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Reconnaissance geologic map of the Dubakella Mountain 15’ quadrangle, Trinity, Shasta, and Tehama Counties, California

The Dubakella Mountain 15' quadrangle is located just south of the Hayfork quadrangle and just east of the Pickett Peak quadrangle. It spans a sequence of four northwest-trending tectonostratigraphic terranes of the Klamath Mountains geologic province that includes, from east to west, the Eastern Hayfork, Western Hayfork, Rattlesnake Creek, and Western Jurassic terranes, as well as, in the southwest corner of the quadrangle, part of a fifth terrane, the Pickett Peak terrane of the Coast Ranges geologic province. The Eastern Hayfork terrane is a broken formation and melange of volcanic and sedimentary rocks that include blocks of limestone and chert. The limestone contains late Permian microfossils of Tethyan faunal affinity. The chert contains radiolarians of Mesozoic age, mostly Triassic, but none clearly Jurassic. The Western Hayfork terrane is an andesitic volcanic arc that consists mainly of agglomerate, tuff, argillite, and chert, and includes the Wildwood pluton. That pluton is related to the Middle Jurassic (about 170 Ma) Ironside Mountain batholith that is widely exposed farther north beyond the Dubakella Mountain quadrangle. The Rattlesnake Creek terrane is a highly disrupted ophiolitic melange of probable Late Triassic or Early Jurassic age. Although mainly ophiolitic, the melange includes blocks of plutonic rocks (about 200 Ma) of uncertain genetic relation. Some scattered areas of well-bedded mildly slaty detrital rocks of the melange appear similar to Galice Formation (unit Jg) and may be inliers of the nearby Western Jurassic terrane. The Western Jurassic terrane consists mainly of slaty to phyllitic argillite, graywacke, and stretched-pebble conglomerate and is correlative with the Late Jurassic Galice Formation of southwestern Oregon. The Pickett Peak terrane, the most westerly of the succession of terranes of the Dubakella Mountain quadrangle, is mostly fine-grained schist that includes the blueschist facies mineral lawsonite and is of Early Cretaceous (about 120 Ma) metamorphic age. Remnants of the Great Valley sequence of dominantly Cretaceous marine sedimentary strata, which once covered much of the southern fringe of the Klamath Mountains, are present at three places in the Dubakella Mountain quadrangle. Mineral production in the quadrangle has included small amounts of gold, chromite, and manganese. This map of the Dubakella Mountain 15' quadrangle is a digital rendition of U.S. Geological Survey Miscellaneous Field Studies Map MF-1808, with various improvements and additions.

California↗

Occurrences of copper minerals in Alaska

The following references give data, as of June 1, 1982, on localities where copper minerals have been found in Alaska. References are keyed by number to locations shown on the accompanying map. An asterisk (*) preceding a locality name indicates recorded production. In most instances the report(s) cited for each occurrence is a summary of data in older reports and was compiled since 1975. Most of the summary reports contain lists of the reports used in their compilation. Citations are in standard bibliographic format with the exception that each includes, in parentheses, an abbreviation for the report or map series and the number of the report or map. Abbreviations used are: AOF, State of Alaska Division of Geological and Geophysical Surveys Open-File Report; B, U.S. Geological Survey Bulletin; BMOF, U.S. Bureau of Mines Open-File Report; C, U.S. Geological Survey Circular; MF, U.S. Geological Survey Miscellaneous Field Studies Map; OF, U.S. Geological Survey Open-File Report; P, U.S. Geological Survey Professional Paper.

Alaska↗

Lode gold and silver occurrences in Alaska

The following references give data, as of September 1, 1981, on localities where lode gold or silver has been found and are keyed to locations shown on the accompanying map. An asterisk (*) preceding a locality name indicates recorded production. In most instances the report(s) cited for each occurrence is a summary of data in older reports and was compiled since 1975. Most of the summary reports contain lists of the reports used in their compilation. Citations are in standard bibliographic format with the exception that each includes, in parentheses, an abbreviation for the report series and the number of the report. Abbreviations are: AOF, State of Alaska Division of Geological and Geophysical Surveys Open-File Report; B, U.S. Geological Survey Bulletin; BMOF, U.S. Bureau of Mines Open-File Report; MF, U.S. Geological Survey Miscellaneous Field Studies Map; OF, U.S. Geological Survey Open-File Report.

