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At least 937 records · Page 52Linked to original sources

USGS2015

Geologic map of Mauritania (phase V, deliverables 51a, 51b, and 51c)

In 1996, at the request of the Government of the Islamic Republic of Mauritania, a team of U.S. Geological Survey (USGS) scientists produced a strategic plan for the acquisition, improvement and modernization of multidisciplinary sets of data to support the growth of the Mauritanian minerals sector and to highlight the geological and mineral exploration potential of the country. In 1999, the Ministry of Petroleum, Energy, and Mines of the Islamic Republic of Mauritania implemented a program for the acquisition of the recommended basic geoscientific information, termed the first Projet de Renforcement Institutionnel du Secteur Minier (Project for Institutional Capacity Building in the Mining Sector, PRISM-I). As a result of the PRISM-I efforts, a great deal of new geological, geophysical, geochemical, remote sensing, and hydrological data became available for evaluation and synthesis. However, the Ministry of Petroleum, Energy, and Mines recognized that additional work was required to extract the full benefit of the data before it could be of greatest use to the international community and of benefit to the Mauritanian minerals and development sector. To achieve this benefit, the Ministry of Petroleum, Energy, and Mines implemented a second Projet de Renforcement Institutionnel du Secteur Minier (PRISM-II) in 2006 to consolidate, synthesize, and interpret all of the existing data, create a new 1:1,000,000 scale geologic map, and define the mineral resource potential of the country. A consortium in which the USGS was the lead scientific agency carried out the majority of the PRISM-II work. In 2008, the USGS Mauritania Minerals Project was interrupted due to political changes in Mauritania. PRISM-II work resumed in 2011, and was completed in 2013 with the delivery of over 40 separate written reports and plates, an access file containing the Mauritanian National Mineral Deposits Database, and an interactive GIS containing all of the multi-disciplinary data and interpretive areas of mineral resource potential in Mauritania. This report contains the USGS results of the PRISM-II Mauritania Minerals Project and is presented in cooperation with the Ministry of Petroleum, Energy, and Mines of the Islamic Republic of Mauritania. The Report is composed of separate chapters consisting of multidisciplinary interpretive reports with accompanying plates on the geology, structure, geochronology, geophysics, hydrogeology, geochemistry, remote sensing (Landsat TM and ASTER), and SRTM and ASTER digital elevation models of Mauritania. The syntheses of these multidisciplinary data formed the basis for additional chapters containing interpretive reports on 12 different commodities and deposit types known to occur in Mauritania, accompanied by countrywide mineral resource potential maps of each commodity/deposit type. The commodities and deposit types represented include: (1) Ni, Cu, PGE, and Cr deposits hosted in ultramafic rocks; (2) orogenic, Carlin-like, and epithermal gold deposits; (3) polymetallic Pb-Zn-Cu vein deposits; (4) sediment-hosted Pb-Zn-Ag deposits of the SEDEX and Mississippi Valley-type; (5) sediment-hosted copper deposits; ( 6) volcanogenic massive sulfide deposits; (7) iron oxide copper-gold deposits; (8) uranium deposits; (9) Algoma-, Superior-, and oolitic-type iron deposits; (10) shoreline Ti-Zr placer deposits; (11) incompatible element deposits hosted in pegmatites, alkaline rocks, and carbonatites, and; (12) industrial mineral deposits. Additional chapters include the Mauritanian National Mineral Deposits Database are accompanied by an explanatory text and the Mauritania Minerals Project GIS that contains all of the interpretive layers created by USGS scientists. Raw data not in the public domain may be obtained from the Ministry of Petroleum, Energy, and Mines in Nouakchott, Mauritania.

