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USGS1996

Offshore gas hydrate sample database with an overview and preliminary analysis

Synopsis -- A database of offshore gas hydrate samples was constructed from published observations and measurements. More than 90 samples from 15 distinct regions are represented in 13 data categories. This database has permitted preliminary description of gas hydrate (chiefly methane hydrate) tendencies and associations with respect to their geological environment. Gas hydrates have been recovered from offshore sediment worldwide and from total depths (water depth plus subseabed depth) ranging from 500 m to nearly 6,000 m. Samples have come from subbottom depths ranging from 0 to 400 m. Various physiographic provinces are represented in the data set including second order landforms such as continental margins and deep-sea trenches, and third order forms such as submarine canyons, continental slopes, continental margin ridges and intraslope basins. There is a clear association between fault zones and other manifestations of local, tectonic-related processes, and hydrate-bearing sediment. Samples of gas hydrate frequently consist of individual grains or particles. These types of hydrates are often further described as inclusions or disseminated in the sediment. Moreover, hydrates occur as a cement, as nodules, or as layers (mostly laminae) or in veins. The preponderance of hydrates that could be characterized as 2- dimensional (planar) were associated with fine sediment, either as intercalated layers or in fractures. Hydrate cements were commonly associated with coarser sediment. Hydrates have been found in association with grain sizes ranging from clay through gravel. More hydrates are associated with the more abundant finer-grained sediment than with coarser sediment, and many were discovered in the presence of both fine (silt and clay) and coarse sediment. The thickness of hydrate zones (i. e., sections of hydrate-bearing sediment) varies from a few centimeters to as much as 30 m. In contrast, the thickness of layers of pure hydrate or the dimensions of individual hydrate grains were most often characterized in terms of millimeters or centimeters, although a pure hydrate layer discovered in the Middle America Trench off Guatemala was as much as 3-4-m-thick. The data suggest that grains, or thin veins or laminae of pure gas hydrate may be ubiquitous in many hydrate zones but that typically they may only comprise a minor component of the thicker zones. In more than 80 percent of the hydrate samples the methane was of biogenic origin. The methane in the remainder was either classified as (or may be at least part) thermogenic. Each site where thermogenic gas was identified is characterized by faults or other manifestions of a dynamic geological environment (e.g., diapirs, mud volcanoes, gas seeps). Every sample in the database came from within the zone of theoretical methane hydrate stability, as determined on the basis of assumed regional pressure and temperature gradients. Most show that they were situated --- expressed in terms of depth --- well above the phase boundary and about 70% of the samples were located more than 100 m above the assumed regional position of that boundary. The calculated subseabed positions of the phase boundaries and the BSRs (bottom simulating reflector) are essentially identical. This may be taken as general corroboration of the regional phase boundary calculations and the concept of the BSR. Three provocative aspects of marine gas hydrates have been disclosed by the database: gas hydrates are frequently situated at much shallower subseabed depths than the assumed contemporary position of the regional phase boundary hydrates are often found in areas typified by faults or other indicators of a dynamic geological environment zones of gas hydrate-bearing sediment tend to be tens of centimeters to tens of meters thick but the hydrate within the thicker zones tends to be only a minor constituent. Whether existing as dispersed particles, cements, or pure layers or vein

Open-File Report↗

USGS1996

Selected hydrologic data, through water year 1994, Black Hills Hydrology Study, South Dakota

This report presents water-level, water-quality, and spring data that have been collected or compiled, through water year 1994, for the Black Hills Hydrology Study. This study is a long-term cooperative effort between the U.S. Geological Survey, the South Dakota Department of Environment and Natural Resources, and the West Dakota Water Development District (which represents various local and county cooperators). This report is the second in a series of biennial project data reports produced for the study. Daily water-level data are presented for 39 observation wells and 2 cave sites in the Black Hills area of western South Dakota. The wells are part of a network of observation wells maintained by the Department of Environment and Natural Resources and are completed in various bedrock formations that are utilized as aquifers in the Black Hills area. Both cave sites are located within outcrops of the Madison Limestone. Data presented include site descriptions, hydrographs, and tables of daily water levels. Annual measurements of water levels collected during water years 1993-94 from a network of 20 additional, miscellaneous wells are presented. These wells are part of a Statewide network of wells completed in bedrock aquifers that was operated from 1959 through 1989 in cooperation with the Department of Environment and Natural Resources. Site descriptions and hydrographs for the entire period of record for each site also are presented. Drawdown and recovery data are presented for five wells that were pumped (or flowed) for collection of water-quality samples. These wells are part of the network of observation wells for which daily water-level records are compiled. Water-quality data are presented for 20 surface-water sites and 22 ground-water sites. Data presented include field parameters, bacteria counts, and concentrations of common ions, solids, nutrients, trace elements, radiometrics and isotopes, cyanide, phenols, and suspended sediment. Spring data are presented for 94 springs and 21 stream reaches with significant springflow components. Data presented include site information, discharge, and field water-quality parameters including temperature, specific conductance, dissolved oxygen, and pH.