Alaska↗

Isopach map of the interval from surface elevation to the top of the Pennsylvanian and Permian Minnelusa Formation and equivalents, Powder River basin, Wyoming and Montana

This map is one in a series of U.S. Geological Survey Miscellaneous Field Studies (MF) maps showing computer-generated structure contours, isopachs, and cross sections of selected formations in the Powder River basin, Wyoming and Montana. The map and cross sections were constructed from information stored in a U.S. Geological Survey Evolution of Sedimentary Basins data base. This data base contains picks of geologic formation and (or) unit tops and bases determined from electric resistivity and gamma-ray logs of 8,592 wells penetrating Tertiary and older rocks in the Powder River basin. Well completion cards (scout tickets) were reviewed and compared with copies of all logs, and formation or unit contacts determined by N. M. Denson, D.L. Macke, R. R. Schumann and others. This isopach map is based on information from 1,480 of these wells that penetrate the Minnelusa Formation and equivalents.

Montana, Wyoming↗

Map showing contours on the top of the Pennsylvanian and Permian Minnelusa Formation and equivalents, Powder River basin, Wyoming and Montana

This map is one in a series of U.S. Geological Survey Miscellaneous Field Studies (MF) maps showing computer-generated structure contours, isopachs, and cross sections of selected formations in the Powder River basin, Wyoming and Montana. The map and cross sections were constructed from information stored in a U.S. Geological Survey Evolution of Sedimentary Basins data base. This data base contains picks of geologic formation and (or) unit tops and bases determined from electric resistivity and gamma-ray logs of 8,592 wells penetrating Tertiary and older rocks in the Powder River basin. Well completion cards (scout tickets) were reviewed and compared with copies of all logs, and formation or unit contacts determined by N. M. Denson, D.L. Macke, R. R. Schumann and others. This isopach map is based on information from 1,480 of these wells that penetrate the Minnelusa Formation and equivalents.

Montana, Wyoming↗

Map showing structure contours on the top of the upper Jurassic Morrison Formation, Powder River basin, Wyoming and Montana

This map is one in a series of U.S. Geological Survey Miscellaneous Field Studies (MF) maps showing computer-generated structure contours, isopachs, and cross sections of selected formations in the Powder River basin, Wyoming and Montana. The map and cross sections were constructed from information stored in a U.S. Geological Survey Evolution of Sedimentary Basins data base. This data base contains picks of geologic formation and (or) unit tops and bases determined from electric resistivity and gamma-ray logs of 8,592 wells penetrating Tertiary and older rocks in the Powder River basin. Well completion cards (scout tickets) were reviewed and compared with copies of all logs, and formation or unit contacts determined by N. M. Denson, D.L. Macke, R. R. Schumann and others. This isopach map is based on information from 2,429 of these wells that penetrate the Minnelusa Formation and equivalents.

Montana;Wyoming↗

Map showing contours on top of the upper Cretaceous Mowry Shale, Powder River basin, Wyoming and Montana

This map is one in a series of U.S. Geological Survey Miscellaneous Field Studies (MF) maps showing computer-generated structure contours, isopachs, and cross sections of selected formations in the Powder River basin, Wyoming and Montana. The map and cross sections were constructed from information stored in a U.S. Geological Survey Evolution of Sedimentary Basins data base. This data base contains picks of geologic formation and (or) unit tops and bases determined from electric resistivity and gamma-ray logs of 8,592 wells penetrating Tertiary and older rocks in the Powder River basin. Well completion cards (scout tickets) were reviewed and compared with copies of all logs, and formation or unit contacts determined by N. M. Denson, D.L. Macke, R. R. Schumann and others. This isopach map is based on information from 4,926 of these wells that penetrate the Minnelusa Formation and equivalents.

