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At least 775 records · Page 43Linked to original sources
USGS2019

Soil mineralogy and geochemistry along a north-south transect in Alaska and the relation to source-rock terrane

Soils collected along a predominately north-south transect in Alaska were used to evaluate regional differences in the soil mineralogy and geochemistry in the context of a geotectonic framework for Alaska. The approximately 1,395-kilometer-long transect followed the Dalton, Elliott, and Richardson Highways from near Prudhoe Bay to Valdez. Sites were selected with a site spacing of approximately 10 road-kilometers; soil was sampled by soil horizon at 175 sites. Terrane boundaries were estimated from digitized versions of the lithotectonic terrane map of Alaska (Silberling and others, 1994). Terrane assignments for each site were based on the site’s distance along the transect. We also present data for 15 minerals or mineral groups and 58 elements, as well as total, inorganic, and organic carbon. Quantitative mineralogy of the mineral-soil horizons was characterized by X-ray diffraction. Elemental contents were determined by a combination of inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS) analysis following a multi-acid or sodium-sinter decomposition of the samples. Total carbon and carbonate carbon contents were determined using an automated carbon analyzer and coulometric titration, respectively; organic carbon content was obtained by calculating the difference between total and carbonate carbon. Mercury and selenium were analyzed using cold-vapor atomic absorption (CV-AA), and hydride-generation atomic absorption spectrometry (HG-AAS), respectively. The mineralogical and geochemical patterns from these soils are used to assess the relation between soil characteristics and the geology of surrounding terranes.

Alaska↗
USGS2024

Facies variation within outcrops of the Triassic Shublik Formation, northeastern Alaska

The Shublik Formation (Middle to Upper Triassic) is a heterogeneous unit that is a major hydrocarbon source rock in northern Alaska and the largest known Triassic phosphate accumulation in the world. This formation, which occurs in the subsurface and crops out within the Arctic Alaska basin, was deposited on a gently sloping ramp along the northwestern Laurentian margin. In this study, we document spatial and temporal facies variations within the Shublik and the overlying Karen Creek Sandstone (Upper Triassic) through 19 outcrop localities in the northeastern Brooks Range. New organic and inorganic geochemical data from these localities support and extend our sedimentologic and petrographic findings. The petrographic data come from an analysis of more than 900 thin sections, whereas age constraints come mainly from species of the pelecypod genera Daonella , Halobia , Eomonotis , and Monotis . Thirteen sites make up a main outcrop belt within which facies of the Shublik are spatially consistent but show marked vertical changes. Six additional outcrops located south of the main belt contain more distal facies of the Shublik that accumulated farther from land. Exposures of the Shublik Formation in its main outcrop belt are divisible into five informal lithologic units, each of which formed during a distinct transgressive to regressive sequence. The basal unit of the Shublik (Anisian? to Ladinian; Middle Triassic) is quartz siltstone to very fine grained sandstone that is locally phosphatic. The three middle units (Ladinian to middle Norian; Middle to Upper Triassic) contain various proportions of siliciclastic, carbonate, phosphatic, and organic material. The uppermost unit (middle to upper Norian; Upper Triassic) is mainly shale and mudstone. Highly phosphatic strata (10–34 percent phosphorus pentoxide) are chiefly Ladinian and lower to middle Norian. Highly phosphatic Ladinian strata have been transported, are granular, and formed during transgression and early regression. In contrast, highly phosphatic Norian strata include event beds and hardgrounds, contain displaced and in situ phosphate peloids and nodules, and cap regressive parasequences. The total organic content reaches 4.97 weight percent in the main belt and is highest in muddy beds, which are found mainly in the lower parts of the three middle units. Distal sections of the Shublik are typically finer grained, more organic-rich (total organic content as high as 6.33 weight percent), and less fossiliferous than those in the main belt. Both temporal and spatial factors shaped facies in the Shublik Formation. Shublik strata accumulated at a time of reduced tectonic activity in Arctic Alaska, resulting in diminished siliciclastic input. Marine upwelling along the northwestern Laurentian margin facilitated the development of heterozoan carbonates, as well as local concentrations of phosphatic and organic matter. Large- and small-scale eustatic cycles also affected this margin and provided further controls on Shublik facies distribution.

