Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “The Alaska Miner”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
USGS1987

The Alaska Mineral Resource Assessment Program: Background information to accompany folio of geologic and mineral resource maps of the Circle quadrangle, Alaska

The geology, geochemistry, geophysics, and Landsat imagery of the Circle quadrangle were investigated by an interdisciplinary research team for the purpose of assessing the mineral potential of the area. The quadrangle covers approximately 15,765 km 2 in east-central Alaska; most of it is included in the mountainous Yukon-Tanana Upland physiographic division, but the northernmost part is in the low-lying Yukon Flats section. The Circle mining district, in the east-central part of the quadrangle, has been a major producing area of placer gold since its discovery in 1893. For descriptive purposes, the Circle quadrangle is divided into three areas: the northwest Circle quadrangle, the area north of the Tintina fault zone, and the area south of the Tintina fault zone. The Tintina fault zone extends northwesterly through the northern part of the quadrangle. The northwest Circle quadrangle contains mostly folded and faulted, slightly metamorphosed sedimentary rocks that are intruded by Tertiary granitic plutons. In the northern part of the area north of the Tintina fault zone (Little Crazy Mountains and northern east Crazy Mountains), the rocks consist primarily of the gabbro and basalt of the Circle Volcanics and minor associated chert, graywacke, and limestone. Elsewhere in this area (south of the Circle Volcanics and in the western Crazy Mountains), the rocks are mostly slightly metamorphosed Paleozoic sedimentary rocks that have been folded and faulted. Rocks in the largest part of the quadrangle, the area south of the Tintina fault zone, consist largely of pelitic rocks that are regionally metamorphosed to greenschist and amphibolite facies. Felsic plutons, mostly Tertiary in age, occur throughout the area. The metamorphic rocks are separated from sedimentary rocks on the northwest by thrust faulting. The aeromagnetic and gravity data show clear differences between the areas north and south of the Tintina fault zone. The metamorphic terrane to the south has low overall gravity and local gravity lows over exposed granitic plutons. It is hypothesized that magnetic chlorite schist infolded with nonmagnetic quartzite and schist account for east-northeast-trending magnetic highs that approximately parallel the regional strike of the most prominent foliation in the metamorphic rocks. North of the Tintina fault zone, the Circle Volcanics are characterized by high gravity and east-west-trending magnetic highs. The Tintina fault zone has an intense magnetic high near the western margin of the Circle quadrangle overlying the magnetic granodiorite of the Victoria Mountain pluton. A magnetic high near Circle Hot Springs is less intense, but broader, and could reflect a buried magnetic pluton similar to that of the Victoria Mountain pluton. Computer-enhanced Landsat images of the Circle quadrangle show trends and patterns of concentrations of linear features. Features trending northeast-southwest predominate throughout the quadrangle; northwest-southeast-trending linear features are found mostly south of the Tintina fault zone. High concentrations of linear features were not found to correspond to areas of known mineralization in any consistent or significant way that could presently be used in locating areas of mineralization. Geochemical and mineralogical studies of stream sediment and heavy-mineral concentrates from the Circle quadrangle identify areas of anomalous concentrations of metallic elements, including gold, silver, tin, tungsten, lead, antimony, zinc, thorium, uranium, and beryllium. The data delineate areas of known mineral occurrences and areas that may contain undiscovered mineral resources. To date, placer gold has been the only significant metallic mineral resource from the Circle quadrangle, but the general geologic setting, especially the presence of post-orogenic plutons, is similar to that of regions that contain tin greisen deposits, tungsten skarn deposits, lode gold deposits in metasedimentary rocks, and uranium vein deposits. Six areas or tracts were identified in which such deposits might occur, and two more tracts were delineated as possible for the occurrence of shale-hosted Lead-zinc deposits. The discovery of two diamonds in the gravels of Cooked Creek point to the slight possibility of finding placer or lode diamond deposits. Although most of the past and present gold mining has taken place in four areas in the quadrangle, a sedimentary basin near the town of Central was identified as possibly containing buried placer gold deposits or sedimentary uranium deposits.

