globorotalia aequa w __,
-~ X X Globorotalia angulata X Globorotalla chapmani
X X X X X X Globorotalia convexa
rx ~ X X Globorotalia esnaensis X IX IX IX IX X Globo rota lia i mitata
X X Globorotalia occlusa
IX IX rx IX IX X X ~ IX D< IX X Globorotalla perclara
X X Globorotalia pseudoscitula
IX :x rx X IX IX X IX X IX IX X Globorotalia reissl
X X IX IX IX X X X X Globorotalia trichotrocha X X X X X Globorotalia wilcoxensls
!X X Globorotalia species A
32
Figure 5 Sampled sections CDFS and CDF7.
ffi ["' ' ..
g 17 C,
I t- ' 0 V> 0 - ..... 0 .... w ~a:' 16
'--15
/. 0
1---14 0 -13
(JP
-12
.._/ -11
F z: 0 ..... .... f .-o· 0: 0 LL
<I'. 17 ' ..... 0. ::>
CT <I'.
f--6 --
.--5 -...:..,,-
~ 1--4 I
-3 , . .._:..,..
-2 I ~ (!:1'
-1 I. '--.:.,
'--" ht va Ive
@LlJ Fine Qralned, silty quartz sand; light brown to •trey, 9radt11g upward
Sl1111J11e to red; scattered quartz pebbles 19 - un=nformity
-18 reet
-17 1--14
-16 Med-fine grained, quartz sand; grading upward from tan to buff;
1-15 few Turrltella and bivalves, shell ghosts ____
-14
f--13
-12 I -13
f--11 I -12
11 .--10 z: 0 ..... ....
-10 i ._9 0: 0 LL
-9 Med-fine grained, qlauconttc-quartz sand; grey-green, muttled; no fossils,
-B shell qhosls
-7 it: - gmdational 0<.mtac•t
-6 1--5
Med grained, glaucontte-quartz sand; -5 olive !lreen; abumlant Turrttell~ and .--4
bivalves
-4 1--3 -gmdational eontact
-3 -2 Med qralned, glaucontte-quartz sand;
-2 dark green; abundant Turrtte 1 la and -1
~2T
-------------------CaC03 cemented greensand layer: bivalves and Turr_!_tella ,--, ~- Sample , I 13 -- ehm-p contact , .
I
'---' "o'. .-..,.
. ,qu
-:-'>
-1?
-11
-10
Med-finl' cwalnPd, glaurn11tlP.-qt1arl1 s.111d; qrP.y-grern; ext,·emPly m>.ny b Iva 1 ves, Sl'lll*' T_urr l_te_i_l ~
f '-·· ~ I ·...:__··CJ!'"·,::-_g - a1-.arp cvmt,.r,t ----------s~lll(' ~~ r ont. ,;
~ ·.c? -8
·--~-:...:..- -7
,.___,. ---:--_, -6 c?
~ . 1-5 ~ -~ -4
,..-.... .
- sha,'P ,,onta"t -··-------Same as rr,et fl throu<1h P
- 1thlll1' ,~,ntu~t -----·-CaC03 cemented greens and hyer; abunifant bhalves and Turrttelh
- sharp <Wntact -
Hed-ftne grained, qlaucontte-(Juartz sand; grey-green;ahundant bivalves, some Turrttella (more shPlls than below,------
t---'---'-· -'-" ~-tf--3 - gmdationnl <!ont,ar,t-----
'----' -2
1
hhdlves Med-fine grained, glaucontte-quartz sand; y11.>en; dhundant blvalvP5 and
________________ ____.j.___ __ j.___ _ __,/.___. --.,,,..._<59 __ ._· -----.. __ · ~·· l_.__1 __ r_u_r_r_1t_e_1_1_~------------1
0 shell gh<Jst ~ Turrttella c;, rebt, le
w w
34
three zonal index species appear: Globigerina velascoensis,
Globorotalia aegua, and Globorotalia occlusa. According to
Stainforth, et al .. (1975), Globigerina velascoensis appears
at the base of the Globorotalia pusi lla pusi lla zone and
ranges through the end of the Globorotalia subbotinae zone.
Globorotalia occlusa and Globorotlia aegua first appear at
the base of the Globorotalia peudomenardii zone and range
upward to the base and middle, respectively, of the
Globorotalia subbotinae zone. The concurrence of these
three species combined with the presence of Globigerina
triloculinoides places the samples in the early to middle
Globorotalia pseudomenardii zone.
The upper two thirds of this section is correlated with
the early to middle Globorotalia oseudomenardii zone. The
lower one third is correlated with the Globorotalia pusilla
pusilla to middle Globorotalia pseudomenardii zone because
of it lacks any distinctive zonal index Foraminifera. It is
physically correlative with the Globorotalia pseudomenardii
zone of two related studies in Virginia (see Correlations).