Alaska↗
USGS2019

Geology and assessment of undiscovered oil and gas resources of the Arctic Alaska Province, 2008

The Arctic Alaska Province encompasses all lands and adjacent continental shelf areas north of the Brooks Range-Herald Arch tectonic belts and south of the northern (outboard) margin of the Alaska rift shoulder. Even though only a small part is thoroughly explored, it is one of the most prolific petroleum provinces in North America, with total known resources (cumulative production plus proved reserves) of about 28 billion barrels of oil equivalent. For assessment purposes, the province is divided into a platform assessment unit, comprising the Alaska rift shoulder and its relatively undeformed flanks, and a fold-and-thrust belt assessment unit, comprising the deformed area north of the Brooks Range and Herald Arch tectonic belts. Mean estimates of undiscovered, technically recoverable resources include nearly 28 billion barrels of oil and 122 trillion cubic feet of nonassociated gas in the platform assessment unit and 2 billion barrels of oil and 59 trillion cubic feet of nonassociated gas in the fold-and-thrust belt assessment unit.

Alaska, Yukon↗
USGS1967

Ground breakage and associated effects in the Cook Inlet area, Alaska, resulting from the March 27, 1964, earthquake

The great 1964 Alaska earthquake caused considerable ground breakage in the Cook Inlet area of south-central Alaska. The breakage occurred largely in thick deposits of unconsolidated sediments. The most important types of ground breakage were (1) fracturing or cracking and the extrusion of sand and gravel with ground water along fractures in various types of landforms, and (2) slumping and lateral extension of unconfined faces, particularly along delta fronts. The principal concentration of ground breakage within the area covered by this report was in a northeast-trending zone about 60 miles long and 6 miles wide in the northern part of the Kenai Lowland. The zone cut across diverse topography and stratigraphy. Cracks were as much as 30 feet across and 25 feet deep. Sand, gravel, and pieces of coal and lignite were extruded along many fissures. It is suggested that the disruption in this zone may be due to movement along a fault in the underlying Tertiary rocks. The outwash deltas of Tustumena and Skilak Lakes in the Kenai Lowland, of Eklutna Lake and Lake George in the Chugach Mountains, of Bradley Lake in the Kenai Mountains, and at the outlet of upper Beluga Lake at the base of the Alaska Range showed much slumping, as did the delta of the Susitna River. Parts of the flood plains of the Skilak River, Fox River, and Eagle River were extensively cracked. A few avalanches and slumps occurred along the coast of Cook Inlet in scattered localities. Some tidal flats were cracked. However, in view of the many thick sections of unconsolidated sediments and the abundance of steep slopes, the cracking was perhaps less than might have been expected. Observations along the coasts indicated changes in sea level which, although caused partly by compaction of unconsolidated sediments, may largely be attributed to crus1tal deformation accompanying the earthquake. Most of the Cook Inlet area was downwarped, although the northwest side of Cook Inlet may have been slightly unwarped. Maximum change in the Cook Inlet area was probably less than 6 feet. Little or no regional tilting was detected in the lake basins of Tustumena and Skilak Lakes.

Alaska↗
USGS1967

Effects of the earthquake of March 27, 1964, on air and water transport, communications, and utilities systems in south-central Alaska