Open-File Report↗

USGS2015

Crystalline basement map of Mauritania derived from filtered aeromagnetic data (deliverable 54_1), Aeromagnetic and geological structure map of Mauritania (phase V, deliverable 54_2), Maximum depth to basement map of Mauritania derived from Euler analysis of Aeromagnetic data (phase V, deliverable 54_3), and color composite image of radioelement data (added value)

Open-File Report↗

USGS2014

Preliminary bedrock and surficial geologic map of the west half of the Sanders 30' x 60' quadrangle, Navajo and Apache Counties, northern Arizona

The bedrock and surficial geologic map of the west half of the Sanders 30' x 60' quadrangle was completed in a cooperative effort of the U.S. Geological Survey (USGS) and the Navajo Nation to provide regional geologic information for management and planning officials. This report provides baseline geologic information that will be useful in future studies of groundwater and surface water resources, geologic hazards, and the distribution of soils and plants. The west half of the Sanders quadrangle encompasses approximately 2,509 km 2 (980 mi 2 ) within Navajo and Apache Counties of northern Arizona and is bounded by lat 35°30' to 35° N., long 109°30' to 110° W. The majority of the land within the map area lies within the Navajo Nation. South of the Navajo Nation, private and State lands form a checkerboard pattern east and west of Petrified Forest National Park. In the west half of the Sanders quadrangle, Mesozoic bedrock is nearly flat lying except near folds. A shallow Cenozoic erosional basin that developed about 20 Ma in the western part of the map area cut across late Paleozoic and Mesozoic rocks that were subsequently filled with flat-lying Miocene and Pliocene mudstone and argillaceous sandstone and fluvial sediments of the Bidahochi Formation and associated volcanic rocks of the Hopi Buttes volcanic field. The Bidahochi rocks are capped by Pliocene(?) and Pleistocene fluvial sediments and Quaternary eolian and alluvial deposits. Erosion along northeast-southwest-oriented drainages have exposed elongated ridges of Bidahochi Formation and basin-fill deposits that are exposed through shallow eolian cover of similarly oriented longitudinal dunes. Stokes (1964) concluded that the accumulation of longitudinal sand bodies and the development of confined parallel drainages are simultaneous processes resulting in parallel sets of drainages and ridges oriented along the prevailing southwest wind direction on the southern Colorado Plateau.

Arizona↗

USGS2015

Geologic map of Kundelan ore deposits and prospects, Zabul Province, Afghanistan; modified from the 1971 original map compilations of K.I. Litvinenko and others

This map and cross sections are redrafted modified versions of the Geological map of the Kundelan ore deposit area, scale 1:10,000 (graphical supplement no. 18) and the Geological map of the Kundelan deposits, scale 1:2,000 (graphical supplement no. 3) both contained in an unpublished Soviet report by Litvinenko and others (1971) (report no. 0540). The unpublished Soviet report was prepared in cooperation with the Ministry of Mines and Industries of the Royal Government of Afghanistan in Kabul during 1971. This redrafted map and cross sections illustrate the geology of the main Kundelan copper-gold skarn deposit, located within the Kundelan copper and gold area of interest (AOI), Zabul Province, Afghanistan. Areas of interest (AOIs) of non-fuel mineral resources within Afghanistan were first described and defined by Peters and others (2007) and later by the work of Peters and others (2011a). The location of the main Kundelan copper-gold skarn deposit (area of this map) and the Kundelan copper and gold AOI is shown on the index map provided on this map sheet. The estimated resources of the Kundelan copper-gold skarn deposit are 21,400 metric tons (t) of copper, 1.6 t of gold, and 133.4 t of molybdenum at an average grade of 1.21 weight percent (wt. %) copper (ranging from 0.66 to 4.03 wt. % copper); 0.9 grams per metric ton (g/t) gold (ranging from 0.3 to 3.1 g/t gold); 0.14 wt. % molybdenum; and as much as 10 g/t silver and 0.03 wt. % bismuth (Peters and others, 2011b). Small past production of gold and base metals is also reported by Douvgal and others (1971) from many prospects within the Kundelan copper and gold AOI. Outside the skarn areas, argillic hydrothermal alteration is present (Abdullah and others, 1977). Most copper and gold prospects in the Kundelan copper and gold AOI are reported to contain commercial-grade ores of copper and (or) gold, and many prospect areas have potential for these commodities to be discovered in commercial volumes. Future initial mine exploration and later development in many of the prospects, and specifically in the Kundelan copper-gold skarn deposit, could result in near-term small- to medium-sized gold mining operations (Peters and others, 2011b). The redrafted map and cross sections reproduce the topology of rock units, contacts, faults, and so forth, of the original Soviet map and cross sections, and they include modifications based on our examination of these documents and our observations made during a brief field visit in August of 2010. We have attempted to translate the original Russian terminology and rock classifications into modern English geologic usage as literally as possible without changing any genetic or process-oriented implications in the original descriptions. We also use the age designations from the original Soviet maps, except for the phase I and II intrusive igneous rocks. Phase I and II igneous rocks are reassigned an Early Cretaceous age (from lower Paleogene) based on a uranium-lead (U-Pb) zircon SHRIMP analysis from quartz diorite, which yielded an age of 104±1 Ma (mega-annum). The information provided in the description of map units is from both the source report by Litvinenko and others (1971) and the original 1:10,000 scale map (graphical supplement no. 18), also from Litvinenko and others (1971). Because of the poor quality of the original map, some map features could not be identified and some features may be misinterpreted. The rock unit colors used on the redrafted maps and cross sections differ from the colors shown on the original Soviet version. Colors were selected according to the color and pattern scheme of the Commission for the Geological Map of the World (CGMW) at http://www.ccgm.org. Elevations on the cross sections are derived from the original Soviet topography and may not match the Global Digital Elevation Model (GDEM) topography used on the redrafted map of this report. Most hydrography derived from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) has not been included on our redrafted version of the map because of a poor fit with alluvial deposits from the unmodified original Soviet map (graphical supplement no. 18; Litvinenko and others, 1971).

