The Marquette Mineral District - University of Minnesota Duluth

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The Marquette Mineral District - University of Minnesota Duluth
THE CLEVELAND-CLIFFS IRON COMPANY
PAPER ON
The Marquette Mineral District
Michigan
1964
Presented to the Conference on Lake Superior Geology
National Science Foundation Summer Conference
Sponsored by Michigan Technological University
BY
BURTON H. BOVUM
CHIEF GEOLOGIST
ISHPEMING. MICHIGAN
17
17
THE MARQUETTE
THE
MARQUETTE MINERAL
MINERAL DISTRICT,
DISTRICT, MICHIGAN
MICHIGAN
by
by
Burton
Burton H.
H. Boyum,
Boyum, Chief
Chief Geologist
Geologist
Mining
Department
Mining Department
The Cleveland-Cliffs
The
Cleveland-Cliffs Iron
Iron Company
Company
Ishpeming,
Michigan
Ishpeming, Michigan
General
Sett
General Setting
The Marquette
Marquette Mineral
Mineral District
District of
is situated
The
of Michigan
Michigan is
situated in
in Marquette
Marquette
It
was
the
first
Countyand
andthe
theeast
east central
central part
County
part of
of Barage
Barage County.
County. It was the first of
of the
the
Lake
Superior iron
iron districts
Lake Superior
districts to
tobe
be discovered
discoveredand
and mined;
mined; and
and iron
iron mining
mining
There has
continues to
to be
be the
the major
major mining
activity to
to this
this date,
continues
mining activity
date. There
has also
also been
been
Figure 11 shows
some production
some
production of
of gold.
gold. Figure
shows the
the outlined
outlined location
location of
of the
the Negaunee
Negaunee
Geographically, the
iron-formation, the
iron-formation,
the principal
principal host
host rock
rock for
for the
the iron
iron ore,
ore. Geographically,
the
Marquette
Marquette District
District is
is located
locatedon
onaa topographic
topographichighland
highland rising
risingsome
some600
600to
to1200
1200
above Lake
Lake Superior
Superior (mean
feet above
feet
(mean sea
sea level
level elevation
elevation+602
+602 feet).
feet). The
The average
average
1400 feet.
feet.
ground
elevation near
near the
ground elevation
the mines
mines at
atIshpeming
Ishpeming and
and Negaunee
Negaunee is
is ++ 1400
feet. Locally,
1875 feet.
Firetower Hill
area rises
Firetower
Hill in
in the
the Tilden
Tilden Mine
Mine area
rises to
to ++1875
Locally, the
the
is
rugged,
with
numerous
lakes
and
swamps.
The
watershed
topography
topography is rugged, with numerous lakes and swamps.
drains both
both to
toLake
LakeSuperior
Superiorand
andLake
Lake Michigan
Michigan from
from the
the Marquette
Marquette high­
high
drains
By tradition,
tradition, in
the
Lake
Superior
Region,
the
topographic
highs
land. By
in the Lake Superior Region, the topographic highs in
in
which
most ofofthe
theiron
irondistricts
districts are
are found
foundare
are called
called "ranges";
Iranges; hence
which most
hence the
the
designation, the
the Marquette
MarquetteIron
IronRange.
Range. The
The three
three principal
principal cities
cities are
are
designation,
Marquette
(County
seat
and
port),
Ishpeming
and
Negaunee.
Forest
Marquette (County seat and port), Ishpeming and Negaunee. Forest products,
products,
education (Northern
(Northern Michigan
Michigan University)
University) and
and tourism
tourism augment
in the
education
augment mining
mining in
the
area's
economic
activity.
area's economic activity.
Historical Setting
Historical
Setting
The first
miners in
in the
the region
region may
may have
have been the
the pre~historic
prehistoric Indian
The
first miners
Indian
1961). We
We know
know
copper miners
miners some
some 3800
(Drier and
and DuTemple,
DuTemple, 1961).
copper
3800 years
years ago (Drier
that
the
French
explorers,
Brule
and
Grenoble,
visited
the
Upper
Peninsula
that the French explorers, Brule and Grenoble, visited the Upper Peninsula
in 1E>22.
122. They
voyageurs.
in
Theywere
werefollowed
followedby
byfur
fur traders,
traders, missionaries and voyageurs.
In
1668
Father
Jacques
Marquette
and
Father
Claude
Dablon
established
In 1668 Father Jacques Marquette and Father Claude Dablon established the
the
believed that
that Father
Father Marquette
Marquette visited
It is
n-ission at
at Sault
mission
Sault Ste.
Ste. Marie
Marie (Soo).
(Soo). It
is believed
visited
site of
and used
used aa campsite
campsite at
the site
of the
the City
City of
of Marquette
Marquette in
in 1670
1670 and
and 1671
1671 and
at
His
name
was
given
to
the
city,
county
and
iron
range
Lighthouse
Point,
Lighthouse Point, His name was given to the city, county and iron range in
in
18
honor of
of his
his early
early work
work here,
here, as
honor
as well
well as
as his
his extensive
extensive efforts
efforts in
in other
other parts
parts of
of
He assisted
assisted Fathers
the north
north central
central states.
states. He
the
FathersAllouez
Allouezand
andDablon
Dablon in
in making
making the
the
first map
in 1672
in Paris.
Paris. Sporadic
first
map of
of the
the Lake
Lake Superior
Superior Region,
Region, published
published in
1672 in
Sporadic fur
fur
trading marked
marked the
the next
next 170
170 years
years in
in this
this vicinity.
trading
vicinity.
Michigan became
became aa State
Dr. Douglass
the first
first State
Michigan
State in
in 1837.
1837. Dr.
Douglas s Houghton,
Houghton, the
State
Geologist, convinced
the State
State Legislature
Legislature that
Geologist,
convinced the
that the
the Federal
FederalLand
LandSubdivision
Subdivision
The Indian
Indian Treaty
Treaty of
Survey should
should have
have geological
geological mapping
as an
Survey
mapping as
an adjunct.
adjunct. The
of
LaPointe, 1842,
LaPointe,
1842, opened
opened the
the Upper
Upper Peninsula
Peninsula to
to the
the white
white men.
men. On
OnSeptember
September
19, 1844,
Survey Party
Party under
19,
1844, a
a Government
Government Survey
under Mr.
Mr. William
William A.
A. Burt
Burtwas
was running
running
Shaft
the
east
line
of
Section
1,
T.
47
N.
and
R.
27
W.
(Mather
Mine
the east line of Section 1, T. 47 N. and R. 27 W. (Mather Mine nBt!
property). AA younger
Jacob, noted
erratic
property).
younger brother
brother of
of Douglass
Douglass Houghton,
Houghton, Jacob,
noted erratic
They sought
sought the
the cause
cause and
and found,
found, as
compass behavior.
compass
behavior. They
as recorded
recorded by
by Douglass
Douglass
Houghton, rrSpathose
"Spathoseand
andmagnetite
magnetiteores
oresabounding.
abounding."
Later, in
Houghton,
rr Later,
in 1846,
1846, Burt
Burt
wrote: ItrrItmay
wrote:
maybe
bereasonably
reasonablyinferred
inferredthat
thatnot
notmore
morethan
thanone-seventh
one-seventh of
of the
the
of Iron
Iron ore
ore beds
beds were
were seen
Township lines;
number
number of
seen during
during the
the survey
survey of
of the Township
lines;
mines
be subdivided
with care
care in
in reference
district of
ofTownships
Townships be
this district
and if
and
if this
subdivided with
reference to
to mines
If
this
view
minerals,
six
times
as
many
more
will
probably
be
found.
and minerals, six times as many more will probably be found. If this view of
of
the Iron
the Northern
Northern Peninsula
Peninsula of
of Michigan
Michiganbebecorrect,
correct, itit far
the
Iron region
region of
of the
far excels
excels
any other
other portion
States in
qualities of
its
any
portion of
of the
the United
United States
in the
the abundance
abundance and
and good
good qualities
of its
Iron ores.
ores."rr
Iron
Word of
ore discovery
discovery spread
state and
and elsewhere
elsewhere
Word
of the
the iron ore
spread through
through the
the state
group of
ofmen
men from
from Jackson,
Jackson, Michigan,
Michigan, formed
formed
In 1845
that winter.
during that
winter. In
1845 aa group
The
treasurer,
Philo
Everett,
and
his
associthe Jackson
Jackson Mining
Mining Company.
Company. The treasurer, Philo Everett, and his as sod­
the
story is
ates, reached
reached Teal
ates,
Teal Lake
Lake in
in June.
June. The story
is told
told that
that the
the Indian
Indian chief,
chief,
stump
sick,
showed
them
the
high
grade
hard
ore
under
the
Marji-Ge
Marji-Gesick, showed them the
hard
under the stump of
of a
a
ore
pine tree.
tree. By
By 1846,
1846, there
there were
were 106
106 mining
mining companies.
companies. The
fallen pine
fallen
The first
first ore
the Soo
Soo Locks
Locks opened
opened
7, 1852.
barrels on July 7.
shipped consisted
shipped
consisted of
of six
six barrels
1852. After the
June, 1855,
in June,
1855, Lake
Lake Superior
Superior iron
iron mining
mining boomed
boomed -- a tribute
tribute to
to the
the farsighted
farsighted
vision of
vision
of Douglass
Douglass Houghton.
Houghton.
Since much
much ofofthe
theore
ore was
wasfound
foundatatorornear
near surface,
surface, the
Since
the early
early mines
mines were
were
As
the
mines
went
deeper,
worked
by
open
pit
methods,
as
shown
in
Figure
2.
worked by open pit methods, as sho\VTI in Figure 2. As the mines went deeper,
skip roads
roads were
were used
bring the
the ore
oretotosurface.
surface. By
By 1880,
1880, most
most of
inclined skip
inclined
used to
to bring
of
the
ore was
was produced
produced from
from underground
underground workings.
the ore
workings. Early methods were
were open
open
by
top-slicing
stoping,
room-and-pillar
stoping,
and
square-sets,
followed
stoping, room-and-pillar stoping, and square-sets,
by top-slicing
Large scale
Sub-level caving
caving was
was used
used where
where conditions
permitted. Large
in 1890. Sub-level
in
conditions permitted.
scale
illustrates
a
sub-level
stoping
Figure
3
block caving was
was introduced
in
1950.
introduced in 1950. Figure 3 illustrates a sub-level stoping
scene.
scene.
Emphasis in
Emphasis
in mining
mmmgwas
wasplaced
placedononthe
the high
high grade
grade direct
direct shipping
shipping ores.
ores.
the 1880t5
several attempts
attempts were
However, in
However,
in the
1880's several
were made
made to
to use
use concentrating
concentrating plants.
plants.
It
produced
Edison
built
a
magnetic
separator
at
Humboldt
in
1888.
Thomas Edison built a magnetic separator at Humboldt in 1888. It produced
Thomas
World War
War
grade concentrate
burned in
893 tons of
of high grade
concentrate before
before it
it burned
in 1889.
1889. After
After World
II,
the
mining
companies
worked
on
developing
economic
processes
of
con
II, the mining companies worked on developing economic processes of con­
•
•
19
19
centrating
grade Negaunee
Negauneeiron-formation,
iron-formation, also
also called
centrating the
the low
low grade
called jaspertr
ffjasper rr or
or
The
first
commercial
plant,
opened
in
1954,
was
the
Humboldt
ttaconite.
rttaconite.
The first commercial plant, opened in 1954, was the Humboldt
Mine of
of The
The Cleveland-Cliffs
Cleveland-Cliffs Iron
Iron Company
Companyand
andFord
Ford Motor
Motor Company.
Company. The
Mine
The
Repuolic
Mine
was
opened
in
1956,
and
the
Empire
Mine
in
1963;
both
partnerRepuolic Mine was opened in 1956, and the Empire Mine in 1963; both partner­
ships of
ships
of various
various steel
steel companies
companies and
and Cleveland-Cliffs.
Cleveland-Cliffs. All
All three
three open
open pit
pit
properties produce
grade pellets.
properties
produce high
high grade
pellets.
II
The Marquette
Marquette Iron
Iron Range
Rangeisis made
made up
upofofthree
three districts
districts (see
The
(see Figure
Figure 4).
4).
From
1852
through
1963,
the
iron
ore
production
from
these
districts
was:
From 1852 through 1963, the iron are production from thes e districts was:
Principal
Principal district
district
Cascade
district
Cas
cade district
Gwinndistrict
district
Gwinn
291,323,507
291,323,507
17,895,700
17,895,700
785, 260
12,
12,785,260
Total
Total
322, 004,467 long
322,004,467
long tons
tons
Of the
the total
total of
of291
291million
milliontons
tonsproduced
produced from
from the
part of
of the
the Range,
Range,
Of
the principal
principal part
4,266,858
long
tons
were
from
the
Bijiki
iron-formation,
and
the
balance
was
4,266,858 long tons were from the Bijiki iron-formation, and the balance was
from the
Negaunee iron-formation.
from
the Negaunee
iron-formation.
Concentration was
was accomplished
Concentration
accomplishedononthe
the Bijiki
Bijiki iron-formation
iron-formation by
by using
using
total
heavy media
media process
the Ohio
OhioMine.