The earthquake of March 27, 1964, wrecked or severely hampered all forms of transportation, all utilities, and all communications systems over a very large part of south-central Alaska. Effects on air transportation were minor as compared to those on the water, highway, and railroad transport systems. A few planes were damaged or wrecked by seismic vibration or by flooding. Numerous airport facilities were damaged by vibration or by secondary effects of the earthquake, notably seismic sea and landslide-generated waves, tectonic subsidence, and compaction. Nearly all air facilities were partly or wholly operational within a few hours after the earthquake. The earthquake inflicted enormous damage on the shipping industry, which is indispensable to a State that imports fully 90 percent of its requirements—mostly by water—and whose largest single industry is fishing. Except for those of Anchorage, all port facilities in the earthquake-affected area were destroyed or made inoperable by submarine slides, waves, tectonic uplift, and fire. No large vessels were lost, but more than 200 smaller ones (mostly crab or salmon boats) were lost or severely damaged. Navigation aids were destroyed, and hitherto well-known waterways were greatly altered by uplift or subsidence. All these effects wrought far-reaching changes in the shipping economy of Alaska, many of them to its betterment. Virtually all utilities and communications in south-central Alaska were damaged or wrecked by the earthquake, but temporary repairs were effected in remarkably short times. Communications systems were silenced almost everywhere by loss of power or by downed lines; their place was quickly taken by a patchwork of self-powered radio transmitters. A complex power-generating system that served much of the stricken area from steam, diesel, and hydrogenerating plants was disrupted in many places by vibration damage to equipment and by broken transmission lines. Landslides in Anchorage broke gas-distribution lines in many places, but the main transmission line from the Kenai Peninsula was virtually undamaged. Petroleum supplies were disrupted, principally by breakage or loss of storage tanks caused by seismic vibration, slides, waves, and fire. Water-supply and sewer lines were also broken in many towns.

Alaska↗
USGS2005

Geologic map of the Ikpikpuk River quadrangle, Alaska

This map is a product of the USGS Digital Geologic Maps of Northern Alaska project, which captures in digital format quadrangles across the entire width of northern Alaska. Sources include geologic maps previously published in hardcopy format and recent updates and revisions based on field mapping by the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys and Division of Oil and Gas, and the U.S. Geological Survey. Individual quadrangles are digitized at either 1:125,000 or 1:250,000 depending on the resolution of source maps. The project objective is to produce a set of digital geologic maps with uniform stratigraphic nomenclature and structural annotation, and publish those maps electronically. The paper version of this map is available for purchase from the USGS Store.

Alaska↗
USGS2006

Geologic map of the Lookout Ridge quadrangle, Alaska

This map is a product of the USGS Digital Geologic Maps of Northern Alaska project, which captures in digital format quadrangles across the entire width of northern Alaska. Sources include geologic maps previously published in hardcopy format and recent updates and revisions based on field mapping by the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys and Division of Oil and Gas, and the U.S. Geological Survey. Individual quadrangles are digitized at either 1:125,000 or 1:250,000 depending on the resolution of source maps. The project objective is to produce a set of digital geologic maps with uniform stratigraphic nomenclature and structural annotation, and publish those maps electronically. The paper version of this map is available for purchase from the USGS Store.

Alaska↗
USGS2006

Geologic map of the Utukok River quadrangle, Alaska

This map is a product of the USGS Digital Geologic Maps of Northern Alaska project, which captures in digital format quadrangles across the entire width of northern Alaska. Sources include geologic maps previously published in hardcopy format and recent updates and revisions based on field mapping by the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys and Division of Oil and Gas, and the U.S. Geological Survey. Individual quadrangles are digitized at either 1:125,000 or 1:250,000 depending on the resolution of source maps. The project objective is to produce a set of digital geologic maps with uniform stratigraphic nomenclature and structural annotation, and publish those maps electronically.

Alaska↗
USGS2008

Geologic map of the Point Lay quadrangle, Alaska

This map is a product of the USGS Digital Geologic Maps of Northern Alaska project, which captures in digital format quadrangles across the entire width of northern Alaska. Sources include geologic maps previously published in hardcopy format and recent updates and revisions based on field mapping by the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys and Division of Oil and Gas, and the U.S. Geological Survey. Individual quadrangles are digitized at either 1:125,000 or 1:250,000 depending on the resolution of source maps. The project objective is to produce a set of digital geologic maps with uniform stratigraphic nomenclature and structural annotation, and publish those maps electronically. The paper version of this map is available for purchase from the USGS Store.