Montana, Wyoming↗

Stream-sediment and panned-concentrate geochemical maps of the Buffalo Peaks Wilderness Study Area, Lake, Park, and Chaffee counties, Colorado

Under provisions of the Wilderness Act (Public Law 88-577, September 3, 1964), the U.S. Geological Survey and the U.S. Bureau of Mines have been conducting mineral surveys of areas selected for possible inclusion in the National Wilderness Preservation System. This report presents results of geochemical studies carried out in June and July, 1982, as part of the investigation of the Buffalo Peaks Wilderness Study Area, Colo. Stream-sediment and panned-concentrate samples were collected from about 80 sites on streams draining the study area. Analytical results and a sample locality map were published by Domenico and others (1984). The geologic and mineral resource potential maps of the study area were prepared by Hedlund and others (1983). The Buffalo Peaks Wilderness Study Area encompasses a major portion of the Mosquito Range, which is structurally part of the east flank of the north-northwest-trending Sawatch anticline. Bedrock in the west two-thirds of the study area is made up of Precambrian igneous and metamorphic rocks of the core of the anticline, whereas bedrock in the east one-third is mostly east dipping Paleozoic sedimentary rocks. In the vicinity of East and West Buffalo Peaks, the sequence of Paleozoic sedimentary rocks is covered by Tertiary extrusive rocks. Major faults generally run parallel to the north-northwest trend of the Arkansas River Valley, which is an expression of the Arkansas River segment of the Rio Grande depression, and the Sawatch anticline in the study area. Some faults are probably of late Precambrian age; major recurrent displacement is known to have occurred on most faults during Laramide time and in the Pliocene and Miocene. The study area is bounded by several areas of known mineralization (Hedl und and others, 1983). Vein and bedding replacement deposits of silver, zinc, and lead were mined from 1890 until about 1918 in the vicinity of Weston Pass (map A), on the northeastern border of the study area. Gold and silver were mined from about 1860 until about 1880 from veins in the Granite area (map A), on the northwestern border of the study area; minor prospecting activity continues today. From 1935 to 1937, veins of gold, silver, and base metals were mined in the vicinity of Fourmile Creek, on the southwestern border of the study area (map A). Recently, active uranium prospecting has been taking place in the vicinity of the Middle Fork of Salt Creek, on the southeastern border of the study area (map A).

Colorado↗

Geochemical map of the Rattlesnake Roadless Area, Coconino and Yavapai counties, Arizona

The geochemical survey of the Rattlesnake Roadless Area was conducted in May 1982 by the U.S. Geological Survey to aid in a mineral resource appraisal of the area. A total of 114 stream-sediment samples, 68 heavy-mineral concentrates from stream sediment, 20 rock samples, and 4 water samples was collected by S.C. Rose, D.E. Hendzel, and W.J. Gerstel, with helicopter support from Jack Ruby, pilot for Helicopters Unlimited. All sample localities are plotted on the map; sample localities showing anomalous barium and lead are also indicated on the map.

Arizona↗

Reconnaissance map showing relative amounts of soil and bedrock in the mountainous part of the Pinewood Lake-Carter Lake Reservoir quadrangles, Boulder and Larimer counties, Colorado

This map shows the relative amounts of soil and hard bedrock within the upper 6 feet (1.8 m) of the land surface. (See schematic section.) It provides information useful for broad-scale land-use decisions. The map is based on reconnaissance field studies and aerial-photograph interpretation. The depth of soil and weathered rock was measured directly in roadcuts and other excavations and was estimated from seismic profiles in areas of few or no excavations or outcrops. Secondary characteristics of map units, such as percentage of outcrop in a given area, steepness of slope, type and amount of vegetation cover, and general appearance of the landscape, were used in drawing the boundaries between map units. Localities were assigned to the different map units by field inspection; lines separating the different map units were then drawn by aerial-photograph interpretation and were transferred photogrammetrically to the base map.