Mine. From
From 1952
the heavy
the
process at
at the
1952 to
to 1960,
1960, a
a total of
of
pit
operations.
745,
620
long
tons
of
concentrate
was
produced
from
several
open
745,620 long tons of concentrate was produced from several open pit operations.
Local
Not all
all Marquette
Marquette Range
Range ores
Not
ores were
wereshipped
shippedtotothe
the blast
blast furnaces.
furnaces. Local
charcoal furnaces,
furnaces, used
used from
from 1857
charcoal
1857 through
through 1893,
1893, produced
produced an
an estimated
estimated one
one
and aa half million
million
and
tons
tons of
of pig
pig iron.
iron.
Sett
Geologic
Geologic Setting
The principal
principal rock
rock units
units are
are Precambrian
The
Precambrian in
in age.
age. Structurally,
Structurally, they
they are
are
al,
to
the
Southern
Province
of
the
great
Canadian
Shield
(Leech
et
assigned to the Southern Province of the great Canadian Shield (Leech et aI,
assigned
Probably they
were subjected
the major
major orogenies
orogenies of
of the
theKenoran
Kenoran and
and
1963), Probably
1963).
they were
subjected to
to the
Penokean
(Hudsonian,
Stockwell,
1962),
as
well
as
more
local
deformation,
Penokean (Hudsonian, Stockwell, 1962), as well as more local deformation.
which the
found was
was called
The
thick sedimentary
sedimentary series
series in
The thick
in which
the iron
iron ore
ore is
is found
called
next
century.
by
Whitney
in
1857,
and
the
term
was
used
for
the
Huronian by Whitney in 1857, and the term was used for the next century.
(1958)pointed
pointedout
outthat
thatthe
theseries
series differs
differs considerably
James (l958)
considerably from
from the
the type
type
section
of
the
Huronian
of
Ontario
and
is
more
firmly
correlated
with
section of the Huronian of Ontario and is more firmly correlated with the
the
Animikie series
series of
Animikie
of northeastern
northeastern Minnesota;
Minnesota; therefore,
therefore, the
theUnited
United States
States GeolGeol­
Goldich,
et
al
(1961)
dated
the
Animikie
ogical
Survey
uses
the
term
Animikie.
ogical Survey uses the term Animikie. Goldich, et al (I96l) dated the Animikie
practice, Stockwell
as middle
Precambrian in
as
middle Precambrian
in age.
age. By
ByCanadian
Canadian practice,
Stockwell(1962)
(1962) would
would
term
Animikie
as
Lower
Proterozoic.
term Animikie as Lower Proterozoic •
20
The
found in
in aa long
long westward
westward plunging
plunging synclinorium
The Animikie
Animikie series
series isis found
which
County line,
the south
south
line, the
which opens
openstoto the
the west
west (see
(see Figure
Figure 4). Near the Barage County
limb
syncline has
has been
been folded
folded into a lesser
lesserdownfold
downfold called
called the
the
limb of the
the major syncline
The sedimentary
sedimentary series
series continues
Republic
Trough. The
continues into
into Baraga,
Baraga, Dickinson
Dickinson
Republic Trough.
and Iron Counties. Older
and
(Archean) rocks
rocks are
are found
found to
to the
the north
north of
Older (Archean)
of the
the syn~
syn
clinorium, To
To the south is
clinorium.
granite complex,
complex, thought
thought to
to be
be related
related to
to the
the
is aa granite
folding of
against the
the older rock
to the
the north.
north.
of the
the synclinorium
synclinorium against
rock buttres
buttresss to
to the
Cascade Range, immediately
The Cascade
immediately to
the southeast
southeast of
of the
the Marquette
Marquette synsyn­
clinorium,
is considered
considered to
to be
be aa faulted
faulted segment
segment of
of the
the main
main structure.
structure. The
clinorium, is
or Swanzy
Swanzy area,
Negaunee, and
Dead
Gwinn
area, some
some 20
20 miles
miles southeast
southeast of
of Negaunee,
and the
the Dead
Gwinn or
of the
the Marquette
Marquette Range,
Range,are
are separate
separate basins,
River area,
basins,
area, a few miles north of
entire district
to contain
contain rocks
rocks of
of the
the Animikie
Animikie series.
thought to
thought
series. The
The entire
district has
has been
been
intruded
by
rocks
of
Keweenawan
age.
Cambrian
and
Ordovician
sandstones
intruded
rocks of Keweenawan age. Cambria.n and Ordovician sandstones
district was
and limestones
limestones are
and
are found
found to
to the
the south
south and
and southeast,
southeast. The
The district
was glaciated
glaciated
extensively.
extensively.
Stratigraphic Column
Stratigraphic
Column
A schematic
schematic summary
summary of
the stratigraphic
A
of the
stratigraphic column
column is
is shown
shown as
as the
the legend
legend
This column
is aa modification
the most
on Figure
Figure 4.
on
4. This
column is
modification of
of the
most recent
recent work
work by
by the
the
United States
States Geological
Geological Survey,
Survey, together
together with
United
with data
data from
from the
the mining
mining companiest
companies I
drill hole
undergroundand
andsurface
surfaceexposure
exposureinformation.
information. Figure
Figure 44 is
drill
hole and
and underground
is aa
plan map
map indicating
indicating the
the principal
principal Animikie
and older
older rock
plan
Animikie and
rock units
units which
which make
make up
up
the
Marquette
synclinorium
and
environs,
Figures
5
and
6
illustrate
spatial
the Marquette synclinorium and environs. Figures 5 and 6 illustrate spatial
relations of
relations
of the
the principal
principal rock
rockunits
units in
inthe
thevicinity
vicinityofofNegaunee
Negaunee and
and Ishpeming.
Ishpeming.
Figure 77 indicates
the relative
Figure
indicates the
relative thicknesses
thicknesses of
of the
the stratigraphic
stratigraphic units
units from
from east
east
reflect several
to west
west in
to
in the
the synclinorium.
synclinorium. Variations
Variations reflect
several features
features such
such as
as the
the
extent of
of primary
primary sedimentation
and later
later erosion.
extent
sedimentation and
erosion. Apparently
Apparently the
the locus
locus of
of
the sedimentation
westerly as
the
sedimentation moved
moved westerly
as the
the younger
younger ro.cks
rocks were
were being
being deposited.
deposited.
Pre-Animikie
Pre-Animikie Basement
Basement Complex
Complex
Both Monographs
Monographs 28
28 and
and 52
52describe
describe the
and Kitchi
Kitchi schists
Both
the Mona
Mona and
schists which
which
They were
were intruded
were called
metasediments and
were
called Keewatin
Keewatin metasediments
and metavolcanics,
metavolcanics. They
intruded
by flLaurentian
by
Laurentian"granites,
granites.now
nowrepresented
representedby
by granites
granites and
and gneisses.
gneisses.
Recent detailed
detailed mapping
mapping by
bythe
the U.
U.S.
Survey (Gair
(Gair et
et aI,
al, 1963,
Recent
S. Geological
Geological Survey
1963,
et seq.)
that the
the Mona
Monaschist
schist consists
consists of
of schistose
schistose and
and massive
massive meta­
meta
et
seq.) has
has found
found that
basalt,
actinolitic
and
chioritic
schists,
ellipsoidal
greenstone,
chioritic
slate
basalt, actinolitic and chloritic schists, ellipsoidal greenstone, chloritic slate
and felsite.
felsite, This
This thick
thick series
series isis intruded
and
intruded by
by tonalite
tonalite and
and granodiorite,
granodiorite, with
with
21
some monzonite,
monzonite, quartz
The dikes
dikes and
and sills
sills cutting
some
quartz monzonite
monzonite and
and granite.
granite. The
cutting the
the
Mona schist
felsic porphyry,
porphyry, frequently
frequently weathering
weathering to
to aa pale
pale pink
pink color.
color.
Mona
schist are
are felsic
A
the Animikie
A widespread
widespread unconformity
unconformityseparates
separatesall
all these
these rocks
rocks from
from the
Animikie series.
series.
Animikie
Series
Animikie Series
Chocolay Group
Group
Chocolay
Three formations
Three
formations make
make up
up the
the Chocolay
Chocolay Group
Group of
of lower
lower Animikie
Animikie sediments.
sediments.
The basal
basal unit
unit is
is the
the Mesnard
quartzite, which
is aa vitreous,
The
Mesnard quartzite,
which is
vitreous, medium-grained,
medium-grained,
thin to
to thick
thick bedded
beddedquartzite,
quartzite, locally
locally brecciated,
brecciated, with
thin
with cross-bedding
cross-bedding and
and
ripple marks.
ripple
marks. Near
NearEnchantment
Enchantment Lake,
Lake, about
about 44 miles
miles southwest
southwest of
of Marquette,
Marquette,
the basal
basal portion
is made
of conglomerate,
conglomerate, graywacke,
graywacke, arkose,
arkose, and
the
portion is
made up
up of
and
sericitic slates
sericitic
slates and
and quartzites
quartzitesalthough
although not
not all
all of
of these
these types
types are
arefound
found in
in the
the
same location.
same
locaUon.
The Kona
Konadolomite
dolomiteoverlies
overlies the
the Mesnard
Mesnard formation
formation and
and is
is the
The
the thickest
thickest and
and
most extensive
most
extensive member
member of
of the
the Chocolay
Chocolay Group
Group in
in the
the area
area between
between Marquette
Marquette and
and
It is
is principally
Negaunee, It
Negaunee.
principally a
a light-colored
light-colored fine
fine to
to medium-grained
medium-grained massive
massive
Locally itit has
has thin
thinlaminated
laminatedchert
chertlayers,
layers, sericitic
sericitic slate,
dolomite. Locally
dolomite.
slate, quartzites
quartzites
In places
places the
is extensively
and laminated
laminated siltite.
siltite. In
and
the dolomite
dolomite is
extensively silicified.
silicified. Recent
Recent
mapping
(Fritts,
1964)
identifies
some
quartzitic
areas
as
Kona,
rather
mapping (Fritts, 1964) identifies some quartzitic areas as Kona, rather than
than
describes the
Mesnard as
as mapped
earlier. Gair
Mesnard
mapped earlier.
Gair et
et al
al (1961)
(1961) describes
the silicification
silicification of
of
rSilicified Kona
Konadolomite
dolomite most
most typically
typically consists
consists
the Kona
dolomite as
as follows:
the
Kona dolomite
follows: rrSilicified
laminations are
are
of thick
thick laminated
laminated masses
masses of
fine-grained quartz
quartz (chert).
of
of fine-grained
(chert). The
The laminations
reddish or
variations in
reddish
or bluish
bluish black
black to
to white,
white, depending
depending on
on variations
in minor
minor amounts
amounts of
of
Massive
siliceous
rock
consisting
different iron
iron oxides
from layer
layer to
different
oxides from
to layer.
layer. Massive siliceous rock consisting of
of
fragments of
white chert
chert in
in aa reddish-brown
hematitic cherty
fragments
of white
reddish-brown hematitic
cherty matrix
matrix apparently
apparently
resulted from
resulted
from post-brecciation
post-brecciation silicification
silicificationof
of the
the dolomitic
dolomitic portion
portion of
of laminated
laminated
Thin sections
sections of
cherty dolomite.
cherty
dolomite. Thin
of silicified
silicified dolomite
dolomite generally
generally show
show aa fine-gràined
fine-grained
mosaic of
cherty quartz
quartz with
small loose
loose clusters
mosaic
of cherty
with small
clusters of
of very
very fine-grained
fine- grained carbonate
carbonate
Not only
only the
the dolomitic
dolomitic portions
portions of
have been
been silicified
silicified but
particles. rr Not
particles.
of the
the Kona
Kona have
but
the slates
slatesand
andquartzites
quartziteshave
havebeen
beenimpregnated
impregnated and
and cut
cutby
bynumerous
numerous
also the
also
quartz veins.
Another distinctive
the Kona
Kona is
the presence
presence of
Another
distinctive feature of
of the
is the
of the
the algal structures,
occur widely
although they
they are
are not
which occur
widely throughout
throughout the
the Kona
Kona although
not confined
confined to
to any
any given
given
Algal
structures
are
locally
associated
with
olites,
which
confirms
horizon.
horizon. Algal structures are locally associated with O'~lites, which confirms
their shallow-water
their
shallow-water origin
origin (Gair,
(Gair, 1962,
1962, oral
oralcommunication).
communication).
The uppermost
uppermost member
Group is
is the
slate, which
The
member of
of the
the Chocolay
Chocolay Group
the Wewe
Wewe slate,
which
has an
has
an estimated
estimated maximum
maximum thickness
thickness of
of nearly
nearly 900
900 feet,
feet. It
It is
is aa gray
gray to
to greenishgreenish­
gray,
laminated
to
massive
slate,
with
interbeds
of
impure
dark
quartzite.
gray, laminated to massive slate, with interbeds of impure dark quartzite. A
A
22
Elsewhere, the
is brecciated
conglomerate is
conglomerate
is found
found locally.
locally. Elsewhere,
the Wewe
Wewe is
brecciated and
and imim­
In places
places the
the rock
has textures
pregnated with
with quartz
quartz and
and specular
specular hematite.
pregnated
hematite. In
rock has
textures
which suggest
suggest the
the presence
presence of
of volcanic
volcanic and
andpyroclastic
pyroclastic materials
materials (Gair,
which
(Gair. 1962,
1962,
oral communication).
oral
communication).