Alaska↗
USGS2009

Geologic Map of the Yukon-Koyukuk Basin, Alaska

This map and accompanying digital files represent part of a systematic effort to release geologic data for the United States in a uniform manner. All the geologic data in this series will be published as parts of the U.S. Geological Survey Data Series. The geologic data in this series have been compiled from a wide variety of sources, ranging from state and regional geologic maps to large-scale field mapping. The data are presented for use at a nominal scale of 1:500,000, although individual datasets may contain data suitable for use at larger scales. The metadata associated with each release will provide more detailed information on sources and appropriate scales for use. Associated attribute databases accompany the spatial database of the geology and are uniformly structured for ease in developing regional- and national-scale maps. The 1:500,000-scale geologic map of the Yukon-Koyukuk Basin, Alaska, covers more than 200,000 square kilometers of western Alaska or nearly 15 percent of the total land area of the state. It stretches from the Brooks Range on the north to the Kuskokwim River and lower reaches of the Yukon River on the south and from Kotzebue Sound, Seward Peninsula, and Norton Sound on the west to the Yukon-Tanana Uplands and Tanana-Kuskokwim Lowlands on the east. It includes not only the northern and central part of the basin, but also the lands that border the basin. The area is characterized by isolated clusters of hills and low mountain ranges separated by broad alluviated interior and coastal lowlands. Most of the lowlands, except those bordering Kotzebue Sound and Norton Sound, support a heavy vegetation cover. Exposures of bedrock are generally limited to rubble-strewn ridgetops and to cutbanks along the rivers. The map of the Yukon-Koyukuk Basin was prepared largely from geologic field data collected between 1953 and 1988 by the U.S. Geological Survey and published as 1:250,000-scale geologic quadrangle maps. Additional data for parts of the Wiseman, Ruby, Medfra, and Ophir quadrangles came from 1:63,360-scale quadrangle maps published by the Alaska Division of Geological and Geophysical Surveys. The map also incorporates some unpublished field data for the Ruby quadrangle collected by R.M. Chapman between 1944 and 1977 and for parts of the Tanana, Bettles, Norton Bay, and Candle quadrangles collected by W.W. Patton, Jr. and others between 1954 and 1985. Sources of geologic map data for each of the eighteen 1:250,000-scale quadrangles used in compiling this 1:500,000-scale map of the Yukon-Koyukuk Basin as well as sources of general geologic information pertaining to the entire map area are provided in the 'Sources of Information' section.

Scientific Investigations Map↗
USGS2006

Surficial Geologic Map of the Tanacross B-4 Quadrangle, East-Central Alaska

The Tanacross B-4 1:63,360-scale quadrangle, through which the Alaska Highway runs, is in east-central Alaska about 100 mi west of the Yukon border. The surficial geologic mapping in the quadrangle is in support of the 'Geologic Mapping in support of land, resources, and hazards issues in Alaska' Project of the USGS National Cooperative Geologic Mapping Program. The Tanacross B-4 quadrangle contains parts of two physiographic provinces, the Yukon-Tanana Upland and the Northway-Tanana Lowland. The gently rolling hills of the Yukon-Tanana Upland, in the northern and eastern map area, rise to about 3,100 ft. The Northway-Tanana Lowland, in the western and southern map area, contains the westerly flowing Tanana River. Elevations along the floor of the lowland generally range between 1,540 and 1,700 ft. The dominant feature within the map is the Tok fan, which occupies about 20 percent of the map area. This large, nearly featureless fan contains a high percentage of volcanic clasts derived from outside the present-day drainage of the Tok River. The map provides interpretations of the Quaternary surficial deposits and associated geologic hazards in this area of the upper Tanana valley. Because the map area is dominated by various surficial deposits, the map depicts 13 different Quaternary surficial units consisting of man-made, alluvial, colluvial, organic, lacustrine, and eolian deposits. Deposits shown on this map are generally greater than 1 m thick. The map is accompanied by a text containing unit descriptions incorporating information pertaining to material type, location, associated hazards, resource use (if any), and thickness.