Zabul Province↗

USGS2016

Preliminary geologic mapping of Cretaceous and Tertiary formations in the eastern part of the Little Snake River coal field, Carbon County, Wyoming

In the 1970s and 1980s, C.S. Venable Barclay conducted geologic mapping of areas primarily underlain by Cretaceous coals in the eastern part of the Little Snake River coal field (LSR) in Carbon County, southwest Wyoming. With some exceptions, most of the mapping data were never published. Subsequently, after his retirement from the U.S. Geological Survey (USGS), his field maps and field notebooks were archived in the USGS Field Records. Due to a pending USGS coal assessment of the Little Snake River coal field area and planned geological mapping to be conducted by the Wyoming State Geological Survey, Barclay’s mapping data needed to be published to support these efforts. Subsequently, geologic maps were scanned and georeferenced into a geographic information system, and project and field notes were scanned into Portable Document Format (PDF) files. Data for seventeen 7½-minute quadrangles are presented in this report. This publication is solely intended to compile the mapping data as it was last worked on by Barclay and provides no interpretation or modification of his work.

Wyoming↗

USGS2018

Bedrock geologic map of the Littleton and Lower Waterford quadrangles, Essex and Caledonia Counties, Vermont, and Grafton County, New Hampshire

The bedrock geologic map of the Littleton and Lower Waterford quadrangles covers an area of approximately 107 square miles (277 square kilometers) north and south of the Connecticut River in east-central Vermont and adjacent New Hampshire. This map was created as part of a larger effort to produce a new bedrock geologic map of Vermont through the collection of field data at a scale of 1:24,000. A large part of the map area consists of the Bronson Hill anticlinorium, a post-Early Devonian structure that is cored by metamorphosed Cambrian to Devonian sedimentary, volcanic, and plutonic rocks. The northwestern part of the map is divided by the Monroe fault which separates Early Devonian rocks of the Connecticut Valley-Gaspé trough from rocks of the Bronson Hill anticlinorium. The Bronson Hill anticlinorium is the apex of the Middle Ordovician to earliest-Silurian Bronson Hill magmatic arc that contains the Ammonoosuc Volcanics, Partridge Formation, and Oliverian Plutonic suite, and extends from Maine, down the eastern side of the Connecticut River in New Hampshire, to Long Island Sound. The deformed and partially eroded arc is locally overlain by a relatively thin Silurian section of metasedimentary rocks (Clough Quartzite and Fitch Formation) that thickens to the east. The Silurian section near Littleton is disconformably overlain by a thicker, Lower Devonian section that includes mostly metasedimentary rocks and minor metavolcanic rocks of the Littleton Formation. The Bronson Hill anticlinorium is bisected by a series of northeast-southwest trending Mesozoic normal faults. Primarily among them is the steeply northwest-dipping Ammonoosuc fault that divides older and younger units (upper and lower sections) of the Ammonoosuc Volcanics. The Ammonoosuc Volcanics are lithologically complex and predominantly include interlayered and interfingered rhyolitic to basaltic volcanic and volcaniclastic rocks, as well as lesser amounts of metamorphic and metasedimentary rocks. The Ammonoosuc Volcanics overlies the Albee Formation that consists of interlayered feldspathic sandstone, siltstone, pelite, and slate. During the Late Ordovician, a series of arc-related plutons intruded the Ammonoosuc Volcanics, including the Whitefield pluton to the east, the Scrag granite of Billing (1937) in the far southeastern corner of the map, the Highlandcroft Granodiorite just to the west of the Ammonoosuc fault, and the Joslin Turn tonalite (just north of the Connecticut River). To the east of the Monroe fault lies the late Silurian Comerford Intrusive Complex, which consists of metamorphosed gabbro, diorite, tonalite, aplitic tonalite, and crosscutting diabase dikes. Abundant mafic dikes of the Comerford Intrusive Complex intruded the Albee Formation and Ammonoosuc Volcanics well east of the Monroe fault. This report consists of a single geologic map sheet and an online geographic information systems database that includes contacts of bedrock geologic units, faults, outcrops, and structural geologic information.