Seaman (1944)
(1944) assigned
assigned the
to the
Seaman
the Wewe
Wewe to
the upper
upper Kona;
Kona; Boyum
Boyum (1954,
(1954, 1963)
1963)
followed the
the same
same practice.
practice. This
followed
This report
report reflects
reflects the
the recent
recentTi.
U. S. Geological
Geological
Survey
mappingand
andre-instates
re-instates the
as aa distinct
Survey mapping
the Wewe
Wewe as
distinct formation.
formation.
Menominee Group
Menominee
Group
The
MenomineeGroup
Groupisis named
namedfor
for the
the Menominee
Menomineedistrict
district of
The Menominee
of southern
southern
James
(1958)
assigned
this
name
to
the
middle
Animikie
Dickinson County.
Dickinson
County. James (1958) assigned this name to the middle Animikie
rocks
rocks of
of the
the Marquette
Marquette Range
Range comprising
comprising the
the Ajibik,
Ajibik, Siamo
Siamoand
andNegaunee
Negaunee
There
appears
to
be
an
erosional
disconformity
between
formations.
formations. There appears to be an erosional dis conformity between the
the
Chocolay and
and Menominee
Menominee Groups.
Groups.
Chocolay
The Ajibik
Ajibikquartzite
quartzite isis vitreous,
vitreous, medium-grained,
The
medium- grained, thin
thinto
tothick
thickbedded,
bedded,
with some
some sericitic
sericitic to
to chloritic
chloritic slate.
with
slate. AAbasal
basalconglomerate
conglomerate is
is found
found in
in
Section
6, T.
T. 47
Section 6,
47 N.,
N., R.
R. 25
25 W.,
W., and
and elsewhere.
elsewhere.
The Siamo
Siamo slate
slate formation
formation contains
laminated to
to massive
massive dark
The
contains laminated
dark gray
gray and
and
gray-green
slates, argillites,
graygreen slates,
argillites,graywacke
graywacke and
and impure
impure quartzite.
quartzite. CharacterCharacter­
istically, the
istically,
the slates
slates weather
weather brownish
brownish or
or reddish.
reddish.
Tyler and
(1952)described
described the
the Goose
Goose Lake
Lake iron-formation,
iron-formation,
Tyler
and Twenhofel
Twenhofel (1952)
Its
thickness
which
is aa magnetic
which is
magnetic member
member of
of the
the Siamo
Siamo formstion.
formstion. Its thickness is
is estimated
estimated
It extends
for some
the strike
strike west
at 50
at
50 to
to 100
100 feet.
feet. It
extends for
some distance
distance along
along the
west and
and northnorth­
The
iron-formation
is
laminated,
west
of
Goose
Lake
(Gair
and
Wier,
1964).
west of Goose Lake (Gair and Wier, 1964). The iron-formation is laminated,
The iron-formation
iron-formation at
magnetic, cherty,
cherty, chloritic
magnetic,
chloritic and
and sideritic.
sideritic. The
at the
the St.
St.
to be
be Goose
27 W.
is though
Lawrence
pit in
Section 5,
5, T.
Lawrence pit
in Section
T. 47
47 N.
N. ,, R 27
W.,, is
though to
Goose Lake,
Lake,
also.
also.
The
Palmer gneiss
The Palmer
gneiss was
was described
described in
in detail
detail by
by Lamey
Lamey (1935).
(1935). He
He concon­
cluded
that the
the Palmer
Palmer gneiss
cluded that
gneiss represented
representedmetamorphosed
metamorphosed (Animikie)
(Animikie) sedisedi­
ments,
formations, and
ments, principally
principally the
the Ajibik
Ajibik and
and Siamo
Siamo formations,
and locally
locally the
the Mesnard
Mesnard
Monographs
28
and
52
describe
the
Palmer
gneiss
as
and Kona
Kona formations.
formations. Monographs 28 and 52 describe the Palmer gneiss as
and
aa belt
belt of
of Laurentian
Laurentian rocks,
rocks, with
withthe
thecomment
comment that
thatT'phases
"phases of
of it
it look
look like
like metameta­
Future
mapping
may
clarify
these
relationships.
morphosed sediments.
morphosed
sediments." Future mapping may clarify these relationships.
The Negaunee
Negauneeiron-formation
iron-formation isis the
the most
The
most important
important and
and interesting
interesting
member of
of the
the entire
entire column,
column, as
as itit is
member
is the
the host
host rock
rock for
for most
most of
of the
the iron
iron ores.
ores.
In general,
general, itit isis similar
In
similartotoother
otherAnimikie
Animikie iron-formations
iron-formations of
of the
the Lake
Lake Superior
Superior
The maximum
maximum stratigraphic
stratigraphic thickness
Region.
Region. The
thickness is
is attained
attained in
in the
the NegauneeNegaunee­
Ishpeming
area where
where itit exceeds
000 feet,
feet, not
including the
the intrusive
intrusive masses.
masses.
Ishpeming area
exceeds 2,
2,000
not including
It
It is
is remarkable
remarkable also
also for
for its
its relative
relativelack
lackof
ofargillaceous
argillaceous and
and arenaceous
arenaceous facies.
facies.
23
The
in this
this summary.
sum.m.ary.
The lithology
lithologyisis discussed
discussed in
in m.ore
more detail
detail later
later in
Baraga
Group
Baraga Group
The Baraga
Baraga Group
Group consists
consists of
major members:
The
of two
two m.ajor
m.em.bers: the
theGoodrich
Goodrich and
and the
the
The Goodrich
Goodrichform.ation
formation isis principally
principally quartzite,
quartzite, with
Michigamme form.ations.
formations. The
Michigam.m.e
with
In m.ost
most localities,
localities, there
interbedded argillites
argillites and
interbedded
and conglomerates.
conglom.erates. In
there is
is aa basal
basal
conglomerate m.ade
made up
up of
of fragm.ents
fragments of
iron-formation. The
conglom.erate
of the
the Negaunee
Negaunee iron-form.ation.
Negaunee-Goodrich contact
contact isis reported
reported to
angular discordance,
Negaunee-Goodrich
to have
have up
up to
to 150
150 angular
discordance,
but com.m.only
commonlythere
there isis little
little noticeable
but
noticeable discordance.
discordance.
Overlying the
the Goodrich
Goodrichquartzite
quartzite isis the
the thickest
thickest member
Overlying
m.em.ber of
of the
the entire
entire
Animikie
Series, the
exceeds 5,000
Anim.ikie Series,
the Michigamme
Michigam.m.e formation
form.ation which
which probably
probably exceeds
5,000 feet.
feet.
It is
is distinctive
also in
It
distinctive also
in its
its areal
areal extent,
extent, not
not only
only in
in the
the Marquette
Marquette District,
District, but
but
over much
of the
the central
central part
over
m.uch of
part of
of the
the Upper
Upper Peninsula.
Peninsula.
Near the
the base
base of
formation isis aa thin
sub-member,
Near
of the
the Michigamme
Michigam.m.e form.ation
thin magnetic
m.agnetic sub-m.em.ber,
termed the
term.ed
the Greenwood
Greenwood formation
form.ationby
bySwanson
Swanson and
and Zinn
Zinn (1930).
(1930). Most
Most of
of the
the
The
Clarksburg
pyroclastics
Michigamme
is
slate,
argillite
and
graywacke.
Michigam.m.e is slate, argillite and graywacke. The Clarksburg pyroclastics
are found
are
found in
in the
the lower
lower portion
portion of
of the
the Michigamme
Michigam.m.e where
where they
they occupy
occupy an
an
The
Bijiki
ironasymmetrical
position
in
the
synclinorium
(see
Figure
4).
asym.m.etrical position in the syncli norium. (see Figure 4). The Bijiki iron­
formation is
the middle
form.ation
is found
found above
above the
m.iddle member
m.em.ber of
of the
the Michigamme.
Michigam.m.e. It
It extends
extends
from north
north of
Humboldt, at
at the
the Bessie
Bessie Mine,
from.
of Hum.boldt,
Mine, to
to west
west of
of Three
Three Lakes.
Lakes. Over
Over
million tons
tons of
of iron
iron ore
from mines
44 m.illion
ore have
have been
been produced
produced from.
m.ines in
in the
the Bijiki.
Bijiki.
the U.S.G.S.
Harold Jam.es
James (1958)
Harold
(1958) in
in the
U.S.G.S. Professional
Professional Paper
Paper 314-C,
314-C,
the Paint
describes the
Paint River
River Group
Group that
that overlies
overlies the
the Michigamme
Michigam.m.e formation.
form.ation.
the southwest
southwest of
the Marquette
Marquette Mineral
These rocks are
These
are found
found to the
of the
Mineral District.
District. In
In
the past,
past, som.e
some geologist
iron-formation with
the
geologist have
have correlated
correlated the
the Bijiki
Bijiki iron-form.ation
with the
River-Crystal Falls
iron-formation of
Riverton iron-form.ation
of the
the Iron
Iron River-Crystal
Fallsiron
irondistricts.
districts. This
This
would m.ean
mean that
that part
part of
formation would
would be
be in
in the
the Paint
Paint River
would
of the
the Michigamme
Michigam.m.e form.ation
River
Group.
Group.
Granite is
Granite
is the
the principal
principal rock
rocktype
type along
along the
the south
southlimb
lim.bof
ofthe
the Animikie
Anim.ikie
There
are
thought
to
be
both
pre-Animikie
and
post-Animikie
synclinorium.
synclinorium.. There are thought to be both pre-Anim.ikie and post-Anim.ikie
Goldich determ.ined
determined an
an age
age of
of 1,900
1,900 m.illion
million years
years on
granites. Goldich
granites.
on one
one sample
sam.ple
south of
of Republic,
Republic, and
and 1,600
1, 600m.illion
millionyears
years on
onanother.
another. Some
south
Som.e students
students believe
believe
that aa portion
the granite-appearing
that
portion of
of the
granite-appearing rocks
rocks were
were formed
form.ed by
by granitization
granitization of
of
sediments.
pre - existing Animikie
pre-existing
Anim.ikie sedim.ents.
Seaman (1944)
suggested periods
Seam.an
(1944) suggested
periods of
of orogeny
orogeny following
following Michigamme
Michigam.m.e time
tim.e
which
he
called
the
Sibley
and
Superior
or
Republic,
preceding
Keweenawan
which he called the Sibley and Superior or Republic, preceding Keweenawan
This would
correspond to
time. This
tim.e.
would correspond
to the
the Penokean
Penokean (Goldich
(Goldich et
et al,
aI, 1961)
1961) and
and may
m.ay
be the
be
the time
tim.e of
of the
the post-Animikie
post-Anim.ikie granites
granites and
and the
the deformation
deform.ation of
of the
the Marquette
Marquette
Range synclinorium..
synclinorium.
Range
I
I
24
intrusive masses found within the
has been
been made
Reference has
Reference
made above
aboveto
to the
the intrusive masses found within the
but are
These intrusives
Negaunee
Negaunee iron-formation.
iron-formation. These
intrusives are
are irregular
irregular in
in shape,
shape, but are
rather than as diorite
They are
described as
as metadiabse
metadiabse rather
often sill-like.
often
sill-like. They
are best
best described
than as diorite
Locally,
the
sills
have been
publications.
greenstone,
as
used
in
earlier
or greenstone, as used in earlier publications. Locally, the sills have been
of recognized primary differences in
used as
as horizon
markers in
used
horizon markers
in the
the absence
absence of recognized primary differences in
these intrusives may be
has been
It has
the Negaunee. It
been suggested
suggested that
that the
the age
age of
of these intrusives may be
Possibly they might be related to the
Clarksburg or
or Keweenawan.
Keweenawan. Possibly
either Clarksburg
either
they might be related to the
of these sillIt
has
also
been
suggested that
that one
one or
or more
more of
Penokean orogeny.
Penokean
orogeny. It has also been suggested
these sill­
indicate
that
bulk
of
the
structural
features
like
masses
is
extrusive,
but
the
like masses is extrusive, but the bulk of the structural featull!es indicate that
of some 700 feet. A
They reach
maximum thickness
they are
are intrusive.
intrusive. They
reach aa maximum
thickness of some 700 feet. A
of 400
400 feet.
general average
average would
order of
general
would be
be of
of the
the order
feet.
both the pre-Animikie and
other intrusives
intrusives are
Various other
are found
found cutting
cutting both the pre-Animikie and
fine-grained
mafic and
andfelsic
felsic dikes,
dikes, others
are
Animikierocks.
rocks. Some
are fine-grained mafic
Animikie
Some are
others are
metapyroxenite
and
metagabbro.
Some
dikes
medium toto coarse-grained
coarse-grained meta-pyroxenite and metagabbro. Some dikes are
medium
are
Locally
they
may
be
inversely
and
texture.
fresh
diabases,
both
in
compoiti.on
fresh diabases, both in composItion and texture. Locally they may be inversely
polarized magnetically.
polarized
magnetically.
sandstone are found south of Marquette.
