DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

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Zz (size of symbol explained on histogram)
p ( Yanomalous colbalt value
Z\ anomalous chromium value

Anomalous nickel value

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(figure 2)

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LOCATION

ee Alaska, Open-File Report 80-905.

DISCUSSION

This map shows the distribution and abundance ‘of
cobalt, chromium, and nickel in 296, minus 80-mesh
(0.2 mm) stream-sediment samples collected during the
1978-1979 field seasons in the West Chichagof-Yakobi
Wilderness Study Area, Sitka quadrangle, Alaska.

The area of this project approximates 600 square
miles (1800 km?). The stream-sediment samples were
collected from active stream channels, draining areas
of approximately 2 square miles (6 km),

The preparation of the stream-sediment samples
prior to analysis consisted of sieving to minus
80-mesh (0.2 mm) and pulverizing to minus 200 mesh
(0.075 mm). The samples were then analyzed hy
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 2
various sample media collected in this West Chichagof- <
Yakobi 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

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GEOCHEMICAL MAP SHOWING THE DISTRIBUTION AND ABUNDANCE OF COBALT , CHROMIUM AND NICKEL IN STREAM-SEDIMENT SAMPLES
IN THE WEST CHICHAGOF-YAKOBI WILDERNESS STUDY AREA, SITKA QUADRANGLE, ALASKA

By
T. D. Hessin, J. D. Hoffman
1981

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OPEN-FILE REPORT

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Figure 1.--Histogram showing cobalt in 296, minus 80-mesh (0.2 mm) stream-
sediment samples from the West Chichagof-Yakobi Wilderness Study Area.
Analysis by optical emission spectroscopy (Grimes and Marranzino, 1968).

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Hexagons indicate anomalous concentrations and class percentages computed on

total sample population.

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Figure 2.--Histogram showing chromium in 296, minus 80-mesh (0.2 mm) stream-
sediments samples from the West Chichagof-Yakobi Wilderness Study Area.
Analysis by optical emission spectroscopy (Grimes and Marranzino, 1968).
Triangles indicate anomalous concentrations and class percentages computed
on total sample population.

L, detected but below level of determination

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Figure 3.--Histogram showing nickel in 296, minus 80-mesh (0.2 mm) stream-
sediment samples from the West Chichagof-Yakobi Study Area. Analysis by
optical emission spectroscopy (Grimes and Marranzino, 1968). Squares
indicate anomalous concentrations and class percentages computed on total
sample population.

L, detected but below level of determination

CORRELATION OF MAP UNITS

Qal QUATERNARY
Tf | Tm TERTIARY (?)
Kd CRETACEOUS (?)
Ks
CRETACEOUS
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KJE | Kom | fF Surasstc
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TRIASSIC(?)
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MESOZOIC AND
MeP2u PALEOZOTC(?)

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

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.

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