New Hampshire, Vermont↗

USGS2020

Focus areas for data acquisition for potential domestic resources of 11 critical minerals in Alaska—Aluminum, cobalt, graphite, lithium, niobium, platinum group elements, rare earth elements, tantalum, tin, titanium, and tungsten, chap. C of U.S. Geological Survey, Focus areas for data acquisition for potential domestic sources of critical minerals

Phase 2 of the Earth Mapping Resources Initiative (Earth MRI) focuses on geologic belts that are favorable for hosting mineral systems that may contain select critical minerals. Phase 1 of the Earth MRI program focused on rare earth elements (REE), and phase 2 adds aluminum, cobalt, graphite, lithium, niobium, platinum-group metals, tantalum, tin, titanium, and tungsten. 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. Definition of focus areas relies on a mineral systems framework that considers geologic features that may influence or control the formation and preservation of a mineral deposit and links the critical commodities to genetically related processes. Mineral systems are therefore larger than any given deposit. Evaluation of these larger systems allows for a broader understanding of how and where critical minerals may move through geologic systems. Delineation of focus areas in Alaska was informed by statewide geological, geochemical, geophysical, and mineral occurrence datasets that are publicly available. Additionally, previously published prospectivity analyses for six different critical mineral-bearing deposit types help identify focus areas. A total of 74 focus areas prospective for the phase 2 critical minerals that occur in 12 different mineral systems were defined in Alaska. Identified focus areas may be used to guide future geologic, geochemical, and geophysical data in the State of Alaska.

Alaska↗

USGS2019

Petrologic and mineral physics database for use with the U.S. Geological Survey National Crustal Model

We present a petrologic and mineral physics database as part of the U.S. Geological Survey National Crustal Model (NCM). Each of 209 geologic units, 134 of which are currently part of the geologic framework within the NCM, was assigned a mineralogical composition according to generalized classifications with some refinement for specific geologic formations. This report is concerned with the petrology and mineral physics of each geologic unit within the NCM, which control the physical behavior of the solid mineral matrix within the rock. This mineral physics database builds on the work of Abers and Hacker to include 13 minerals specific to continental rock types. We explored the effect of this database on zero-porosity anharmonic P- and S-wave rock velocities and density relative to a well-used empirical study of relations between wavespeeds and density by Brocher. We found that empirical relations between P-wave velocity and S-wave velocity or density do well on average but can differ from mineral physics calculations by up to 15 percent in S-wave velocity and almost 40 percent in density. This is consistent with Brocher’s study where he obtained similar results for in situ measurements and laboratory rock specimens. Additionally, the substantial presence of quartz in many rocks plays a major role in crustal seismic velocities and density due to quartz’s α – β phase transition, which can interfere with these empirical relationships. With increasing depth, quartz P-wave velocity can suddenly jump by 15 percent accompanied by little change in S-wave velocity and a modest decrease in density. Empirical relations based on observed P-wave velocity where P-wave velocity is positively correlated with S-wave velocity and density would then significantly overestimate both S-wave velocity and density.

