PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY AND …...I would first like to acknowledge the tremendous ... The final, but greatest, thanks go to my Lord Jesus Christ. He has given me

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


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


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


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


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


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


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


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).


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



Age: Middle Paleocene


Globorotalia pusilla pusilla to the

occurrence of Globorotalia pseudomenardii.

Globorotalia pseudomenardii Zone

Category: Range zone


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



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


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


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


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


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


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


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


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)


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


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)


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)


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


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)


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


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


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


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


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


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.


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


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


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.


paratypes.

Globorotalia species A


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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White, M. P., 1928, Some index Foraminifera of the Tampico embayrnent area of Mexico: Jour. Paleontology, v. 2, pp. 177-215.

Witmer, R. J., 1975, Taxonomy and Biostratigraphy of Lower

69

Tertiary Dinoflagellate assemblages: & SU, 168 pp.

M.S. Thesis, VPI

Youseffnia, I., 1978, Paleocene benthonic Foraminiferal paleoecology of Atlantic Coastal Plain: Jour. Foram. Research, v. 8, no. 2, pp. 114-126.

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.

Documents

PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHY AND …...I would first like to acknowledge the tremendous ... The final, but greatest, thanks go to my Lord Jesus Christ. He has given me