DEPARTMENT OF THE INTERIOR
UNITED STATES GEOLOGICAL SURVE

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Geochemical Symbols

Size of symbols explained on histogram

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46.5 ay
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QUADRANGLE LOCATION

C)Anomatous silver value (figure 1 A)

(YAnoma lous arsenic value (figure 1 B)

Anomalous gold value (figure 1 C)

WX Anomalous tin value (figure 1 D)

Z\ Aroma tous tungsten value (figure 1 £)

St,

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INDEX SHOWING LOCATION OF STUDY AREA

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the low-density minerals. The panned sample was

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DISCUSSION

This map shows the distribution and abundance of
silver, arsenic, gold, tin, and tungsten in 287,
nonmagnetic, heavy-mineral concentrate samples
collected during the 1978-1979 field seasons in the
West Chichagof-Yakobi Wilderness Study Area, Sitka
quadrangle, southeastern Alaska. The area of this
project is about 600 square miles (1800 km’).

The heavy-mineral concentrate samples were taken
from the active channels of streams 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

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.

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.

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

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aa

Reefs

Base from U. S. Geological Survey 1;250,000, 1951
Sitka; Mt. Fairweather

SCALE 1:125 000

8 KILOMETERS
1

Geology simplified by B. R. Johnaon and S. My Karl, 1981

GEOCHEMICAL MAP SHOWING THE DISTRIBUTION AND ABUNDANCE OF SILVER, ARSENIC, GOLD, TIN, AND TUNGSTEN IN THE NONMAGNETIC,
HEAVY—MINERAL CONCENTRATE SAMPLES IN THE WEST CHICHAGOF—YAKOBI WILDERNESS STUDY AREA,

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.

SITKA QUADRANGLE, SOUTHEASTERN ALASKA

By

TD. Hessin, M.G. Maslowski, and G.W. Day
1981

Qal
TE

Kd

Ks
Kkb
KJ£
KJm
Trw
Trg
MzPzu

CORRELATION OF MAP UNITS

Qal QUATERNARY
TE Tm TERTIARY (?)
Kd CRETACEOUS (?)
Ks
CRETACEOUS
Kkb

CRETACEOUS AND
KE | KJm | f Jurassic

TRIASSIC(?)
Trg

MESOZOIC AND
PALEOZOIC(?)

IMzPzu|

LIST OF MAP UNITS

ALLUVIAL DEPOSITS--Undivided

FELSIC PLUTONIC ROCKS--Dominantly tonalitic

MAFIC PLUTONIC ROCKS--Dominantly gabbroic

DIORITE SILL--Extensively altered

SITKA GRAYWACKE

KELP BAY GROUP--Metasediments and metavolcanics

FELSIC PLUTONIC ROCKS--Dominantly granodiorite

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

GOON DIP GREENSTONE

UNDIVIDED METASEDIMENTARY--Metavolcanic and metaplutonic rocks

OPEN-FILE REPORT

Fregu ency

Zz t s

81-27-U

7 [2 73 “9s percent

Aar?s

per

Fi

N

Millon

As

Lords
Per
Mion

Au

Arts

per,

200

BOO

2000

/s00
2000

3000
froso
Ss
6000
7oso
Beg

Peco

LO,090

© S percen t

gure 1-A.--Histogram for silver in 287, nonmagnetic, heavy-mineral
concentrate samples from the Chichagof-Yakobi Wilderness Study Area.
Symbols denote anomalous concentrations and class percentages computed on

total sample population. Analysis by optical emission spectroscopy (Grimes

and Marranzino, 1968). Ninety-five percent of the samples have no reported
values. The remaining five percent (14 samples) have values ranging from
0.5 to 50 parts per million.

N, not detected at limit of detection

Values shown at sample site

Fregvency
i ee ee
( 4 280 98 percent
rd
i

Figure 1-B.--Histogram for arsenic in 287, nonmagnetic, heavy-mineral

4
/o
4S
26
JO
go
70

400

concentrate samples from the Chichagof-Yakobi Wilderness Study Area.

Symbols denote anomalous concentrations and class percentages computed on
total sample population. Analysis by optical emission spectroscopy (Grimes
and Marranzino, 1968). Ninety-eight percent of the samples have no reported
values. The remaining two percent (7 samples) have values ranging from 300
to 10,000 parts per million.

N, not detected at limit of detection

Values shown at sample site

freguenc y

u 2 . n =

Figure 1-C.--Histogram for gold in 287, nonmagnetic, heavy-mineral concentrate

Mi llren

Sr

Barts

per

Million

16
4S
20
30
so
To
100
“ge

200

Toe

L000

samples from the Chichagof-Yakobi Wilderness Study Area. Symbols denote
anomalous concentrations and class percentages computed on total sample
population. Analysis by optical emission spectroscopy (Grimes and
Marranzino, 1968). Ninety-nine percent of the samples have no reported
values. The remaining one percent (4 samples) have values ranging from less
than 5 to 100 parts per million.

N, not detected at limit of detection
Values shown at sample site

Freguen <y
s

od / 2 3

nN 2 >

rh

Figure 1-D.--Histogram for tin in 287, nonmagnetic, heavy-mineral concentrate

70
U-)
S50
236
360

S00
700
7/000
7506
2000
jaca
See
700

10000

samples from the Chichagof-Yakobi Wilderness Study Area. Symbols denote
‘anomalous concentrations and class percentages computed on total sample
population. Analysis by optical emission spectroscopy (Grimes and
Marranzino, 1968). Ninety-seven percent of the samples have no reported
values. The remaining three percent (5 samples) have values ranging from 20
to 1,000 parts per million.

N, not detected at limit of detection

Values shown at sample site

Geguencsy
6 q 2 3 4 s
1 : : : ;

Figure 1-E.--Histogram for tungsten in 287, nonmagnetic, heavy-mineral

concentrate samples from the Chichagof-Yakobi Wilderness Study Area.

Symbols denote anomalous concentrations and class percentages computed on
total sample population. Analysis by optical emission spectroscopy (Grimes
and Marranzino, 1968). Ninety-five percent of the samples have no reported
values. The remaining five percent (13 samples) have values ranging from 50
to 10,000 parts per million.

N, not detected at limit of detection

Values shown at sample site

44 278 77

4 we "283 99 percent

/ percen #4

Rercen fF

XxX 3 percent

( ig 274 95 percent