Exposures of
Exposures
of Jacobsville
Jacobsville Cambrian
Cambrian sandstone are found south of Marquette.
friable sandstone with some conglomerate
Typically,
the
Jacobsville
is
reddish,
Typically, the Jacobsville is reddish, friable sandstone with some conglomerate
are found, too, in the Gwinn
and reddish
reddish shale.
shale. Some
and
Some sandstones
sandstones exposures
exposures are found, too, in the Gwinn
the Ordovician rocks. Through all
Still further
District. Still
further south
south is
is the
the onlap
onlap of
of the Ordovician rocks. Through all
of the recent Quaternary surficial material
of the
the district,
district, variable
of
variable amounts
amoun~s of the recent Quaternary surficial material
of glacial
glacial origin.
are found,
are
found, principally
principally of
origin.
(see Figure 4) has been compared to
The column
column in
in the
the Gwinn
District (see Figure 4) has been compared to
The
Gwinn District
Allen (1914):
the
principal
synclinorium,
and
the principal synclinorium, and is
is summarized
summarized as
as follows
follows from
from Allen (1914):
Ordovician
Ordovician
Cambrian
Cambrian
Paleozoic
Paleozoic
Keweenawan
Keweenawan
Late
Late
Baraga
Baraga
j
s::
n:l
.....
1-4
~n:l
uU
Q)
Middle
Middle
1-4
O-i
Early
Early
Menominee
Menominee
Limestones and sandstone
Limestones and sandstone
Intrusives
Intrusives
Princeton Series
Princeton Series
Ferruginous slate, cherty
Ferruginous slate, cherty
quartzite
and graywacke
quartzite and graywacke
conglomerate
conglomerate
Gwinn
Series
Gwinn Series
Dark
gray slate, graywacke
Dark gray slate, graywacke
Iron-formation
Iron-formation
Dark gray to graphitic slate
Dark gray to graphitic slate
arkose and conglomerate
arkose and conglomerate
Granite,
greenstone
Granite, greenstone
•
•
25
25
Some geologist
geologist have
have considered
considered the
the iron-formation
iron-formation in
District
Some
in the
the Gwinn
Gwinn District
the
Michigamme
formation.
as
correlative
to
the
Bijiki
iron-formation
in
as correlative to the Bijiki iron-formation in the Michigamme formation.
Metamorphic
Metamorphic Zones
Zones
Studies have
have been
been made
made on
the metamorphic
Studies
on the
metamorphic zones
zones in
in the
the Upper
Upper Peninsula.
Peninsula.
The
area
Particularly noteworthy
Particularly
noteworthy is
is the
the study
study of
of James
James(1955).
(1955). The area around
around Republic
Republic
and
the
Republic
Trough
is
shown
on
his
maps
to
be
of
the
highest
intensity,
and the Republic Trough is shown on his maps to be of the highest intensity, in
in
metamorphic intensity
the
the sillimanite
sillimanite zone.
zone. The
The metamorphic
intensity in
in the
the balance
balance of
of the
the Marquette
Marquette
The Ishpeming-Negaunee
Ishpeming-Negaunee extremity
extremity of
Iron Range
Rangedecreases
decreases to
to the
the east.
east. The
Iron
of the
the
The
metamorphic
isograd6
cross
producing
district
is
in
the
chlorite
zone.
producing district is in the chlorite zone. The metamorphic isograds cross the
the
This suggests
geologic structures
structures at
angles in
in many
areas. This
geologic
at high
high angles
many areas.
suggests that
that the
the metameta­
morphism isis post-structure.
post-structure.
morphism
Of considerable
considerable interest
interest is
Of
is the
the paper
paper by
by James
Jamesand
andClayton
Clayton (1962)
(1962) relating
relating
mineral
formation
temperatures
to
their
oxygen
isotope
fractionization.
mineral formation temperatures to their oxygen isotope fractionization. Some
Some
samples from
from the
Range were
were tested,
tested, specifically
samples
the Marquette
Marquette Range
specifically from
from the
the Athens
Athens
They tentatively
tentatively conclude:
and Greenwood
Greenwood Mines
Mines and
and the
the Republic
Republic district.
district. They
and
conclude:
(1) on
on the
the basis
basis of
of internal
internal consistency
and consistent
consistent relations
(1)
consistency and
relations to
to the
the mineralogic
mineralogic
evidence
of
metamorphic
zoning,
the
isotopic
data
yields
at
least
a
fair
evidence of metamorphic zoning, the isotopic data yields at least a fair approxapprox­
imation of
of temperatures
temperatures of
imation
of metamorphism
metamorphism through
through the
the garnet
garnet zones;
zones; (2)
(2) the
the
2000
temperature
of
metamorphism
for
the
chlorite
zone
reaches
zpproximately
temperature of metamorphism for the chlorite zone reaches zpproximately 200 0
that of
and that
of the
the biotite
biotite zone
that of
C. , that
C.,
zone approximately
approximately 275°
275 0 C.
C.,, and
of the
the garnet
garnet zone
zone
0
(3) the
approximately 3350°C.
approximately
50 C. ;; (3)
the rocks
rocks in
in the
the staurolite
staurolite and
and sillimanite
sillimanite zones
zones
(upper part
part of
amphibolite facies
facies and
and amphibolite
amphibolite facies,
facies, respectively)
(upper
of the
the epidote
epidote amphibolite
respectively)
0
the present
and the
350°C.
were formed
at temperatures
were
formed at
temperatures above
above 350
C., and
present isotopic
isotopic composition
composition
of
the
oxygen
of
these
rocks
is
due
to
retrograde
equilibration
during
temperature
of the oxygen of these rocks is due to retrograde equilibration during temperature
,
decline.
decline.
Nome
nc1atur e
Nomen.clature
From the
until 1949
little
From
the time
time of
of the
the publication
publication of
of Monograph
Monograph 52
52 in
in 1911
1911 until
1949 little
change
occurred
in
the
petrographic
nomenclature
of
the
Marquette
Mineral
change occurred in the petrographic nomenclature of the Marquette Mineral
that time,
District. At
District.
At that
time, The
The Cleveland-Cliffs
Cleveland-Cliffs Iron
IronCompany
Company undertook
undertook aa sweepsweep­
ing revision
revision of
of many
many ofofits
its rock
rock names.
names, Numerous
ing
Numerous old
old or
or ambiguous
ambiguous terms
terms
names had
replaced with
with modern
modern or
or more
more precise
were replaced
were
precise terms.
terms. Various
Various names
had been
been
past; at
used for
the iron-formation
iron-formation in
used
for the
in the
the past;
at this
this time,
time, the
the term
termrtjrofl
rtiron formationt'r
-formation rr
of des
description
was adopted
adoptedasas the
the sole
sole name.
name. A
was
A uniform
uniform system
system of
cription was
was effected
effected
also..
also
I
26
I
rrsoft ore jaspertr previously used were
The terms
terms "hard
'hard ore
The
ore jasper"
jasper rr and
and rrsoft ore jasper rr previously used were
and Republic Mine are
Our beneficiating
beneficiating plants
eliminated. Our
eliminated.
plants at
at the
the Humboldt
Humboldt and Republic Mine are
processing
rtjasper
or taconitetT;
sometimes referred
referred to
to in
in the
the press
press as
sometimes
as processing ttjasper fY or rrtaconite";
,iron_formationrrr is
is preferred.
however, the
however,
the expression
expression "iron-formation
preferred.
Primary
Primary Iron-Formation
Iron-Formation
I
Sedimentary Facies of Iron-
The summary
summary of
The
of James
James (1954)
(1954) on
on the
the Sedimentary Facies of Iron­
sulphide, silicate and
Formation emphasized
emphasized the
the four
four facies:
fades: carbonate,
Formation
carbonate, sulphide, silicate and
Boyum_AndersonHan (1955)
(1955)Primary
PrimaryFeatures
Other references
references are
are Boyum-Anderson-Han
oxide. Other
oxide.
Features
Relationship
and
Anderson-Han
(1956)
The
of the
the Negaunee
Iron-FormatiOn and Anderson-Han (1956) The Relationship
of
Negaunee Iron-Formation;
and Secondary Oxidation to the Concentrating
of Diagenesis,
Diagenesis, Metamorphism
of
Metamorphism and Secondary Oxidation to the Concentrating
of the
the Marquette
Range. The
Characteristics of
Iron-Formation of
Characteristics
of the
the Negaunee
Negaunee Iron-Formation
Marquette Range. The
of
been
the
principal
primary
constituent
carbonate facies
carbonate
facies is
is thought
thought to
to have
have been the principal primary constituent of
remnant
Plate 1-A
the Negaunee
iron..formation, Plate
the
Negaunee iron-formation.
I-A illustrates
illustrates an
anunoxidized
unoxidized remnant
James
(1954
pages 258 et seq.),
iron-formation.
of typical
typical cherty
of
cherty carbonate
carbonate iron-formation. James (1954 pages 258 et seq.),
oxide
fades
(as
hematite)
in the upper
advances arguments
arguments for
for the
advances
the primary
primary oxide facies (as hematite) in the upper
The summary
summary byStone
and Qimberlidge
part of
iron-formation. The
part
of the
the Negaunee
Negaunee iron-formation.
by S tone and Glmberlidge
suggests
that
both
hematite
and magnetite
(1964) on
on the
the Groveland
Groveland Mine
(1964)
Mine geology
geology suggests that both hematite and magnetite
he
believes
is
(1962) has
has found
found some
some magnetite
were primary.
primary. Han
were
Han (1962)
magnetite which
which he believes is
places in
iron-formation.
primary oxide
facies in
in several
primary
oxide facies
several places
in the
the Negaunee
Negaunee iron-formation.
sulphides and
and silicates
silicates from
the Marquette
Specific illustrations
illustrations of
primary sulphides
Specific
of primary
from the Marquette
Range are
are not
Range
not readily
readily available.
available.
I
chioritic clastic iron-formation
Plate I-B
Plate
I-B illustrates
illustrates the
the magnetitic
magnetitic chloritic clastic iron-formation
Tilden Mine in the southeast portion of the
found
at
the
Empire
Mine
and
the
found at the Empire Mine and the Tilden Mine in the southeast portion of the
found on the Cascade Range.
Cla.stic iron-formation
iron-formation is
is also
Marquette Range.
Marquette
Range. Clastic
also found on the Cascade Range.
southeast
of
the
synclinorium.
This suggests
suggests aa source
This
source to
to the
the southeast of the synclinorium.
Alteration of
the Iron-Formation
Iron-Formation
Alteration
of the
iron-formation has been by oxidation and
The principal
principal alteration
alteration of
The
of the
the iron-formation has been by oxidation and
The average iron content of primary
enrichment under
enrichment
under varying
varying conditions.
conditions. The average iron content of primary
The average altered Negaunee ironironformation approximates
iron-formation
approximates 26%
26%. dried.
dried. The average altered Negaunee iron­
Locally in
in the
the Negaunee
area, the
dried. Locally
formation approximates
Fe, dried.
formation
approximates 31%
31% Fe,
Negaunee area, the
A general increase in porosity
is higher,
higher, reaching
reaching about
about 35%,
average is
average
35%. A general increase in porosity
accompanies the
accompanies
the alteration.
alteration.
frequently characterized
enrichment has
has occurred,
occurred, it
Where enrichment
it is
is most
most frequently characterized
iron oxides, primarily hematite and
replacement of
of the
the primary
primary chert
by replacement
chert by
by iron oxides, primarily hematite and
I
27
greater part
goethite, and
goethite,
and locally
locally magnetite.
:magnetite. The
The greater
part of
of this
this alteration
alteration has
has been
been
volume-for-volume replace:ment
replacement as
as very
very little
volu:me-for-volu:me
little slumping
slu:mping has
has been
been noted.
noted. In
In
numerous instances
instances it
from the
nu:merous
it is
is possible
possible to
to follow
follow the
the primary
pri:mary bedding
bedding fro:m
the ironiron­
The ore
ore contacts
formation into
into the
the ore.
for:mation
ore. The
contacts frequently
frequently cut
cut the
the bedding
bedding at
at high
high
angles.
angles.
The folding
folding of
of the
the Marquette
Marquette Range
The
Range synclinorium
synclinoriu:m was
was accompanied
acco:mpanied by
by
the
development
of
a
strong
joint
system
which
increased
the
permeability
the develop:ment of a strong joint syste:m which increased the per:meability of
of
Exploration and
and :mining
mining in
in recent
recent years
the iron-formation.
the
iron-for:mation. Exploration
years have
have indicated
indicated
that both
both oxidation
oxidation and
and enrich:ment
enrichment extend
extend toto far
far greater
greater depths
that
depths than
than thought
thought
Numerous drill
drill holes
holes have
have cut
cut rich
rich ore
ore grade
earlier. Nu:merous
earlier.
grade material
:material to
to depths
depths of
of
term trorerr
oretr isis used
over 5,
000 feet
feet fro:m
from the
the present
present land
over
5, 000
land surface.
surface. The
The ter:m
used here
here
as
as
meaning high
and does
does not
not neces
necessarily
imply an
an econo:mic
economic profit
:meaning
high iron
iron content
content and
sarily i:mply
profit
hole on
the Range
was drilled
drilled
as the
term is
customarily. The
the ter:m
is defined custo:marily.