Open-File Report↗

USGS1980

Zeolitization of Tertiary tuffs in lacustrine and alluvial deposits in the Ray-San Manuel area, Final and Gila Counties, Arizona

Specimens of tuff in the Ray-San Manuel area, southeastern Arizona, have been X-rayed to determine the present approximate mineralogic composition and the type and degree of alteration of the tuffs. Some of the tuffs consist largely of glass or have been partly or completely altered to calcium montmorillonite; many of them have been almost completely zeolitized or contain a zeolite and some clay. Only three zeolitized specimens contain a little glass. With four exceptions, the zeolitie is clinoptilolite; the exceptions are one altered to chabazite, one to mordenite, one to erionite, and one to erionite, clinoptilolite, and chabazite. The tuffs are mostly of airfall origin and of rhyolitic or probable rhyolitic composition and generally contain negligible percentages of crystal and lithic fragments. Two specimens are tuffaceous sedimentary rocks, and two are ash-flow tuffs. The tuffs range in age from early Pliocene or late Miocene to Oligocene. Some were deposited in lacustrine or playa environments; others were deposited in freshwater alluvial environments. All the beds examined in the lower Miocene and older formations have been zeolitized. Zeolitization of beds in younger formations depends on the environment of deposition. Zeolitized tuffs that contain at least 80 percent zeolite and are in beds more than one-third meter thick are considered potentially minable.

Arizona↗

USGS1984

The Mid-Cretaceous Frontier Formation near the Moxa Arch, southwestern Wyoming

The Frontier Formation in the Green River Basin of Wyoming, Utah, and Colorado, consists of sandstone, siltstone, and shale, and minor conglomerate, coal, and bentonite. These strata were deposited in several marine and nonmarine environments during early Late Cretaceous time. At north-trending outcrops along the eastern edge of the overthrust belt, the Frontier is of Cenomanian, Turonian, and early Coniacian age, and commonly is about 610 m (2,000 ft) thick. The formation in that area conformably overlies the Lower Cretaceous Aspen Shale and is divided into the following members, in ascending order: Chalk Creek, Coalville, Allen Hollow, Oyster Ridge Sandstone, and Dry Hollow. In west-trending outcrops on the northern flank of the Uinta Mountains in Utah, the Frontier is middle and late Turonian, and is about 60 m (200 ft) thick. These strata disconformably overlie the Lower Cretaceous Mowry Shale. In boreholes on the Moxa arch, the upper part of the Frontier is of middle Turonian to early Coniacian age and unconformably overlies the lower part of the formation, which is early Cenomanian at the south end and probably Cenomanian to early Turonian at the north end. The Frontier on the arch thickens northward from less than 100 m (328 ft) to more than 300 m (984 ft) and conformably overlies the Mowry. The marine and nonmarine Frontier near the Uinta Mountains, marine and mnmarine beds in the upper part of the formation on the Moxa arch and the largely nonmarine Dry Hollow Member at the top of the Frontier in the overthrust belt are similar in age. Older strata in the formation, which are represented by the disconformable basal contact of the Frontier near the Uinta Mountains, thicken northward along the Moxa arch and westward between the arch and the overthrust belt. The large changes in thickness of the Frontier in the Green River Basin were caused mainly by differential uplift and truncation of the lower part of the formation during the early to middle Turonian and by the shoreward addition of progressively younger sandstone units at the top of the formation during the late Turonian and early Coniacian. The sandstone in cores of the Frontier, from boreholes on the Moxa arch and the northern plunge of the Rock Springs uplift, consists of very fine grained and fine-grained litharenites and sublitharenites that were deposited in deltaic and shallow-water marine environments. These rocks consist mainly of quartz, chert, rock fragments, mixed-layer illite-smectite, mica-illite, and chlorite. Samples of the sandstone have porosities of 4.7 to 23.0 percent and permeabilities of 0.14 to 6.80 millidarcies, and seem to represent poor to fair reservoir beds for oil and gas. The shale in cores of the Frontier Formation and the overlying basal Hilliard Shale, from the Moxa arch, Rock Springs uplift, and overthrust belt, was deposited in deltaic and offshore-marine environments. Samples of the shale are composed largely of quartz, micaillite, mixed-layer illite-smectite, kaolin, and chlorite. They also contain from 0.27 to 4.42 percent organic carbon, in humic and sapropelic organic matter. Most of the sampled shale units are thermally mature, in terms of oil generation, and a few probably are source rocks for oil and gas.

Professional Paper↗

USGS1989

Studies of geology and hydrology in the Basin and Range Province, Southwestern United States, for isolation of high-level radioactive waste - Basis of characterization and evaluation