Thus, the whole outcrop is correlated with the early to
Globorotalia pseudomenardii zone.
35
Locality CDF5
Locality CDF5 is contained wholely in the Globorotalia
velascoensis zone (Figure 3). Globigerina linaperta and
Globorotalia wilcoxensis occur for the first time in sample
CDF5-l (Figures 4,5). According to Stainforth, et al.
( 1975), these species first occur in the middle of the
Globorotalia velascoensis zone. They also state that in the
absence of the index species the zone is recognized by the
presence of Globorotalia acuta, which is present at this
locality. The absence of Globigerina triloculinoides and
other forms which become extinct in earlier zones is
consistent with this interpretation. This locality is
assigned to the middle to upper Globorotali a wi lcoxensi s
zcne.
Locality CDFl
No planktonic Foraminifera were found at this locality
(Figure 6). Leaching was extensive and the samples that did
contain Forarninifera had only benthic forms. This locality
is included for discussion because based on the
reconstruction in the Correlation section, the upper
Globorotalia pseudomenardii zonal boundary is thought to
occur in the lower half of the section. The upper half of
the section is stratigraphically equivalent to locality
36
Figure 6 Sampled sections CDFl and CDF8.
ffi[' r W!L!I ~ffi f" I I (CDF 8l
g 17 g 17 Banded brown and orange silty I- Sample I- quartz sand Vl :::! - Fine 9ralned, silty quartz sand; -=onformity w w
6 a:' 16 -18 buff colored a:' 16 -'
~15 17 -unconformity [" ($1' Med-fine grained, qlauconite-quartz I <> -16 sand; light green; extremely many ~14 I Turritella 14
:0 15-gradational aontad
f-13 I I J--13 -14
t--12 I . I Med-fine grained, glauconite-quartz
~" /1 -I
Med-fine grained glauconlte-quartz -13 sand; green; few fossils, mainly sand; olive green; no fossils,
of · I weathered Turrltella shells abundant grey shell ghosts, ~ollthes f-11 I 11
-12
10 z
10 z 11 - gradational aontaat 8 0 I-
,- i ~ 9
a: -10 0 9 a: LL
) .1 I w 0 LL -...J
8 -9 8 c( ~ 0 ;; ~- ::, 0 0 c( -8 c(
7 7
J -7 Med-fine grained glauconite-quartz t--6 I sand; dark green; abundant Turrltella, 6 I· . : I Sample
few bivalves . -6 5 - gradational aonta<'t--
f-5 I (sJ' I 5 -5 -4
t--4 I ·I 4 a,· Fine-med grained glauconite-quartz -4 sand; dark green, grading upward to
-Jolive green; no fossils, abundant f-3 \. -....
·.1-3 3 grey shell ghosts
c<l'.) -2 .- 2 I
-2
t--/. 0 -1 unconformity -1 Coarse grained, limonitic, quartz
"tb sandstone; mottled, burrowed; layer of quartz pebbles at base
....._/ bivalve fP'" Turrltella <'7 shell !Jhost 0 pebble ~ fu:ro 1 i thes
38
CDFS, which is contained in the Globorotalia velascoensis
zone.
into
index
The
the
lower half extends below the base of CDFS and
Globorotalia pseudomenardii zone.
fossils were recovered, the
Although no
stratigraphic
reconstruction ( Figure 7) indicates the zonal boundary at
this location.
Physical Stratigraphy
Outcrop CDF8 ( Figure 6) had at its base an orange,
mottled, burrowed, limonitic sandstone which is overlain
unconformably by greensands. This unconformity may
represent a boundary between the lower Cretaceous and
Tertiary. At some localities, the Aquia/Cretaceous contact
is marked by a conglomerate bed (Ruhle, 1962; Seaton, 1982).
However, Drobnyk (1965) indicates that the conglomerate bed
is not everywhere described and is not essential for
recognition of the boundary. The sediments below the
unconformity accord with descriptions of the Lower
Cretaceous (Clark and Miller, 1912; Ruhle, 1962; Reinhardt,
Christopher, and Owens, 1980).
Two miles southwest of CD28, at locality AUX (Figure
1), i::he limonitic sandstone is exposed. The sandstone is
conformably underlain by a bed containing abundant quartz
39
pebbles. This section is li tho logically similiar to
section VI I from near Aquia Creek, of Clark and Miller
( 1912) . They also considered the limonitic bed to be Lower
Cretaceous.
The dip of the Aquia Formation directly along the river
is to the southeast. Assuming the dip to be approximately
thirteen feet per mile and the formation thickness to be one
hundred feet (Clark and Miller, 1912; Shifflett, 1948;
Ruhle, 1962), an upper contact can be projected seven miles
downdip. The projected contact is approximately one eighth
of a mile east of locality CDFS.
