A QUANTITATIVE SEDIMENTARY ANALYSIS
OF THE ORDOVICIAN DEPOSITS EN THE
MICHIGAN EASIN

Thais {w fho Darn of M. 5.,
MICHIGAN STATE UNIVERSITY
Laurence S. Cooke, .Ir.

E956

 

SUPPLEM g

AT m *AL
INBACKOF BOOK

 

 

A QUANTITATIVE SEDIMENTARY ANALXSIS OF THE
ORDOVICIAN DEPOSITS IN THE MICHIGAN BASIN

By
LAURENCE s. QQOKE, J'R.

A THESIS
Submitted to the School of Graduate Studies of Michigan
State University of Agriculture and Applied Science

in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Geology
1956

{Rs

7-10—54

ACKNOWLEDGEMENT S

The author wishes to express his sincere gratitude
to Dr. B. T. Sandefur. His constant encouragement was a
tremendous aid in the completion of this investigation.
Dr. Sandefur was extremely helpful in the editing and
compiling of the final manuscript.

The writer also wishes to thank Dr. W. A. Kelly for
his assistance in determining the marker horizons and his
constructive editing of the manuscript.

Sincere appreciation is also due to Messrs. Robert
M. Ives and Garland D. Ells of the Michigan Geological
Survey for their great assistance in selecting the wells
for this study. Dr. W. D. Baten of the Statistics Depart-
ment was very generous with his time in helping with the

statistical analysis.

CONTENTS

PAGE
INTRODUCTION 000......COOOOOOOOOOOOOOOOOOOOOO0.... 1

History of Ordovician Investigation in the
MiChigan BaSin 0......OOOOOOIOOOOCOOOCOOOOO...

Facies Analysis ................................
Purpose ........................................
WELL SELECTION AND DISTRIBUTION ..................
Stratigraphy of the Section Analyzed ...........

Requirements for Well Selection ................

~O CD (I 0‘ #7 K» F4

SBIGCtion Of wells 00.0.000000000000000000000000
LABORATORY PROCEDURE ............................. 14

Sampling MethOd ooooooooooo0.0000000000000000... lu

Removal of Water Solubles ...................... 15
Removal of Acid Solubles ....................... 16
Disaggregation ................................. l7
Dispersion ..................................... l9
Sieving ........................................ 2O
Pipetting ...................................... 21

Mounting and Analyzing the Sand Grains ......... 23

Laboratory Equipment ........................... 2h
Errors in the Analyses ooooooooooooooooooooooooo 2a
Results of the Laboratory Analyses ............. 25

LITHOLOGIC VARIATION 0.0.0....OOOOOOOOOOOOOOOOOOOO 27

Lithologic Ratios ..............................
Facies Map Construction ........................
INTERPRETATION OF FACIES MAPS ....................
Methods of Geological Interpretation ...........
Methods of Statistical Interpretation ..........
Errors Involved in Interpretation ..............
Interpretations ................................
Geological Interpretation ....................
Statistical Interpretation ...................
REGIONAL TECTONICS ...............................
Structural Relations of the Michigan Basin .....

Structural Interpretation in Relation to

TeCtoniCS oooooooooooooooooooooooooooooooooooo
Teetonic ASpeCt oooooooooooooooooooooooooooooooo
CONCLUSIONS oooooooooooooooooooooooooooooooooooooo

REERENCES 00......00.00.00...OOOOOOOOOOOOOOOOO0..

PAGE
27
29
31
31
32
36
37
37
1+5
N6
he

’47
1+9
51
52

TABLE

II
III

IV

TABLES AND FIGURES

Lithology and Thickness of Section Analyzed ...
Wells Used in Analysis ........................
Quantitative Analysis .........................
Lithologic Ratios .............................

Analysis of Variance of Quartz-Chart Ratios
in the MiChj—gan Basin OOOOOOOOOOOOOOOOOOOOOOO

FIGURE

I

Relations Between ISOpachs and Facies Lines ...

PAGE

12

25
28

33

II

III

IV

VI
VII

MAPS

Outcrop Pattern and Areal Extent of the Upper

and Middle Ordovician Rocks in Michigan ...

Location of Wells and Partitioning of State

for Statistical Analysis ..................
Clastic Ratio Map ..............................
Sand-Shale Ratio Map ...........................
Evaporite Ratio Map ............................

ISOPaCh Map ooocoooooooooooooooooooooooooooooooo

Quartz-Chart Ratio Map

PAGE

10

ll
Pocket
Pocket
Pocket
Pocket

Pocket

INTRODUCTION
History of Investigation of the Michigan Basin

Subsurface investigation of the Michigan Basin has
been a subject of interest for many years. But, not until
the turn of the century was there enough information from
deep borings to intensify the study.

The main problem was the extensive cover of Pleisto-
cene glacial deposits. These deposits attain a thickness
of nearly 1,300 feet in certain portions of the lower
peninsula.

The outcrop pattern of the Paleozoic deposits is
elliptical in outline, with the major axes trending north-
east-southwest. Map I shows the extent of the outcrops.
These sediments are arranged in concentric rings with the
Pennsylvanian deposits in the center, and progress towards
the outer margin through the Mississippian, Devonian,
Silurian, Ordovician, and the Cambrian. Smith (1912)
states, "The depth of the Basin is so small in comparison
with its diameter that the inclination of its several memr
hers is ordinarily between 25 and 50 feet per mile, and
rarely exceeds 60 feet."

In describing the areal extent of the Michigan

Basin, Newcombe (1933) stated:

The area comprising the Michigan

Basin includes about 106,700 square miles

and stretches from Fort Wayne, Indiana, on

the south, to Whitefish Point near Sault

Ste. Marie, Michigan, on the north, and

from.west to east about 370 miles.

The deepest portion, or center of the Basin, conforms
(approximately to the center of the lower peninsula of
IMdchigan. According to Pirtle (1932), the structures
'bounding the Basin are: the Wisconsin arch in the west,
and two limbs of the Cincinnati arch in the south, the
Kankakee arch in the southwest, and the Findley arch in the
southeast. The northern boundary is the pre-Cambrian
complex of the Canadian Shield, and the eastern boundary
is the Algonquin arch.

Because of the economic importance attached to the
intra-basinal structures, they have been closely studied.
Smith (1912) described the six best developed folds which
occurred mainly near the margins of the Southern Peninsula
and in Western Ontario. ~He depicts most of these anti-
CIines as being relatively low and short. Some faulting
has also occurred in the Basin with displacements gener-
ally around 50 to 60 feet. Most of the information for
his study was obtained by reconnaissance mapping and from a
few well logs.

