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At least 1,189 records · Page 66Linked to original sources
USGS2008

Geologic Maps and Cross Sections of the Tuba City Open Dump Site and Vicinity, With Implications for the Occurrence and Flow of Ground Water

This report is designed to make available to interested parties geologic and limited hydrologic and geochemical information about the Tuba City Open Dump (TCOD) site. This information has been gathered during studies of the site from January to September 2008. Mapping by the authors and construction of cross sections show that a section of gently northeast-dipping Jurassic sedimentary rocks underlies the TCOD and vicinity. Low mesas in the area are capped by variably cemented gravels and siliceous limestones. Surficial sediments are composed of eolian sand and fluvially reworked eolian sand that overlie bedrock underneath the TCOD. Nearby Pasture Canyon is underlain by fluvial and floodplain sediment consisting of sand and silt. Shallow ground water of the water-table aquifer at the TCOD moves westward through the surficial sediment and the underlying weathered bedrock to Pasture Canyon then southward along the canyon. A fracture zone extends up the wash that passes just to the north of the TCOD and brings deeper ground water of the N-aquifer to the water-table aquifer. Bedrock consists of the Jurassic Navajo Sandstone composed of thick sections of eolian crossbedded sandstone with lesser laterally discontinuous layers of silty sandstone, siltstone, and limestone. Below the Navajo Sandstone is a section informally known as the Kayenta Formation-Navajo Sandstone transition zone. It is composed of calcareous sandstone, silty sandstone, siltstone, and limestone beds that intertongue with crossbedded sandstone. The finer grained rocks in both major bedrock units form aquitards that limit downward movement of ground water. The water-table aquifer is perched on these aquitards, which locally occurs beneath the two open dumps that form the TCOD site. A monocline occupies the position of Pasture Canyon west of the TCOD. Fractures likely related to the monocline are exposed in several localities. Deep ground waters consist of dilute calcium-bicarbonate waters low in all trace elements. Shallow ground water is variably affected by near-surface processes, which add varying amounts of sodium, chloride, sulfate, and trace elements. Locally, human influences, such as the TCOD, affect shallow ground-water chemistry.

Open-File Report↗
USGS2024

Short-term sediment dispersal on a large retreating coastal river delta via 234Th and 7Be sediment geochronology: The Mississippi River Delta Front

Many Mississippi River Delta studies have shown recent declines in fluvial sediment load from the river and associated land loss. In contrast, recent sedimentary processes on the subaqueous delta are less documented. To help address this knowledge gap, multicores were collected offshore from the three main river outlets at water depths of 25–280 m in June 2017 just after the peak river discharge period, with locations selected based on 2017 U.S. Geological Survey seabed mapping. The coring locations included the undisturbed upper foreset, mudflow lobes, gullies, and the undisturbed prodelta. Nine multicores were analyzed for Beryllium-7 activity, and four cores were analyzed for excess Thorium-234 activity via gamma spectrometry, granulometry and X-radiography. Our results indicate a general trend of declining 7 Be and 234 Th activities and inventories with increasing distance from sources and in deeper water. The core X-radiographs are graded from the predominantly physically stratified nearshore to the more bioturbated offshore, consistent with the sedimentation patterns. Sediment focusing assessed via the 7 Be and 234 Th sediment inventories shows preferential sedimentation in gully and lobe environments, whereas the upper foreset and prodelta focusing factors are relatively depleted. Overall, short-term sediment deposition from the main fluvial source remains active offshore from all three major river outlets, despite the overall declining river load.