Open-File Report↗

USGS2020

Preliminary geologic map of the Greater Antilles and the Virgin Islands

Introduction This geologic map of the Greater Antilles and the Virgin Islands is a compilation of information from the literature, integrated to provide a seamless geologic map of the region. The geology shown on sheet 1 covers Cuba, the island of Hispaniola, which includes Haiti and the Dominican Republic, Jamaica, the Cayman Islands, Puerto Rico, and the U.S. and British Virgin Islands. A second more detailed sheet shows the geology of Puerto Rico and the Virgin Islands. The map units shown here are integrated across the islands of the Greater Antilles and the Virgin Islands. The Greater Antilles and the Virgin Islands, although they appear to reflect the character of a magmatic arc, actually represent multiple, distinct geologic features. Only in Cuba are there unquestioned Jurassic-age, and perhaps older, rocks present. On the islands of Hispaniola (Haiti and the Dominican Republic) and Puerto Rico, metamorphic assemblages contain rocks that may be of Jurassic age. Ophiolite assemblages that may include rocks of Jurassic age are present in Cuba, the Dominican Republic, Haiti, and Puerto Rico. Metamorphic rocks of Cretaceous age are more widespread, present in Cuba, Hispaniola, and the U.S. and British Virgin Islands. Cretaceous plutonic rocks are present in Cuba and Puerto Rico, as well as in the Dominican Republic (in the Cordillera Central and in the eastern part of the country). Gabbro and trondhjemite of inferred Early Cretaceous age are present in the U.S. Virgin Islands. Cretaceous volcanic rocks are widespread in Cuba, Hispaniola, Puerto Rico, and the Virgin Islands; they are of variable age and do not appear to reflect a single arc system. Cretaceous volcanic rocks are also found in Jamaica, in inliers on the eastern part of the island. Eocene volcanic rocks are prominent in southern Cuba, Haiti, eastern Jamaica, Puerto Rico, and the Virgin Islands. Volcanic rocks possibly as young as early Miocene are present in the southern Dominican Republic; the youngest volcanic rocks in the region are the Low Layton Lavas of Jamaica of late Miocene age and alkali basalt of Quaternary age on Hispaniola. Carbonate rocks are an important component of the sedimentary section in the Greater Antilles, which is as old as Jurassic in Cuba and as young as Holocene in many areas. In Cuba, Early Cretaceous sedimentary rocks tend to be dominantly carbonates; volcanic clasts and debris are not present until the Late Cretaceous in Cuba, as well as in Jamaica and Puerto Rico. In contrast, Early Cretaceous volcaniclastic sedimentary rocks are common in the Virgin Islands. Olistostrome deposits are commonly described in latest Cretaceous and Eocene rocks; in the Paleocene and the early Eocene, these deposits are commonly associated with mélange units. Volcanic debris and tuff are common in sedimentary rocks of Paleocene and Eocene age, typically associated with carbonate rocks. Sedimentary rocks that postdate the Eocene either are dominantly carbonates or are mixed clastic and carbonate rocks in which the clastic component reflects erosion of earlier units, including older carbonate rocks. Rocks that contain lignite, which are only present in Cuba and on Hispaniola, generally are of Miocene age.