Pirtle (1932) suggests that the folds within the

Basin have a persistent northwest-southeast trend. And this

3
gnxrallelism.of folds is most evident in the central and

eastern part of the state. He believes the folds in the
suyuthwestern part of the state are different from.those in
tflie central and eastern portions. They are much shorter and
txrend to the northeast. He suggests they are related to
tflae Kankakee arch. In his conclusion, he states; "It is
'believed that the principle folds now existing in the later
sediments are controlled by trends of folding or lines of
structural weakness which existed in the old basement
rocks." Most of Pirtle's information was obtained from
structural contours drawn on the top of the Trenton forma-
tion of the Ordovician.

Newcombe (1933) published a thorough report on the
sedinwnts and structures in the basin. His conclusions
followed very closely those proposed by Pirtle. His find-

ings are based on both structural contour and isopach maps.
Facies Analysis

Moore (19h9) defines sedimentary facies as, "Any
areally restricted part of a designated stratigraphic unit
Which exhibits characters significantly different from
those of other parts of the unit." The facies analysis
Inethod of interpreting structures was used by 81033,
'Krumbein, and Dapples (19h9) in determining structural

relations from.a map showing lateral variations of rock

character within a certain stratigraphic interval.

Moore (l9h9) defines two different types of facies;
lithofacies and biofacies. Lithofacies are "groups of
strata demonstrably different in lithologic aSpect from
laterally equivalent rocks." Biofacies are laterally
equivalent biotic assemblages differing in their biologic
aSpect. A third facies is proposed by 81033, Krumbein, and
Dapples (l9h9) as "tectofacies" where it is defined as,

"a group of strata of different tectonic aSpect from later-
ally equivalent strata."

Lithofacies and biofacies maps in general express
similar trends and limits. These maps also would show minor
variations in sedimentary environment. A tectofacies map,

on the other hand, would show the broad tectonic variations.
Purpose

The purpose of this paper is to attempt to determine
the structures during Ordovician time in the Michigan Basin
by a lithofacies analysis.

Even with the scarcity of samples from wells pene-
trating the Ordovician, it was felt by this writer that a
reasonable interpretation of the tectonic environment of
this section could be made. It was necessary that this
analysis be conducted on a well defined rock system.

The Ordovician system was chosen for this study

5
because of the small amount of written information avail-
able on these formations throughout the Basin. It is hoped
that the maps and data obtained from this analysis may add

to the information found through earlier research.

WELL SELECTION AND DISTRIBUTION
Stratigraphy of the Section Analyzed

Due to the difficulty in selecting a top and a
bottom for the Ordovician system, this analysis contains
some lower Silurian deposits and omits the lower Ordovician
deposits. Table I describes the section analyzed.

A top and bottom that were reasonably consistent
throughout the well samples was chosen. The concensus of
opinion among several authors place the top of the Ordo-
vician at the break between the Manitoulin, which is a buff
dolomite, and the dark shale of the Queenston. In many
of the wells, there is no such break, showing a gradua-
tional change instead. For the top, the red shale of the
Cabot Head was the best marker bed that could be found.

The base of this horizon was chosen instead of a similar red
bed in the Cincinnatian to include as much of the Ordovician
as possible.

The bottom of the Ordovician is Just as difficult to
ascertain because of the deep erosion and crustal.movement
during and following the deposition of the lower Ordovician
deposits. There is much ambiguity as to the correlation of
some of these sediments, especially the sandstone beds. In
sonw areas, it is very difficult to tell whether the sand is

St. Peter, New Richmond or Cambrian. For this reason, the

7

bottmm of the Black River Formation was used as the lower

limit marker.

It is realized that this is not an analysis of the

entire Ordovician system and should not be interpreted as

such.

TABLE I

LITHOLOGY AND THICKNESS OF SECTION ANALYZED

 

 

Age Formation

Lithology

Average thickness

Western Eastern
Michigan Michigan

 

SILURIAN
Cataract

Cabot Head

Manitoulin

ORDOVICIAN
Cincinnatian

Queenston

Lorraine

Green, greenish-
gray and red
Shale o

Buff to light
brown dolomite
with some inter-
bedded chert and
Shale 0

Gray and red
shale with thin
beds of limestone
and dolomite.

Gray shale with
thin beds of lime-

stone and dolomite.

no: 70:

 

Ace! 805!

 

 

.Age Formation

TABLE I (Cont.)

Lithology

Average thickness

Eastern
Michigan

Western
Michigan

 

Utica

Trenton

Black River

St. Peter

Prairie Du Chien

Dark gray to
black shale

Brown and gray
crystalline lime-
stone and dolomite
with some shale and
argillaceous lime-
stone.

Brown and gray
crystalline lime-
stone and dolomite
with some shale,
chert and argil-
laceous limestone.

Well rounded quartz
grains with some
chert and con-
glomerate.

Buff dolomite, chert,

sandstone and green
to greenish-gray
shale.

J

 

d

LLOS'
A15 '
11.70 '

230' 0'

Requirements for Well Selection

Krumbein and Sloss (1951) compared the cable-tool

'method.of drilling with.the rotary-tool method.

Rotary-tool

Samples are contaminated by "the rotation of the drill pipe

and each removal and reintroduction of the tools which

cause a certain amount of caving from the sides of the bore."
On the other hand, cable-tool samples are relatively uncon-
taminated "with a minor amount of material knocked off
uneased portions of the bore by the passage of tools and the
bailer." Another comparison of these two methods by Krumbein
and Pettijohn (1938), draws the same conclusion; the samples
for analysis are the least contaminated if obtained from
cable-tool wells.

Because of the scarcity of wells that penetrate the
Ordovician, all of those available were used. For this
reason, there was little problem in the Spacing of the wells.

The wells selected in the Upper Peninsula were those
where most of the lower Silurian sediments were present.
Along the eastern margin of the state, from Alpena County
to Claire County and in the middle of the basin, there were
no wells selected. Map I gives the outcrop pattern and the
areal extent of the Ordovician deposits within the state of

Michigan.
Select ion of Wells

Half the wells selected for this study were cable-
tool wells. Because of the depth at which the Ordovician
is found, most of the wells are located towards the peri-

Phery of the state. For each well, the section analyzed

 

 

 

 

 

 

 

  

 

 

 

 

 

 

MICHIGAN
MAP I

Outcrop pattern and
areal extent of Upper
and Middle Ordovician
rocks in Michigan

KM.
(“DIN I Dru- by Allin I. hull-
“ 31m toll-u, Dori. of Tool. l he.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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...—J.._. _..i__....¥_...
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69’1"." "51

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MICHIGAN

MAP II

Location of wells and
Partitioning of state

KM.
(onfllod I. Dun by Auto! 0. Potoldo
lid. Silo“ (ollogo, Iop't. oI Tool. I Goo.

for statistical analys is

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 
 
  

       

 

 

   
 

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(olopfrou

Copyright 1951

 

12

was obtained from the Michigan Geological Survey.

Map II shows the location of the wells and Table II

defines the wells used in this study.

Included in the table

ease the county and township, company and farm, location,

auad.the thickness of the section studied for each well.