Colorado↗

Mineral occurrence and drill-hole location map of the International Falls 1 degree by 2 degrees quadrangle, Minnesota and Ontario

A project to assess the mineral potential of the U.S. part of the International Fall 1° x 2° quadrangle was undertaken by the U.S. Geological Survey (USGS) in the early 1984, as part of the Conterminous United States Mineral Assessment Program (CUSMAP). Because glacial drift covers most of the basement rocks south of the U.S.-Canada border and mineral production in this part of Minnesota has been virtually nonexistent, data from the adjacent part of Ontario has been used to understand the geologic framework and to evaluate mineral-deposit models relevant to the assessment of the U.S. part of the International Falls quadrangle. This map and accompanying tables show the locations of mineral occurrences, prospects and mines in both Canada and the United States, and summarize their lithologic association and the characteristic metals found in them. Locations of drill holes within the United States and completed before 1987 are also included on the map.

Minnesota, Ontario↗

Map showing thickness of principal clay unit, Hartford South Quadrangle, Connecticut

This map show the distribution and thickness of the principal clay unit. The clay unit consists of a thick, massive bed of relatively pure clay in some areas; in other areas it consists of discrete layers of clay alternating with layers of silt and very fine sand (varved clay). The upper layers of the clay unit commonly grade into a layer of silt and very fine sand. Small, isolated clay deposits not associated with the principal clay unit are not mapped.

Connecticut↗

Map showing unconsolidated materials, Southwick quadrangle, Massachusetts-Connecticut

This map is intended to serve as an aid in reconnaissance evaluation of unconsolidated materials and can be used to identify areas of potential interest. The units on this map indicate the first material of substantial thickness (generally greater than 3 feet (1 m) encountered beneath the soil layer. The soil layer (commonly a foot or two (about 0.5 m) thick) is not mapped. Other materials, different in composition, may underlie each map unit (see block diagram) or may occur as minor lenses within each map unit.

Connecticut, Massachusetts↗

Mineral deposits and occurrences in the McCarthy Quadrangle, Alaska

The McCarthy quadrangle contains numerous and diverse mineral deposits in various geologic settings. Copper is the dominant mineral commodity, both historically and in terms of potential future production. Gold and silver are the only other metals that have been produced. The metalliferous deposits are concentrated in a northwest-trending belt along the southern flank of the Wrangell Mountains, and, to a lesser extent, in a similar belt along the northeast flank of the range. Both belts have upper Paleozoic (Skolai Group) basements, abundant Mesozoic rocks, and some Tertiary intrusive rocks. They are marked by numerous faults, mainly northwest-striking. Mineral deposits are uncommon elsewhere in the quadrangle, especially in large tracks underlain by Wrangell Lava and in smaller areas underlain by the Kaskawulsh Group of Kindle (1953). Both the Wrangell Lava and the Kaskawulsh underlie rugged mountainous regions with extensive snow and ice cover, and could conceivably contain undetected concealed deposits. The metallic, nonmetallic, and energy resources of the quadrangle are described sequentially. Copper, gold, and silver, because of their importance, are described early in the section on metal commodities; descriptions of the other metals follows in alphabetic sequence. Locations of the deposits and relative supplementary data for individual deposits are given in the accompanying map and table.

Alaska↗

Mineral resources map of the McCarthy Quadrangle, Alaska

The mineral resources map is an assessment of the occurrence of mineral deposits in the McCarthy quadrangle by area and type of deposit. Descriptions of known mineral deposits and occurrences in the quadrangle provided by MacKevett (1976b) should be used in conjunction with this map. Areas enclosing both known deposits and areas favorable for unfound deposits are delineated in the mineral resources map. Types of deposits known to be widely scattered throughout the quadrangle, such as placer gold, and types with only a slight chance of being in the quadrangle are not delineated. Selection of favorable areas was based on occurrences of known deposits and geologic, geophysical, geochemical, and earth satellite data presented in the McCarthy folio (U.S. Geol. Survey MF maps 773A, B, D-N and Circular 739) and some additional geochemical data published in open-file form (O'Leary and others, 1976). Delineation of boundaries was made by the informed judgment of the team members, but final responsibility rests with the authors of this map.

Alaska↗