Greater Antilles, Hispaniola, Puerto Rico, Virgin ↗

USGS2020

Temperature model in support of the U.S. Geological Survey National Crustal Model for seismic hazard Ssudies

The U.S. Geological Survey National Crustal Model (NCM) is being developed to assist with earthquake hazard and risk assessment by supporting estimates of ground shaking in response to an earthquake. The period-dependent intensity and duration of shaking depend upon the three-dimensional seismic velocity, seismic attenuation, and density distribution of a region, which in turn is governed to a large degree by geology and how that geology behaves under varying temperatures and pressures. A three-dimensional temperature model is presented here to support the estimation of physical parameters within the U.S. Geological Survey NCM. The crustal model is defined by a geological framework consisting of various lithologies with distinct mineral compositions. A temperature model is needed to calculate mineral density and bulk and shear modulus as a function of position within the crust. These properties control seismic velocity and impedance, which are needed to accurately estimate earthquake travel times and seismic amplitudes in earthquake hazard analyses. The temperature model is constrained by observations of surface temperature, temperature gradient, and conductivity, inferred Moho temperature and depth, and assumed conductivity at the base of the crust. The continental plate is assumed to have heat production that decreases exponentially with depth and thermal conductivity that exponentially changes from a surface value to 3.6 watts per meter-Kelvin at the Moho. The oceanic plate cools as a half-space with a geotherm dependent on plate age. Under these conditions, and the application of observed surface heat production, predicted Moho temperatures match Moho temperatures inferred from seismic P-wave velocities, on average. As has been noted in previous studies, high crustal temperatures are found in the western United States, particularly beneath areas of recent volcanism. In the central and eastern United States, elevated temperatures are found from southeast Texas, into the Mississippi Embayment, and up through Wisconsin. A USGS ScienceBase data release that supports this report is available and consists of grids covering the NCM across the conterminous United States, for example, surface temperature and temperature gradient, that are needed to produce temperature profiles.

Open-File Report↗

USGS2020

Calibration of the U.S. Geological Survey National Crustal Model

The U.S. Geological Survey National Crustal Model (NCM) is being developed to include spatially varying estimates of site response in seismic hazard assessments. Primary outputs of the NCM are continuous velocity and density profiles from the Earth’s surface to the mantle transition zone at 410-kilometer (km) depth for each location on a 1-km grid across the conterminous United States. Datasets used to produce the NCM may have a resolution of better than 1 km near the Earth’s surface in some regions, but, with increasing depth, NCM resolution decreases to tens to hundreds of kilometers in the mantle. Basic subsurface information is provided by the NCM geologic framework, thermal model, and petrologic and mineral physics database. In this report, the velocities and densities that can be extracted from the NCM are calibrated through the development of a porosity model based on Biot-Gassmann theory and more than 2,000 compressional- and (or) shear-wave velocity profiles less than 10 km deep from across the conterminous United States and southwestern Canada. Sediment and rock porosities are derived from shear-wave velocity and are found to depend on effective pressure, rock type, and age (for sedimentary and extrusive volcanic deposits). Porosity-effective pressure functions are then estimated for each rock type (and age for sedimentary and extrusive volcanic deposits). Unconsolidated sediments are found to have higher porosities than consolidated units, which have higher porosities than unweathered igneous units; young sedimentary units (for example, Quaternary age units) tend to have higher porosities than older sedimentary units (for example, pre-Cenozoic age units); porosity decreases with increasing effective pressure; and porosities can decrease quickly through the weathered layer of intrusive rocks. Comparing two Los Angeles area velocity models and the U.S. Geological Survey Bay Area velocity model with the NCM, the NCM does a better job on average of reproducing observed shear-wave velocities below 1 km per second because it has less bias and uncertainty. Approaching and above 1 km per second, the NCM tends to underpredict observed shear-wave velocity. Whereas several factors could contribute to this, the primary factor is probably bias in the NCM geologic framework. For example, the NCM will predict lower velocities in places where the depth to bedrock and basement appear shallower in the measured velocity profiles than specified in the NCM geologic framework. With regard to observed compressional-wave velocity and density, the NCM has significantly less bias than California models for the former, especially below 2 km per second, and all models tend to overpredict density for densities less than about 2,200 kilograms per cubic meter.