The geologic and hydrologic factors in selected regions of the Basin and Range province were examined to identify prospective areas for further study that may provide isolation of high-level radioactive waste from the accessible environment. The six regions selected for study were characterized with respect to the following guidelines: (1) Potential repository media; (2) Quaternary tectonic conditions; (3) climatic change and geomorphic processes; (4) ground-water conditions; (5) ground-water quality; and (6) mineral and energy resources. The repository medium will function as the first natural barrier to radionuclide travel by virtue of associated slow ground-water velocity. The principal rock types considered as host media include granitic, intermediate, and mafic intrusive rocks; argillaceous rocks; salt and anhydrite; volcanic mudflow (laharic) breccias; some intrusive rhyolitic plugs and stocks; partially zeolitized tuff; and metamorphic rocks. In the unsaturated zone, the permeability and hydrologic properties of the rocks and the hydrologic setting are more important than the rock type. Media ideally should be permeable to provide drainage and should have a minimal water flux The ground-water flow path from a repository to the accessible environment needs to present major barriers to the transport of radionuclides. Factors considered in evaluating the ground-water conditions include ground-water traveltimes and quality, confining beds, and earth materials favorable for retardation of radionuclides. Ground-water velocities in the regions were calculated from estimated hydraulic properties of the rocks and gradients. Because site-specific data on hydraulic properties are not available, data from the literature were assembled and synthesized to obtain values for use in estimating ground-water velocities. Hydraulic conductivities for many rock types having granular and fracture permeability follow a log-normal distribution. Porosity for granular and very weathered crystalline rock tends to be normally distributed; porosity of fractured crystalline rock probably follows a log-normal distribution. The tectonic setting needs to prevent an increase in radionuclides to the accessible environment. Data on historic seismicity and heat flow, Quaternary faults, volcanism, and uplift were used to assess the tectonic conditions. Long-term late Cenozoic rates of vertical crustal movement in the Basin and Range province range from less than 2 meters per 104 years to greater than 20 meters per 104 years. Shortterm rates of vertical movement may be more than an order of magnitude greater, based on geodetic leveling. Changes in tectonic and climatic processes may potentially cause changes in hydrologic conditions and geomorphology that could affect the integrity of a deep, mined repository either adversely or beneficially. The transition from a full-glacial climate to the current interglacial condition has occurred within the past 15,000 years. Reconstructions of the last full-glacial climate indicate that, at that time, there was greater water availability for runoff and vegetation growth than there is now. Based on the increased water availability and depending on seasonal distribution of precipitation, on soil characteristics, on topography, and on other characteristics, ground-water recharge during the full-glacial climate is estimated to have been possibly 2 to 10 or more times the modern rate. During the full-glacial climate, more than 100 lakes occupied closed basins in the province. Any increase in ground-water recharge and refilling of Pleistocene lakes will tend to decrease the distance of ground-water flow and its time of travel. The unsaturated zone this zone is considered a potential host medium where the thickness is greater than 150 m will be decreased by these changes. In contrast, incision of streams and other geomorphic, tectonic, or climatically induced changes that lower the ground-water discharge level will tend to increase the thickness of the unsaturated zone. Aggradation in basinal troughs may either decrease or increase the thickness of the unsaturated zone. Aggradation in basins that causes the ground-water discharge level to rise will tend to decrease the thickness of unsaturated zone in the adjacent uplands; aggradation in basins where the ground-water discharge level remains the same or is lowered will increase the unsaturated thickness of basin fill. Records show that, throughout late Cenozoic time in the Basin and Range province, continued vertical crustal movements have tended to maintain mountain ranges and closed basins, whereas aggradation of the basins and erosion of the mountain ranges have tended to decrease the topographic relief. Maximum rates of denudation for small basins in areas climatically similar to the Basin and Range province are about 2 meters per 104 years. For sites unaffected by stream incision and scarp retreat, a conservative estimate of erosion affecting long-term changes in depth of burial would appear to be 2 meters per 104 years, or, equal to the long-term rate of vertical crustal movement where greater than 2 meters per 104 years. The response of the ground-water conditions to climatic and geomorphically induced boundary conditions is significant from the points of: (1) The potential maximum change in the ground-water flow system; (2) the time of response of the ground-water system; and (3) the present state of the ground-water system as a result of past changes. Effects of longterm climatic and tectonic changes on hydrologic and geomorphic conditions differ from area to area, and rates of change of geomorphic and hydrologic conditions may vary significantly. Therefore, sitespecific studies need to be made to assess the long-term integrity of deep, mined repositories.

Arizona, California, Idaho, Nevada, New Mexico, Te↗

USGS1990

Stratigraphy of the Mesaverde Group in the central and eastern greater Green River basin, Wyoming, Colorado, and Utah

This paper establishes a stratigraphic framework for the Mesaverde Group, nearly 5,000 ft thick, in the central and eastern greater Green River basin based on data from measured outcrop sections and drill holes. Stratigraphic correlations are supported by ammonite zonation. No new stratigraphic names are introduced, and no nomenclature problems are discussed. Five long measured sections through the Mesaverde Group are described. The lower part of the Mesaverde Group, comprising the Rock Springs, Blair, Haystack Mountains, Allen Ridge, and Iles Formations, was deposited during a major eastward regression of the interior Cretaceous seaway of North America during the late Santonian and early Campanian. This regression was followed by regional uplift of the central Rocky Mountain area during the middle Campanian. The regional uplift was accompanied by widespread nondeposition and erosion, which, in turn, were followed by deposition of the Ericson and Pine Ridge Sandstones. The upper part of the Mesaverde Group, comprising the Almond and Williams Fork Formations, was deposited during a major westward transgression of the interior seaway in the early Maestrichtian. The major marine transgressions and regressions of the interior seaway were caused by eustatic changes of sea level, whereas intervening periods of nondeposition and erosion resulted from tectonism in the Sevier orogenic belt west of the study area. Formations of the Mesaverde Group are composed of sediments deposited in a landward-seaward progression of alluvial-plain, floodplain, coastal-plain, barrier-plain, tidal-flat, delta-plain, marine-shoreline, and marine-shelf and slope depositional environments. Each of these depositional environments is represented by specific lithofacies, sedimentary structures, and fossils, which are characteristic of depositional settings determined by water salinity, water depth, sedimentary and diagenetic processes, and the nature of sediment source terranes. The Mesaverde Group was deposited mainly along the western margins of the interior Cretaceous seaway as marine shorelines that trended north to northeast across the study area. Arcuate deltas, which formed at the mouths of major rivers along these shorelines, spread eastward onto shallow marine shelves. Embayed shoreline areas between the deltas were the sites of barrier-island and tidal-flat deposition. Alluvial-plain, flood-plain, and coastal-plain environments were present inland. The marine shorelines were tidally influenced and wave dominated, and shoreline deposits were mostly thick, linear sheets of quartzose sandstone. Deposition was largely controlled by the emergence or submergence of shoreline areas. Stillstands occurred close to local transgressions and regressions, depending on rates of sedimentation and subsidence.