Alaska↗
USGS1983

The Alaska Mineral Resource Assessment Program: Guide to information contained in folio of geologic and mineral resource maps of the Philip Smith Mountains quadrangle, Alaska

The geology and mineral resources of the Philip Smith Mountains quadrangle were virtually unexplored until the investigations for oil began in northern Alaska. Construction of the Trans-Alaskan Pipeline System has now made the quadrangle accessible by road. In 1975 and 1976 a team of geologists, geochemists, and geophysicists investigated the quadrangle in order to assess its mineral resource potential. This report is a guide to the resulting folio of twelve maps that describe the geology, stream sediment geochemistry, aeromagnetic features, Landsat imagery, and mineral resources of the area. The bedrock geology and aeromagnetic surveys show that mineral deposits associated with intrusive rocks are probably absent. However, the geology and geochemical anomalies do indicate the possibility of vein and strata-bound deposits of copper, lead, and zinc in the Paleozoic shale and carbonate rocks in the southern part of the quadrangle and of stratabound deposits of zinc and copper in the Permian and Mesozoic shales along the mountain front. The northwestern part of the quadrangle has a low to moderate potential for oil or gas; Mississippian carbonate rocks are the most likely reservoir. The only minerals produced to date have been construction materials.

Alaska↗
USGS1983

The Alaska Mineral Resource Assessment Program: Background information to accompany folio of geologic and mineral resource maps of the Ambler River quadrangle, Alaska

The Ambler River quadrangle, consisting of 14,290 km2 (5,520 mi2) in northwest Alaska, was investigated by an interdisciplinary research team for the purpose of assessing the mineral resource potential of the quadrangle. This report provides background information for a folio of maps on the geology, reconnaissance geochemistry, aeromagnetics, Landsat imagery, and mineral resource evaluation of the quadrangle. A summary of the geologic history, radiometric dates, and fossil localities and a comprehensive bibliography are also included. The quadrangle contains jade reserves, now being mined, and potentially significant resources of copper, zinc, lead, and silver.

Alaska↗
USGS1982

The Alaska Mineral Resource Assessment Program: Guide to information about the geology and mineral resources of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska

The Ketchikan and Prince Rupert 1-degree by 2-degree quadrangles, which encompass about 16,000 km2 at the south tip of southeastern Alaska, have been investigated by integrated field and laboratory studies in the disciplines of geology, geochemistry, geophysics, and Landsat data interpretation to determine their mineral-resource potential. Mineral deposits in the study area have been mined or prospected intermittently since about 1900, and production of small tonnages of ores containing gold, silver, copper, lead, zinc, and tungsten has been recorded. Extensive exploration and development currently (1981) is underway at a molybdenum prospect about 65 km east of Ketchikan. Our mineral-resource assessment indicates that the area contains potentially significant amounts of those metallic commodities, as well as of molybdenum, iron, antimony, and barite. The results of these studies have been published in a folio of maps accompanied by descriptive texts, diagrams, tables, and pertinent references. The present report serves as a guide to these investigations, provides relevant background information, and integrates the component maps and reports. It also describes revisions to the geology based on studies completed since the folio was published and includes a list of specific and general references on the geology and mineral deposits of the study area.

Alaska↗
USGS1995

The Alaska Mineral Resource Assessment Program: Background information to accompany geologic and mineral-resource maps of the Killik River 1°x3° quadrangle, northern Alaska

This report summarizes results of integrated geological, geochemical, and geophysical field and laboratory studies conducted by the U.S. Geological Survey in the Killik River 1°x3° quadrangle, Brooks Range, northern Alaska. These studies were designed to provide an assessment of the mineral resources of the quadrangle. The geological and geochemical data were the primary sources of information used to assess the mineral-resource potential of the quadrangle. The presence of permissive host rocks and favorable geochemical signatures in stream- and lake-sediment and (or) heavy-mineral-concentrate samples were used to infer the potential for undiscovered resources of minerals in deposits of different types. The Killik River quadrangle may contain undiscovered resources of preciousand base-metals (principally lead, silver, and zinc) in veins and breccias hosted by Devonian and Mississippian clastic sedimentary rocks or in stratiform massive sulfide deposits hosted primarily by Mississippian and Pennsylvanian sedimentary rocks. Resources of barium, phosphate, and manganese may be present in Mississippian to Jurassic sedimentary rocks. Cretaceous fluvial sedimentary rocks in the northern part of the quadrangle are permissive hosts for uranium deposits, as well as for placer deposits of heavy minerals such as gold and chromite; however, geochemical data suggest that the potential for deposits of this type is low. Numerous coal beds are present in the Cretaceous rocks throughout the northern part of the quadrangle, but the limited thickness and lateral extent of most of the beds reduce their resource potential. Although the southern third of the quadrangle has no potential for petroleum resources, there is potential in the northern two-thirds.