Locality CDFS is li thologically typical of the Aquia
Formation (Figure 4). It consists of glauconitic sands with
scattered bivalves and Turri tel la. The presence of zonal
index Foraminifera indicates that it is correlative with the
upper Paleocene Globorotalia velascoensis zone. Moving
upsection, variously colored (pink, blue, red) blocky clays
with quartz pebble stringers are encountered. The clay unit
is roughly twelve to fifteen feet thick and is comparable
with descriptions of the Marlboro Clay ( Clark and Miller,
1912; Reinhardt, Christopher, and Owens, 1980). Overlying
the clay unit is a clay-rich glauconitic sandstone with thin
indurated beds and burrows. This unit was considered by
Ruhle ( 1962; Fairview Beach locality) to be Aquia, because
of the presence of indurated beds and Turri tell a mortoni.
40
However, Clark and Miller (1912) report indurated beds in
the Nanj emoy Formation in Virginia. Cushman ( 1944)
exarninied benthic Foraminifera from this locality and
thought the unit may belong to the Nanjemoy. The high clay
content and burrows are similiar to decriptions of the
Nanjernoy Formation by Reinhardt, et al. (1980).
Based on the sedimentological characteri sties of the
clay unit and the overlying greensand, these two units are
considered in this study to be the Marlboro Clay and the
Nanj emoy Formation, respectively. This conclusion is
supported by the projected contacts of the Aquia and
overlying formations and the foraminiferal study of Cushman
( 1944).
Correlations
The present study is correlated with two other studies
of the Aquia Formation in Virginia involving planktonic
Foraminifera. The Marlboro Clay/ Aquia Formation contact
is considered to be fixed stratigraphic level from which to
standardize the sections.
Reinhardt, et al. ( 1980) studied a continuously-cored
drill hole near Oak Grove, Virginia. The location of the
hole is 23 miles south-southeast of the present area of
41
study (Figure 1). The Aquia Formation is represented by 114
feet of sediment in the core. The only planktonic
foraminiferal zone recognized in the core is the
Globorotalia pseudomenardii zone (Figure 7). The zone is
distinguished by the occurrence of Globorotalia
pseudomenardii and Globorotalia velascoensis (?) within a 6
foot interval in the core. The upper and lower boundaries
of the zone are interpolated from known relationships to
calcareous nannoplankton zones. These nannoplankton zones
were recognized in the core by Gibson, et al. ( 1980). -They
relate to the present section as shown in Figure 7.
Locality CDF7 of the present study is equivalent to the
middle of the Globorotalia pseudomenardii zone in the Oak
Grove Core (Figure 7). It is important to note that the
first occurrence of the 2 index species in the Oak Grove
Core is stratigraphically within 1 1/2 feet of the first
occurrence of the 3 Globorotalia pseudomenardii zonal index
species in the present area of study. This may represent a
related event in the 2 areas.
Seaton (1982) examined outcrops of the Aquia Formation
along the Pamunkey River, Virginia (Figure 1). The Aquia
Formation is approximately 70 thick in this area. As seen
in Figure 7, he recognizes the Globorotalia pseudomenardii
and Globorotalia velascoensis zones. His lower Globorotalia
pseudomenardii zonal boundary is at the same stratigraphic
42
Figure 7 Biostratigraphic correlation of three foraminiferal studies of the Aquia Formation in Virginia.
OAK GROVE SEATON, 1982 PRESENT STUDY CORE, 1980 .... MARLBORO CLAY en UJ
~ ~ AQUIA FORMATION ~D I I i ~ ~ 0 Cl 0::: U ~ ~ u r7 c en NP9
ca C C) _, _, UJ
1 u 1 I le.:,> • • UJ z
C C 0::: N C
C z NP8 - UJ
~
BRUPT !NDEX ~OSSIL. ~ g g ~ . APPEARANCE ~ ~ u ca en ~
c o.. NP6-?7 w _, ~ c.:, ....
; I L I I f'o• NP5 U/C ••••• ~
C C :j N
en :::, Q..
CC ~u :::; :j c C ~ u ~ :::, U/C i a..
ca 'SHADED AREA DENOTES PRESENCE OF INDEX FOSSILS --.......___ I I ::!
c.:, I I
U/C
44
level as the boundary as placed in the Oak Grove Core.
Seaton (1982) reports this boundary 2 feet below the top of
his locality 1 ( 9 feet above the base) . This is
approximately 10 feet stratigraphically below the base of
locality CDF7 of the present study (Figure 7).
The top of Seaton's (1982) section (locality 4) is
correlated with the Globorotalia velascoensis zone. The
presence of Globigerina linaperta and Globorotalia
wilcoxensis restricts this locality to the middle to upper
portion of the zone. Locality CDFS of the present study
also contains these 2 index species and is correlated with
the upper one-half of the zone.
Regional Overview
The basinal geometry portrayed by the correlations in
this study shows a thinning of Aquia sediments to the south
and west. The thinning may
sedimentation rates or by
be accounted for by varying
sedimentation beginning at
different times throughout the basin.