Louisiana↗
USGS2002

Basis and methods of NASA airborne topographic mapper lidar surveys for coastal studies

This paper provides an overview of the basic principles of airborne laser altimetry for surveys of coastal topography, and describes the methods used in the acquisition and processing of NASA Airborne Topographic Mapper (ATM) surveys that cover much of the conterminous US coastline. This form of remote sensing, also known as "topographic lidar", has undergone extremely rapid development during the last two decades, and has the potential to contribute within a wide range of coastal scientific investigations. Various airborne laser surveying (ALS) applications that are relevant to coastal studies are being pursued by researchers in a range of Earth science disciplines. Examples include the mapping of "bald earth" land surfaces below even moderately dense vegetation in studies of geologic framework and hydrology, and determination of the vegetation canopy structure, a key variable in mapping wildlife habitats. ALS has also proven to be an excellent method for the regional mapping of geomorphic change along barrier island beaches and other sandy coasts due to storms or long-term sedimentary processes. Coastal scientists are adopting ALS as a basic method in the study of an array of additional coastal topics. ALS can provide useful information in the analysis of shoreline change, the prediction and assessment of landslides along seacliffs and headlands, examination of subsidence causing coastal land loss, and in predicting storm surge and tsunami inundation.

Journal of Coastal Research↗
USGS1982

Reconnaissance Geology of the Jabal as Sukkah Quadrangle, Sheet 21/43 B, Kingdom of Saudi Arabia

The Jabal as Sukkah quadrangle (21/43 B) lies in the southern Najd region within the Arabian Shield between lat 21°30' and 22°00' N. and long 43°30' and 44°00' E. The oldest rocks exposed are a very thick sequence of volcanic flow rocks of mostly felsic to intermediate composition interbedded with volcaniclastic and sedimentary rocks. The layered rocks reflect a less primitive state of crustal evolution than has generally been ascribed to this sequence. These rocks were deposited upon an emerging basement of mafic to intermediate composition, and the sedimentary materials reflect a source terrane of mostly intermediate to felsic character. The layered rocks were subjected to three separate episodes of compressional deformation, each followed by appreciable talc-alkalic plutonism. Each of the plutonic suites contains a differentiated series that began with the emplacement of mafic to intermediate rocks, progressed to talc-alkalic granites, and terminated with an end-member granite rich in silica and total alkalis. The petrography and rock chemistry indicate that the more alkalic members of the talc-alkalic granites were capable of generating ore-bearing fluids and perhaps ore deposits of large size in the region. However, subsequent erosion likely removed all but some of the deeper, smaller vestiges of such deposits from within the study area. No exploitable deposits were found during the course of this investigation.

Jabal as Sukkah Quadrangle↗
USGS2017

Geophysical characterization of seismic station sites in the United States – The importance of a flexible, multi-method approach

Noninvasive geophysical site characterization methods were used in two recent projects to obtain shear-wave velocity (VS) profiles to a minimum depth of 30 m and the time-averaged VS of the upper 30 meters (VS30) at seismic station sites. These projects include the 2009 American Recovery and Reinvestment Act (ARRA) funded U.S. Geological Survey site characterization project for 191 sites in California and the Central-eastern United States (CEUS), and the 2012 Electric Power Research Institute (EPRI) funded project for 33 additional CEUS sites. These sites are located in rural to urban settings with topographic conditions ranging from relatively flat sedimentary basins to mountaintop ridges. About 60 percent of the ARRA sites and 80 percent of the EPRI sites are located on rock or have thin sediment cover over rock, including Quaternary volcanic rock, Tertiary sediments and sedimentary rock, and Mesozoic (or older) crystalline or sedimentary rock. The remaining sites consist of thick sequences of Quaternary sediments overlying older sediments and rock. ARRA sites were characterized using non-invasive active and passive surface-wave methods, including the horizontal-tovertical spectral ratio (HVSR) method and one or more of the following: spectral analysis of surface waves (SASW), multichannel analysis of surface waves (MASW; Rayleigh and Love waves) and, occasionally, array microtremor (linear and 2-D arrays) methods. P-wave seismic refraction data were also acquired at rock and shallow-rock sites. S-wave seismic refraction and/or Love-wave MASW methods were applied at sites where characterization proved difficult with Rayleighwave methods. Based on our experience from the ARRA project, we acquired Rayleigh- and Love-wave based MASW and P- and S-wave refraction data for the EPRI project at CEUS sites. The HVSR method was found to be useful for identifying shallow-rock sites and for evaluating the relative variability of the depth-to-rock interface beneath the seismic station and the testing array(s). The fundamental mode modeling assumption was generally valid at most of these sites; nevertheless, multi-mode or effective-mode modeling routines were occasionally required, particularly in the case of shallow high-velocity layers. Deep sediment sites were characterized using active and, when appropriate, passive surface-wave based methods. Rock and shallow sediment sites were generally more challenging to characterize than deep sediment sites. About 10 percent of rock sites could not be characterized using surface wave methods, thus these sites were characterized using body-wave refraction methods. Love wave methods were found to be more effective than Rayleigh wave methods at some rock and shallow-rock sites (e.g., sites with shallow rock and sites with a thin low-velocity, highly attenuating surface layer). Lateral velocity variability was found to be very common at rock and shallow-rock sites, often causing significant scatter in the surface-wave dispersion data. Seismic refraction models have demonstrated that it may not be unusual for VS30 to vary by 20 percent, or more, over small distances (several tens of meters) at such sites. Based on these experiences, it is important to consider the application of combinations of methods when using noninvasive geophysical approaches to characterize seismic site conditions.