Scientific Investigations Map↗
USGS2012

Geology of the Prince William Sound and Kenai Peninsula region, Alaska: Including the Kenai, Seldovia, Blying Sound, Cordova, and Middleton Island 1:250,000-scale quadrangles

The Prince William Sound and Kenai Peninsula region includes a significant part of one of the world’s largest accretionary complexes and a small part of the classic magmatic arc geology of the Alaska Peninsula. Physiographically, the map area ranges from the high glaciated mountains of the Alaska and Aleutian Ranges and the Chugach Mountains to the coastal lowlands of Cook Inlet and the Copper River delta. Structurally, the map area is cut by a number of major faults and postulated faults, the most important of which are the Border Ranges, Contact, and Bruin Bay Fault systems. The rocks of the map area belong to the Southern Margin composite terrane, a Tertiary and Cretaceous or older subduction-related accretionary complex, and the Alaska Peninsula terrane. Mesozoic rocks between these two terranes have been variously assigned to the Peninsular or the Hidden terranes. The oldest rocks in the map area are blocks of Paleozoic age within the mélange of the McHugh Complex; however, the protolith age of the greenschist and blueschist within the Border Ranges Fault zone is not known. Extensive glacial deposits mantle the Kenai Peninsula and the lowlands on the west side of Cook Inlet and are locally found elsewhere in the map area. This map was compiled from existing mapping, without generalization, and new or revised data was added where available.

Alaska↗
USGS2012

Geologic map of Mount Gareloi, Gareloi Island, Alaska

Gareloi Island (lat 51.7° N., long 178.8° W.) is located in the Delarof Islands group of the Aleutian Islands, approximately 2,000 km west-southwest of Anchorage and 150 km west of Adak, the westernmost town in Alaska. This small (~8- x 10-km diam), uninhabited island is constructed exclusively of eruptive products from Mount Gareloi volcano, a Pleistocene and Holocene, steep-sided, composite stratocone that rises 1,573 m (5,161 ft) above sea level (asl). Mount Gareloi has been one of the most active Aleutian volcanoes since its discovery by the Bering expedition in the 1740s, though, because of its remote location, detailed observations of eruptive activity have been scant. As part of an effort to both monitor and study all historically active volcanoes in Alaska, the Alaska Volcano Observatory (AVO) undertook a field program at Mount Gareloi in the summer of 2003. During a month-long period, seismic networks were installed at Mount Gareloi and the neighboring Tanaga volcanic cluster. During this time, we undertook the first geologic field study of the volcano since Robert Coats visited Gareloi Island for four days in 1946. Understanding the geology of this relatively small island is important from a hazards perspective, because Mount Gareloi lies beneath a heavily trafficked air route between North America and Asia and has frequently erupted airborne ash since 1760. At least two landslides from the island have deposited debris on the sea floor; thus, landslide-generated tsunamis are also a potential hazard. Since seismic instruments were installed in 2003, they have detected small but consistent seismic signals from beneath Mount Gareloi's edifice, suggesting an active hydrothermal system. Mount Gareloi is also important from the standpoint of understanding subduction-related volcanism, because it lies in the western portion of the volcanically active arc, where subduction is oblique to the arc front. Understanding the compositional evolution of Mount Gareloi fills a spatial gap in along-arc studies.

Alaska↗
USGS2014

Geologic map of the Kechumstuk fault zone in the Mount Veta area, Fortymile mining district, east-central Alaska

This map was developed by the U.S. Geological Survey Mineral Resources Program to depict the fundamental geologic features for the western part of the Fortymile mining district of east-central Alaska, and to delineate the location of known bedrock mineral prospects and their relationship to rock types and structural features. This geospatial map database presents a 1:63,360-scale geologic map for the Kechumstuk fault zone and surrounding area, which lies 55 km northwest of Chicken, Alaska. The Kechumstuk fault zone is a northeast-trending zone of faults that transects the crystalline basement rocks of the Yukon-Tanana Upland of the western part of the Fortymile mining district. The crystalline basement rocks include Paleozoic metasedimentary and metaigneous rocks as well as granitoid intrusions of Triassic, Jurassic, and Cretaceous age. The geologic units represented by polygons in this dataset are based on new geologic mapping and geochronological data coupled with an interpretation of regional and new geophysical data collected by the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys. The geochronological data are reported in the accompanying geologic map text and represent new U-Pb dates on zircons collected from the igneous and metaigneous units within the map area.