The possibility of varying rates of sedimentation is
discounted because of the equal amounts of sediments between
time lines { zonal boundaries). As seen in Figure 7, the
Aquia Formation is approximately 37 feet thick between the
45
lower Globorotalia pseudcmenardii zonal boundary and the
upper boundary of that zone. The Globorotalia velascoensis
zone is approximately 21 feet thick between the Globorotalia
pseudomenardii upper boundary and the Marlboro Clay. If the
rates of sedimentation were different at the three
localities, expanded zonal intervals would be expected.
Differential subsidence is possible as the reason for
the differences in sediment thicknesses below the lower
Globorotalia pseudomenardii boundary. Subsidence may have
begun in the northeast and spread southwestward as the
transgression progressed. Sometime prior to the beginning
of the Globorotalia pseudomenardii zone, subsidence evened
out within the basin. From this point on, Aquia sediment
deposition was uniform throughout the basin.
The transgression in which the Aquia Formation was
deposited apparently began in the northeast and spread
southwestward.
SUMMARY
Planktonic Foraminifera from the Aquia Formation in the
type area along the Potomac River, Virginia, were studied to
provide a biostratigraphic correlation with other sections
in the state.
Two genera and 22 species were identified and
illustrated using the Scanning Electron Microscope.
The ranges of the Foraminifera are shown Figure 4 The
lower one half of locality CDF7 contains fewer planktonic
Foraminifera and only 1 zonal index species. The number of
planktonic species increases upward in this locality. The
upper one-third of the outcrop is characterized by the
concurrence of 3 zonal index species This locality is
correlated with the Globorotalia pseudomenardii zone of
Stainforth, et al. (1975).
Locality CDFS contains significantly fewer planktonic
Foraminifera than locality CDF7. The presence of 6 zonal
index species enables recognition of the Globorotalia
velascoensis zone. The presence of 2 particular index
species at the base of the locality further restricts it to
the middle to upper Globorotalia velascoensis zone.
The Aquia / Cretaceous contact is recognized at the
base of the unfossiliferous locality CDFS. The boundary is
marked by an irregular erosional contact and lithology
46
47
change.
The Marlboro Clay is present one-eighth of a mile east
of locality CDFS. Farther east ( up section) the Nanj emoy
Formation is exposed at Fairview Beach, Virginia. This
exposure was considered by Ruhle (1962) to be Aquia, but is
considered to be Nanjemoy in this study on the basis of
lithology. This conclusion is supported by the benthonic
foraminiferal study of Cushman (1944).
Two recent planktonic foraminiferal studies of the
Aquia Formation are correlated with the present study.
Reinhardt, et al. (1980) studied a core from near Oak Grove,
Virginia, and Seaton (1982) studied the Aquia Formation
along the Pamunkey River, Virginia.
The Oak Grove Core is twenty miles downdip from the
present area of study and exhibits a thicker section of
Aquia sediments. A complete section of the Aquia Formation
was recovered in the core, but only the Globorotalia
pseudomenardii zone was recognized. The zone was
distinguished by the occurrence of 2 zonal index species.
This occurrence is at the same stratigraphic level as a
similiar occurrence in the present study and may represent a
local datum or event.
The study of Seaton (1982) involved the Aquia Formation
along the Pamunkey River, Virginia. The formation is much
thinner in that area. The lower Globorotalia pseudomenardii
48
zonal boundary is present in the lower one-fourth of his
section and is at the same stratigraphic level as the
boundary in the Oak Grove Core. The base of locality CDF7
is 10 feet stratigraphically above this boundary. The upper
one-fourth of the present study and that of Seaton (1982)
are both in the Globorotalia velascoensis zone. This study
concerns the middle part of the zone and Seaton' s ( 1982)
concerns the top.
The Aquia Formation was deposited in the earliest phase
of a Tertiary marine transgression in Virginia. This
transgression began in the northeast and spread
southwestward. The uniform sediment thicknesses within
zonal intervals at the three localities suggests equivalent
sedimentation rates implying uniform subsidence throughout
the basin beginning sometime prior to the Globorotalia
pseudomenardii zone.
SYSTEMATIC PALEONTOLOGY
The Foraminifera recovered in this investigation were
identified and classified using the classification of
Loeblich and Tappan (1957) and Stainforth, et al. (1975).
All the illustrations were done with a JEOL35 Scanning
Eletctron Microscope. Descriptions are included when Aquia
specimens vary significantly from previous descriptions.
Brief remarks follow many species and are intended to
clarify specific differences and/or similarities.
Two genera and twenty-two species are included.
49
Phylum PROTOZOA
Class SARCODINA
Order FORAMINIFERIDA
Family GLOBIGERINIDAE
Genus Globigerina d'Orbigny, 1826
Globigerina aguiensis Loeblich and Tappan, 1957
Plate l, figures 1,2,3
Globigerina aguiensis Loeblich and Tappan, 1957b, p. 180,
pl. 51, figs. 4,5; pl. 56, figs. 4-6. Nogan, 1964, p.