Professional Paper↗

USGS1998

Transport, behavior, and fate of volatile organic compounds in streams

Volatile organic compounds (VOCs) are compounds with chemical and physical properties that allow the compounds to move freely between the water and air phases of the environment. VOCs are widespread in the environment because of this mobility. Many VOCs have properties making them suspected or known hazards to the health of humans and aquatic organisms. Consequently, understanding the processes affecting the concentration and distribution VOCs in the environment is necessary. The U.S. Geological Survey selected 55 VOCs for study. This report reviews the characteristics of the various process that could affect the transport, behavior, and fate of these VOCs in streams.

Professional Paper↗

USGS2000

Geologic studies in Alaska by the U.S. Geological Survey, 1997

The eight papers that follow continue the series of U.S. Geological Survey (USGS) reports on investigations in the geologic sciences in Alaska. The series presents new and sometimes preliminary findings that are of interest to earth scientists in academia, government, and industry; to land and resource managers; and to the general public. Reports presented in Geologic Studies in Alaska cover a broad spectrum of topics from all parts of the State (fig. 1), which serves to emphasize the diversity of USGS efforts to meet the Nation's needs for earth-science information in Alaska. The papers in this volume are organized under the topics Resources, Geologic Framework, and Environment and Climate. Such an organization is intended to reflect the scope and objectives of USGS programs currently active in Alaska. Resource papers include one that presents detailed observations from a Mississippian Zn-Pb-Cu-Ag occurrence in the Brooks Range (Werdon). Mineralogic, chemical, and isotopic data provide the basis for a proposed relationship between this vein-breccia deposit and the shale-hosted massive sulfide deposit type, which includes the active Red Dog mine in the western Brooks Range. Also included under the topic of Resources is a paper that presents geochemical and isotopic data from the Greens Creek and Woewodski Island volcanogenic massive sulfide deposits in southeastern Alaska (Newberry and Brew). The depositional environment and sedimentological setting of Tertiary coal beds in the Matanuska and Susitna Valleys is the focus of a third paper under the topic of Resources (Flores and others). Geologic Framework studies provide background information that is the scientific basis for present and future studies of the environment, mineral and energy resources, paleoclimate, and hazards in Alaska. One paper presents the results of sedimentologic and paleontologic comparisons of lower Paleozoic, deep-water-facies rock units in central Alaska (Dumoulin and others). The authors show which of these units are likely to correlate with one another, suggest likely source regions, and provide a structural restoration of units that have been fragmented by large fault motions. A second framework paper provides a map, rock descriptions, and chemical compositions of volcanic rocks in a newly recognized, geologically young volcanic center in the Aleutian volcanic arc (Hildreth and others). A third paper presents an interesting summary of gravity changes that occurred in south-central Alaska during the great earthquake of 1964 and for the following 25 years (Barnes). Gravity changes correlate with land-elevation changes in some cases, but not in others, which means that different processes are responsible for the gravity changes.

Alaska↗

USGS2006

Rates, trends, causes, and consequences of urban land-use change in the United States

Over the past 200 years, changes to the Nation's urban areas have been dramatic. Changes that have occurred relate both to the location of urban centers, as well as to the spatial extent of land dedicated to urban uses. Urban areas at the beginning of the 19th century were located primarily along major rivers or bodies of water, as waterways provided the most efficient means for transporting goods and people. As railroads became prominent, urban areas were able to expand or develop away from the water's edge. Geographic features such as steep slopes, wetlands, and lack of freshwater impeded settlement. In 1902, the National Reclamation Act was passed and with it came funding for the construction of water storage and transportation systems. This encouraged urban expansion in the arid west. After World War II, the Nation's urban areas continued to expand outward away from the city center as populations migrated to the margins of urban areas, where land was less expensive and the environment was less polluted. In 1956, the Federal Highway Act and the building of Interstate highways further facilitated urban expansion across the Unite States. Rural towns, small industrial centers, and farmland were engulfed by expanding urban centers. Over the past 200 years, numerous social, cultural, economic, and political incentives have encouraged urban expansion. In the 1800s, the industrial revolution influenced where people lived and worked. Many people shifted from agricultural production in rural areas to factory work in urban centers. Advances in transportation systems, such as rail transport in the 19th and early 20th centuries, followed by the mass production of the automobile and convenient air travel, facilitated a mobile society and a national economy. Economic growth and a population boom after World War II spurred increased suburbanization-the shifting of residential areas to the outlying section of a city or to a separate municipality-on the fringe of urban areas. Other economic and political incentives that shaped the urban environment included Federally backed home loans, credit and tax mechanisms that encouraged new development, and less restrictive municipal ordinances regarding building codes, environmental laws, and zoning regulations. Throughout the past two centuries land use changes associated with increasing urbanization have had impacts that resonate at local, regional, and even national scales. Landscape changes resulting from urbanization can be mapped and studied over time. Understanding these changes requires a study of the causes of change as related to social, economic, and political influences. Understanding these changes also requires analysis of how urbanization physically spreads across the landscape. The knowledge gained from studying urban land-use change can be helpful when it flows into local, regional, and national decisionmaking that relates to land-use decisions that impact the people, the economy, and the environment. Deriving a correlation between physical change and the explanations of the causes of change can help anticipate and mitigate the impacts of future change. Throughout the past two centuries changes to the Nation's urban areas are inextricably linked to population changes. The Nation's population started growing slowly along the eastern seaboard during the 17th and 18th centuries, accelerated in the second half of the 19th century, and then continued steadily spreading westward throughout the next hundred years. Currently, nearly 80 percent of the U.S. population resides in urban areas. Land area dedicated to urban use continues to expand, although differently than it has in the past. Most newly urbanized areas are much less densely populated and less intensively developed than they were 50 to 100 years ago.