TABLE II

WELLS USED IN ANALYSIS

 

 

 

tJell County and Company and Farm Sec. Twp. Rg. Thickness
ITtunber Township Of Section
1 Alpena Charles W. Teater 18 32N 6E 1121I
Long Rapids Nevins #1 ' -
2 Jackson The Taggert Co. 13 As 2E 1h12'
Norvell Watkins Farm Inc. -
#1
3 Monroe Dow Chemical Co. 7 SS 7E IMO?!
London Loyal Grassey #1 _
£1 Barry Rex Oil and Gas Co. A 3N 9W 1139'
Rutland J. and J. Robertson 0
#1
ES Cass D. B. K. Van Raalte 36 78 th 923'
Calvin Wma Gemberling #1 _
65 Schoolcraft B. P. Pettison 1h k2N 16W 577'
Hiawatha Alphonse Verschure _
#1
'7 Schoolcraft Schoolcraft Dev. 31 th 13W 85h!
Seul Choix Synd. . .
Schoolcraft Dev.
Synd. #2
8 Washtenaw Calvin and Assoc . 12 28 "(E 1579!
Superior 1

w

TABLE II (Cont.)

13

 

 

Lyon

Gowans 22.21. #1

tfell County and Company and Farm Sec. Twp.) Rg. Thickness
Thumber Township Of Section
9 Mason Dow-Brazos-Taggert 27 19N 18W 68h'
Hamlin Dow-BrazosdTaggert -
10 Wayne Penna. Salt Mfg. Co. 5 ES llE 1h61'
Monguagon Penna. Salt Mfg. Co. -
#14
11 Ottawa Mich. Petroleum Co. 6 9N 13W 805'
Chester Charley Moe #1 .
12 Mason Superior Oil Co. 25 17N 16W 803'
Eden M. Sippy gt_gl, #17 -
13 Wayne Woodson Oil Co. 17 18 BE 1786'
Northville .Det. H. of C. #3 -
1h. Mackinaw C. Van Keuren l7 ANN 9W 766'
Garfield Hiawatha Sportsman -
Club 23 31. #1
15 Oakland Top 0' Mich. Dev. 22 EN 8E 1659'
Springfield Co. - -
Williams #1
16 Oakland C. W. Collin 35 IN 7B

1553'

LABORATORY PROCEDURE
Sampling Method

Samples for each well were obtained from.the Michigan
(}emological Survey. The Ordovician section of the wells was
represented by seven to twelve trays, each containing about
225? vials. Each vial contained a sample of five to ten feet
(of‘ the drilled section.

In order to obtain the best results in a mechanical
TallanfliS, approximately one hundred and twenty-five grams of
Ehaanple are necessary (Wentworth 1926). The vertical section
Ertaidied ranged from about 800 feet to 1500 feet. At one gram
(DI? sample for every ten feet, the composite approaches
WentworthIs figure.

There were from eight to ten grams of sample in each
Vtiala The selection of one-half to one and one-half gram
WTNlld be a sufficient sample for analysis and would not de-
tluact from.the value of the original sample.

A AOO m1. beaker was weighed and labeled for each
Well. As the sample from each vial was weighed, it was
.Pliiced in.the beaker to form a composite sample for the
Well. A small magnet was used on the composite sample to
reIncve the small pieces of drill bit. If obvious contami-

Ila-t; ion were present in the two rotary tool wells, it was

15

removed. To check the weighing accuracy, the net weight of
the composite sample was divided by one-tenth. This should
equal the number of feet sampled.

None of the wells showed an error of more than one-
half gram, which is not considered. significant enough to

alter the results.
Removal of Water Solubles

Very little of the Ordovician in Michigan is composed
of water soluble material. But it was necessary to include
these minor amounts of electrolytes in the analysis.

Weigner (1927) found that by boiling the sample in
water the ionic particles will go into solution and may be
removed by filtering or siphoning. Because of the small
mount of electrolytes present, they caused no apparent
flocculation of the fine clastics during the treatments.

Each well was treated with about 200 ml. of tap water
and boiled for two hours. All the fine material in the
beaker was allowed to settle. Then the water was filtered
and 10 m1. of the filtrate was added to a test tube.
Another test tube was filled with 10 ml. of tap water. Into
each, was placed about one-half gram of silver nitrate
crystals. If the filtrate gave more white precipitate than
the tap water, another treatment was necessary.

The samples were stirred several times during each

I?)

A

16
treatment to insure better access of the sample to the
water. Three or four treatments were sufficient to remove
all the water solubles. The weight of the fine material
left on the filter paper was obtained by weighing the filter
paper before and after filtration. This residue was later
added to the clay fraction. The sample was then dried on a

hot plate and weighed.
Removal of Acid Soluble

The remaining portion of the non-Clastic material
eras composed mostlyof limestone and dolomite.

Because of the great effervescence of limestone, the
first treatment was a 25 percent solution of hydrochloric
ac 1d. About 100 ml. of the solution was added to the sample
very slowly. The sample was then stirred until all effer-
Vescence ceased. Most of the fine material was allowed. to
Settle from the liquid before filtering.

A 50 percent solution was used for the second treat-
ITIent and a 100 percent acid solution was used for the final
tI‘eatment. After effervescence stopped in the last treat-
ment, the beaker was placed in a warm sand bath and stirred
intermittantly until all action ceased. Because of the
large amount of dolomite present, the solution was heated
for several hours. Contrary to the Opinion of some, gentle

bOiling did not bring about cementation.

17

Because of the hydrochloric acid content of the
jliquid, the fine material in suspension flocculated very
:rapidly. After the liquid was cooled and the finer mater-
:ial.settled out, the liquid was filtered. The sample was
‘tlaen washed with tap water until blue litmus paper showed
Iro change. Each filter paper was washed several times to
Imemove as much acid as possible. The acid caused a great
ijncrease in weight if it were not removed. Again the
cflnange in weight of the filter paper was added to the clay
.ffiraction. The sample was allowed to dry and the weight loss

citie to the acid solubles was recorded.
Disaggregation

Most of the shale was broken down in treating the
Esample for the water solubles and the acid solubles. But
Esome black carbonaceous bits, probably from.the Utica for-
Ination, still remained.

Krumbein and Pettijohn (1938) define disaggregation
113 "the breaking down of aggregates into smaller clusters or
linto individual grains." They also state; "avoid the use
<Jf harsh chemicals", although they advocate their use in
S ome instances .

Before disaggregation, the large pieces of shale were

Crushed with a mortar and pestle to about a 30 mesh seive

size to facilitate the treatments.

18

The techniques used in disaggregation are as follows:

1. Tolmachoff (1932) suggested soaking the shale in
a hot solution of "hypo" (sodium hyposulfite). Upon cooling
the supersaturated solution, crystallization starts and is
accompanied by the disintegration of the shale. This
method seemed to have little effect.