Open-File Report↗

USGS2021

A geologic field guide to S P Mountain and its lava flow, San Francisco Volcanic Field, Arizona

Introduction We created this guide to introduce the user to the San Francisco Volcanic Field as a terrestrial analog site for planetary volcanic processes. For decades, the San Francisco Volcanic Field has been used to teach scientists to recognize the products of common types of volcanic eruptions and associated volcanic features. The volcanic processes and products observed in this volcanic field are like those observed on lunar and Martian surfaces. As a result, this region has been a favored location for training National Aeronautics and Space Administration astronauts and engineers since the Apollo missions. Though the San Francisco Volcanic Field has more than 600 volcanic vents and flows, this guide will focus on S P Mountain (known locally as S P Crater, located ~30 miles north of Flagstaff, Arizona), one of the best preserved and most accessible of the volcanic cones and lava flows. S P Mountain presents both major types of basaltic eruptions—explosive and effusive—as well as some commonly associated tectonic landforms. We assume that the user has a basic understanding of geologic concepts and terminology. For more specialized terminology, we include tables showing the classification scheme for lava compositions, styles of eruptions, and tephra sizes (tables 1, 2, and 3). If a further introduction or refresher in volcanological terminology is desired, we suggest reviewing such terms on the U.S. Geological Survey Volcano Science Center’s online glossary ( https://volcanoes.usgs.gov/vsc/glossary/ ). One term requires clarification at the start of this guide—the term cinder. The terms cinder and cinder cone are widely used to describe the material and edifice produced by lava fountains. However, the term comes from the mining and construction industries and has no clear or formal definition. The international committees in geology and volcanology have chosen the term tephra to be the general term to describe pyroclasts (material ejected through a volcanic explosion or from a volcanic vent). Therefore, in this guide, we use the term tephra rather than cinder. This guide is outlined as follows: A brief tour of volcanism across the solar system A brief geologic history of the Colorado Plateau and San Francisco Volcanic Field Background on distributed volcanism and S P Mountain Driving directions and field stops Questions for discussion Each field stop includes a brief description, learning goals, tasks, and a summary of key points. At the end of the field guide are discussion points and questions that will ask the user to consider what they have observed and learned and how such knowledge can be used to better our understanding of geologic processes on other planetary bodies. Upon the completion of this field guide, we expect the user to: Have a basic understanding of the volcanic processes relevant to S P Mountain and its lava flow. Be able to identify different volcanic textures that are associated with tephra cones. Be aware of the different observations one can make at different scales (for example, observing lava flow morphology from aerial or satellite imagery versus tephra characteristics in the field).

Arizona↗

USGS2022

Preliminary bedrock geologic map of the Blythe 30' x 60' quadrangle, California and Arizona

The Blythe 30' x 60' quadrangle in southeastern California and southwestern Arizona displays complex geology that includes Mesozoic contractional deformation, metamorphism, and magmatism in addition to Cenozoic extensional deformation and magmatism. Previous geologic map compilations predate recent geologic mapping efforts that have contributed new insights into the stratigraphy and structure of this quadrangle. This new map, compiled in collaboration with the Arizona Geological Survey, incorporates these recent mapping efforts to provide an updated depiction of the quadrangle’s geologic framework. The scope of this map is limited to bedrock units of Miocene and older age because younger deposits have not been mapped in enough detail across the quadrangle to support a systematic compilation.

Arizona, California↗

USGS2023

Implementation plan of the National Cooperative Geologic Mapping Program strategy—Northeast region of the United States: New York and New England

Complexly deformed igneous, metamorphic, and sedimentary rocks form the bedrock of the Northeast region of the United States. Variably thick unconsolidated sediments deposited by glacial, fluvial, and eolian systems locally cover the bedrock. New geologic mapping focuses on areas lacking modern, detailed studies or syntheses, and contributes to existing framework research. This report addresses plans for the continued development of regionally and nationally consistent geologic maps and map databases, efforts to answer outstanding geologic questions, and societal concerns associated with related geologic topics, such as hazards, geologic and hydrologic resources, and environmental issues.

