DEPARTMENT OF THE INTERIOR
UNITED STATES GEOLOGICAL S'
f ; 7

sei) MSs
Geochemical Symbols DISCUSSION
(size of symbols explained on histogram)

This map shows the distribution and abundance of
{Anomalous cobalt value (fig. 1) cobalt, chromium and nickel in 287, nonmagnetic,

heavy-mineral concentrate samples collected during the
Z\ Anomalous chromium value (fig, 2) 1978-1979 field seasons in the West Chichagof-Yakobi
Wilderness Study Area, Sitka quadrangle, southeastern
Anomalous nickel value (fig. 3) Alaska.

The area of this project is about 600 square
miles (1800 km?), The heavy-mineral concentrate
samples were taken from the active stream channels
draining areas of about 2 square miles (6 km’),

The preparation of the heavy-mineral concentrates
prior to analysis involved panning stream sediment in
the field to remove most of the low-density minerals.
The panned sample was sieved through a 20-mesh
(0.8 mm) sieve and the minus 20-mesh (0.8 mm) fraction
was separated into light- and heavy-mineral fraction
using bromoform (specific gravity of 2.86). The high
density or heavy-mineral fraction was further prepared
by removing magnetite and other strongly magnetic
minerals by using a hand magnet.

TP onake Rte
T S

Vi

The remaining heavy-mineral fraction was passed
through a Frantz Isodynamic Separator! at a setting of
0.6 amperes, thereby separating the magnetic fractions
from the nonmagnetic. A‘split of the nonmagnetic
fraction was pulverized with mortar and pestle and
analyzed by semiquantitative emission spectroscopy
(Grimes and Marranzino, 1968).

The analytical data were compiled and used in
preparing the histograms and geochemical map. The
histograms were used to identify the range of
anomalous values for each element.

A listing of results from the analysis of the
various sample media collected in this Wilderness
Study Area appears in Hessin and others, (1980).

REFERENCES CITED

Grimes, D. J., and Marranzino, A. P., 1968, Direct-
current and alternating-current spark emission
spectrographic field methods for the semi-
quantitative analysis of geologic materials:
U.S. Geological Survey Circular 591, 6 p.

Hessin, T. D., Spectman, W. S., Crenshaw, G. L.,
Hoffman, J. D., and Cooley, E. F., 1980,
Analytical results of various types of samples
taken in the West Chicagof-Yakobi Wilderness
Study Area, Sitka quadrangle, southeastern
Alaska, Open-File Report 80-905,

lyse of brand names in this report is for descriptive
purposes only and does not constitute endorsement by
the U.S. Geological Survey.

1 50'S
Khaz
(Breakers.

x
a
a
} o : 136°40°
[58°
SS)
S 157’
K__|
or IN SHOWING LOCATION i
QUADRANGLE LOCATION es DEY SHOWING LOCATION OF STHQNY AREA } . beds Fab 0
\ Salistrexun Sound et
: ° 4 0 ee Se
\ y EP Sli Ce
‘ : pe _ ei : " 3 eee Siti” senitgen
- if : : \ p, \~ 2 —< = } if
Base from U. S. Geological Survey 1:250,000, 1951 ates ooo Geology simplified by B. R. Johnson and S. M. Karl, 1981
Sitka; Mt. Fat th *
Fairweather 2 ° 2 4 6 8 MILES
= 7
2 oO 2 4° 6 8 KILOMETERS
——— i

GEOCHEMICAL MAP SHOWING THE DISTRIBUTION AND ABUNDANCE OF COBALT, CHROMIUM, AND NICKEL IN THE NONMAGNETIC, HEAVY-MINERAL
CONCENTRATE SAMPLES IN THE WEST CHICHAGOF-YAKOBI WILDERNESS STUDY AREA, SITKA QUADRANGLE, SOUTHEASTERN ALASKA
By
TD. Hessin and GW. Day
1981

£60

Parts
- pee
Mallon

N

L

OPEN-FILE REPORT

81-27-T
Crag cency
o lo ta 3B te st ce ee & Be ae
| | oe
Preeonl
ans
— ee eee ee Oe 3
| . O Pores”
eon
Prvcos

Figure 1.--Histogram showing cobalt in 287, nonmagnetic, heavy-mineral
concentrates from the West Chichagof-Yakobi Wilderness Study Area.
Analysis by optical emission spectroscopy (Grimes and Marranzino, 1968).
Hexagons indicate anomalous concentrations and class percentages computed
on total sample population.

6-
wee en =
O fe CO Fe we St 60 20 Fe Ge je0

L 1 re

a 84
a Poreast
|
| —~ ~ 12
2
-—— A barest

LA port
e

L rN Sipe
L A\ ms

Figure 2.--Histogram showi ng chromium in 287 i i
nonmagnetic, heavy-m
concentrates from the West Chi chagof-Yakobi Wilderness study’ Ares
Analysis by optical emission spectroscopy (Grimes and Marranzino, 1968),

Triangles indicate anomalous concent rati
ations and
on total sample cope class percentages computed

7 Frequencs/
o 10 10 %B8 40 SO 66 76 80 40 100
— ee
fT
. {
a= i
i BF
——— Pevcent
|
st
i
|
— i
|
a ——— — —

i id
+r _ _ _ L Paveent€
! 3

_ c _ _ Pereen€
| ~ 2
bo _ =a _ Parcen€

Figure 3.--Histogram showing nickel in 287, nonma i i
k gnetic, heavy-mineral
concent rates from the West Chichagof-Yakobi Wilderness Study Area.
Analysis by optical emission spectroscopy (Grimes and Marranzino, 1968),

Squares indicate anomalous concent rations
and class perc
total sample population. Reo Seated on

N, not detected at limit of detection

L, detected but below the limit of determination

CORRELATION OF MAP UNITS

Qal QUATERNARY
te | tm TERTIARY (?)
Kd CRETACEOUS (?)
Ks
CRETACEOUS
Kkb
CRETACEOUS AND
KJ£ | KJm | F Surasstc
Trw
TRIASSIC(?)
Trg
MESOZOIC AND
IMzPzul PALEOZOIC(?)

LIST OF MAP UNITS

Qal ALLUVIAL DEPOSITS--Undivided

TfL FELSIC PLUTONIC ROCKS--Dominantly tonalitic

Tm MAFIC PLUTONIC ROCKS--Dominantly gabbroic

Kd DIORITE SILL--Extensively altered

Ks SITKA GRAYWACKE

Kkb KELP BAY GROUP--Metasediments and metavolcanics

KJ£ FELSIC PLUTONIC ROCKS--Dominantly granodiorite

KJm MAFIC PLUTONIC ROCKS--Dominantly quartz diorite, diorite, and gabbro
Trw WHITESTRIPE MARBLE

Trg GOON DIP GREENSTONE

MzPzu UNDIVIDED METASEDIMENTARY--Metavolcanic and metaplutonic rocks

Studies Related to Wilderness

The Wilderness Act (Public Law 88-577, Sept. 3,
1964) and related Acts require the U.S. Geological
Survey to survey certain areas on Federal lands to
determine their mineral resource potential. Results
must be made available to the public and be submitted
to the President and the Congress. This report presents
the results of a geochemical survey of the West Chicagof-
Yakobi Wilderness Study Area, Sitka quadrangle, southeastern
Alaska.