37, pl. 3, figs. 16-18.
Description: Test trochospiral to subglobular, usually with
four chambers in the final whorl. Periphery broadly
rounded, peripheral outline lobate. Sutures depressed;
oblique to very gently curved on spiral side, radial on
umbilical side. Umbi lieus open; aperture umbi lie al;
high, open arch, may have faint lip, previous apertures
visible. Surface hispid to spinose, especially in
umbilical region, earlier chambers somewhat cancellate.
Remarks: Compares well with paratypes of Loeblich and Tappan
( 1957b) .
Globicrerina chascanona Loeblich and Tappan, 1957
Plate l, figures 4,5,6
Globigerina chascanona Loeblich and Tappan, 195 7b, p. 180,
(pt.) pl. 61, fig. 8 (not pl. 49, fig. 4-5).
50
51
Description: Test trochospiral, five chambers in final
whorl, final chamber reduced in size and bulla-like.
Periphery rounded, peripheral outline lobate. Sutures
distinct, depressed; slightly curved on spiral side,
less curved on umbilical side. Umbilicus moderately
wide and deep; aperture a small umbilical arch with
narrow lip. Surface perforate, very spinose, final
chamber smooth.
Remarks: Aquia specimen compares well with paratype, but not
with holotype. Only one specimen was found, so the
range of variability of this species may well include
both holotype and paratypes.
Globigerina linaperta Finlay, 1939
Plate l, figures 7,8,9
Globigerina linaperta Finlay, 1939, p. 125, pl. 13, figs.
54-56. Belli, 1957, p. 163, pl. 36, fig. 5.
Hornibrook, 1958, p. 33, pl. l, figs. 19-21 (holotype
refigured). Bermudez, 1960, p. 1188, pl. 4, fig. 5· I
pl. 5, fig. 1. Blow, 1969, p. 230. Stainforth, et
al., 1975, pp. 201-202, fig. 63.
Globigerina (Subbotina) linaperta Finlay. Jenkins, 1971,
pp. 162-163, pl. 18, figs. 551-554 (holotype
refigured).
52
Globigerina mckannai White, 1928
Plate l, figures 10,11,12
Globigerina mckannai White, 1928, p. 194, pl. 27, fig. 16.
Loeblich and Tappan, 1957b, pp. 181-182, pl. 47, fig.
7; pl. 53, figs. 1-2; pl. 57, fig. 8· I pl. 62, figs.
5-7. Premoli Silva, 1970, pp. 140-141, pl. 25, fig. 3.
Stainforth, et al., 1975, p. 205, .: . .... 1g. 66 .
Remarks: Aquia specimens tend to have a more closed
umbilicus than paratypes.
Globigerina cf. Q. mckannai
Plate 2, figures 1,2,3
Description: Test high-spired trochospiral to subglobular,
five and one half chambers in final whorl. Inner
whorls disproportionately smaller than final whorl.
Chambers subspherical, somewhat axially elongate, and
only gradually increasing in size. Periphery
subcircular, very slightly lobate. Sutures depressed;
oblique to slightly curved on spiral side, radial on
umbilical. Umbilicus moderately wide and open.
Aperture a low arch, extraumbilical-umbilical. Surface
hispid and somewhat cancellate.
Remarks: Specimens are not identified as Globigerina
rnckannai because of their high trochospire, moderately
53
wide umbilicus, and slightly curved spiral sutures.
Globigerina spiralis Belli, 1957
Plate 2, figures 4,5,6
Globigerina spiralis Belli, 1957, p. 70, pl. 16, figs.
16-18. Loeblich and Tappan, 1957b, p. 183, pl. 47,
fig. 3; pl. 49, fig. 3; pl. 51, figs. 6-9; pl. 53, fig.
3. Olsson, 1960, p. 43, pl. 7, figs. 19-21.
Remarks: Aquia specimens compare very well with hypotypes.
Globigerina triloculinoides Plummer, 1926
Plate 2, figures 7,8,9
Globigerina triloculinoides Plummer, 1926, p. 134, pl. 8,
fig. 10. Belli, 1957, p. 70, pl. 15, figs. 18-20.
Nogan, 1964, pl. 4, figs. 7-9. Stainforth, et al.,
1975, p. 234, fig. 92.
Globigerina velascoensis (Cushman, 1925)
Plate 2, figures 10,11,12
Pulvinulina velascoensis Cushman, 1925, p. 19, pl. 3, fig. 5.
Globigerina velascoensis (Cushman). Belli, 1957, p. 76, pl.
20, figs. 1-3. Loeblich and Tappan, 1957b, p. 196, pl.
4, figs. 1-2. Luterbacher, 1964, pp. 681-686, figs.