Alaska↗
USGS2015

Advanced Land Observing Satellite (ALOS) Phased Array Type L-Band Synthetic Aperture Radar (PALSAR) mosaic for the Kahiltna terrane, Alaska, 2007-2010

The U.S. Geological Survey (USGS) has initiated a multi-disciplinary study investigating the applicability of remote sensing technologies for geologic mapping and identification of prospective areas for base and precious metal deposits in remote parts of Alaska. The Kahiltna terrane in southwestern Alaska was selected for investigation because of its known mineral deposits and potential for additional mineral resources. An assortment of technologies is being investigated to aid in remote analysis of terrain, and includes imaging spectroscopy (hyperspectral remote sensing), high spatial resolution electro-optical imagery, and Synthetic Aperture Radar (SAR). However, there are significant challenges to applying imaging spectroscopy and electro-optical imagery technologies in this area because of the low solar angle for parts of the year, seasonal periods of darkness and snow cover, and the frequently cloudy weather that characterizes Alaska. Synthetic Aperture Radar (SAR) was selected because this technology does not rely on solar illumination and has all-weather capability. The USGS has compiled a continuous, cloud-free 12.5-meter resolution radar mosaic of SAR data of approximately 212,000 square kilometers to examine the suitability of this technology for geologic mapping. This mosaic was created from Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) data collected from 2007 to 2010 spanning the Kahiltna terrane and the surrounding area. Interpretation of these data may help geologists understand past geologic processes and identify areas with potential for near-surface mineral resources for further ground-based geological and geochemical investigations.

Alaska↗
USGS2015

Geologic map of Alaska

Summary This map and associated digital databases are the result of compilation and interpretation of published and unpublished 1:250,000-scale and limited 1:500,000- to 1:63,360-scale maps. Covering the entire state of Alaska, it reflects more than a century of work by a host of geologists and almost two decades of compilation work. There are two versions of the map: a detailed digital version, and a simplified, “generalized” map for print. The map units described in the accompanying pamphlet reflect those of the detailed digital map. At the end of each unit description, the generalized map unit for that unit is listed. Compilation of this map began in September 1996, using available 1:250,000-scale data to compile and release a regional map of central Alaska (Wilson and others, 1998). An ongoing iterative process was used to describe and correlate individual geologic units to produce the units for this statewide map and its interim products—a series of regional geologic map compilations—which were released as the process continued (in the references cited in the pamphlet that are shown with an *). As additional geologic data were acquired, previously released data, correlations, and interpretations were updated as needed. Compilation of this map was complex, because the original source maps were made by different generations of geologists, mapping with very different ideas. Several of the older maps were completed before the concepts of accreted (suspect) terranes or even plate tectonics existed. On the other hand, some of the more recent maps were so governed by terrane analysis that conventional stratigraphic nomenclature was not used or is obscured. We adopted a traditional stratigraphic approach and avoided use of the sometimes controversial and commonly inconsistently defined or applied terrane terminology. Our decision to adopt a traditional approach is evident in a map that emphasizes the age and lithology of map units, rather than differences among fault-bounded packages of rocks. We did our best to resolve conflicting interpretations and map data from the regional compilations and from the individual source maps in areas where regional compilations had not been produced. We made every effort to preserve the original geologic map information, incorporating, where available, new data, but we were careful to not overinterpret the geologic data. Yet even our willingness to make interpretations and revisions did not enable us in some areas to resolve mapping conflicts or to reconcile different mapping styles. Therefore, there are several areas on the map where map units are separated by “quadrangle boundary faults.” More data and fieldwork may allow resolution of these conflicts. This Alaska compilation is unique in that it is integrated with a rich database of information provided in the spatial datasets and standalone attribute databases. Within the spatial files every line and polygon is attributed to its original source; the references to these sources are contained in related tables, as well as in stand-alone tables. Additional attributes include typical lithology, geologic setting, and age range for the map units. Also included are tables of radiometric ages.