Conference Paper↗
USGS2012

Review and update of the applications of organic petrology: Part 1, geological applications

Organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry. Coal petrology was then considered a branch of coal science. Later, with the development of specialized nomenclature, classification of coal components, and the standardization and improvement of analytical (microscopical) methods, this discipline expanded in interests and name, becoming organic petrology. Organic petrology carries a broader context, being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources. At present, organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences. Throughout the 20th century several important monographs have been published on the discipline of organic petrology, including “Stach's textbook of coal petrology” (1st edition 1935, 2nd 1975, 3rd 1982), updated as the more general “Organic petrology” by Taylor et al. (1998). More recently, the text “Applied coal petrology: the role of petrology in coal utilization” was published by Suárez-Ruiz and Crelling (2008). This review is the first in a two-part review series that describes and updates the role of organic petrology in geosciences. A second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow.

International Journal of Coal Geology↗
USGS2021

Contribution of deep-sourced carbon from hydrocarbon seeps to sedimentary organic carbon: Evidence from radiocarbon and stable isotope geochemistry

Sulfate-driven anaerobic oxidation of methane (AOM) limits the release of methane from marine sediments and promotes the formation of carbonates close to the seafloor in seepage areas along continental margins. It has been established that hydrocarbon seeps are a source of methane, dissolved inorganic carbon, and dissolved organic carbon to marine environments. However, questions remain about the contribution of deep-sourced carbon from hydrocarbon seeps to the sedimentary organic carbon pool. In this study, we analyzed carbon quantity, radiocarbon content (as percent modern carbon, pMC), stable carbon isotopic compositions (as δ 13 C) of organic matter enclosed within seep carbonates from the Gulf of Mexico and the South China Sea to assess if sediment organic matter may be used as a proxy for methane seepage intensity. The δ 13 C values of organic matter (δ 13 C org ) exhibited a large range from −81.4‰ to −23.9‰. Radiocarbon contents of the carbonate-bound organic matter in seep carbonates ranged from 6% to 28% pMC, suggesting organic matter of the carbonates is a mixture of marine particulate organic matter (δ 13 C = −22‰ VPDB and 90% modern carbon) and biomass resulting from methane oxidation (assumed to have 0% modern carbon). Assuming constant productivity in the marine photic zone, it is proposed that seepage intensity and duration are the most important factors controlling the contribution of methane-derived carbon to the sedimentary column. This study reinforces the potential for using δ 13 C values of organic carbon to discern methane-rich environments in ancient sedimentary environments where authigenic carbonate is not present and to constrain the record of AOM through Earth history.

