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THE UNITED STATES GEOLOGICAL SURVEY IN ALASKA:
This report of .accomplhhments of the U.S. Geo-
logical Survey in Alaska during I981 mtalns summary
and topical accounts of the results of studies on a wide
range of topics of economic and scientific interest. In
addition, many more detailed maps and reports are In-
cluded in the lists of references cited for each article
and in the appended compilations of 277 reports on Ai-
aska published by the U.S. Geological Survey and of
103 reports by U.S. Geological Survey authors in
various other scientific publications.
Rre U.S. Geological Survey is engaged in many
scientific investigations on various aspects of the land
and water in Alaska. Pmlucts of the Surveyt investl-
gations include reports describing the phydcal findings
and their significance. This volume includes summmy
discussions, topid rcwults, and some nerratives of the
course of the studles on just a few of the various
Earth-science subjects currently being Investigated in
Alaska. POT the reader's convenience h peruslng
reports that cover specific areas of interest, the
articles are grouped by areas corresponding to the SIX
regional geographic onshore subdivisions shown in fig-
ure 1, by offshore average, and by those article that
cover more than one geographical region or are State-
wide in scope. Index maps showing the study areas or
sites discussed are Lncluded near the beginning of each
subdivision (figs. 1, 5, 13, 19, 23, 44, 72, 90). An
author index at the back of the volume should amkt in
identifying and locating work by specific authors
reported herein or in the appended compilations of
current reports on Alaska by U.S. Geological Survey
authors and their associates.
(Ffgure 1 shows the quadrangles and regions
referred to in this volume)
ACCOMPLlSHMENTS DURING 1981
Warren L. Coonrad and Raymond 1. Elliott, Editors
rangles (fig. 2) have been completed. These maps are
the major summary prdcts of the U.S. Geologlcal
Survey's Branch of Alaskan Geology's telegeologlc
research effort, funded under the auspices of the Alas-
kan Mineral Resource Assessment Program. Synthesfs
of the data compiled from these studies indicates that
the major features oommonly observable on Landsat
images of Alaska are lineaments, circular and arcuate
features, and anomalously colored areas.
Lineaments
Lineaments observed in Alaska can gener* be
divided into three groups on the basis of scale: (1)
Statewide Uneament trends (northwest, north-south,
northeast, and east-west; see Lathram and molds,
1977), corresponding to the regmatic shear pattern,
that not only transect tectonic and stratigraphic
boundaties but also coincide with these boundaries in
places; (2) regional trends, such as for the set of lin-
eaments along the DenaU fault in the Talkeetna quad-
rangle (Steele land Albert, 1978a) or along the Coast
Range megallneament in the Ke tchikan quadrangle;
and (3) local trends that ere commonly restricted to
specific terranes and various geologic phenomena, or
to structures caused by unknown (local) tectonlo
events.
That many lineaments (generally from several
Wlorneters to several tens of kllometers long) which
make up sets of subparallel to parellel Uneaments
detected on Landset images may reflect relatively
narrow (generay less than 10 krn wide) zones of
associated(?) fractures is particularly well shown in
the Ketch- quadrangle (Steele and Albert, 1978b;
Le Compte, 1981b). Only a few (1-10 percent) of the
Uneaments there are faults, although many faults that
are mappable at 1:250,000 scale can be detected on
Landsat images. Lineament extensions beyond the
terminations of the many faults mapped by field
methods are also evident in places.
Circular and Arcuate Features
8nmlwrgat~t~e~~~lnAlngkn Circular and arcuate features detected on Land-
sat Images of Alaska can generally be divided into two
BY Jam- R CMnpte, Willhrn Cltntaa b ebi and goups. The first group consists of circular and arcu-
lUairnRD.Albeet ate features larger than 50 km in diameter, such as
several circular features Ln the eastern Brooks hnge
Landsat-image interpretation and (or) Landsat- (Le Compte, 1970a); few logical explanations have
feature map for 27 Aleakan 1:250,000-scale quad- been found for features this Large. The second group