Alaska↗
USGS2004

Occurrence and distribution of trace elements in snow, streams, and streambed sediments, Cape Krusenstern National Monument, Alaska, 2002-2003

Cape Krusenstern National Monument is located in Northwest Alaska. In 1985, an exchange of lands and interests in lands between the Northwest Alaska Native Association and the United States resulted in a 100-year transportation system easement for 19,747 acres in the monument. A road was then constructed along the easement from the Red Dog Mine, a large zinc concentrate producer and located northeast of the monument, through the monument to the coast and a port facility. Each year approximately 1.3 million tonnes of zinc and lead concentrate are transported from the Red Dog Mine via this access road. Concern about the possible deposition of cadmium, lead, zinc and other trace elements in the monument was the basis of a cooperative project with the National Park Service. Concentrations of dissolved cadmium, dissolved lead, and dissolved zinc from 28 snow samples from a 28 mile by 16 mile grid were below drinking water standards. In the particulate phase, approximately 25 percent of the samples analyzed for these trace elements were higher than the typical range found in Alaska soils. Boxplots of concentrations of these trace elements, both in the dissolved and particulate phase, indicate higher concentrations north of the access road, most likely due to the prevailing southeast wind. The waters of four streams sampled in Cape Krusenstern National Monument are classified as calcium bicarbonate. Trace-element concentrations from these streams were below drinking water standards. Median concentrations of 39 trace elements from streambed sediments collected from 29 sites are similar to the median concentrations of trace elements from the U.S. Geological Survey?s National Water-Quality Assessment database. Statistical differences were noted between trace-element concentrations of cadmium, lead, and zinc at sites along the access road and sites north and south of the access road; concentrations along the access road being higher than north or south of the road. When normalized to 1 percent organic carbon, the concentrations of these trace elements are not expected to be toxic to aquatic life when compared to criteria established by the Canadian government and other recent research.

Scientific Investigations Report↗
USGS2006

Preliminary volcano-hazard assessment for the Emmons Lake volcanic center, Alaska

The Emmons Lake volcanic center is a large stratovolcano complex on the Alaska Peninsula near Cold Bay, Alaska. The volcanic center includes several ice- and snow-clad volcanoes within a nested caldera structure that hosts Emmons Lake and truncates a shield-like ancestral Mount Emmons edifice. From northeast to southwest, the main stratovolcanoes of the center are: Pavlof Sister, Pavlof, Little Pavlof, Double Crater, Mount Hague, and Mount Emmons. Several small cinder cones and vents are located on the floor of the caldera and on the south flank of Pavlof Volcano. Pavlof Volcano, in the northeastern part of the center, is the most historically active volcano in Alaska (Miller and others, 1998) and eruptions of Pavlof pose the greatest hazards to the region. Historical eruptions of Pavlof Volcano have been small to moderate Strombolian eruptions that produced moderate amounts of near vent lapilli tephra fallout, and diffuse ash plumes that drifted several hundreds of kilometers from the vent. Cold Bay, King Cove, Nelson Lagoon, and Sand Point have reported ash fallout from Pavlof eruptions. Drifting clouds of volcanic ash produced by eruptions of Pavlof would be a major hazard to local aircraft and could interfere with trans-Pacific air travel if the ash plume achieved flight levels. During most historical eruptions of Pavlof, pyroclastic material erupted from the volcano has interacted with the snow and ice on the volcano producing volcanic mudflows or lahars. Lahars have inundated most of the drainages heading on the volcano and filled stream valleys with variable amounts of coarse sand, gravel, and boulders. The lahars are often hot and would alter or destroy stream habitat for many years following the eruption. Other stratocones and vents within the Emmons Lake volcanic center are not known to have erupted in the past 300 years. However, young appearing deposits and lava flows suggest there may have been small explosions and minor effusive eruptive activity within the caldera during this time interval. Mount Hague may have experienced minor steam eruptions. The greatest hazards in order of importance are described below and summarized on plate 1.

Alaska↗