The deepest hole
on the
Range was
size, and
and encountered
encountered oxidation
and enrichinch) size,
depth of
365 feet,
feet, NX
NX (3
to aa depth
of 6,
6,365
(3 inch)
oxidation and
enrich­
During late
late Preca:mbrian
Precambrian ti:me
time when
the alteration
alteration may
nay
the bottom.
ment to
:ment
to the
botto:m. During
when the
have occurred,
occurred, the
greater.
have
the depth
depth of
of this
this alteration
alteration was
was undoubtedly
undoubtedly greater.
Some parts
parts of
contain considerable
considerable silicates
silicates such
So:me
of the
the Negaunee
Negaunee contain
such as
as
sericite,
grunerite-cummingtonite,
hornblende
and
garnet
in
the
higher
sericite, grunerite-cu:m:mingtonite, hornblende and garnet in the higher meta:meta­
morphis zones
minnesotaite,
:morphis
zones (such
(such as
as at
at Humboldt
Hu:mboldt and
and Republic);
Republic); and
and :minnesotaite,
stilpnomelane and
and chlorite
chlorite in
stilpno:melane
in the
the diagenetic
diagenetic or
or lower
lower metamorphic
:meta:morphic zones
zones
(such as
as at
at E:mpire).
Empire). According
or all
all of
of these
these silicates
silicates are
(such
According to
to one
one view,
view, many
:many or
are
derived by
by the
the :meta:morphis:m
metamorphismofofearlier
earlier pri:mary
primary silicates.
silicates. Others
derived
Others believe
believe that
that
these silicates
silicates are
these
are the
the result
result of
of the
the reaction
reaction of
of earlier
earlier iron
iron minerals
:minerals (carbonate
(carbonate
and/or
the silica
and/
or oxides)
oxides) and
and the
silica of
of the
the chert
chert under
under metamorphic
:meta:morphic conditions.
conditions.
Plate I-C
of the
the silicates.
silicates. Plate
Plate
I-C shows
shows the
the development
develop:ment of
Plate I-D
I-D is
is aa polished
polished slab
slab
are photoof :magnetite
magnetite carbonate
carbonate silicate
silicate iron-formation.
of
iron-for:mation. Plates
Plates I-E
I-E and
and F
Fare
photo­
micrographs of
the portions
portions rich
:micrographs
of the
the slab
slab showing
showing the
rich and
and lean
lean in
in magnetite,
:magnetite.
Ore
Ore Occurrences
Occurrences
There
There
are four
four general
general types
types of
of ore
orewhich
which have
have been
been produced
produced and
and shipped
are
shipped
They are:
from the
Marquette Iron
fro:m
the Marquette
Iron Range. They
are:
High grade
grade direct
direct shipping
shipping rrsoftu
rrsoft tr ores,
ores.
High grade
grade direct
direct shipping
"hardtttr ores,
ores,
High
shipping "hard
Siliceous
ores,
Siliceous ores,
Concentrates and
agglomerates (pellets)
Concentrates
and agglo:merates
(pellets) from
fro:m low
low grade
grade
iron-formations.
iron-for:mations.
Traditionally in
in the
the Lake
Lake Superior
Superior Region,
Region, the
the direct
direct shipping
Traditionally
shipping ores
ores have
have
Recently,
the
direct
natural (moisture
aa base
base iron
iron content
content of
of 51.5%
51. 5% natural
(:moisture included).
included). Recently, the direct
1
J
28
28
I
the competition of
averaged 54% Fe, natural-, reflectingores
ores
have
shipping
have aof
shipping ores have averaged 54% paid
Fe, natural,
reflecting
competition
for the hard
lump the which
premium is
the foreign
foreign ores.
ores. AA premium
Thea
the
isTheir
paid average
for the hard
lump
ores
which
have
content
is
61.
5%.
iron
inch
-8
inch.
range
of
+2
size
size range of +2 inch -8 inch. Their average
iron content
61. 5%. of
The
small isshipments
specialty grade, constitutes
siliceous type
type of
of ore,
ore, aa specialty
from
siliceous
grade,
constitutes
small
shipments
of
which averages 38% Fe. The pellets range
richer iron_formation
richer
iron-formation which averages 38% Fe. The pellets range from
natural.
61 to
to 65%
Fe, natural.
61
65% Fe,
between rrsoftrt
For
For
made a distinction
many years the miners have made a distinction between
earthy
many years the miners havesoft
rrsoft"
ores are porous, friable,
"hard" ores. In generals the
ores and
and r'hard"
ores
ores. In general,
the soft
ores are porous,
and martite
friable,
(locally
earthy
chiefly
of hematite,
semi_plastic
and
are
made
up
to
and
to semi-plastic and are made upamounts
of hematite,
and martitechert,
(locally
of
goethite unreplaced
and with minor chiefly of
still magnetite)
The
other
still
magnetite) and with minor amounts
goethite,
unreplaced
chert,
and
through
P).
(see Plate III - M
(mica,
chlorite)
locally
silicates
with
low
locally silicates (mica, chlorite) (see hard,
Plate dense,
III - M compact,
through P). The other
hard ores which are hard,
extreme
dense compact
ext
reme are
are the
the hard ores which are
dense,
compact,
with low
magnetite martite,
The
iron
minerals
are
porosity.
These
ores form
porosity. The iron minerals are magnetite,
martite,
T).dense compact
specularite (see Plate III - Q through
hematite,
and
would
fall
hematite, and specularite (see Plate
III -ofQhigh
through
T).oreThese
form
grade
minedores
amount
A
substantial
the lump
"semi-hard"
the
lump product.
product. A substantial
amount
of high
grade
oreasmined
would fall
Terms
such
these two end
types.
somewhere
in
between
tonnageS
of rr
somewhere in between these two end orebodies,
types. Terms
such as "semi-hard
substantial
Locally in the soft
been
used.
have been used. Locally in the soft orebodies,
appearance
have
substantial
tonnages
of
macroscopic
found which are similar in
"hard"
ores
have
been
"hard" ores have been found which
are similar in in
macroscopic
appearance
Plate III.
of the hard ore mines, as shown
to the
the hard
hard ores
ores of
to
the hard ore mines. as shown in Plate III.
Soft Ores
Ores
Soft
total production of the Marquette Iron Range,
per cent
of the
Seventy per
gradeRange,
direct
Seventy
cent of the total production
the of
Marquette
been
the high Iron
and
Gwinn Districts, has of
including
the
Cascade
in
the
basal
including the Cascade and Gwinn
Districts,
has for
been
the high
theofmost
part,grade direct
The ores
occurred,
shipping
type
of
soft
ore.
be asinthick
as
shipping type of soft ore.iron_formation.
The ores occurred,
the most
the basal
Thesefor
deposits
maypart,
of
the
Negaunee
portion
The
lateral
extent.
portion of the Negaunee iron-formation.
These deposits may be as thick as
the bedding, and have considerable
Z60 feet,
feet, normal
normal to
260
to the bedding,
and
have
considerable
lateral
extent.bounded
The
and in fault
structures
found in the synclineS
orebodies
are
generally
north-south
section
lookorebodies are generally found in the
synclines
and
in
fault
structures
bounded
along at least one side. Figure 6 is a
by
basic
dikes
Negaunee showing
a
by basic dikes along at least one side.side
Figure
is a of
north-south
section look­
of the6 City
through the eastern
ing west
west passing
passing through
ing
theineastern
side
of
the
City
of
Negaunee
showing
a
this vicinity.
variety
of
ore
occurrences
variety of ore occurrences in this vicinity.
which are chimneys of
Locally the soft ores are found in "ore pipes"
of the ironLocally the soft ores are found incutting
"ore pipes"
which are chimneys
of
the stratification
distance vertically,
ore
extending
some
and
are
ore extending some
distance
vertically,
cutting
the
stratification
of
the
iron­
ZOO
to
300
feet
across
generals these ore pipes are
In general,
formation. In
iron_formation.
formation.
theseofore
are dikes
200 to cutting
300 feet
and are
theacross
twopipes
or more
at
the
intersection
localized
phosphorus
content
localized at the intersection of two or more
the iron-formation.
alsodikes
by itscutting
low
type of ore has been characterized
This
This type of ore has been characterized also by its low phosphorus content
ground."
and
by "heavy
"heavy ground.
and by
It
the large intrusive sills
The other major type of soft ore occurs on
some sills
of the
The other major type
of soft ore occurs
on soft
the large
intrusive
These
ores were
part of the iron_formation.
near
the
upper
distribution
near the upper part of
soft
were some of the
The ore
is ores
of irregular
in the
theiron-formation.
Ishpeming area. These
first to
to be
be exploited
exploited in
locality
in
which
first
theand
Ishpeming
area.
The
ore
is
of
irregular
distribution
its thickness. The principal
as to its occurrence
both
of the
Ishpeming
toward
the axis
both as to its occurrence and its the
principal
locality
in which
souths.of The
orebodieS were found is to thicknes
these
these orebodies were found is to the south of Ishpeming toward the axis of the
I
I
I
I
I
I
I
29
29
Marquette Range
Range synclinorium.
synclinorium. We
Marquette
We do
do not
not have
have any
any mines
mines operating
operating in
in this
this
type of
of are
ore occurrence
occurrence at
type
at this
this time,
time, although
although around
around the
the turn
turn of
of the
the century
century
It is
is interesting
this was
an important
important ore
ore source.
this
was an
source. It
interesting to
t01 note
note that
that these
these soft
soft
structural
ores, lying
sheets, are
ores,
lying on
on the
the metadiabase
metadiabase sheets,
are limited
limitedby
by the
the same
same structural
In general,
general, the
controls as
controls
as the
the ore
ore lying
lying on
on the
the footwall
footwall contact.
contact. In
the ores
ores were
were
high in
in iron
high
iron content
content and
and low
low in
in phosphorus
phosphorus and
and sulphur.
sulphur.
A sizable
sizable tonnage
of soft
soft ore
ore in
A
tonnage of
in Ngaunee
Negaunee is
isimpregnated
impregnatedwith
with gypsum.
gypsum.
The
gypsiferous
ores
analyses range
2 to
Sulfur analyses
Sulfur
range from
from0.0.2
to over
over 3.
3. 0%. The gypsiferous ores occur
occur at
at
cutting
across
the
bedding
of
definite
elevations
(near
the
present
sea
level)
definite elevations (near the present sea level) cutting across the bedding of
iron formation.
the ironthe
Ores
Hard Ores
The hard
hard ores
of the
the total
total production
The
ores amount
amount to
to 20%
20% of
production to
to date.
date. Most
Most of
of
them
are
found
in
the
uppermost
portion
of
the
Negaunee
iron-formation
and
them are found in the uppermost portion of the Negaunee iron-formation and
ores were
immediately below
the Goodrich
formation contact.
immediately
below the
Goodrich formation
contact. The
The ores
were made
made up
up
hematite, and
of hard,
hard, compact
of
compact to
to specular
specular hematite,
andmagnetite
magnetite(see
(seePlate
PlateIll).
III). AccesAcces­
the ore
may include
include garnet
garnet and
sory minerals may
and tourmaline.
tourmaline. The
The footwall
footwall of
of the
ore
iron-formation of
!jaspilite?!
may be
be unoxidized
unoxidized iron-formation,
iron-formation, oxidized
may
oxidized iron-formation
of the
the"
jaspilite"
hanging wall
wall may
may consist
consist of
type, or
the intrusive
intrusive sills.
sills. The
type,
or one
one of
of the
The hanging
of material
material
less
commonly
of the
the Goodrich
Goodrichformation,
formation, oxidized
oxidized iron-formation
iron-formation or
or - less commonly -­
of
The orebodies
orebodies are
are frequently
material. The
intrusive material.
intrusive
frequently related
related to
to intrusive
intrusive dikes.
dikes.
features
are
noted
in
the
hard
ores
as
well
as
in
Replacement features are noted in the hard ores as well as in the
Replacement
the soft
soft ores.
ores.
are frequently
related to
The outlines
hard orebodies
The
outlines of hard
orebodies are
frequently related
to structural
structural features
features
as folds,
folds, faults
faultsand
anddikes.
dikes.Some
Some hard
hard ores
ores are
are also
such as
such
also found
found locally
locally
the soft
soft orebodies.
orebodies.
near the
base of
of the
theNegaunee
Negaunee iron-formation,
iron-formation, as
near
the base
as aa part
part of
of the
basal Goodrich
material consists
consists of
conglomerates, argillites,
The basal
The
Goodrich material
of conglomerates,
argillites,
Locally
a
conglomerate
may
contain
a
sufficient
slates
and
quartzites.
slates and quartzites. Locally a conglomerate may contain a sufficient amount
amount
of ore,
ore, either
or the
the matrix
matrix material,
of
either in
in the
the form
form of
of pebbles
pebbles or
material, to
to be
be merchantable
merchantable
The intrusives
intrusives which
cut the
the hard
hard ore
for mining.
for
mining. The
which cut
ore are
are quite
quite frequently
frequently confused
confused
Both
materials
are
fine-grained
and
highly
with the
the argillite
argillite of
with
of the
the Goodrich.