92-94, 98-99. Postuma, 1971, pp. 218-219. Stainforth,
54
et al., 1975, pp. 240-241, fig. 97.
Remarks: This species differs from Globigerina linaperta by
having slightly appressed chambers, a larger aperture,
and a more coarsely perforate surface.
Family GLOBOROTALIIDAE
Genus Globorotalia Cushman, 1927
Globorotalia acuta Toulmin, 1941
Plate 3, figures 1,2,3
Globorotalia wilcoxensis Cushman and Ponton, var. acuta
Toulmin, 1941, p. 608, pl. 82, fig. 6-8.
Globorotalia acuta Toulmin. Loeblich and Tappan, 1957b, p.
185, pl. 47, fig. 5; pl. 55, figs. 4-5; pl. 58, fig. 5.
Luterbacher, 1964, p. 686, figs. 101-104. Nogan,
1964, p. 39, pl. 4, figs, 13-15. Stainf orth, et al. ,
1975, p. 163, fig. 30.
Remarks: Aquia specimens lack the well developed
ornamentation on the shoulders of the chambers.
55
Globorotalia aequa Cushman and Renz (1942)
Plate 3, figures 4,5,6
Globorotalia crassata (Cushman) var. aequa Cushman and Renz,
1942, p. 12, pl. 3, fig. 3. Cushman and Renz, 1942, p.
44, pl. 8, figs. 7-9.
Globorotalia aegua Cushman and Renz. Nogan, 1964, p. 39,
pl. 4, figs. 16-18. Stainforth, et al. , 1975, pp.
163-164, fig. 31.
Globorotalia angulata (White, 1928)
Plate 3, figures 7,8,9
Globigerina angulata White, 1928, p. 191, pl. 27, fig. 13.
Acarinina conicotruncata (Subbotina) (part). Subbotina,
1953, pp. 220-222, pl. 20, fig. 11. Subbotina, 1971,
pp. 281, 284-287, pl. 20, fig. 11.
Globorotalia angulata (White). Nogan, 1964, p. 39, pl. 5,
figs. 1-3. Stainforth, et al., 1975, p. 167, fig. 34.
Globorotalia chapmani Parr, 1938
Not figured
Globorotalia chaomani Parr, 1938, p. 87, pl. 9, figs. 8-9.
Stainforth, et al., 1975, p. 176-178, fig. 42.
56
Globorotalia convexa Subbotina, 1953
Plate 4, figures 1,2,3
Globorotalia convexa Subbotina, 1953, p. 209, pl. 17, figs.
2-3. Loeblich and Tappan, 1957b, p. 188, pl. 48, fig.
4; pl. 50, fig. 7; pl. 53, figs. 6-8; pl. 57, figs.
5-6; pl. 61, fig. 4; pl. 63, fig. 4. Olsson, 1960, p.
45, pl. 9,figs. 13-15.
figs. 10-12.
Nogan, 1964, p. 40, pl. 5,
Remarks: Aquia specimens compare well with topotypes in USNM
collections.
Globorotalia esnaensis (LeRoy, 1953)
Plate 4, figures 4,5,6
Globigerina esnaensis LeRoy, 1953, p. 31, pl. 6, figs. 8-10.
Globorotalia esnaensis (LeRoy). Loeblich and Tappan, 1957b,
p. 189, pl. 61, figs. 1-2, 9. Berrgren, 1960, pp.
1; pl. 10, fig. 3. 92-93, pl. 5, fig. 3; pl. 6, ~· ... 1g.
Remarks: Aquia specimens compare well with the hclotype and
paratypes.
Globorotalia imitata Subbotina, 1953
Plate 4, figures 7,8,9
Globorotalia imi tat a Subbotina, 1953, p. 206, pl. 16, figs.
14-16. Loeblich and Tappan, 1957b, p. 190, pl. 44,
57
fig. 3; pl. 45, fig. 6; pl. 54, figs. 8-9; pl. 59, fig.
5; pl. 63, fig. 3. Olsson,1960, p. 46, pl. 9, figs.
7-9. Nogan, 1964, pp. 40-41, pl. 5, figs. 16-18.
Remarks: Aquia specimens compare well with hypotypes in USNM
collections.
Globorotalia occlusa Loeblich and Tappan, 1957
Plate 5, figures 1,2,3
Globorotalia occlusa Loeblich and Tappan, 1957b, p. 191, pl.
55, fig. 3; pl. 64, fig. 3. Nogan, 1964, p. 41, pl. 5,
figs. 19-21. Luterbacher, 1964, pp. 690-692.
Stainforth, et al., 1975, pp. 208-210, fig. 70.
Remarks: Aquia specimens compare well with holotype and
paratypes in USNM collections. They differ from
Globorotalia acuta by being more lenticular.
