DEPARTMENT OF THE INTERIOR
UNITED STATES GEOLOGICAL SURVEY

DISCUSSION “

\ MS Sh This map shows the distribution and abundance of . Vy
re H ) p \ copper, lead, zinc, and barium in 287, nonmagnetic, . Js
fa 4 A G AS Ns heavy-mineral concentrate samples collected during the

1978-1979 field seasons in the West Chichagof-Yakobi

C > if ; ‘ . 4 LOM, Yom Pay Wilderness Study Area, Sitka quadrangle, southeastern A
. Al . a
Geochemical Symbols (size of symbol explained on histogram) =z aska
Fi . Ne The area of this project is about 700 square *«
Z\\ Aroma ious copper value (figure 1) CO) noma tous barium value (figure 4) )) miles (1800 km2). The heavy-mineral concentrate : i
Vf . \ F i, samples were taken from the active channels of streams ,* fs
: Crag [_ JAnomatous lead value (figure 2) DE Soap if draining areas of about 2 square miles (6 km2). ~
\: Mith* NONI .
ee € Yanomat ous zinc value = (figure 3) Sf OWY The preparation of the heavy-mineral concentrates fen e
2 : oy / prior to analysis involved panning stream sediment in a aS =
VAR the field to remove most of the low-density minerals. \
AN \\ The panned sample was sieved through a 20-mesh

8 Peake is

(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. j—

}135°30" |

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

% % € 6 : Z , 7 eel S \ gs E < if various sample media collected in this Wilderness

A aT: TS P. ttt a =i Ke \ = ex y . ee q( Sy Af P 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.

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Cat
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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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QUADRANGLE LOCATION INDEX SHOWING LOCATION OF STUDY AREA
\, = fia
Base from U. S. Geological Survey 1:250,000, 1951 SCALE 1:125 000 Geology simplified by B. R. Johnson and S. M. Karl, 1981
Sitka; Mt. Fairweather a o 3 4 é @ MILES
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GEOCHEMICAL MAP SHOWING DISTRIBUTION AND ABUNDANCE OF COPPER, LEAD, ZINC, AND BARIUM IN THE NONMAGNETIC, HEAVY-MINERAL
CONCENTRATE SAMPLES IN THE WEST CHICHAGOF-YAKOBI WILDERNESS STUDY AREA, SITKA QUADRANGLE, SOUTHEASTERN ALASKA
By
TD. Hessin, MG. Maslowski and EF. Cooley
1981

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.

OPEN-FILE REPORT

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Figure 1.--Histogram showing copper in 287, nonmagnetic, heavy-mineral
concentrates 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.
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Figure 2.--Histogram showing lead in 287, nonmagnetic, heavy-mineral
concentrates from the Chichagof-Yakobi Wilderness Study Area. Analysis by
optical emission spectroscopy (Grimes and Marranzino, 1968). Squares
indicate anomalous concentrations and class percentages computed on total
sample population.
N, not detected at limit of detection
L, detected but below level of determination
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Figure 3.--Histogram showing zinc in 287, nonmagnetic, heavy-mi neral
concentrates from the Chichagof-Yakobi Wilderness Study Area. Analysis by
optical emission spectroscopy (Grimes and Marranzino, 1968). Hexagon
indicates anomalous concentrations and class percentages computed on total
sample population.

N, not detected at limit of detection

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Figure 4.--Histogram showing barium in 287, nonmagnetic, heavy-mineral
concentrates from the Chichagof-Yakobi Wilderness Study Area. Analysis by
optical emission spectroscopy (Grimes and Marranzino, 1968). Circles
indicate anomalous concentrations and class percentages computed on total
sample population,

Qal
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Ks
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CORRELATION OF MAP UNITS

Qal QUATERNARY

Tf Tm TERTIARY (?)

Kd CRETACEOUS (?)
Ks
CRETACEOUS
Kkb
CRETACEOUS AND
KJ£ | KJm | f Jurasstc
Trw
TRIASSIC(?)
Trg
MzPoul MESOZOIC AND

PALEOZOIC(?)

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

MzPzu  UNDIVIDED METASEDIMENTARY--Metavolcanic and metaplutonic rocks