Professional Paper↗

USGS2008

Lithofacies, Age, and Sequence Stratigraphy of the Carboniferous Lisburne Group in the Skimo Creek Area, Central Brooks Range

The Lisburne Group, a mainly Carboniferous carbonate succession that is widely distributed across northern Alaska, contains notable amounts of oil and gas at Prudhoe Bay. Detailed studies of the Lisburne in the Skimo Creek area, central Brooks Range, delineate its lithofacies, age, conodont biofacies, depositional environments, and sequence stratigraphy and provide new data on its hydrocarbon source-rock and reservoir potential, as well as its thermal history, in this area. We have studied the Lisburne Group in two thrust sheets of the Endicott Mountains allochthon, herein called the Skimo and Tiglukpuk thrust sheets. The southern, Skimo Creek section, which is >900 m thick, is composed largely of even-bedded to nodular lime mudstone and wackestone intercalated with intervals of thin- to thick-bedded bioclastic packstone and grainstone. Some parts of the section are partially to completely dolomitized and (or) replaced by chert. A distinctive, 30-m-thick zone of black, organic-rich shale, lime mudstone, and phosphorite is exposed 170 m below the top of the Lisburne. The uppermost 40 m of section is also distinctive and made up of dark shale, lime mudstone, spiculite, and glauconitic grainstone. The northern, Tiglukpuk Creek section, which is similar to the Skimo Creek section but only ~760 m thick, includes more packstone and grainstone and less organic-rich shale. Analyses of conodonts and foraminifers indicate that both sections range in age from late Early Mississippian (Osagean) through Early Pennsylvanian (early Morrowan) and document a hiatus of at least 15 m.y. at the contact between the Lisburne and the overlying Siksikpuk Formation. No evidence of subaerial exposure was observed along this contact, which may represent a submarine erosional surface. Lithofacies and biofacies imply that the Lisburne Group in the study area was deposited mainly in midramp to outer-ramp settings. Deepest water strata are mud rich and formed below storm or fair-weather wave base on the outer ramp to outer midramp; shallowest facies are storm, sand-wave, and shoal deposits of the inner midramp to inner ramp. A relatively diverse, open-marine fauna occurs throughout much of the Lisburne in the study area, but some beds also contain clasts typical of more restricted, shallow-water environments that were likely transported seaward by storms and currents. Radiolarians are abundant in the shale and phosphorite unit at Skimo Creek and also occur in equivalent strata at Tiglukpuk Creek; high gamma-ray response and elevated total organic-carbon contents (max 5?8 weight percent) also characterize this unit at Skimo Creek. Lithologic, faunal, and geochemical data all suggest that these rocks formed mainly in an outer-ramp to basinal setting with low sedimentation rates, high productivity, and poorly oxygenated bottom water. Shale and mudstone at the top of the Lisburne Group accumulated in a similarly sediment starved, mainly outer ramp environment but lack comparable evidence for high nutrient and low oxygen levels during deposition. Vertical shifts in rock types and faunas delineate numerous parasequences and six probable third-order sequences in the study area; the same sequences are also recognized in the Lisburne Group to the east. Transgressive-system tracts in these sequences generally fine upward, whereas highstand-system tracts coarsen upward. Sequences in the Tiglukpuk Creek section are mostly thinner, contain thinner and more numerous parasequences, and accumulated in somewhat shallower settings than those in the Skimo Creek section. These differences reflect the more seaward position and, thus, increased accommodation space of the Skimo Creek section relative to the Tiglukpuk Creek section during deposition. Organic-rich calcareous shale in the shale and phosphorite unit has a cumulative thickness of at least 15 m and a lateral extent of >50 km; this lithology is the best potential hydrocarbon source rock in the Lisburne Group

Professional Paper↗

USGS2017

Zirconium and hafnium

Zirconium and hafnium are corrosion-resistant metals that are widely used in the chemical and nuclear industries. Most zirconium is consumed in the form of the main ore mineral zircon (ZrSiO 4 , or as zirconium oxide or other zirconium chemicals. Zirconium and hafnium are both refractory lithophile elements that have nearly identical charge, ionic radii, and ionic potentials. As a result, their geochemical behavior is generally similar. Both elements are classified as incompatible because they have physical and crystallochemical properties that exclude them from the crystal lattices of most rock-forming minerals. Zircon and another, less common, ore mineral, baddeleyite (ZrO 2 ), form primarily as accessory minerals in igneous rocks. The presence and abundance of these ore minerals in igneous rocks are largely controlled by the element concentrations in the magma source and by the processes of melt generation and evolution. The world’s largest primary deposits of zirconium and hafnium are associated with alkaline igneous rocks, and, in one locality on the Kola Peninsula of Murmanskaya Oblast, Russia, baddeleyite is recovered as a byproduct of apatite and magnetite mining. Otherwise, there are few primary igneous deposits of zirconium- and hafnium-bearing minerals with economic value at present. The main ore deposits worldwide are heavy-mineral sands produced by the weathering and erosion of preexisting rocks and the concentration of zircon and other economically important heavy minerals, such as ilmenite and rutile (for titanium), chromite (for chromium), and monazite (for rare-earth elements) in sedimentary systems, particularly in coastal environments. In coastal deposits, heavy-mineral enrichment occurs where sediment is repeatedly reworked by wind, waves, currents, and tidal processes. The resulting heavy-mineral-sand deposits, called placers or paleoplacers, preferentially form at relatively low latitudes on passive continental margins and supply 100 percent of the world’s zircon. Zircon makes up a relatively small percentage of the economic heavy minerals in most deposits and is produced primarily as a byproduct of heavy-mineral-sand mining for titanium minerals. From 2003 to 2012, world zirconium mineral concentrates production increased by more than 40 percent, and Australia and South Africa were the leading producers. Global consumption of zirconium mineral concentrates generally increased during the same time period, largely as a result of increased demand in developing economies in Asia and the Middle East. Global demand weakened in 2012, causing a decrease in world production of zirconium mineral concentrates and delaying the development of several new mining projects. Global consumption is expected to increase in the future, however, as demand from the ceramics, chemicals, and metals industries increases (driven by renewed growth in developing economies) and demand for zirconium and hafnium metal increases (driven by the construction and operation of new nuclear powerplants). The behaviors of zirconium and hafnium in the environment are very similar to one another in that most zirconium- and hafnium-bearing minerals have limited solubility and reactivity. Anthropogenic sources of zirconium, and likely hafnium, are from industrial zirconium-containing byproducts and emissions from the processing of sponge zirconium, and exposure to the general population from these sources is small. Zirconium and hafnium are likely not essential to human health and generally are considered to be of low toxicity to humans. The main exposure risks are associated with industrial inhalation and dermal exposure. Because of the low solubility of zirconium and hafnium, ecological health concerns in the aquatic environment and in soils are minimal. Heavy-mineral-sand mining may lead to increased erosion rates when the mining is managed improperly. In addition, surface mining requires removal of the overlying organic soil layer and produces waste material that includes tailings and slimes. The soil removal and mining activity disturbs the surrounding ecosystem and alters the character of the landscape. Dry mineral separation processes create high amounts of airborne dust, whereas wet mineral separation processes do not. In operations that restore the landscape to pre-mining conditions, the volume of waste and the impact on the landscape may be relatively temporary.