Alaska↗
USGS1992

The Alaska Mineral Resource Assessment Program: Background information to accompany geologic and mineral-resource maps of the Cordova and Middleton Island quadrangles, southern Alaska

This report summarizes recent results of integrated geological, geochemical, and geophysical field and laboratory studies conducted by the U.S. Geological Survey in the Cordova and Middleton Island 1°x3° quadrangles of coastal southern Alaska. Published open-file reports and maps accompanied by descriptive and interpretative texts, tables, diagrams, and pertinent references provide background information for a mineral-resource assessment of the two quadrangles. Mines in the Cordova and Middleton Island quadrangles produced copper and byproduct gold and silver in the first three decades of the 20th century. The quadrangles may contain potentially significant undiscovered resources of precious and base metals (gold, silver, copper, zinc, and lead) in veins and massive sulfide deposits hosted by Cretaceous and Paleogene sedimentary and volcanic rocks. Resources of manganese also may be present in the Paleogene rocks; uranium resources may be present in Eocene granitic rocks; and placer gold may be present in beach sands near the mouth of the Copper River, in alluvial sands within the canyons of the Copper River, and in smaller alluvial deposits underlain by rocks of the Valdez Group. Significant coal resources are present in the Bering River area, but difficult access and structural complexities have discouraged development. Investigation of numerous oil and gas seeps near Katalla in the eastern part of the area led to the discovery of a small, shallow field from which oil was produced between 1902 and 1933. The field has been inactive since, and subsequent exploration and drilling onshore near Katalla in the 1960's and offshore near Middleton Island on the outer continental shelf in the 1970's and 1980's was not successful.

Alaska↗
USGS1990

The Alaska Mineral Resource Assessment Program: Background information to accompany folio of geologic and resource maps of the Ugashik, Bristol Bay, and western part of Karluk quadrangles, Alaska

The Ugashik, Bristol Bay, and western part of Karluk quadrangles (1:250,000) are a part of the Alaska Peninsula in southwestern Alaska. This circular, in conjunction with a companion folio of MF-series maps, two I-series geologic maps, and three bulletins, represents the results of integrated field and laboratory studies on the geology, geophysics, geochemistry, paleontology, geochronology, and mineral resources of the quadrangles. These studies were undertaken to provide a modern assessment of the mineral and energy resources of the quadrangles. Each map contains descriptive text, explanatory material, tables, diagrams, and pertinent references. This circular provides background information for the mineral resource assessment map (MF-1539-1) and integrates the component M F- and I-series maps. A comprehensive bibliography cites both specific and general references relevant to the geology and resources of the quadrangles.

Alaska↗
USGS1995

1995 annual report on Alaska's mineral resources

Section 1011 of the Alaska National Interest Lands Conservation Act (ANILCA) of 1980, as amended, requires that "On or before October 1, 1982, and annually thereafter, the President shall transmit to the Congress all pertinent public information relating to minerals in Alaska gathered by the United States Geological Surveys, United States Bureau of Mines, and any other Federal agency." This report has been prepared in response to that requirement. This circular is the fourteenth in the series of annual mineral reports mandated by the ANILCA. The report provides information about current Alaskan mineral projects and events during 1994; the emphasis is on Federal activity. The report addresses both onshore and offshore areas of Alaska. The U.S. Geological Survey (USGS), U.S. Bureau of Mines (USBM), and Minerals Management Service (MMS) are the principal Federal agencies that publish information about energy and mineral resources in Alaska. Their reports and data form the basis for decisions by other Federal agencies regarding land use, access, environmental impacts, and mining claim evaluation. The time required for sample analysis, data synthesis, and publication is lengthy; as a result, scientific reports are generally issued a year or more after initial sample and data collection. Other sources of information for this report include additional Federal and State publications, trade and professional journals, presentations at public meetings and hearings, and press releases. Information is provided for two broad categories of minerals: energy resources and nonfuel-mineral resources.

Circular↗
USGS2011

Lithogeochemistry of mineralized and altered rock samples from the northern Talkeetna Mountains, south-central Alaska

Mineralized and altered rock samples collected from the northern Talkeetna Mountains, Alaska, were analyzed by two different inductively coupled plasma atomic-emission spectrometry (ICP-AES) methods for as many as 44 elements; by fire assay and either direct-coupled plasma (DCP) or atomic absorption spectrophotometry (AAS) for gold (Au); by cold vapor atomic absorption (CVAA) for mercury (Hg); and by irradiated neutron activation analysis (INAA) for tungsten (W). The analytical results showed that some samples contain high values of multiple elements and may be potential indicators of hydrothermal mineralization in the area.