Chemical Geology↗
USGS2018

Storm impacts on hydrodynamics and suspended-sediment fluxes in a microtidal back-barrier estuary

Recent major storms have piqued interest in understanding the responses of estuarine hydrodynamics and sediment transport to these events. To that end, flow velocity, wave characteristics, and suspended-sediment concentration (SSC) were measured for 11 months at eight locations in Chincoteague Bay, MD/VA, USA, a shallow back-barrier estuary. Daily breezes and episodic storms generated sediment-resuspending waves and modified the flow velocity at all sites, which occupied channel, shoal, and sheltered-bay environments with different bed-sediment characteristics. Despite comparable SSC during calm periods, SSC at the channel locations was considerably greater than at the shoal sites during windy periods because of relatively more erodible bed sediment in the channels. Sediment fluxes were strongly wind modulated: within the bay’s main channel, depth-integrated unit-width sediment flux increased nonlinearly with increasing wind speed. When averaged over all sites, about 35% of the flux occurred during windy periods (wind speed greater than 6 m s −1 ), which represented just 15% of the deployment time. At channel sites, the net water and sediment fluxes were opposite to the direction of the wind forcing, while at shoal sites, the fluxes generally were aligned with the wind, implying complex channel– shoal dynamics. Yearly sediment fluxes exceed previous estimates of sediment delivery to the entirety of Chincoteague Bay. These observations illustrate the dynamic sedimentary processes occurring within microtidal back-barrier lagoons and highlight the importance of storm events in the hydrodynamics and overall sediment budgets of these systems.

Maryland↗
USGS2013

Mineral resource of the month: diatomite

The article discusses the properties and applications of the mineral diatomite. According to the author, diatomite is a soft, friable and very fine-grained siliceous sedimentary rock made of the remains of fossilized diatoms. The author adds that its properties make diatomite very useful as a filtration medium and as a component in cement.

Earth↗
USGS2005

Geology of the Vienna Mineralized Area, Blaine and Camas Counties, Idaho

The Vienna mineralized area of south-central Idaho was an important silver-lead-producing district in the late 1800s and has intermittently produced lead, silver, zinc, copper, and gold since that time. The district is underlain by biotite granodiorite of the Cretaceous Idaho batholith, and all mineral deposits are hosted by the biotite granodiorite. The granodiorite intrudes Paleozoic sedimentary rocks of the Sun Valley Group, is overlain by rocks of the Eocene Challis Volcanic Group, and is cut by numerous northeast-trending Eocene faults and dikes. Two mineralogically and texturally distinct vein types are present in a northwest- and east-trending conjugate shear-zone system. The shear zones postdate granodiorite emplacement and joint formation, but predate Eocene fault and dike formation. Ribbon veins consist of alternating bands of massive vein quartz and silver-sulfide (proustite and pyrargyrite) mineral stringers. The ribbon veins were sheared and brecciated during multiple phases of injection of mineralizing fluids. A quartz-sericite-pyrite-galena vein system was subsequently emplaced in the brecciated shear zones. Both vein systems are believed to be the product of mesothermal, multiphase mineralization. K-Ar dating of shear-zone sericite indicates that sericitization occurred at 80.7?2.8 Ma; thus mineralization in the Vienna mineralized area probably is Late Cretaceous in age.

Bulletin↗
USGS2013

Geologic map of the east half of the Lime Hills 1:250,000-scale quadrangle, Alaska