Professional Paper↗

USGS2011

Historical bathymetry and bathymetric change in the Mississippi-Alabama coastal region, 1847-2009

Land loss and seafloor change around the Mississippi and Alabama (MS-AL) barrier islands are of great concern to the public and to local, state, and federal agencies. The islands provide wildlife protected areas and recreational land, and they serve as a natural first line of defense for the mainland against storm activity (index map on poster). Principal physical conditions that drive morphological seafloor and coastal change in this area include decreased sediment supply, sea-level rise, storms, and human activities (Otvos, 1970; Byrnes and others, 1991; Morton and others, 2004; Morton, 2008). Seafloor responses to the same processes can also affect the entire coastal zone. Sediment eroded from the barrier islands is entrained in the littoral system, where it is redistributed by alongshore currents. Wave and current activity is partially controlled by the profile of the seafloor, and this interdependency along with natural and anthropogenic influences has significant effects on nearshore environments. When a coastal system is altered by human activity such as dredging, as is the case of the MS-AL coastal region, the natural state and processes are altered, and alongshore sediment transport can be disrupted. As a result of deeply dredged channels, adjacent island migration is blocked, nearshore environments downdrift in the littoral system become sediment starved, and sedimentation around the channels is modified. Sediment deposition and erosion are reflected through seafloor evolution. In a rapidly changing coastal environment, understanding historically where and why changes are occurring is essential. To better assess the comprehensive dynamics of the MS-AL coastal zone, a 160-year evaluation of the bathymetry and bathymetric change of the region was conducted.

Scientific Investigations Map↗

USGS2006

A cyclostratigraphic and borehole-geophysical approach to development of a three-dimensional conceptual hydrogeologic model of the karstic Biscayne aquifer, southeastern Florida

A fundamental problem in the simulation of karst ground-water flow and solute transport is how best to represent aquifer heterogeneity as defined by the spatial distribution of porosity, permeability, and storage. Combined analyses of cyclostratigraphy, including lithofacies and depositional environments, and borehole-geophysical logs, has improved the conceptualization of porosity, permeability, and storage within the triple-porosity karstic Biscayne aquifer in an approximately 95-square-mile study area of Miami-Dade County in southeastern Florida. The triple porosity of the Biscayne aquifer is principally: (1) matrix of interparticle and separate-vug porosity, providing much of the storage, and under dynamic conditions, diffuse-carbonate flow; (2) touching-vug porosity creating stratiform ground-water flow passageways; and (3) less common conduit porosity composed mainly of bedding-plane vugs, thin solution pipes, and cavernous vugs. These three conduit porosity types are all pathways for conduit ground-water flow. To develop an accurate three-dimensional conceptual hydrogeologic model of the Biscayne aquifer in the study area, a detailed analysis of data was conducted that include continuously drilled cores, digital borehole images, borehole-fluid conductivity and temperature logs, and borehole-flowmeter measurements from 25 wells that fully penetrate the Biscayne aquifer. Six depositional environments for major lithologic components of the Biscayne aquifer--the Tamiami Formation, Fort Thompson Formation, and Miami Limestone--include: (1) middle ramp, (2) platform margin-to-outer platform, (3) open-marine platform interior, (4) restricted platform interior, (5) brackish platform interior, and (6) freshwater terrestrial environments. High-frequency cycles form the fundamental building blocks of the rocks composing the Biscayne aquifer. Vertical lithofacies successions, which have stacking patterns that reoccur, fit within the high-frequency cycles. Upward-shallowing subtidal cycles, upward-shallowing paralic cycles, and aggradational subtidal cycles define three types of ideal high-frequency cycles that occur within the Fort Thompson Formation and Miami Limestone. Based on vertical cycle patterns, high-frequency cycles group into two cycle sets: an older progradational cycle set and an overlying younger aggradational cycle. A primary observation is that a predictable vertical pattern of porosity and permeability commonly exists within the three ideal cycles because the porosity and permeability relate directly to lithofacies. Sixteen major lithofacies of the Fort Thompson Formation and Miami Limestone have been assigned to one of three pore classes (I, II, and III). Touching-vug porosity and conduit porosity characterize pore class I, which commonly comprises the lower part of upward-shallowing cycles within the Fort Thompson Formation and an upper aggradational cycle of the Miami Limestone. Matrix porosity distinguishes pore class II, which commonly occurs in the upper part of the upward-shallowing subtidal cycles and middle part of the upward-shallowing paralic cycles. Micrite-dominated, leaky, low-permeability lithologies are characteristic of pore class III, which commonly caps upward-shallowing paralic cycles and occurs throughout much of a lower aggradational cycle of the Miami Limestone. These relations among lithofacies, cyclicity, and aquifer attributes (porosity, permeability, and storage) are crucial features of the architecture of a three-dimensional conceptual hydrogeologic model of the karstic Biscayne aquifer. This study shows that development of these relations is critical to producing a realistic cycle-based karstic aquifer framework for the Biscayne aquifer and for karst aquifers within other platform carbonates.