Good'rich. Both materials are fine-grained and highly
altered, making
altered,
making identification
identification difficult.
difficult.
Presently there
there are
hard ore
Presently
are two
two active
active hard
ore properties
properties in
in the
the Range:
Range: the
the
Cliffs
Cliffs
Shaft and
andthe
theChampicm
ChampionMines.
Mines. Former
Former major
now
Shaft
major hard
hard ore
ore properties,
properties, now
include the
the Lake
Lake Superior
Superior Hard
Hard Ore,
inactive, include
inactive,
Ore, Humboldt,
Humboldt, Republic,
Republic, Michigamme
Michigamme
The
Cliffs
Shaft
Mine
structure
is
a
westerly
and
Greenwood
Mines.
and Greenwood Mines. The Cliffs Shaft Mine structure is a westerlyplunging
plunging
The Greenwood
syncline, having
syncline,
having a
a cross-fold
cross-foldunder
underthe
thetown
town of
of Ishpeming.
Ishpeming. The
Greenwood
and Champion
ChampionMines,
Mines,by
bycontrast,
contrast, are
and
are located
located on
on the
the south
south limb
limb of
of the
the synsyn­
These
hard
orebodies
have
a
definite
westward
plunge
and
extend
clinorium.
clinorium. These hard orebodies have a definite westward plunge and extend
At Republic
Republic Mine
Mine the
the ores
ores
some distance
distance below
below the
the present
present land
some
land surface.
surface. At
were mined
some 4,
4,000
feet along
along the
the plunge,
plunge, or
or 2,800
2,800 feet
feet vertically.
were
mined some
000 feet
vertically.
30
Concnetrating Ores
Concnetrating Ores
properties in Michigan was the
the modern beneficiating
The
first
of
grade
concentrates
producing
high in
The first of
the property
modern beneficiating
properties
Michiganspecularitic
was the
has
been
This
Humboldt Mine.
consists
of the
The
crude
ore
Humboldt Mine. This property
has
been
producing
high
grade
concentrates
Concentration is
and peUets since 1960.
since 1954,
Negaunee.
since
1954, and pellets
since 1960.
consists of the specularitic
theThe
topcrude
of theore
iron-formation
at
production
magnetic cherty
having started
magnetic cherty ironformation
at
the
top
of
the
Negaunee.
Concentration
is
Mine
is
similar,
Republic
The
and specularitic
flotation.
by
froth
the
specularitic
by froth flotation. The
Republic Mine
is similar, having started production
L illustrate
1956. Plates II- K and
Both Humboldt and Republic
of pellets
pellets in
crude the
ores.
of
iniron-formations
1956. Plates II·
K
and
L
illustrate
specularitic and specularitic
which
are
the
magnetitic iron- formations whichofare
magnetitic
thegrade
crudeores.
ores. Both Humboldt and Republic
high
formerly producers
were formerly
Mines were
Mines
producers of high grade ores.
silicate cherty ironmagnetitic
carbonate
mining
a
Concentration
is
iron-formation.
The Empire Mine
The Empire
Mine
is
mining
a
magnetitic
carbonate
silicate
cherty
iron­
of
the
Negaunee
lower section
I, and
J
H,
formation in the lower
and Plates II-G,
formation in theseparation.
section
of the
Negaunee
iron·formation.
Concentration
Plates
I-D,
E and F,
is by
is
by magnetic
magnetic separation. Plates I-D, E and F, and Plates II-G, H, I, and J
illustrate some of this crude ore.
illustrate some of this crude ore.
Genesis of the_High Grade Ores
Genesis of the High Grade Ores
on the origin of the high grade
universal
agreement
There has been no
also, regarddifference
in opinion,
There
are
There has beenIron
no universal
agreement
on
the
ongm
of
the
high
Range.
opposed
hard ores as grade
the
Marqiette
ores
of
enrichment
of
the
ores of the Marquette
Iron
Range.
There
are
difference
in
opinion,
also,
regard­
timing
of
the
and the
ing both the method and
discussed
first.
ing both the method
the
timing
of
the
enrichment
of
the
hard
ores
as
opposed
The soft ores are
to the
the soft
ores. The
to
soft ores.
soft ores are discussed first.
Soft Ores
hypotheses of the origin of the soft
to
most
are
common
Certain features
Soft Ores
ores:
ores:
Certain features are common to most hypotheses of the origin of the soft
iron-formation was important in permitting
Fracturing
of
the
silica and
1.
iron-formation,
to remove
primary
1.
Fracturing
of
the
ironformation
was
important
in
permitting
oxidize the
access for water to
of the
silica. to remove silica and
much
access for water
to
oxidize
the primary
ironformation,
the iron which replaced
to
transport
to transport the iron which replaced much of the silica.
solutions that
removed presumably by the same
have been
The
silica
was
silica
2.
remnants
of theby removed
2.
The silica
was removed
presumably
the same carried
solutions
that
Inasmuch
as
no
to the
carried the iron. Inasmuch as no remnants
that it was
it
is
assumed
carried the iron. Marquette
of the removed silica have been
Range,
identified on the
identified on the Marquette Range, it is assumed that it was carried to the
ancient surface.
ancient surface.
and Bijiki ironfound only in the Negaunee
The
orebodies
are
altered and en3.
mayNegaunee
have been
in
the
column
3.
The
orebodies
are
found
only
in
the
and
iron­ found
has been
formations. Other rock types tonnage of high grade soft oreBijiki
formations. Other
rock
types
in
the
column
may
have
been
altered
and
en­
but no significant
riched
locally,
numbers.
riched locally,
but geologic
no significant
tonnage of high grade soft ore has been found
other
in any of the
in any of the other geologic numbers.
the
and on
found lying on the Siamo footwallThese
orebodies
are
less
The soft
uopen_facinght structures.
4,
or
4.
The
soft
orebodies
are
found
lying
on
the
Siamo
footwall
and
on
the
in
trough-like"
metadiabase sheets
metadiabase sheets in "trough-like" or "open-facing 11 structures.
These less
—
•
•
31
31
permeable members
members may
may be
be folded
foldedandlor
and/or faulted,
faulted, but
but appear
appear to
to act
act as
as "bottom"
'bottom"
permeable
surfaces.
surfaces.
major structural
5.
The major
structural controls
controls of
of folding,
folding, faulting
faulting and
and most
most intrusives
intrusives
Some intrusives
and, according to
to some
some observers,
were pre-ore.
were
pre - ore. Some
intrusives are post-ore and,
observers,
faulting and
and possibly
possibly some
some of
of the
the folding
folding are
are post-ore.
some faulting
post-ore.
Few of
of the
the deeper
deeper major
Few
major orebodies
orebodies extend
extend to
to ledge
ledge surface
surface up
up the
the dip
dip
or up
or
up the
the pitch,
pitch, but
but the
the oxidation
oxidation of
of the
the iron-formation
iron-formation adjacent
adjacent to
to the
the orebodies
orebodies
definitely does
definitely
does extend
extend to
to ledge.
ledge.
6.
Any
hypotheses must
must account
account for
for the
7.
Any hypotheses
the circulation
circulationof
ofa.
a. hydraulic
hydraulic
system which
extends to
to depths
depths of
of over
over 6,
000feet
feet from
from present
present surface.
system
which extends
6, 000
surface.
Most soft
soft ores
ores contain
amounts of
of clay
clay mineral
mineral assemblages
8. Most
contain varying
varying amounts
assemblages
that
temperatures higher
that indicate
indicate temperatures
higher than
than normal
normal ground-water
ground-water temperatures.
temperatures.
The relations
relations of
these clay
minerals to
The
of these
clay minerals
to the
the iron
iron minerals
minerals is
is not
not conclusive.
conclusive.
They are
are not
They
not established
established as
as definitely
definitely contemporaneous.
contemporaneous.
Cold
Water Origin
Cold Water
Origin
Monograph28
28reviewed
reviewedthe
thevariolJ.s
varioiis ideas
ideas of
of soft
soft ore
Monograph
ore origin
origin and
and advanced
advanced
agent of
of oxidation,
oxidation, solution
solution of
of silica,
silica, and
the basic
basic cold
the
cold water
water hypothesis.
hypothesis. The
The agent
and
The
iron
which
replaced
introduction of
of iron
iron was
was oxygen-bearing
oxygen-bearing ground-waters.
ground-waters. The iron which replaced
introduction
In 1935,
the silica
silica was
the
was derived
derived from
from other
other portions
portions of
of the
the iron-formation.
iron-formation. In
1935, C.
C. K.
K.
Leith et
Leith
et al
al (pages
(pages 2424- 26),
26), modified
modified the
the hypothesis
hypothesis by
by proposing
proposing that
that the
the chemical
chemical
activity of
the circulating
circulating ground-waters
activity
of the
ground-waters had
had been
been increased
increased by
by heating
heating due
due to
to
They
also
observed
that
oxidation
is
found
Keweenawan
lavas
and
intrusives.
Keweenawan lavas and intrusives. They also observed that oxidation is found at
at
greater depth
be expected
expected of
of normal
normal ground-water
ground-water circulation
greater
depth than
than would
would be
circulation even
even
under
under mountainous
mountainous conditions.
conditions.
Hydrothermal Origin
Hydrothermal
Origin
In 1926,
J. W.
In
1926, J.
W. Gruner
Gruner proposed
proposed aa hydrothermal
hydrothermal origin
origin for
for Vermilion
Vermilion Iron
Iron
In 1929
he extended
extended this
this hypothesis
hypothesis to
to the
Range ores.
ores. In
Range
1929 he
the formation
formation of
of high
high grade
grade
Gruner's hypothesis
stressed the
ores throughout
the Lake
Lake Superior
Superior region.
ores
throughout the
region. Gruner's
hypothesis stressed
the
The
thermal
conditions
would
greater dissolving
hot water
water on
on silica.
silica. The thermal conditions would
greater
dissolving power
power of
of hot
Objections were
were raised
raised to
stimulate hydraulic
stimulate
hydraulic circulation.
circulation. Objections
to the
the idea
idea that
that these
these
waters
were
juvenile
on
the
basis
that
most
of
the
Lake
Superior
intrusives
waters were juvenile on the basis that most of the Lake Superior intrusives were
were
his "modified
theory'
basic and
and therefore
thereforerelatively
relatively"dry".
'dry'. In
basic
In 1937,
1937, he
he published
published his
"modified th
eory ll
which
proposes
that
the
ore-forming
fluids
were
principally
meteoric
waters
which proposes that the ore-forming fluids were principally meteoric waters
which had
hadbeen
beenheated
heatedby
byigneous
igneousemanations.
emanations. He
also0 that
which
He conceded
conceded als
that not
not all
all of
of
Gruner
explained
the
observed
the
introduced
iron
came
from
these
emanations.
the introduced iron carne from these emanations. Gruner explained the observed
differences in
in resultant
resultant ore
differences
ore types
types as
as being
being related
related to
to differences
differences in
in primary
primary ironiron­ formation, structural
formation,
structural conditions,
conditions, temperatures
temperatures of
of the
the water,
water, and
and relative
relative
quantities
quantities of
of emanations.
emanations .
32
Summary on
Soft Ore
Ore Genesis
Summary
on Soft
Genesis
dissimilar. Aside from
The theories
theories of
Gruner are
are not
The
of Leith
Leith and
and Gruner
not too
too dissimilar. Aside from
is almost the same, the
Gruner's
"emanations,"
the
ore-forming
process
Gruner's "emanations," the ore-forming process is almost the same, the
The geometry of the soft orebodies
differences being
only aa matter
matter of
differences
being only
of degree.
degree. The geometry of the soft orebodies
complicated
plumbingH
of the hydraulic systems.
is significant
in stressing
stressing the
is
significant in
the complicated "plumbing" of the hydraulic systems.
Some
the "open"
"open' side
structural traps.
Many of
of the
the orebodies
orebodies are
are found
Many
found on
on the
side of
of structural
traps. Some
surface.
have no
no apparent
apparent relationship
relationship to
have
to the
the present
present surface.
Recent microscopic work by
also. Recent microscopic work by
The mineralogy
The
mineralogy may
may be
be significant
significant also.
in the
the soft
soft ores,
ores, as
shown in Plate
Tsu-Ming
Han has
has found
found appreciable
appreciable martite
martite in
TsuMing Han
as shown in Plate
soft orebodies are essentially
The semi-hard
0 and
III. a
III.
and P.
P. The
semi-hardores
oresfound
found in
in the
the soft orebodies are essentially
contains traces
traces to
appreciable
martite, some
some of
which contains
up of
equigranular martite,
made up
made
of equigranular
of which
to appreciable
martitization was contemporaneous
remnants, Han
magnetite remnants.
magnetite
Hansuggests
suggeststhat
that the
the martitization was contemporaneous
the soft
with the
soft ore
are formation.
formation.
clay minerals suggest temperature
Lastly, as
Lastly,
as pointed
pointed out
out above,
above, some
some of
of the
the clay minerals suggest temperature
The
writer noted dickite and chrome
higher
than
those
of
normal
ground-waters.
higher than those of normal ground- waters. The writer noted dickite and chrome
in 1945,
as described
by Gruner (1946).
nontronite in
in the
ores in
nontronite
the Marquette
Marquette Range
Range ores
1945, as
described by Gruner (1946).