This map is compiled from geologic mapping conducted between 1985 and 1992 by the U.S. Geological Survey as part of the Alaska Mineral Resource Assessment Program. That mapping built upon previous USGS work (1963–1988) unraveling the magmatic history of the Alaska–Aleutian Range batholith. Quaternary unit contacts depicted on this map are derived largely from aerial-photograph interpretation. K-Ar ages made prior to this study have been recalculated using 1977 decay constants. The east half of the Lime Hills 1:250,000-scale quadrangle includes part of the Alaska–Aleutian Range batholith and several sequences of sedimentary rocks or mixed sedimentary and volcanic rocks. The Alaska–Aleutian Range batholith contains rocks that represent three major igneous episodes, (1) Early and Middle Jurassic, (2) Late Cretaceous and early Tertiary, and (3) middle Tertiary; only rocks from the latter two episodes are found in this map area. The map area is one of very steep and rugged terrain; elevations range from a little under 1,000 ft (305 m) to 9,828 ft (2,996 m). Foot traverses are generally restricted to lowermost elevations. Areas suitable for helicopter landings can be scarce at higher elevations. Most of the area was mapped from the air, supplemented by direct examination of rocks where possible. This restricted access greatly complicates understanding some of the more complex geologic units. For example, we know there are plutons whose compositions vary from gabbro to granodiorite, but we have little insight as to how these phases are distributed and what their relations might be to each other. It is also possible that some of what we have described as compositionally complex plutons might actually be several distinct intrusions.

Alaska↗
USGS2024

Hyperspectral (VNIR-SWIR) analysis of roll front uranium host rocks and industrial minerals from Karnes and Live Oak Counties, Texas Coastal Plain

VNIR-SWIR (400–2500 nm) reflectance measurements were made on the surfaces of various cores, cuttings and sample splits of sedimentary rocks from the Tertiary Jackson Group, and Catahoula, Oakville and Goliad Formations. These rocks vary in composition and texture from mudstone and claystone to sandstone and are known host rocks for roll front uranium occurrences in Karnes and Live Oak Counties, Texas. Spectral reflectance profiles, 569 in total, were reduced to 125 representative spectral signatures, which were analyzed using the U.S. Geological Survey's (USGS) Material Identification and Characterization Algorithm (MICA). MICA uses an automated continuum-removal procedure together with a least-squares linear regression to determine the fit of observed sample spectral absorption features to those of reference mineral standards in a spectral library. The reference minerals include various clay, mica, carbonate, ferric and ferrous iron minerals and their mixtures. In addition, absorption feature band-depth analysis was done to identify rock surfaces exhibiting absorption features related to uranium and zeolite minerals, which were not included in the command files used to execute MICA. Rocks from each of the four geologic units produced broadly similar spectral signatures as a result of comparable mineral compositions, but there were some notable differences. For example, Ca- and Na-montmorillonite was matched most frequently to the spectral absorption features in 2-μm (∼2000–2500 nm) wavelengths, while goethite occurred often at 1-μm (∼400–1000 nm) wavelengths. The latter is related to limonitic iron-staining in and around oxidized zones of the uranium roll front as described in previous papers. Rocks of the Jackson Group differed from those of the Catahoula, Oakville and Goliad units in that the former exhibited spectral features we interpret as being due to the presence of lignite-bearing mudstone layers. Goliad rocks exhibit spectral features related to dolomite, gypsum, anhydrite, and an unidentified green clay mineral that is possibly glauconite . Jackson Group rocks also exhibit weak but well-resolved absorption features at 964 and 1157 nm related to either or both zeolite minerals clinoptilolite and heulandite. These zeolite minerals and a few spectra exhibiting hydrous silica absorption features are indicative of alteration of volcanic glass in tuffaceous mudstone and claystone layers. A few sample spectra exhibited strong absorption features at around 1135 nm related to the uranium mineral coffinite. Both the 1135 nm coffinite and 1157 nm zeolite absorption features overlap somewhat, potentially making them difficult to distinguish without additional hyperspectral field, laboratory or remote sensing data. The results of this study were compared to mixtures of minerals described for ore, gangue and alteration minerals in deposit models for sandstone-hosted uranium, sedimentary bentonite and sedimentary zeolite. Use of these spectra can help facilitate mapping of both waste materials from the legacy mining of the above commodities, as well as future exploration and resource assessment activities.