Alaska↗
USGS2022

Marine minerals in Alaska — A review of coastal and deep-ocean regions

Minerals occurring in marine environments span the globe and encompass a broad range of mineral categories, forming within varied geologic and oceanographic settings. They occur in coastal regions, either from the continuation or mechanical reworking of terrestrial mineralization, as well as in the deep ocean, from diagenetic, hydrogenetic, and hydrothermal processes. The oceans cover most of the Earth’s surface and as a result, any inventory of global resources is incomplete without the inclusion of marine minerals. This study by the U.S. Geological Survey reviews current knowledge regarding deep-ocean and coastal marine minerals within the marine areas surrounding Alaska, including the Alaska Outer Continental Shelf (OCS). For the purposes of this study, we have divided these areas in to eight regions: (1) Gulf of Alaska seamounts, (2) Chukchi Borderland, (3) Canada Basin, (4) Aleutian Arc, (5) Seward Peninsula, (6) Goodnews Bay, (7) Bristol Bay and Alaska Peninsula, and (8) southern and southeastern Alaska. The Alaska OCS encompasses several areas broadly conducive to marine mineral formation, including extensional basins resulting from an active subduction zone where massive sulfide deposits may form, deep abyssal plains with conditions that may lead to manganese nodule formation, seamounts that can provide substrate for the growth of ferromanganese crusts, and erosional settings and submerged continental crust where placer deposits are found. For deep-ocean hydrothermal minerals and manganese nodules, the Alaska OCS contains prospective regions, including the Canada Basin and the Aleutian Arc; however, no such minerals have yet been identified. We explore the probability that these minerals occur based on reviews of existing geologic and oceanographic data within the relevant sections. In regions far from shore data are limited. Deep-ocean ferromanganese crusts are known to occur in two regions: (1) the Gulf of Alaska seamounts and (2) the Chukchi Borderland in the Arctic Ocean. Limited sampling has occurred in both regions, and along the Chukchi Borderland the sampling was outside of the OCS and the U.S. Exclusive Economic Zone. Data relevant to coastal minerals is more extensive, and in some places fairly systematic sampling was conducted. Several nearshore placer deposits have been exploited for decades; however, the potential for nearshore extension of terrestrial ore deposits is less well considered. This contribution considers the state of knowledge regarding marine mineral occurrences within the Alaska regions and identifies the data gaps in order to help inform future marine mineral related research efforts around Alaska.

Alaska↗
USGS2022

Alaska focus area definition for data acquisition for potential domestic sources of critical minerals in Alaska for antimony, barite, beryllium, chromium, fluorspar, hafnium, magnesium, manganese, uranium, vanadium, and zirconium

Phase 3 of the Earth Mapping Resources Initiative (Earth MRI) focuses on geologic belts that are favorable for hosting mineral systems that could contain the critical minerals antimony, barite, beryllium, chromium, fluorspar, hafnium, magnesium, manganese, uranium, vanadium, and zirconium. Prior phases of the Earth MRI program in Alaska focused only on rare earth elements, aluminum, cobalt, graphite, lithium, niobium, platinum-group metals, tantalum, tin, titanium, and tungsten. An additional 11 critical minerals planed for future phases of Earth MRI (As, Bi, Cs, Ga, Ge, In, Re, Rb, Sc, Sr, Te) are considered prospective in these focus areas. Together, Alaska focus areas address 22 of the 35 minerals or mineral material groups presently deemed critical. This report describes the methodology and techniques utilized to define focus areas for future data acquisition in Alaska; the conterminous United States are covered in a separate report. Focus areas are identified using a mineral systems framework, which accounts for all the possible tectonic and geologic settings where co-genetic mineral deposits may form. These deposits contain many commodities, including byproduct and critical minerals. Large system-scale processes may be evaluated using such a framework to determine the influence they play on critical mineral endowment within the deposits. Analyzing larger mineral systems provides an integrated and broad context to determine how and where critical minerals are sourced, transported, and deposited in geologic systems. Statewide geological, geochemical, geophysical, and mineral occurrence datasets informed the delineation of focus areas in Alaska. For some mineral systems, previously published data-driven prospectivity analyses for critical mineral-bearing deposit types provided the basis for focus areas. We report a total of 22 new focus areas that are prospective for phase 3 critical minerals. These new focus areas represent four different mineral systems that are known or suspected to occur in Alaska. An additional 55 focus areas that were previously identified for phase 1 and phase 2 commodities were also identified as being prospective for phase 3 critical minerals. Collectively, 102 focus areas in Alaska have known or suspected potential for hosting phase 1, phase 2, and (or) phase 3 critical minerals. These focus areas represent 17 different mineral systems also containing critical minerals that are planned for consideration in future Earth MRI phases. Thus, the focus areas delineated herein, and in previous reports for Alaska, are comprehensive for all critical minerals as presently defined and may be used to guide the collection of new geologic, geochemical, and geophysical data in the region.

Alaska↗