Krumbein and Pettijohn suggest the use of an alkaline
digest, either a KOH or NaOH solution.

2. A supersaturated solution of NaOH was first
tried. 100 ml. of solution was mixed with the sample in a
250 ml. beaker. The sample was boiled for three days and
water was added when needed. Some disaggregation was noted,
but the process was too slow to be acceptable.

3. KOH was the best compound used for disaggregation.
The solution was prepared in boiling water and was extremely
supersaturated. Care was taken not to add the KOH too
I'aLpidly to the water as a violent reaction would result.
After boiling the solution ten or twelve hours a day for two
days, the shale was almost completely disaggregated. The
disaggregated material was siphoned off into a 600 m1. beaker
and the remaining particles were again subjected to the KOH
tI‘eatment. Three treatments were sufficient to disaggregate
all the shale in 111 of the wells.

The small amount of shale remaining in the other two

Wells was removed as explained later in this chapter.

19

Prior to dispersion, it was necessary to remove the
KOH from the sample. Four to six washings of tap water were
necessary. Red litmus paper was used to determine when the
sample was neutral. After each washing, the fine materials
were allowed to settle before the liquid was filtered. Each
filter paper was then washed with tap water to remove the
KOH. The difference in weight of the filter was added to
the clay fraction.

The purpose of disaggregation was to separate any
sand that may be present from the shale. Also to insure
the material left on the sieve in the sieving process

( explained later) will be only sand.
Diapersion

Clay and silt size particles tend to flocculate even
in a neutral'solution unless the potential of the electri-
cally charged particles is increased. Krumbein and Petti-
John (1938) suggest several different peptizing agents.

A .01 N sodium oxalate was found by them to be the most
effective. The solution was prepared by adding .67 gram of
dry sodium oxalate to one liter of water. Before disper-
sion, the residue was completely dried so as much of the

peptizing agent as possible could be used.

20

Sieving

Prior to removing the sand size particles, approxi-
Inertely 200 m1. of the sodium oxalate solution was added to
'tlie dry residue. This was allowed to stand for several
minutes until a mud formed.

This mud was then washed through a 230 mesh Tyler
531JSV6. Wentworth (1922) suggested this sieve as the divi-
Eiixan between the silt and the sand size particles. The
Inerterial and solution passing through the sieve was caught
21:1 a flat bottomed pan. It was imperative, that not more
1:T1an.800 ml. of the sodium oxalate solution be used in this
Iazeocess. About 500 ml. or 600 ml. of the solution was
Ixsrually necessary to remove all the silt and clay from the
S ieve. The suspension in the pan was then funneled into a
ILC)OO ml. graduated cylinder and saved for the pipette ana-
ILzrsis. The sand left on the sieve was allowed to dry and the
Iveaight was recorded. For each well, a small vial was labeled
into which the sand was poured and saved for the quartz-
Cllert analysis.

Under microscopic inSpection, four of the wells
SllfiDwed some shale particles left on the sieve. Before
'tllezse sands were placed in the vials, a separation was
FNSIFformed to remove the shale.

A bromoform alcohol solution was prepared in a large

Ihlruael which was closed at the bottom by a rubber tube and a

21
clamp. The correct solution was determined by placing a
piece of quartz and a piece of shale into the funnel con-
taining bromoform and adding alcohol until the quartz sank
and the shale remained on top. The sand was then poured
into the solution and allowed to settle. The clamp was
opened to allow the sand and some of the liquid to pass onto
a filter paper in a lower funnel. The difference in weight
of the filter paper was recorded as the sand fraction. The
remaining shale was then washed with alcohol from the first
funnel and onto another filter paper. The weight of the
Small amount of shale for each of the four wells was divided
into percentages and added to the silt and clay fractions.
These percentages were computed from the pipette analysis
Of each well. Less than one gram of shale residue was pre-

sent in each case.
Pipetting

Robinson (1922) devised a method of separating fine
Clastic material using the ordinary pipette. In theory,
the pipette method is based on Stoke's law of settling
Velocities, where the method actually determines the density
of the suSpension at a fixed depth as a function of time
(Krumbein and Pettijohn, 1938). By using a 1000 ml. graduated

c3Y11nder, they also found that after two hours and three

 

22

minutes all the suspended particles ten cm. or less from the
surface of the liquid will be clay. The amount sampled is
representative of the total amount of material in the cylin-
der having smaller settling velocities. Wentworth (1922)
suggested 1/256 mm. in diameter as the dividing line between
clay and silt size particles, of which clay is the smallest.

To the 1000 m1. graduated cylinder prepared during
the sieve analysis, is added enough sodium oxalate solution
to bring the level the liquid to 1000 ml.

The material was agitated by inserting a glass tube
attached to a rubber hose to the bottom of the graduate.
Air from_an air jet was forced slowly through the hose.
Care has to be taken to prevent excessive bubbling which
might result in losing some of the material._ The material
was allowed to settle for two hours and three minutes.
After which, a twenty m1. pipette was inserted to a depth of
ten cm. and twenty ml. of solution was withdrawn. Inserting
the pipette and withdrawing the material must be done rather
slowly to avoid excess agitation. This material was placed
in a 50 m1. beaker and dried in a warm sand bath. The
difference in weight of the beaker represented 1/50 of the
weight of the clay in the 1000 ml. graduate and of this
weight, .013 g. represented 1/50 the weight of the sodium

oxalate. To obtain the weight of all the clay in the

23
graduate, the proportionality factor for the sodium oxalate
(0.013 g.) was subtracted from.the weight of the clay sam-
ple. The resultant weight was then multiplied by fifty.

To this weight was added the filter paper residue
obtained from the previous analyses plus the percentages of
the undisaggregated shale. This weight represents the total
amount of clay present in the well.

The silt fraction was obtained by subtraction of the
non-clastics, sand, and clay from the weight of the original

sample.

Mounting and Analyzing the Sand Grains

A hot plate and Bunsen burner were used to heat a
clean glass slide. After the slide was hot, a small amount
of canada balsam was placed on it and allowed to cook for
several minutes. Meanwhile, the sand saved from the sieve
analysis was sieved through a 60 mesh Tyler sieve to facili-
tate mounting on the slide. Most of this sand was then
sprinkled on the melted canada balsam and a cover glass was
placed over it.

Under the microscope, only the percentages of quartz
and chert were estimated. But it was discovered that in all
cases more than fifty percent of the sand was composed of
qurite crystals. Each slide was considered representative

le the entire sand in the well.