Texas↗
USGS2008

On the in situ aqueous alteration of soils on Mars

Early (>3 Gy) wetter climate conditions on Mars have been proposed, and it is thus likely that pedogenic processes have occurred there at some point in the past. Soil and rock chemistry of the Martian landing sites were evaluated to test the hypothesis that in situ aqueous alteration and downward movement of solutes have been among the processes that have transformed these portions of the Mars regolith. A geochemical mass balance shows that Martian soils at three landing sites have lost significant quantities of major rock-forming elements and have gained elements that are likely present as soluble ions. The loss of elements is interpreted to have occurred during an earlier stage(s) of weathering that may have been accompanied by the downward transport of weathering products, and the salts are interpreted to be emplaced later in a drier Mars history. Chemical differences exist among the sites, indicating regional differences in soil composition. Shallow soil profile excavations at Gusev crater are consistent with late stage downward migration of salts, implying the presence of small amounts of liquid water even in relatively recent Martian history. While the mechanisms for chemical weathering and salt additions on Mars remain unclear, the soil chemistry appears to record a decline in leaching efficiency. A deep sedimentary exposure at Endurance crater contains complex depth profiles of SO4, Cl, and Br, trends generally consistent with downward aqueous transport accompanied by drying. While no model for the origin of Martian soils can be fully constrained with the currently available data, a pedogenic origin is consistent with observed Martian geology and geochemistry, and provides a testable hypothesis that can be evaluated with present and future data from the Mars surface. ?? 2008 Elsevier Ltd.

Geochimica et Cosmochimica Acta↗
USGS2005

Use of relational databases to evaluate regional petroleum accumulation, groundwater flow, and CO2 sequestration in Kansas

Large-scale relational databases and geographic information system tools are used to integrate temperature, pressure, and water geo-chemistry data from numerous wells to better understand regional-scale geothermal and hydrogeological regimes of the lower Paleozoic aquifer systems in the mid-continent and to evaluate their potential for geologic CO2 sequestration. The lower Paleozoic (Cambrian to Mississippian) aquifer systems in Kansas, Missouri, and Oklahoma comprise one of the largest regional-scale saline aquifer systems in North America. Understanding hydrologic conditions and processes of these regional-scale aquifer systems provides insight to the evolution of the various sedimentary basins, migration of hydrocarbons out of the Anadarko and Arkoma basins, and the distribution of Arbuckle petroleum reservoirs across Kansas and provides a basis to evaluate CO2 sequestration potential. The Cambrian and Ordovician stratigraphic units form a saline aquifer that is in hydrologic continuity with the freshwater recharge from the Ozark plateau and along the Nemaha anticline. The hydrologic continuity with areas of freshwater recharge provides an explanation for the apparent underpressure in the Arbuckle Group. Copyright ?? 2005. The American Association of Petroleum Geologists. All rights reserved.

American Association of Petroleum Geologists Bulle↗
USGS2004

Re-Os sulfide geochronology of the Red Dog sediment-hosted Zn-Pb-Ag deposit, Brooks Range, Alaska

The Red Dog sediment-hosted deposit in the De Long Mountains of northern Alaska is the largest Zn producer in the world. Main stage mineralization is characterized by massive sulfide ore and crosscutting subvertical veins. Although the vein mineralization is clearly younger than the massive ore, the exact temporal relationship between the two is unclear. Re-Os geochronology of pyrite is used to determine the absolute age of main stage ore at Red Dog. A 10-point isochron on both massive and vein pyrite yields an age of 338.3 ?? 5.8 Ma and is interpreted to represent the age of main stage ore. The Re-Os data indicate that both massive and vein ore types are coeval within the resolution of the technique. Formation of the Red Dog deposit was associated with extension along a passive continental margin, and therefore the Re-Os age of main stage ore constrains the timing of rifting as well as the age of the host sedimentary rocks. Sphalerite from both massive and vein ore yields imprecise ages and shows a high degree of scatter compared to pyrite. We suggest that the Re-Os systematics of sphalerite can be disturbed and that this mineral is not reliable for Re-Os geochronology. ?? 2004 by Economic Geology.