Connecticut, Massachusetts, Maine, New Hampshire, ↗

USGS1955

Engineering geology as applied to highway construction

A geologic study of the site for a relocated segment of State Highway 93 northwest of Denver Colo., was made by by the Engineering Geology Branch of the U.S. Geological Survey as a demonstration of the applicability of geologic mapping to problems of highway construction. The relocated segment provides access to the Rocky Flats plant of the Atomic Energy Commission. The geologic conditions along five miles of the relocation route were examined. In most places apparently well-indurated sandstones of the Upper Cretaceous Fox Hills sandstone and Laramie formation can be excavated without using explosives. The intersection of a six foot thick coal seam in the roadbed in one proposed cut was predicted and removal and replacement with more suitable subgrade material was recommended. Near Marshall the alignment crosses three northeast-trending normal faults which do not adversely affect the highway. Clay minerals with expanding properties are present in some of the claystones of the Laramie, and special measures must be taken to ensure that ground water will not seep into them and cause swelling beneath the roadbed. Late Tertiary or Early Quaternary gravel cap pediments along the mountain front. Ground water issuing from seeps and springs found at the contact between these gravels and the underlying bedrock should be intercepted and removed from beneath the roadbed.

Colorado↗

USGS1955

Geology of the Canyon Reservoir site on the Guadalupe River, Comal County, Texas

In response to a request by Colonel Harry O. Fisher, District Engineer of the Fort Worth District of the Corps of Engineers, United States Army (letter of Dec. 13, 1954), a reconnaissance investigation was made of the geology of the Canyon (F-1) reservoir site on the Guadalupe River in Comal County, Tex. The purpose of the investigation was to study the geology in relation to possible leakage - particularly leakage of water that might then be lost from the drainage area of the Guadalupe River - and to add to the general knowledge of the ground-water hydrology of the San Antonio area. The dam (F-1) was originally designed for flood control and conservation only, with provision for the addition of a power unit if feasible. Since the completion of the investigation by the Corps of Engineers, the city of San Antonio has expressed an interest in the reservoir as a possible source of public water supply. The Corps of Engineers has made a thorough engineering and geologic study of the dam site (Corps of Engineers, 1950), which has Congressional approval. The geology and water resources of Comal County have been studied by George (1952). The rocks studied are those within the reservoir area and generally below the 1,000-foot contour as shown on the Smithson Valley quadrangle of the U.S. Geological Survey.

Texas↗

USGS1970

Bibliography of reports resulting from U.S. Geological Survey participation in the United States Technical Assistance Program: Supplement for 1968-1969

U. S. Geological Survey Bulletin 1263, by Jo Ann Heath and Nancy B. Tabacchi lists the reports that resulted from a wide variety of geologic and hydrologic investigations, .and institutional development programs undertaken by the U. S. Geological Survey and counterpart agencies in 51 foreign countries from 1940-67. This supplementary list, for the years 1968 and 1969, includes geologic and earth-science reports of investigations in 17 countries: Reports on hydrology are not included. Only reports written by U. S. Geological Survey personnel or in collaboration with their local counterparts are included.

Open-File Report↗

USGS1972

Interim results of geological investigations in the vicinity of the Ergani-Maden massive copper deposits near Maden, Elazig, Turkey

As a result of geologic studies and geochemical reconnaissance by Griffitts, Albers, and brier in 1969 in the Ergani-Maden district of eastern Turkey, seven areas were recommended for more detailed investigation. Two of these, here termed Areas 1 and 2, were mapped geologically and sampled geochemically in June and July 1970 by .4. E. Weissenborn, U. S. Geological Survey, and Omer Oner and Metin Sengun, Mineral Research and Exploration Institute (MTA), an agency of the Turkish Government. This study was part of a mineral exploration and training project conducted by the U. S. Geological Survey in cooperation with MTA under the auspices of the Agency for International Development, U. S. Department of State. Mapping and sampling of four of the other areas was completed in August and September by Oner and Sengun, but this report concerns only Areas 1 and 2. The geological environment in Areas 1 and 2 appears favorable for additional ore bodies of the Ergani-Maden type, which have been Turkey's most important producer of copper. Weak but distinct anomalies developed by the geochemical sampling in Area 1 adjacent to the Mihrap Dagi deposit suggest that other ore bodies maybe found along the northwesterly trend defined by the Mihrap Dagi, Arpa Meydan, Ana Yatak mines, and the Mizir Tepe prospect. Recommendations are made for 8 drill holes in Area 1 to test this possibility. Two additional holes are also recommended in Arc.: 1. Two less pronounced anomalies were developed in Area 2. Two drill holes are suggested to test them.

Elazig↗