Globorotalia perclara Loeblich and Tappan, 1957
Plate 5, figures 4,5,6
Globigerina cf. pseudobulloides Plummer. Shifflett, 1948,
p. 71, pl. 4, figs. 14-15.
Globoratalia perclara Loeblich and Tappan, 1957b, pp.
191-192, pl. 40, fig. 7; pl. 41, fig. 8; pl. 42, fig.
4; pl. 45, fig. 11; pl. 46, fig. 3; pl. 47, &' .... :.g. 6;
pl. so, fig. l; pl. 54, fig. 6-7; pl. 57, fig. 3-4; pl.
58
60, fig. 5. Olsson, 1960. p. 46, pl. 9, fig. 1-3.
Nogan, 1964, p. 41, pl. 5, fig. 22-24.
Remarks: Aquia specimens compare well with holotypes and
paratypes in USNM collections.
Globorotalia pseudoscitula Glaessner, 1937
Plate 5, figures 7,8,9
Globorotalia pseudoscitula Glaessner, 1937, pp. 32, 49,
text. fig. 3. Loeblich and Tappan, 1957b, p. 193, pl.
46, fig. 4; pl. 48, fig. 3; pl. 53, fig. 5; pl. 59,
fig. 2; pl. 63, fig. 6. Nogan, 1964, p. 42, pl. 6,
figs. 7-9.
Globorotalia reissi Loeblich and Tappan, 1957
Plate 6, figures 1,2,3
Globorotalia reissi Loeblich and Tappan, 1957b, p. 194, pl.
50, fig. 3; pl. 58, fig. 3; pl. 60, fig. 7. Olsson,
1960, p.48, pl. 10, fig. 4-6.
Description: High trochospiral, biconvex test, five to six
chambers gradually increasing in size in final whorl.
Periphery subangular, slightly lobate peripheral
outline, strongly convex on the spiral side, inner
whorls distinctly raised above succeeding whorls.
Sutures depressed; slightly curved on spiral side,
59
often indistinct in the inner whorls, radial on
umbilical side. Aperture a
umbilical arch with narrow lip.
low extraumbilical-
Surface smooth, finely
perforate, may have a few spines in umbilical region
and on inner whorls on spiral side.
Remarks: Aquia specimens compare well with holotype and
paratypes in USNM collections. They differ from
Globorotalia perclara by being much smaller, distinctly
convex on spiral side, and chambers only gradually
increasing in size and less inflated.
Globorotalia trichotrocha Loeblich and Tappan, 1957
Plate 6, figures 4,5,6
Globorotalia trichotrocha Loeblich and
195-196, pl. 50, fig. 5; pl. 57,
1960, p.49, pl. 10, figs. 1-3.
Tappan, 1957b, pp.
figs. 1-2. Olsson,
Remarks: Aquia specimens compare well with ho lo type and
paratypes in USNM
Globorotalia reissi
and hispid surface.
perclara by having
collections. They differ from
by having a flattened spiral side
They differ from Globorotalia
less inflated chambers which only
gradually increase in size. The sutures on Globorotalia
perclara are much more distinct and depressed.
60
Globorotalia wilcoxensis Cushman and Ponton, 1932
Plate 5, figures 10,11,12
Globorotalia wilcoxensis Cushman and Ponton, 1932, p. 71,
pl. 9, fig. 10. Bolli, 1957, p. 79, pl. 19, figs. 7-9.
Stainforth, et al., 1975, p. 243, fig. 98.
Remarks: Aquia specimens compare well with holotype and
paratypes.
Globorotalia species A
Plate 6, figures 7,8,9
Description: Test trochospiral, two and one-half whorls.
Chambers subspherical, low, peripheral shoulders sub-
acute; five to six chambers in final whorl, gradually
increasing in size. Peripery rounded, peripheral
outline lobate.
slightly curved
whorls, radial
Sutures depessed, distinct; oblique to
on spiral side, indistinct in inner
to slightly curved on umbilical side.
Umbilicus wide and shallow. Aperture interiomarginal
(?). Surface smooth and very finely perforate.
Remarks: This form differs from Globorotalia imitata because
the chambers increase in size more gradually and are
more numerous in the final whorl, the chambers are less
lunate on the spiral side, the spiral is less distinct,
and the test is more finely perforate. It differs from
Globorotalia reissi by ha?ing more spherical chambers,
61
sutures more distinct, and is not biconvex.
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Geol.-Razved. Inst. Trudy, n. ser., no.
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Teifke, R. H., 1973, Stratigraphic units of the Lower Cretaceous through Miocene series; and Paleogeography of Early Cretaceous through Miocene time: in Geologic Studies, Coastal Plain of Virginia, Va. Div. Min. Res. Bull. 83, pts 1 & 2, 102 pp.
Thalmann, H. E., 1942, its' subgenera: 809-820.
Foraminiferal Amer. Journal
genus Hantkenina Sci., v. 240,
and pp.