Laboratory Equipment

For the quantitative analysis of one well, the follow-
ing laboratory equipment was used:

50 ml. beaker

250 ml. beaker

hOO m1. beaker

600 ml. beaker

30 mesh Tyler sieve

60 mesh Tyler sieve
230 mesh Tyler sieve
flat bottom pan

large funnels

2 foot glass tube

3 foot rubber hose
glass stirring rod

20 cc. pipette

1000 ml. graduated cylinder
sample vial and cork
glass slide

cover glass

electric hot plate
sand bath

chainomatic balance and weights
polarizing micrOSOOpe
Bunsen burner

hot plate

15 cm. #1 filter paper

HHHHHHHHHHHHHHNHHHHHHHH

Errors in the Analyses

Some error did exist in forming the composite sample.
This may be due in part to loss as dust or to some accumu-
lative error in weighing. After boiling in the KOH solution,
it was impossible to remove some of the material stuck to
the sides of the beaker. This amount was determined to be

less than l/lO g. in all instances and was added to the clay

25

fraction. Some error would have occurred in washing the

material through the sieve in the sieve analysis. This

error, however, was undeterminable.

Results of the Laboratory Analyses

Table III represents the data obtained from the
quantitative analyses of the 16 wells. This data was used
to compute the first three ratios of Table IV. The quartz-
chert ratio data was determined from a microscopic exami-

nation of the sand grains.

TABLE III

QUANTITATIVE ANALYSIS

 

 

Well Sample Water Acid Sand Silt Clay
Number Weight Solubles Solubles Fraction Fraction Fraction

 

I

1 112.17g. 0.u78. 7e.h8g. 0.68g. 20.69g. 13.85g.
2 1t1.2t 0.88 94.85 0.u8 25.75 19.31
3 1h0.72 0.35 80.h8 0.15 29.95 25.23
h 113.9h 0.61 8h.hh 0.18 15.73 12.98
5 92.35 1.31 57.h3 0.10 18.51 15.98
6 57.93 0.03 38.17 0.07 6.97 12.u9
7 85.u1 0.u9 58.17 0.20 12.63 13.90
8 157.96 0.29 110.2h 0.3h 21.8h 25.25

TABLE III (Cont.)

26

 

 

 

Well Sample Water Acid Sand Silt Clay
Number Weight Solubles Solubles Fraction Fraction Fraction
9 68.L15 0.19 118.92 0.111 8.15 11.05
:10 lh6.16 0.h2 96.28 0.22 25.20 2h.0h
11. 80.58 0.2h ,53.23 0.03 16.32 10.75
12 80.30 0.61.1 56.95 0.26 9.112 13.03
13 178.67 1.28 123.03 3.09 27.113 23.83
111 76.63 0.66 511.77 0.1.16 8.70 12.05
:15 165.95 0.3u 118.70 0.1h 21.56 25.21
:16 155.37 0.88 112.h9 0.15 17.15 2h.70

2?
LITH OLOGIC VARIAT ION

Lithologic Ratios

Because of the growing abundance of subsurface ex-
ploration in recent years, samples for analysis and mapping
have become more abundant. Krumbein (19h8) devised a system

of ratios for mapping purposes.

"The thickness (or percentage) of clastics
are added together and divided by the sum of the
thicknesses (or percentages) of the non-clastics.
The resulting number is defined as the "elastic
ratio". The elastic ratio is augmented by a
"sand-shale ratio" which is the ratio of sand-
stone (plus conglomerate) to shale in the sec-
tion, regardless of the amount of non-clastics

present:
conglomerate + sandstone + shale
Clastic ratio = --------------------------------
limestone + dolomite + evaporite
conglomerate + sandstone
sand-shale ratio = ------------------------

A Clastic ratio of 2, for example, means
that on the average 2 feet of elastic material
were deposited per foot of non-clastics."

Another ratio that is very widely used is the evapor-
ite ratio where:
evaporites
evaporite ratio = --------------------

limestone + dolomite

A quartz-chert ratio where:

Quartz-chert ratio = ........

i

ll

28
was devised to determine statistically whether there is a
significant trend in chart content from.the eastern to the
western part of the state.

A pyrite to sand or a pyrite to chert-quartz ratio
may be feasible in this paper. But, for lack of time, this
analysis was not attempted.

The analysis showed very little evaporite (water
soluble) material present. For this reason, it is question-
able whether the ratio is significant. Any small errors that
may occur in the analysis are apt to show here. This is
also true for the sand. 0f the four ratios, the elastic
ratio and the quartz-chert ratio will be the most signifi—
cant.

Table IV shows the lithologic ratios for each well.

These ratios were obtained from the data on Table III.
TABLE IV

LITHOLOGIC RATIOS

Well Clastic Sandéshale Evaporite Quartz-Chart

 

Number Ratio Ratio Ratio Ratio
1 0.h6 0.019 0.006 2.08
2 0.h8 0.011 0.009 2.00

3 0.68 0.002 0.003 0.33

 

TABLE IV (Cont.)

29

 

 

 

Well Clastic Sand-Shale Evaporite Quartz-Chert

Number Ratio Ratio Ratio Ratio
h 0.3M 0.007 0.007 l.h0
5 0.58 0.003 0.023 0.50
6 0.51 0.003 0.001 3.00
7 O.h6 0.008 0.008 0.2h
8 0.h3 0.007 0.003 1.20
9 0.39 0.007 0.004 2.50
10 0.51 0.00h 0.005 3.00
11 0.51 0.001 0.005 1.00
12 0.39 0.011 0.011 1.33
13 0.hh 0.060 0.010 3.00
In 0.38 0.022 0.012 9.00
15 0.39 0.003 0.003 2.50
16 0.28 0.00M 0.008 0.20

 

 

Facies Map Construction

In constructing the facies maps, it was first neces-
sary to obtain a good base map. The ratios were then
plotted in their respective positions on the map. Contour

lines of equal ratio were constructed from this data.

30
These lines were plotted with an arithmetic rather than a
geometric interval (krumbein 1952).

To facilitate interpretation of the maps, rather than
constructing isopach lines over the ratio contours, a sepa-
rate isopach map was made on semi-tranSparent paper. The
ratio maps were constructed on Opaque paper. Therefore,
the isopach map may be placed over any of the ratio maps
to aid in interpretation.

Maps III, IV, and V are the elastic ratio, sand-
shale ratio, and evaporite ratio maps respectively. Map V1
is the isopach map. Each was constructed using the data

obtained from the analyses of the 16 wells.

31
INTERPRETATION OF FACIES MAPS

Methods of Geological Interpretation

Krumbein (1952) devised a unique classification of
relationships between the lines of an isopach map and the
contours of a lithofacies map. By superimposing the isopach
on the lithofacies map, certain angles are formed by the
contour lines. He defines six relations that can be found
between any set of isopachs and lithofacies lines. Some of
the illustrations he gives for these patterns are as
follows: "The linear sub-parallel pattern may occur under
conditions where clastic sediments are Spread over a sub-
siding area in decreasing amount away from.the source, so
that the elastic ratio lines tend to decrease as the isopachs
increase ...", and the "curvilinear-discordant pattern may
arise when a local concentration of clastics is poured into
a subsiding area, as a delta."