(non-definitive),
(l96Q)describes
describes dickite,
dickite, kaolinite
The paper
paper by
Bailey and
The
by Bailey
and Tyler
Tyler (196P:L
kaolinite (non-definitive),
clinochrysotile,
muscovite, lizardite,
lizardite, clinochrysotile,
nacrite, talc,
nacrite,
talc, pyrophyllite,
pyrophyllite, 1M
1M and
and 2M1
2M 1 muscovite,
trioctahedral
chlorite,
dioctahedral and trioAl-serpentine, dioctahedral
AI-serpentine,
dioctahedral and
and trioctahedral chlorite, dioctahedral and trio­
and
regular
inter
stratifications of
ctahedral montmorillonite,
skite, and regular inter stratifications
ctahedral
montmorillonite, palygor
palygorskite,
of
non-clay minerals apatite, alunite,
chloritemontmorill0flite, as
chlorite-montmorillonite,
as well
well as
as the
t'he non-clay minerals apatite, alunite,
and Tyler state on pages 155 and
rhodochrosite. Bailey
gypsum, clacite,
clacite, and
gypsum,
and rhodochrosite.
Bailey and Tyler state on pages 155 and
by field
data and
156, "In
"In summary,
summary, both
156,
both the
the synthesis
synthesis data
and the
the evidence
evidence provided
provided by- field
in the world suggest that the clay
relationships for
for similar
relationships
similar clays
clays elsewhere
elsewhere in the world suggest that the clay
is primarily the result of hydromineral assemblage
iron ores
mineral
assemblage in
in the
the Michigan
Michigan iron
ores is primarily the result of hydro­
intimate association
of the clay minerals with the
.
The intimate
.
.
thermal activity.
thermal
activity.
The
association of the clay minerals with the
differences may also extend to the origin of the ore
ore suggests
these differences
iron are
iron
suggests that
that these
may also extend to the origin of the ore
itself.''II
itself.
chlorite zone of metaAs noted
As
noted earlier,
earlier, the
the soft
soft ores
ores are
are found
found in
in the
the chlorite zone of meta­ morphism.
morphism.
Hard Ores
Hard
Ores
the soft ores. There may be two
hard ores
ores are
are more
more complex
The hard
The
complex than
than the soft ores. There may be two
Significant features are:
origin and
and times
times of
formation.
or more
more modes
or
modes of
of origin
of formation.
Significant features are:
1.
formation.
2.
2.
under
less
under less
200 feet of the Negaunee ironThe hard
upper 200
The
hard ores
ores are
are found
found in
in the
the upper
feet of the Negaunee iron­
the Goodrich contact.
Most
commonly,
the
hard
ore
is
at
Most commonly, the hard ore is at the Goodrich contact.
such as anticlinal flexures,
The hard
The
hard ores
ores are
are in
in 'closed"
ilclosedll structures,
structures, such as anticlinal flexures,
permeable rocks.
permeable
rocks.
33
33
3.
Common
ly, the
adjacent to
ore is
is the
the "oxide"oxide­
3.
Commonly,
the iron-formation
iron-formation adjacent
to the
the ore
facies"
jaspilite, the
reddish, pinkish
pinkish banded
banded chert
the miners
miners once
once called
called
facies" -- jaspilite,
the reddish,
chert the
"hard
"hard ore
ore jasper."
jasper."
4.
Hard ores
tend to
little to
to no
no
Hard
ores tend
to have
have equigranular
equigranular iron
iron minerals,
minerals, little
porosity,
few vugs
vugs and
and no
porosity, few
no botryoidal
botryoidal textures.
textures.
The magnetite
magnetite ores
ores are
masses in
5.
The
are commonly
commonly in
ln discontinuous
discontinuous masses
in
specularitic iron-formation
specularitic
iron- formation and
and ore,
ore. The
The chert
chert associated
associated with
with magnetite
magnetite ore
ore
is gray
In some
some areas
areas magnetite
is
gray rather
rather than
than reddish.
reddish. In
magnetite orebodies
orebodies and
and magnetitic
magnetitic
iron-formation
traversed by
by quartz
quartz veins
veins containing
containing tourmaline,
very coarse
coarse
iron-formation are
are traversed
tourmaline, very
specularite and
crystalline siderite
specularite
and crystalline
siderite with
with minor
minor pyrite,
pyrite, sphalerite
sphalerite and
and chalcopyrite.
chalcopyrite.
Frequently the
6.
Frequently
the hard
hard ores
ores extend
extend down
down into
into the
the iron-formation
iron-formation as
as
"droppers,"" appearing
"droppers,
appearing to
to have
have been
been formed
formed by
by replacing
replacing the
the iron-formation.
iron- formation.
Locally, at
contact, some
7.
Locally,
at the
the Goodrich
Goodrich contact,
some massive
massive hard
hard ore
ore contains
contains
detrital
quartz
which
suggests
that
the
original
iron
minerals
may
have
detrital quartz which suggests that the original iron minerals may have had
had a
a
similar detrital
similar
detrital origin.
origin.
Above the
the hard
hard ores
ores and
8.
Above
and at
at the
the base
base of
of the
the Goodrich,
Goodrich, one
one finds
finds
conglomerates of
conglomerates
of varying
varying thickness.
thickness. The
The conglomerate
conglomerate may
may contain
contain much
much detrital
detrital
chert or
chert
or quartz,
quartz, and
and some
some ore
ore fragments
fragments that
that appear
appear to
to have
have been
been ore
ore at
at the
the time
time
of deposition.
deposition.
of
Dynamic metamorphism
metamorphism has
has been
been responsible
responsible for
9. Dynamic
for the
the formation
formation of
of the
the
specular
hematite
in
the
ores
and
adjacent
iron-formation.
specular hematite in the ores and adjacent iron-formation.
10.
10.
No hard
hard ore
ore is
in the
the Bijiki
Bijiki iron-formation.
No
is found
found in
iron-formation.
Hypotheses of
of Hard
Hard Ore
Ore Origin
Hypotheses
Origin
Monograph 52,
52, pages
pages 278278-279,
Monograph
279, outlines
outlines a
a possible
possible origin
origin and
and time
time sequence
sequence
upper portion
portion of
iron-formation was
The upper
of ore
ore formation.
of
formation. The
of the
the Negaunee
Negaunee iron-formation
was exposed
exposed
to weathering
weathering and
and concentration
concentration (mechanical
(mechanical classification?)
classification?) to
to
to produce
produce an
an iron
iron
Burial by
rich product.
rich
product. Burial
by the
the Goodrich
Goodrich and
and later
later formations
formations followed.
followed. After
After the
the
deposition of
of the
the Michigamme
Michigamme formation,
formation, the
deposition
the Animikie
Animikie sediments
sediments were
were folded,
folded,
The metamorphism
metamorphism associated
associated with
with the
the structural
structural deformafaulted and
faulted
and intruded.
intruded. The
deforma­
tion formed
formed the
the hard
hard ores
ores from
tion
from the
the weathered
weathered ores.
ores.
re-exposed the
iron-formaPost-Keweenawan erosion re-exposed
Post-Keweenawan
the Negaunee
Negaunee and
andBijiki
Bijiki iron-forma­
They
were
altered
by
ground-waters
to
form
the
soft
ores,
as
outlined
They were altered by ground-waters to form the soft ores, as outlined
ores were
earlier. Since the
the soft
soft ores
were formed
formed after
after the
the dynamic
dynamic metamorphism,
metamorphism, they
they
do not
not display
display the
the specular
specular hematite
hematite and
the hard
hard ore.
do
and other
other features
features of
of the
ore.
tions,
tions.
J.'
34
I
I
The objection
concept centers on
on the
the trweathered_surfaceu
"weathered-surfacer! origin
ongln
objection to
to this
this concept
for
the hard
necessary to
to postulate
postulate some
some introduction
introduction of
of iron
for all of the
hard ores. It
It is necessary
to
explain both
of many
many hard orebodies.
orebodies.
to explain
both the
the geometry
geometry and
and detailed
detailed features
features of
This
introduction of
of iron
must have
have been
been accomplished
accomplished before
or during
during metameta­
This introduction
iron must
before or
morphism.
morphism.
The
school of
of thought
thought would
much of
The hydrothermal school
wouldascribe
ascribe much
of the
the hard ores
to replacement of the iron-formation by high
high temperature
solutions.
to
temperature solutions.
An Alternate Time
Time Sequence
Sequence
The
by the mining
mlnlng companies,
companies, and
and the
The continuing
continuingresearch
research each year
year by
mapping by
Geological Survey,
add materially to
to our
our informainforma­
current mapping
by the
the U.
U. S.
S. Geological
Survey, add
tion
More age-dating
age -dating will
will be
be done
done to
to
tion on
on the
the geology
geology ofofthe
the Marquette
MarquetteRange.
Range. More
help
time - sequences of
of ore-formation. The
The writer
that aa
help establish
establish time-sequences
writer believes that
better
understanding of
the Clarksburg
Clarksburg
better understanding
of the
the relationship
relationship of
of the
the metadiabases,
metadiabases, the
pyroclastics
and the Penokean
Penokean orogeny
pyroclastics and
orogeny will
willalter
alter the
the classic
classic time-sequence.
This
understand the
the effects
effectsof
ofKeweenawan
Keweenawan vulcanism.
vulcanism.
This will help us understand
Other Ores of
of Economic
Economic Interest
Other
Interest
Numerous gold,
silver and
and lead
lead prospects
prospects have
have been
been noted
noted north
north of
of
Numerous
gold, silver
Ishpeming
The age
of the
is
Ishpeming inin the
the Pre-Animikie
Pre-Animikie series.
series. The
age of
the mineralization is
thought
M. Broderick
Broderick(1945)
(l945) who
who described
des cribed
thought to
to be
be post-middle
post-middle Animikie
Animikie by
by T.
T. M.
the
gold occurrence
occurrence at
at the
the Ropes
Ropes Gold
Gold Mine.
Mine. AAtotal
totalofof$703,
$703,000
000 was
was
the major gold
recovered
this operation
operation during
during the
the period
periodof
of1883
1883 to
to 1897.
1897.
recovered from this
Significant amounts
iron­
Significant
amounts of
of uranium
uranium oxide
oxide have
have been
been detected
detected in
in the
the ironformation
on the Marquette
Marquette Range
Range and
and in
in the
the Gwinn
Gwinn District.
rich
formation on
District. ThoriumThorium-rich
monazite
noted in
Goodrich quartzite
and conglomerate
conglomerate of
of the
the
monazite has
has been noted
in the Goodrich
quartzite and
Cascade District,
Cascade
Vickers (1956).
(l956).
District, as
as described
described by Vickers
Acknowledgment
Grateful acknowledgment
acknowledgment is
Grateful
is made
colleagues in
in The
The
made to
to the
the writer's
writerts colleagues
Cleveland-Cliffs Iron Company,
Cleveland-Cliffs
Company and
and Laughlin
Laughlin
Company, Inland
Inland Steel
Steel Company
and Jones
Jones and
Steel Corporation, and
Steel
and their
their managements,
for assistance
assistance in
in preparing
preparing this
managements, for
summary. The
summary.
The writer
writerparticularly
particularlyappreciates
appreciatesthe
thecooperation
cooperationand
and contributions
contributions
by the
the U.
by
U. S.
S. Geological
Geological Survey
Survey and
and the
the Michigan
Michigan Geological
Geological Survey.
Survey. Special
I
~
II
I
I
I
I
I
I
I
I
J
J
J
35
thanks are
are due
to Dr.
Dr. Jacob
thanks
due to
Jacob Gair.
Gair.
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of the
the
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Minnesota Geologica.l
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, (1937)
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the
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of
and Its
I ts Effect
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onMetallurgical
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Paper
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at Institute
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Upper
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((Covers
Covers from!
shpeming to
to Champion)
Harold L.
Soft Iron
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Michigan"
James,
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of the
the Soft
of Michigan"
James, Harold
pp.
726-'728
Vol.
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Harold L.
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and
in
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'l
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Royce, Stephen
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W. H. Newhouse, pp. 54- 63
2icGeoiar,
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37
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Marquette and
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1943"
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Stockwell,
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riA Tectonic
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27
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Lake Superior
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from
MetamorphosedIron-Formation
Iron-Formation'" Bulletin,
Metamorphosed
Bulletin, Geological
Geological Society
Society
of America,
America, Vol.
of
Vol. 60,
60, pp.
pp. 1101-1124
1101-1124
Tyler, S.
StratiTyler,
S. A.
A. and
andTwenhofel,
Twenhofel, W.
W. H.
H. (1952)
(1952) "Sedimentation
"Sedimentation and
and Stratigraphy
of
the
Huronian
of
Upper
Michigan"
American
Journal
graphy of the Huronian of Upper Michigan" American Journal of
of
Science, Vol.
Science,
Vol. 250,
250, pp.
pp. 1-27,
1-27, 118-151
118-151
Hise, C.
Lake
Van
VanHise,
C. R.
R. and
and Leith,
Leith, C.
C. K.
K. (1911)
(1911) "The
"The Geology
Geology of
of the
the Lake
Superior Region" Monograph
Monograph52,
52, U.