Toulmin, C. D., 1941, Salt Mountain Paleontology, v.
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69
Tertiary Dinoflagellate assemblages: & SU, 168 pp.
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PLATES
70
Figure
1,2,3
4,5,6
7,8,9
10,11,12
71
PLATE 1
Globigerina aguiensis Loeblich and Tappan. l, umbilical view. 2, spiral view. 3, edge view: xl50.
Globigerina chascanona Loeblich and Tappan. 4, umbilical view. 5, spiral view. 6, edge view. xl50.
Globigerina linaperta Finlay. 7, umbilica! view. 8, spiral view. 9, edge view. xl80.
Globigerina mckannai White. 10, umbilical view. 11, spiral view. 12, edge view. xl60.
Page
53
53
54
55
72
Figure
1,2,3
4,5,6
7,8,9
10,11,12
73
PLATE 2
Globigerina cf. Q. mckannai. l, umbilical view. 2, spiral view. 3, edge view. xl50.
Globigerina spiralis Bolli. 4, umbilical view. 5, spiral view. 6, edge view. xl80.
Globigerina triloculinoides Plummer. 7, umbilical view. 8, spiral view. 9, edge view. x220.
Globigerina velascoensis (Cushman). 10, umbilical view. 11, spiral view. 12, edge view. x 150.
Page
55
56
56
56
74
Figure
1,2,3
4,5,6
7,8,9
75
PLATE 3
Globorotalia acuta Toulmin. 1, umbilical view. 2, spiral view. 3, edge view. x300.
Globorotalia aegua Cushman and Renz. 4, umbilical view. 5, spiral view. 6, edge view. x240.
Globorotalia angulata (White). 7, umbilical view. 8, spiral view. 9, edge view. x 180.
Page
57
58
58
76
Figure
1,2,3
4,5,6
7,8,9
77
PLATE 4
Globorotalia convexa Subbotina. l, umbilical view. 2, spiral view. 3, edge view. x240
Globorotalia esnaensis (LeRoy). 4, umbilical view. 5, spiral view. 6, edge view. x260.
Globorotalia imitata Subbotina. 7, umbilical view. 8, spiral view. 9, edge view. x260.
Page
59
59
59
Figure
1,2,3
4,5,6
7,8,9
10,11,12
79
PLATE 5
Globorotalia occlusa Loeblich and Tappan. 1, umbilical view. 2, spiral view. 3, edge view. x240.
Globorotalia perclara Loeblich and Tappan. 4, umbilical view. 5, spiral view. 6, edge view. x200.
Globorotalia pseudoscitula Glaessner. 7, umbilical view. 8, spiral view. 9, edge view. x160.
Globorotalia wilcoxensis Cushman and Ponton. 10, umbilical view. 11, spiral view. 12, edge view. x260.
Page
60
60
61
62
80
Figure
1,2,3
4,5,6
7,8,9
81
PLATE 6
Globorotalia ressi Loeblich and Tappan. l, umbilical view. 2, spiral view. 3 edge view. x400.
Globorotalia trichotrocha Loeblich and Tappan. 4, umbilical view. 5, spiral view. 6, edge view. x220.
Globorotalia species~-7, umbilical view. 8, spiral view. 9, edge view. x300.
Page
61
62
63
82
83
APPENDIX
Virginia Planar Coordinates are used to describe the exact position
of sampling localities.
These coordinates are found on the following Virginia Division of
Mineral Resources 7 1/2 minute series (topographic) maps;
CDFl- 246300 N
2351250 E
CDF5- 244600 N
2355300 S
CDF7- 257600 N
2345250 S
CDF8- 270550 N
2331600 S
The vita has been removed from the scanned document
PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY AND CORRELATION OF
THE AQUIA
FORMATION IN THE TYPE AREA, ALONG THE POTOMAC RIVER VIRGINIA
by
Craig Duncan Faris
(Abstract)
Planktonic Foraminifera were examinied from the Aquia
Formation ( Late Paleocene) from 2 localities in the Aquia
type area along the Potomac River 7 miles southeast of
Stafford, Virginia to: identify taxa present, and to effect
biostratigraphic correlation with other Paleocene studies on
the Virginia Coastal Plain. Two genera and twenty-two
species were recovered, allowing recognition of the
Globorotalia pseudomenardii and Globorotalia velascoensis
zones, and correlation with The Oak Grove Core, 23 miles to
the southeast (Gibson,
locality 50 miles to
et al. 1980), and a Pamunkey River
the south (Seaton, 1982). This
correlation shows equal thicknesses of the
zonal boundaries over the Potomac River
Aqui a within
Oak Grove
Pamunkey River area, suggesting uniform rates of Aquia
sedimentation in this portion of the Salisbury Embayment.
Correlation of the Oak Grove Core, which was zoned via the
Tertiary NP zonation indicates the presence of NP zones
5,6-?7,8,9 in the A~~ia type area.