Three patterns are eSpecially suited to an intra-
cratonic basin such as the Michigan Basin (Krumbein 1952).

The discordant-ovate pattern would indicate either
a nearby organic source or a nearby epeirogenic source.

A concentric—ovate pattern could indicate either a
nearby orogenic source, a nearby epeirogenic source, or a

distant source.

 

32
A curvilinear pattern usually shows a nearby oro-
genic source.
These relationships should give a good basis for
interpreting the source areas and their relative distance.

Figure I illustrates the relations.

Methods of Statistical Interpretation

Krumbein (1955) suggests the use of analysis of
variance to stratigraphic or lithologic variations. In the

discussion of stratigraphic populations, he states:

"A stratigraphic unit has certain sta-
tistical properties when it is thought of as a
population of attributes. Some of these pro-
perties can be translated into geological
terms, and they provide useful concepts in the
study of facies maps. For example, the total
population may be homogeneous, so that samples
drawn from any one subarea are similar to
those drawn elsewhere; or the population may
have a gradient, so that the measured proper-
ties vary systematically in some direction
over the map."

This type of statistical analysis of facies maps is
relatively new. It is designed primarily to test facies
patterns that are Spotty and give no indication of trending
in any particular direction.

In testing data by analysis of variance, a hypothesis
is chosen which in this problem states, there is no signi-

ficant difference between the position means.

FIGURE I

Relationships Between Isopachs (Solid) and
Facies Lines (After Krumbein, 1952)

33

 

 

 

 

 

 

 

 

Linear
Subparallel

Linear
Discordant

 

 

 

 

 

 

 

 

 

Curvilinear
Discordant

Concentric
Ovate

 

 

 

 

 

 

 

 

 

 

Discordant
Ovate

Irregular
Spotty

3A

The sum of squares for positions was obtained by
summing each column of data. Each of these figures was
then squared and divided by the number of observations for
each position. These three values were then added together.
From this number, is subtracted a figure computed as fol-
lows; each observation is squared and summed, then divided
by the total number of observations. The resultant value
from the subtraction is the sum of squares for positions.

The total sum of squares was calculate by summing
the square of each observation and subtracting the same
value as above.

The error sum of squares was Obtained by subtracting
the position value from the total.

Degrees of freedom were determined by subtracting
the number one from the number of values used in the calcu-
lations. For example, there are three values for positions
so the degrees of freedom for positions are two. The total
degrees of freedom are the total number of observations
minus one or 16 minus one equals 15. The error term was
obtained by subtraction.

To determine the mean Square value for positions,
divide the sum of squares by the degrees of freedom. This
was also the method of calculating the error mean square.

The F ratio was obtained by dividing the position

mean square by the error mean square. The F tables were

——I

35
found in Goulden (1952). The degrees of freedom for the

numerator in the F ratio are the horizontal values in the
tables. The degrees of freedom for the denominator are the
vertical values. If the calculated value for the F ratio
is greater than the table value, the means of the positions
are considered significantly different at the five percent
level. The light numerals in the table constitute the five
percent level.

A Significant difference in means suggests a definite
gradient in the values. In this analysis, no significant
difference was evident.

Map VII is the facies map for the quartz-chert ratio.
Map II illustrates the breakdown of the state into the three
positions; eastern, central, and western. These positions
are of equal length and constitute the columns in the anal-

ysis of variance. The analysis is Shown in Table V.

TABLE V

ANALYSIS OF VARIANCE OF QUARTZ-CHERT RATIOS IN THE MICHIGAN BASIN

 

 

 

Raw Data
West Central East
Section Section Section
3.00 9.00 2.08

0.2h 1.h0 2.50

 

TABLE v (Cont.)

36

 

 

 

 

 

Raw Data
West Central East
Section Section Section
2.5h 2.00 0.20
1.33 ’ 1.20 3.00
1.00 3.00
0050 0'33
Analysis of Variance
Source Sum of Degrees of Mean F
Squares Freedom. Square
Positions ......... 2.12 2 1.06 (,1 NS
Within positions .. g3.38 l}_ 3.36
Total A5.50 15

F(O.9S) (2, 13) = 3.80

 

 

Errors Involved in Interpretation

Many errors are involved in analyzing and interpreting

the section used in this study. The most obvious is the

great amount of interpolation necessary in constructing the

OOOOOOOOO

37

maps. Some large and some small structures are undoubtedly
omitted. However, most of the large irregularities are
brought out in the analysis. These structures are broad
and persistent and in some cases tend to be accentuated by
this composite study.

Very little erosion has occurred during or after the
deposition of these sediments. So the isopach and litho-
facies maps should be very conclusive.

It was difficult to construct and interpretate the
quartz-chert ratio map because of the limited number of wells
and the Spotty pattern of deposition of the chart. The
statistical analysis was much more significant for this type
of deposit. The analysis was used to measure an east-west

trend.
Interpretations
Geological Interpretation

The facies maps were interpreted separately, by
placing the isopach over each one. It was thought necessary
to use counties as a basis for interpreting the structures.
It would be helpful to have a county map of Michigan to
refer to during the following discussion.

The elastic ratio map. This type of map is considered

to be the most accurate of the facies maps. For this rea-

38
son, the results from this map should take preference over
most differences brought out on the other maps.

In the northern peninsula, a curvilinear discordant
pattern is found in Mackinac, Luce, and Chippewa counties.
The nose of the clastic ratio contours points away from the
basin indicating a possible subsidence or trough present in
the area. These ratio contours continue beyond the scope
of the iSOpach map. This trough seems to have affected the
whole northern section of the state.

Applying Krumbein's (1952) theory of the tectonic
factors controlling depOSition in an intracratonic basin,

a curvilinear discordant pattern of this type would indi-
cate a relatively distant orogenic source. This could be
called an "inverted" curvilinear discordant pattern.

The western part of the state is characterized
generally by a linear subparallel pattern. However, there
is some evidence of another inverted curvilinear discordant
pattern in Mason and Manistee counties; in fact, the isopach
shows some thickening of sediments in this area, while the
clastic ratios decrease, indicating some degree of subsi-
dence.

South of this area, between Mason and Ottawa counties,
there is a definite linear subparallel relation. Krumbein
(1952), referring to this pattern, states, "elastic sedi-

ments are Spread over a subsiding area in decreasing amount

39

away from the source, so that the Clastic ratio lines tend
to decrease as the isopachs increase because of increasing
lime deposition."

In the southwest, the relationship between the iso-
pach lines and the ratio contours range from a slightly
curvilinear discordant and linear subparallel pattern to a
' relatively strong curvilinear discordant pattern. This indi-
cates a strong regional subsidence or trough effect to the
southwest. This effect is evident from Ottawa to Hillsdale
County. ’

A rather intricate pattern is found in the south-
eastern section of the state. In Oakland and Macomb coun-
ties, there is a strong discordant ovate pattern. But,
farther to the southeast, in Monroe, Wayne, and Washtenaw
counties and into southwest Ontario, the pattern changes to
an inverted curvilinear discordant relationship. This is
suggestive of a nearby orogenic or epeirogenic source in
Oakland and Maoomb counties as against an area of subsidence
to the south and southeast.