U. S.
S. Geological
Geological Survey
Survey (641
(641 pp)
pp)
R. C.
Vickers, R.
C. (1956)
(1956) "Geology
"Geology and
and Monazite
Monazite Content
Content of
of the
the Goodrich
Goodrich
Quartzite, Palmer
Quartzite,
Palmer Area,
Area,Marquette
MarquetteCounty,
County, Michigan"
Michigan"
U.S.
Survey, Bulletin
U.
S. Geological
Geological Survey,
Bulletin 1030-F
1030-F
Zinn, Justin
of the
the Portion
Zinn,
Justin (1931)
(1931) "Geology
"Geology of
Portion of
of the
the Marquette
Marquette Range
Range
between
and Lake
Lake Michigamme
between Humboldt
Humboldt and
Michigamme Covered
Covered by
by the
the
Michigan
Geological Survey
Survey in
Michigan Geological
in 1930"
1930" Michigan
Michigan Geological
Geological
Survey (Mimeographed
Survey
(Mimeographed -- 18 pp)
pp)
,
xj
1.a.
0
C-,.
Cl)
CD
CD
C,)
0
CD
()
CD
I..'.
JQ
0
C-,.
C)
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P
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CD
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C)CD
C)CD
CD
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0
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Figure 2 -
North Jackson Mine No.
I Pit, 1860
MARQUETTE IRON RANGE, MICHIGAN
THE CLEVELAND-CLIFFS IRON COMPANY
—
+
DEER
L AKE
4
+
JN
A
C-
II5
14
Il
I
BUSH
4
J6,
9
7
r
LOG
LAKE
4
JiGLASS
c
II
4(
120
30
I
'3
8
'5
48 29
'tAKE
26
29
/
%L
N
LDM/NE
4K
LAKE'
,,1
7
——-.7_
—
\35
32
36
34
SPRUCE
&NW
HEARILAKEJ
4430•
—-'
8);q
10
I
2
---1h
'CE
Jj7y(LAE
(/
'3
'4
15
18
4731
4(
'—'{20
22.-
21
..
20
24
.. --
LEGEND
34
tAlla lU1U111Ul
I
8
1
7
°
6
2I
35
TY
'-"
&
lUc
I
9'
SANDSTONE, CONGLOMERATE
DIABASE
KEWEENAWAN
INTRSOIVES, LAVA FLOWS, SANDSTONES
S RA N IT ES
BASIC MET/I— ISNEOSS
4
PAINT RIVER
MOSTLY INTRUSIVE
FOUND IN THE SOUTHWEST SF THE MARQUETTE RANGE
GROUP
BA RAG A
MICHIGAMME
GROUP
l4
23
22
3
MI DDLE
'5
I
46 '30
46
20
22
2R
26
28
..I PEN
LASE
HEAD
II
:1
35
36
y
rE
33
5805
29
27
IL
89.So•
32
-
CLARKSBURS PYROCLASTICS
GREENWOOD MAGNETIC MEMBER
GOODRICH
QUARTZITE, ARSILLITE, CONGLOMERATE
NEGAUNEE
IHON FORMUTION
MENOMINEE
PRE — CAMBRIAN
(OIUMS-AJIBIIY
GROUP
24
UPPER ARGILLITE, SRUYWACKE
RIJIKI IRON FORMATION
MIDDLE ARSILLITE, URUYWUCKE
LOWER ARGILLITE, SLATE, SRAYWACKE
0
tRANT
33
JACOBS VILLE
CAMBRIAN
LATE
•-
j, LAKE
32
RECENT GLACIAL DEPOSITS
QUATERNARY
PAL EOZ OIC
I
5
34
OF THE
GEOLOGIC
;:
h':
3V
3'
PRINCIPAL DISTRICT
COLUMN
MODIFIED FROM U.S. GEOLOGICAL SURVEY
,• 25
26
27
0
CHOCO LAY
UNDIFFERENTIATED
IN
URSILLITE, SRAYWACIYE
CONTAINS SGSSE LAKE
SLATE
AJI 81 K
QUARTZITE — T4IINTGTHICK
WEWE
GRAY SLATE — LOCALLY QUARTZTES , CONSLSMERATE
KONG
DOLOMITE — M'NOR QUARYZIYESILT!YE
MESNARD
IR SNFORMAT ISN
QSARTZITE
CONGLOMERATE, GRAYWACKE, ARKOSE
FELSITE PORPHYRY
EARLY
WESTERN PSRTIONI
SI AMO
GROUP
MONA
MUD
20
TONALITE, GRANODIORITE
SCHISTS, METASEDIMENTS, SNEISOES
GREENSTONE, MASSIVE — ELLIPSOIDAL
FELSITE, METABASALT
8
6
7\REI
48 26
E
1421
—--
23
22
LL
2/
a :)uN
-:S
jACR
DAM
26
25
26
27
'3
24
23
21
PETrICOATK
32
_r
CKY
E
ROUND
ALAKE
'I6
8
5
18
5
FIGURE 4
25
41
S7J
I
\
\\
AROUETr
H
I
I
•
5
l5
29
MAR QUE TIE
IRON
RANGE
MICHIGAN
GENERAL IZED
CROSS SECTION
Nrn-S
ONE MILE EAST OF WEST LINE OF R.26W
FIGURE
6
LOOKING WEST
S
N
TRACY MINE
NEGAUNEE - MAAS
ilpgu- /964-
FIGURE
7
GRAPH SHOWING RELATIVE THICKNESSES OF ANIMIKIE SEDIMENTS ON THE MARQUETTE RANGE
LOOKING NORTH
HUMBOLDT
M I C HI GAM ME
ENCHANTMENT LAKE
ISHPEMING
3 m SW of Marquette
EROSION
7,,
/
/ / //
U
///
/
/
/
/ /
/
/ // /
9
0
0
(9
(1)
/7
4
—
—
LLJ—
zl
/
/
/
—
=
(9
2
i: —---
7
—
—0——
—
—
7 —-
F-
—
—
/
/
/
—
7
7
—_
GO°
7
0.
0
0
(9
U
U
z
*
WEWE
/
7
77
7
V
/
V
0
/
/
/
(0 /
c,
I
I
/
/
/
4) /
/
I,
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1/
z—
/
//
4
0
0
/
7
(9,
/
V
V
V
0
,0
-J
,,,0
7-
'N
I0
—
KONA
I
——
— — +- ___(I)_
w
-7
84S4L,
—
SLAMO — AJI8IK
-I--I
400
400
FEET
800
200
Vertical
Scale
SEcT,0
UNDI FFERENTLATED
Dl STRIBUTION
Horizontal
8000
Scale - —
000
8000
FEET
6000
2
'
24000
t
C')
p
with magnetite - che rt carbonate - silicate
Chert-silicate containino
carbonate and rnagnetie
Magnetite lan-dna alternating
Magnetite lamina alternating
with magnetite-chertcarbonate -silicate
Silicate -chert containing
some carbonate
Magnetite lamina alternating
with silicate-carbonate
Silicate -carbonate
granules, various shades;
chert, white
D.
Magnesium iron carbonate
t
'1
Thin section ZGUX Athens Mine
A. Cherty Carbonate I-Fm.
0
n
0
0rt-
Polished slab of Inn-Formation
Natural scale
S
g roundmas s
E. and F. Pol.Sec. lCUX
B. Mag. Chloritic Ciastic I-Fm.
C. Mag. Urunetitic Cherty I-Fm.
Thin section i O X Empire Mine
Thin section IGUX Republic Mine
Coarse magnetite and quartz
Grunetite, gray; chert, dusty
granules with chioritic
white: magnetite. black
1
0
I:
CD
oi
U)
H
I
0
C
whitish gray; chert and
quartz, dark gray
Martite, white; magnetite,
H. Same - Pol. Sec. 100X
G. Martitic Cherty Clastic
I-Fm. Natural size
Cherty Goethitic I-Fm.
Natural size
Martite, white; goethite,
gray; chert, dark gray;
and pits, black
J. Same - Pal. Sec. bOX
I.
gray; chert, dark gray
Cherty I-Fm. Pal. Sec. 100X
Hematite, white; magnetite,
L. Magnetitic Specularitic
K. Specularitic Cherty I-Fm.
Pal. Sec. 100X - Hematite,
white; chert, black
U)
oQ
0
0
0
(L
çi
';!
AAf
fl
grey.
As N. 500x
Hematite, white; and
gangue and pores, dark
A
;,
soft hematite.
Hematite white.
Pci. sac. lOOx.
i. Nather
:
: t: .
e
*
.a:
+1*
?
••
Ø
''S
—
— —— —
Pol. sec. bOx
P. Mather hard rnartitic ore. K. Cliffs-Shaft Magnetite.
Magnetite, greyih white;
Martite, white; pore,
black,
hematite, white; gangue
Pol. sec. lOOx.
dark grey, and pit black.
Fob. sec. lOOx
I
T. As S. Fob. sec. lOOx
Hematite, greyish
white; martite, white,
gangue, dark grey.
0. Mather soft martitic ore. Q. Cliffs—Shaft hard hematite S. Cliffs—Shaft ore
conglomerate.
Hematite, white; and
Martite, white, chert,
Natural size.
Magnetite,
greyish
white.
dark
Fob. sec. lOOx
Hematite, greyish white.
•
V
V
I
0
0
CD
p
GEOLOGY OF NEGAUNEE IRON FORMATION
EMPIRE MINE AREA AND CASCADE DISTRICT
1000
000
2000
l0O0
GENERALIZED CROSS SECTION
MINE AREA, SEC. 19, 47-26
E-W X-SEC. A-A' LOOKING NORTH
EMPIRE
400
4?0
800
+1600
PM 0
0.01-1. 9
+ 200
+ 800
--(i_—
2
21122
201121
22 23
LEGEND
I!
GOODRICH QUARTZITE
UNOX. IRON FORMATION
OX.
IRON
DIORITE
LOWER
MIDDLE
ANIMIKIAN
E1
METASEDIMENTS
OX.
IRON FORMATION
ARGILLITE
————-————-——-—-—--—————___._____.L0_____________
30
EMPIRE
INTRUSIVE
P7 ROCLA ST IC
CLASTIC
SIAMO—AJIBIK
FORMATION
28
CONC. PLANT
32
LATT
MiNE
27
OF
GEOLOGY
THE REPUBLIC
MINE
AREA
PA
....\
'A
\\.
f;
r
.
::..•1I.
55
N
PIT
GENERALIZED
CROSS SECTION
LdOKING
A—A'
N— E
-dole'4t0
000
S
6
Ef FL AN AT tN
Metasnd imentn
I4ichipamnme Formation
Nicacmoan, parmetiferoas aod amphibalitic nchints
tdoadrick Formafian
Qnartzites, metapraymacken and mica schists
Negaannn Iron—Format Ion
Coeplameratic iron tormatiar
Spmcalar hematite — mapnotite cherty iron—formation
Silicate iron—formation
AJitik Formation
lgnmaan
Ojartzites, metapraymackas. feldnpathic pmmisnnn and mica nchintn
('I)
*.ImtadioniteS & knph,bolites
ftntly nralitic nub
fepabi ic Camplen
Pnrphynitin and epnipraenlar oraniton mith ainphitol iten.
At leant in part represents pranitizod sediments
Faa It
Contact (appronimate)
Strike and dip of tnddinp
S
Strike and dip of foliation
tnrike and dip of jointing
tntcrop area
OPhIL,
19t3
-
4
3
—
THE CLEVELAND-CLIFFS IRON COMPANY
O)MARQUETTE IRON RANGE, MICHIGAN
GEOLOGIC
COLUMN
OF THE
PRINCIPAL DISTRICT
MODIFIED FROM U.S. GEOLOGICAL SURVEY
RECENT GLACIAL DEPOSITS
SANDSTONE, CONGLOMERATE
S NA N IT ES
BASIC META— IGNEOUS
MOSTLY INTRUSIVE
MARQUETTE RANGE
FOUND IN THE SOUTHWEST OF THE
UPPER ARUILLITE, URAYWUCKE
BIJIKI IRON FORMATION
MIDDLE ARUILLITE, GRAYWACKE
CLURKSBURG PYROCLASTICU
GREENWOOD MAGNETIC MEMBER
LOWER ARSILLITE, SLATE, URAYWACKE
QUARTZITE, ARUILLITE, CONGLOMERATE
IRON FORMATION
ISIAMO—AJIBIK
UNDIFFERENTIATED
ARGILLITE, GRAYWACKE
SLATE — CONTAIN SAUUSELAK E
IN WESTERN
IR ONFORMAT ION
QUARTZITE — THINTOTHICIIB EBBED
GRAY SLATE — I. OCALLY
QUARTZflEG
DOLOMITE — ONOR 000RTZITE
,
CONGLOMEBAT
SIL1IlE
QUARTZ lIE
CONGLOMERATE, GRAYWACKE, ARKOSE
FELSITE PORPHYRY
TONALITE, URANODIORITE
GCHIDTU, METASEDIMENTS, GNEISSES
GREENUTONE, MASSIVE — ELLIPSOIDAL
FELSITE, METABASALT
FIGURE 4