Economic Geology↗
USGS1967

Preliminary geologic section from Pahute Mesa, Nevada Test Site, to Enterprise, Utah

The 154-mile long geologic cross section trends nearly perpendicular to the structural grain of the Basin-Range province in Nevada, and in Utah extends eastward into the transition zone between the Basin-Range and Colorado Plateau provinces. The structure is characterized by complex thrust: faults, involving uppermost Precambrian to lower Mesozoic sedimentary rocks, and normal faults which cut: the thick sequence of Tertiary volcanic rocks as well as older rocks. Some of the normal faults are the result of caldera collapse. The principal normal faults trend northerly west: of Delamar, Nev., and form north-trending basins and ranges. Farther east the principal faults trend northwesterly, and form a moderately rugged highland rather than distinct basins and ranges. The uppermost Precambrian-Paleozoic strata thin markedly eastward across the region. The pre-Pennsylvanian sedimentary rocks vary from 32,500 feet: in thickness at the Nevada Test: Site (Harley Barnes, E. N. Hinrichs, F. A. McKeown and P. P. Orkild, written commun., 1963) to 4,500 feet: in the Beaver Dam Mountains in western Utah (Cook, 1960). Thick Mesozoic deposits, similar to those of the Colorado Plateau, are present in western Utah, but are represented in eastern Nevada by only thin patches of Triassic rock.

Nevada, Utah↗
USGS2017

Geologic map of the Fittstown 7.5΄ quadrangle, Pontotoc and Johnston Counties, Oklahoma

This 1:24,000-scale geologic map includes new geologic mapping as well as compilation and revision of previous geologic maps in the area. Field investigations were carried out during 2009–2011 that included mapping and investigations of the geology and hydrology of the Chickasaw National Recreation Area, Oklahoma, west of the map area. The Fittstown quadrangle is in Pontotoc and Johnston Counties in south-central Oklahoma, which is in the northeastern part of the Arbuckle Mountains. The Arbuckle Mountains are composed of a thick sequence of Paleozoic sedimentary rocks that overlie Lower Cambrian and Precambrian igneous rocks; these latter rocks are not exposed in the quadrangle. From Middle to Late Pennsylvanian time, the Arbuckle Mountains region was folded, faulted, and uplifted. Periods of erosion followed these Pennsylvanian mountain-building events, beveling this region and ultimately developing the current subtle topography that includes hills and incised uplands. The southern and northwestern parts of the Fittstown quadrangle are directly underlain by Lower Ordovician dolomite of the Arbuckle Group that has eroded to form an extensive, stream-incised upland containing the broad, gently southeast-plunging, Pennsylvanian-age Hunton anticline. The northeastern part of the map area is underlain by Middle Ordovician to Pennsylvanian limestone, shale, and sandstone units that predominantly dip northeast and form the northeastern limb of the Hunton anticline; this limb is cut by steeply dipping, northwest-southeast striking faults of the Franks fault zone. This limb and the Franks fault zone define the southwestern margin of the Franks graben, which is underlain by Pennsylvanian rocks in the northeast part of the map area.

Oklahoma↗
USGS2018

Geologic map of the Osage SW 7.5ʹ quadrangle, Newton, Madison, and Carroll Counties, Arkansas

This map summarizes the geology of the U.S. Geological Survey Osage SW 7.5-minute quadrangle in the Ozark Plateaus region of northern Arkansas. Physiographically, the Osage SW quadrangle is located within a transitional area between the Boston Mountains to the south, and the Springfield Plateau to the north. Geologically, the area is on the southern flank of the Ozark dome; an uplift with the oldest rocks exposed at its center in the St. Francois Mountains in Missouri. Exposed within the quadrangle is an approximately 1,460-foot-thick sequence of Ordovician, Mississippian, and Pennsylvanian carbonate and clastic sedimentary rocks that have been mildly deformed by a series of faults and folds. The southeasternmost corner of the map area falls within the Buffalo National River—a park which encompasses the Buffalo River and adjacent land that is administered by the National Park Service.

Arkansas↗