The ovate pattern on the iSOpach in Wayne and Oakland
counties indicates the thickest accumulation of sediments.
However, the elastic ratio map places the greatest deep
water deposits farther to the northwest.

Relatively little information is available in the

hO
east, but the pattern seems to be linear subparallel. Be-
cause of the large area covered by this pattern, it is pos-
tulated that the material came from a distant source.

The following is a summary of the major structural
trends determined from the elastic ratio map.

1. An area of subsidence in Mackinac, Luce, and
Chippewa counties trending to the north into the Lake
Superior Basin.

2. A wideSpread general subsidence in the southwes-
tern section of the state. This structure trends to the
southwest.

3. In Wayne and Livingston counties, there is a
narrow deep trough indicated with source material nearby
both to the northeast and southwest.

The sand-Shale ratio map. Because of the exclusion
of the lower Ordovician sediments, which contain most of
the sand, the sand-shale ratio is extremely small.

In Schoolcraft and western Mackinac counties, there
is a relatively weak curvilinear discordant pattern. This
indicates a slight increase in sand content. Both to the
west and east of this structure, there are slight indi-
cations of subsidence. The trough to the southeast corres-
ponds to the conclusions drawn in the clastic ratio inter-

pretation of this area.

hl

There are two ridge-like structures. One trends to
the northeast through Oceana, Mason, and Lake counties,
and the other east through Allegan, Kent, Barry, and Ionia
counties. The isopach through both of these areas indicates
the exactly opposite structure. This may be due to the
error introduced by the relatively small amount of sand,
but the writer thinks not.

The southwest corner of the state shows a strong
low in the sand-shale ratio and illustrates an excellent
inverse curvilinear discordant pattern. This low extends
to the southwest and correSponds to the elastic ratio inter-
pretation.

In the southeast, a distinct inverse curvilinear dis-
cordant pattern exists, trending southeast through Washtenaw,
Wayne, and Monroe counties. The northwestern corner of
Wayne County shows an extremely high sand-shale ratio.

This is possibly a good example of error due to contamina-
tion in sampling or a small increase in sand content in the
section. The high is represented by a ratio of .060.

To the west of this area, passing through Lenawee
County is a rather small structure indicated by an increase
in sand content. The contour relations show a linear
discordant pattern. I

The east is represented by a linear subparallel

E2
pattern, as it was on the elastic ratio map, indicating a
distant source of material.

The major structural features represented on the
sand-shale ratio map are as follows:

1. Two trough-like structures in the Upper
Peninsula. One passing northward through Schoolcraft coun-
ty and the othertrending northward through Mackinac and
Luce counties.

2. In the west, two ridge-like structures. Both,
however, are contrary to the interpretations of the iSOpach
map.

3. The southwest shows a trough trending to the
southwest with relative highs on both sides.

h. Another trough is represented in the southeast
trending east through Washtenaw and Wayne counties.

5. An exceptionally high area is present in north-
west Wayne county. This is probably due to the error pre-
viously discussed.

The evaporite ratio mgp. "The concentric ovate
pattern is characteristic of evaporites in an intracra-
tonic basin" (Krumbein 1952). This pattern is especially
obvious in the Oakland and Wayne county area.

Another ovate pattern is formed in the southwest in

St. Joseph, Kalamazoo, Calhoun, and Branch counties. This

11.3

structure conforms to the southwest trending trough already
discussed.

Just to the north of this structure, there is a
strong high shown on the lithofacies map. This high is
accompanied by a thickening of sediments shown on the iso-
pach. However, this structure is probably part of the
trough to the south. The nose of the contour trends to the
southeast through Allegan, Ottawa, and Barry counties.

Along the western edge of the state, the iSOpach and
evaporite contours closely parallel each other. This sug—
gests a distant source of material.

A distinct relationship between the isopach lines and
facies contours is represented in the Upper Peninsula. The
isopach lines Show thinning to the northwest as the facies
lines thicken toward the basin. A trough-like structure
trending northwest is suggested. This structure is located
in Schoolcraft, Luce, and Western Mackinac counties.

Interpolation in the eastern part of the state indi-
cates much the same type of deposition as was suggested
from the other facies maps.

The following is a summary of the prominent struc-
tures indicated by the evaporite lithofacies map:

1. A small area of basinal deposition in Wayne and

Oakland counties.

ha
2. Another area of basinal deposition is

elongated to the southwest. The width of this structure
stretches from Allegan County southeast to Hillsdale County.

3. A small trough is indicated in the Upper Penin-
sula, trending northwest through Schoolcraft, Luce, and
Westgrn Mackinac counties.

The quartz-chert ratio mgp. This map generally has
an irregular Spotty pattern which, according to Krumbein
(1952), is indicative of either a nearby epeirogenic source
or a distant source.

There are extreme differences in the ratios between
southwestern Schoolcraft County and northwestern Mackinac
County, which indicates to some extent a random type of
deposition.

In the southwest corner of the state, however, there
is an inverted curvilinear discordant pattern that is rather
pronounced. This shows some increase in the relative quan-
tity of chert which indicates subsidence. This structure
trends to the southwest.

In Wayne, Washtenaw, Livingston, and Oakland counties
there is a concentric ovate relation which is characteristic
of evaporite deposition in an intracratonic basin. This
structure indicates deep water deposition which conforms to

the isopach interpretation of this area.

115’

The major structures indicated by the quartz-chert
ratio map are as follows:

1. A random type of deposition in the Upper Penin-
sula.

2. A trough through Kalamazoo, Cass, and St. Joseph
counties trending southwest.

3. A deep water intracratonic basin deposit in

Livingston, Oakland, Washtenaw, and Wayne counties.
Statistical Interpretation

Only the quartz-chert ratio map was analyzed statis-
tically. This was done because of the irregular Spotty
type of deposition. The other ratio maps showed strong
trends and needed no statistical interpretation.

Before the analySis, there was presumed to be some
variation from east to west in the chert content. The
analysis showed, however, no trend whatsoever. There could
be some local trends, but on this regional scale they would

tend to cancel each other.

E6
REGIONAL TECTONICS

Structural Relations of the Michigan Basin

The greatest Paleozoic unconformity in the Michigan
Basin is found at the break between the St. Peter sandstone
and the Trenton and Black River limestones. The St. Peter
marks the time of uplift and erosion. From west to east,
the lower and middle Ordovician deposits successively rest
on the upper Cambrian to the pre-Cambrian crystalline rocks
(Eardley 1951).