Florida↗

USGS2007

Ground water redox zonation near La Pine, Oregon: Relation to river position within the aquifer–riparian zone continuum

Increasing residential development since in the 1960s has lead to increases in nitrate concentrations in shallow ground water in parts of the 247 square mile study area near La Pine, Oregon. Denitrification is the dominant nitrate-removal process that occurs in suboxic ground water, and suboxic ground water serves as a barrier to transport of most nitrate in the aquifer. Oxic ground water, on the other hand, represents a potential pathway for nitrate transport from terrestrial recharge areas to the Deschutes and Little Deschutes Rivers. The effects of present and potential future discharge of ground-water nitrate into the nitrogen-limited Deschutes and Little Deschutes Rivers are not known. However, additions of nitrogen to nitrogen-limited rivers can lead to increases in primary productivity which, in turn, can increase the magnitudes of dissolved oxygen and pH swings in river water. An understanding of the distribution of oxic ground water in the near-river environment could facilitate understanding the vulnerability of these rivers and could be a useful tool for management of these rivers. In this study, transects of temporary wells were installed in sub-river sediments beneath the Deschutes and Little Deschutes Rivers near La Pine to characterize near-river reduction/oxidation (redox) conditions near the ends of ground-water flow paths. Samples from transects installed near the center of the riparian zone or flood plain were consistently suboxic. Where transects were near edges of riparian zones, most ground-water samples also were suboxic. Oxic ground water (other than hyporheic water) was uncommon, and was only detected near the outside edge of some meander bends. This pattern of occurrence likely reflects geochemical controls throughout the aquifer as well as geochemical processes in the microbiologically active riparian zone near the end of ground-water flow paths. Younger, typically less reduced ground water generally enters near-river environments through peripheral zones, whereas older, typically more reduced ground water tends to discharge closer to the center of the river corridor. Such distributions of redox state reflect ground-water movement and geochemical evolution at the aquifer-scale. Redox state of ground water undergoes additional modification as ground water nears discharge points in or adjacent to rivers, where riparian zone processes can be important. Lateral erosion of river systems away from the center of the flood plain can decrease or even eliminate interactions between ground water and reducing riparian zone sediments. Thus, ground water redox patterns in near-river sediments appear to reflect the position of a river within the riparian zone/aquifer continuum. Spatial heterogeneity of redox conditions near the river/aquifer boundary (that is, near the riverbed) makes it difficult to extrapolate transect-scale findings to a precise delineation of the oxic-suboxic boundary in the near-river environment of the entire study area. However, the understanding of relations between near-river redox state and proximity to riparian zone edges provides a basis for applying these results to the study-area scale, and could help guide management efforts such as nitrogen-reduction actions or establishment of Total Maximum Daily Load criteria. Coupling the ground-water redox-based understanding of river vulnerability with ground-water particle-tracking-based characterization of connections between upgradient recharge areas and receiving rivers demonstrates one means of linking effects of potential nitrate loads at the beginning of ground-water flow paths with river vulnerability.

Oregon↗

USGS2007

An Assessment of the Potential Effects of Aquifer Storage and Recovery on Mercury Cycling in South Florida

Mercury contamination in the environment is a global concern, especially in areas with abundant wetlands, such as south Florida. As the causal factors of this concern improve, scientists find that many factors that do not necessarily affect mercury concentrations, such as flooding and drying cycles, or changes to carbon and sulfate loading, can profoundly affect net mercury toxicity. Especially important are ecological factors that alter the conversion of mercury to methylmercury, which is the most bioaccumulative and toxic form of mercury in the environment. Resource managers, therefore, need to be aware of possible deleterious affects to mercury toxicity that could result from land and water management decisions. Several aspects of the Comprehensive Everglades Restoration Plan (CERP), including the planned Aquifer Storage and Recovery (ASR) program, have the potential to affect the abundance of methylmercury. In response to these concerns, the U.S. Geological Survey and U.S. Army Corps of Engineers collaborated on a study to evaluate how the proposed ASR program may affect mercury cycling and toxicity. This project was conducted as an initial assessment of the possible effects of the CERP ASR program on mercury in the south Florida environment. A twofold approach was employed: field sampling and controlled laboratory benchmark experiments. The field sampling survey collected ground-water samples from the Floridan and surficial aquifer systems for the ASR program to determine existing levels of mercury and methylmercury. Laboratory experiments, on the other hand, were designed to determine how the injected surface water would interact with the aquifer during storage periods. Overall, very low levels of mercury and methylmercury (mean values of 0.41 and 0.07 nanograms per liter, respectively) were observed in ground-water samples collected from the Floridan and surficial aquifer systems. These results indicate that 'recovered water' from the CERP ASR program would not represent a significant additional direct load of mercury and methyl-mercury to ASR 'receiving waters'. Net production of methylmercury, however, can result from additions of sulfate or natural organic carbon. Thus, because the Upper Floridan aquifer generally has elevated concentrations of sulfate (relative to ambient Everglades conditions) and surface waters near Lake Okeechobee (the assumed target for ASR receiving waters) are elevated in organic carbon and sulfate, at least some potential for increased methylmercury production might arise from the release of recovered ASR water to locations in or near the Everglades.