Prior to Devonian time, the Michigan and Illinois-
Indiana-Kentucky basins were continuous; "But beginning in
the Devonian, the Kankakee arch began to form, and the two
basins became increasingly individualistic thereafter"
(Eardley 1951). The Kankakee arch is the southern and
southwestern boundary of the Michigan Basin.

Early in the Ordovician, the northeastern branch of
the Cincinnati arch, the Findlay arch, began to form (Cohee
19MB). The Wisconsin arch, which bounds the basin on the
west, began to form in early Cambrian but the major move-
ment was post-Cambrian. According to Ekblaw (1938), the
major movement of the Wisconsin arch occurred after the Lower

Ordovician.

I47
Cohee (19k8) suggests the basin continues in the

north as a narrow trough between pre-Cambrian crystalline
and metamorphic rocks. The basin was possibly continuous
with the Lake Superior geosyncline which follows the present
lake in a half-moon shape around the upper peninsula. The
connection was near the north tip of the Lower Peninsula
(Pirtle 1932).

Now, let's consider the relationships of the facies

maps with the regional structure during Ordovician time.

Structural Interpretations in Relation to Tectonics

Most of the major intrabasinal structures are repre-
sented in the facies maps. The evaporite ratio and quartz-
chert ratio maps indicate the deep areas of deposition. On
the other hand, the sand-shale and clastic ratio maps magni-
fy the marginal areas and areas of uplift.

Cohee (19k8) made an extensive study of the Cambrian
and Ordovician rocks in the Michigan Basin. Using well
logs for data, he constructed two maps showing the thick-
nesses of both the Upper and Middle Ordovician sediments.
The center of the basin is shown on these maps as a trough
extending from Saginaw County southeast to Oakland County.

A similar structure was shown on the maps in this analysis.

NB

The elastic ratio and sand-shale ratio maps indicate
a possible extension of this trough to the east and south-
east. In referring to this depression, Cohee (19h8) states,
"This sag probably served as a connection between the
Michigan and the Appalachian Basins at various times."

Both to the north and south of the depression, are located

structural highs. During the lower Ordovician, the Findlay
arch was beginning to form. Intermittant linking with the

Appalachian Basin due to fluctuations during the formation

of the arch, is probably a more accurate interpretation of

this trough than the presence of a continuous connection.

In the southwest section of the state, a broad con-
tinuous depression which connected the Michigan Basin to the
Illinois-Indiana-Kentucky Basin existed. This interpretation
correSpondS to the conclusions of both Eardley (1951) and
Cohee (19h8). According to Eardley (1951), the Kankakee
arch began to form in the Devonian. This statement is
partially supported by the great amount of faulting exhi-
bited in the Trenton Limestone in Northern Ohio, which
indicates postJTrenton movement (Cohee, 19h8).

The Wisconsin arch is a broad fold trending north-
west (Pirtle, 1932). Most of the movement of this arch
occurred in post-Cambrian time. This would indicate that

during the Ordovician it was not a very prominent feature.

M '

1+9
The type of deposition in the western part of the state
indicates the existence of this kind of structure.

Cohee (19h8) suggests the possibility of a connection
between the Michigan Basin and the Lake Superior Basin. The
Lake Superior Basin was postulated to be present during
Ordovician time. All the maps, with the exception of the
quartz-chert ratio map, Show the presence of a shallow
trough, trending northwest, through Mackinac, Luce, and
Schoolcraft counties.

Because of the scarcity of information in the eastern
part of the state, the conclusions drawn are rather incon-
clusive. But the material for deposition seems to be from
a rather distant source. The Findlay arch, because of its
low attitude did not affect deposition in this area to any

extent.

Tectonic Aspect

The interpretation of the facies maps indicates the
Michigan Basin as a relatively broad depression. Because of
the relatively small amount of evaporites present, it is
inferred that the basin was rather stable and continually
below water. Most of the highlands surrounding the basin
were eroded to relatively low positive structures during the

period between the St. Peter and Black River depositions.

50
This environment may also account for the small amount of

sand in the analysis. The lithologic change from the lime-

stones and dolomites of the middle Ordovician to the shales

of the upper Ordovician indicate some uplift on the peri-
phery of the basin.

51
CONCLUSIONS

Most of the structures interpreted from this analysis
are not shown in the present structure of the Michigan
Basin. These structures represent the beginning of the
formation of the basin and have changed considerably since
deposition of the Ordovician sediments. One of the most
marked changes is the shift in the position of the center
of the basin from Oakland County, northwest, to the vicinity
of Clare County. The presence of some of these structures
was extremely valuable in the interpretation of the tectonic
activity during the deposition of the Ordovician sediments.

In recent years at Michigan State University, this
type of analysis has been performed on most of the Paleozoic
sediments. With the completion of the remaining systems, a
great deal of information will be available concerning the

Michigan Basin.

52
REFERENCES
Cohee, G. V. (19h8), Cambrian and Ordovician Rocks in

Michigan and Joining Areas, Am. Assoc. Petrol. Geol.
Bull., V01. 32, pp. 1h17-1HLF

 

Eardley, A. J. (1951), Structural Geology 2f North America,
Harper Bros., New York, pp. 29~3l.

 

 

Eckblaw, G. E. (1938), Kankakee Arch in Illinois, Bull.
Geol. Soc. America, Vol. A9, p. 1h28.

 

 

Goulden, C. H. (1952), Methods of Statistical Analysis,
John Wiley and Sons, Inc., New York, pp. Hh6-EL9.

 

Krumbein, W. C. (1952), Principles of Facies Map Interpre-
tation, Jour. Sed. Petrology, Vol. 22, pp. 200-211.

 

 

 

Krumbein, W. C. (l9h8), Lithofacies Maps and Regional Sedi-
mentary-Stratigraphic Analysis, Am. Assoc. Petrol.
Geol. Bull., V01. 32, pp. 765-7887" ' '

Krumbein, W. C. (1955), Statistical Analysis of Facies
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,//

41".. ..

    

Demco-293

 

Date Due

 

 

 

 

 

 

 

CLASTIC RATIO

OF ORDOVICIAN

Interval: 0.05 Cl'astic Ratio

 

ogu

 

 

 

 

 

 

 

 

 

 

SAND-SHALE RATIO

OF OR DOVICIAN

 

Ratio

.005 Sand—Shale

Interval:

 

 

 

 

 

 

 

 

 

 

 

 

_,_
,_
i.

EVAPORITE RATIO -

OF ORDOVICIAN

     

Ratio

.005 Evaporite

Interval:

06.7

 

 

 

 

 

 

 

 

 

 

 

 

ISOPACH OF

ORDOVICIAN

 

 

IOO FEET

INTERVAL:

 

 

 

 

 

 

oeV

 

. 2415;31 J.

 

 

 

 

 

 

 

 

QUARTZ‘ CHERT

RATIO

OF ORDOVICIAN

 

0.50 Quartz— Chert Ratio

Interval:

003V

 

 

 

 

 

 

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