Scientific Investigations Report↗

USGS2009

Impact of wildfire on levels of mercury in forested watershed systems: Voyageurs National Park, Minnesota

Atmospheric deposition of mercury to remote lakes in mid-continental and eastern North America has increased approximately threefold since the mid-1800s (Swain and others, 1992; Fitzgerald and others, 1998; Engstrom and others, 2007). As a result, concerns for human and wildlife health related to mercury contamination have become widespread. Despite an apparent recent decline in atmospheric deposition of mercury in many areas of the Upper Midwest (Engstrom and Swain, 1997; Engstrom and others, 2007), lakes in which fish contain levels of mercury deemed unacceptable for human consumption and possibly unacceptable for fish-consuming wildlife are being detected with increasing frequency. In northern Minnesota, Voyageurs National Park (VNP) (fig. 1) protects a series of southern boreal lakes and wetlands situated on bedrock of the Precambrian Canadian Shield. Mercury contamination has become a significant resource issue within VNP as high concentrations of mercury in loons, bald eagle eaglets, grebes, northern pike, and other species of wildlife and fish have been found. The two most mercury-contaminated lakes in Minnesota, measured as methylmercury in northern pike ( Esox lucius ), are in VNP. Recent multidisciplinary U.S. Geological Survey (USGS) research demonstrated that the bulk of the mercury in lake waters, soils, and fish in VNP results from atmospheric deposition (Wiener and others, 2006). The study by Wiener and others (2006) showed that the spatial distribution of mercury in watershed soils, lake waters, and age-1 yellow perch ( Perca flavescens ) within the Park was highly variable. The majority of factors correlated for this earlier study suggested that mercury concentrations in lake waters and age-1 yellow perch reflected the influence of ecosystem processes that affected within-lake microbial production and abundance of methylmercury (Wiener and others, 2006), while the distribution of mercury in watershed soils seemed to be partially dependent on forest disturbance, especially the historic forest fire pattern (Woodruff and Cannon, 2002). Forest fire has an essential role in the forest ecosystems of VNP (Heinselman, 1996). Because resource and land managers need to integrate both natural wildfire and prescribed fire in management plans, the potential influence of fire on an element as sensitive to the environment as mercury becomes a critical part of their decisionmaking. A number of recent studies have shown that while fire does have a significant impact on mercury at the landscape level, the observed effects of fire on aquatic environments are highly variable and unpredictable (Caldwell and others, 2000; Garcia and Carrigan, 2000; Kelly and others, 2006; Nelson and others, 2007). Caldwell and others (2000) described an increase in methylmercury in reservoir sediments resulting from mobilization and transport of charred vegetative matter following a fire in New Mexico. Krabbenhoft and Fink (2000) attributed increases in total mercury concentrations in young-of-the-year fish in the Florida Everglades to release of mercury resulting from peat oxidation following fires. A fivefold increase in whole-body mercury accumulation by rainbow trout ( Oncorhynchus mykiss ) following a fire in Alberta, Canada, apparently resulted from increased nutrient concentrations that enhanced productivity and restructured the food web of a lake within the fire’s burn footprint (Kelly and others, 2006). For this study, we determined the short-term effects of forest fire on mercury concentrations in terrestrial and aquatic environments in VNP by comparing and contrasting mercury concentrations in forest soils, lake waters, and age-1 yellow perch for a burned watershed and an adjacent lake, with similar samples from watersheds and lakes with no fire activity (control watersheds and lakes). The concentration of total mercury in whole, 1-year-old yellow perch serves as a good biological indicator for monitoring trends in methylmercury concentrations in food webs of lakes in North America (Wiener and others, 2007). With a limited gape, age-1 yellow perch that hatched the previous year and resided in a lake for 1 year feed largely on zooplankton and small benthic invertebrates. Thus, age-1 yellow perch provide a baseline for methylmercury concentrations for individual lakes that can be compared across spatial areas. The nine appendixes that accompany this report contain the complete datasets for soils, lake waters, and age-1 yellow perch collected for this study. This report uses data from these three media to provide a framework for evaluating short-term effects of fire on mercury in forested soils and possible effects of the mobilization of mercury from soils on lake water quality and aquatic health.

Minnesota↗

USGS2011

Evaluation of LiDAR-acquired bathymetric and topographic data accuracy in various hydrogeomorphic settings in the Deadwood and South Fork Boise Rivers, West-Central Idaho, 2007

High-quality elevation data in riverine environments are important for fisheries management applications and the accuracy of such data needs to be determined for its proper application. The Experimental Advanced Airborne Research LiDAR (Light Detection and Ranging)-or EAARL-system was used to obtain topographic and bathymetric data along the Deadwood and South Fork Boise Rivers in west-central Idaho. The EAARL data were post-processed into bare earth and bathymetric raster and point datasets. Concurrently with the EAARL surveys, real-time kinematic global positioning system surveys were made in three areas along each of the rivers to assess the accuracy of the EAARL elevation data in different hydrogeomorphic settings. The accuracies of the EAARL-derived raster elevation values, determined in open, flat terrain, to provide an optimal vertical comparison surface, had root mean square errors ranging from 0.134 to 0.347 m. Accuracies in the elevation values for the stream hydrogeomorphic settings had root mean square errors ranging from 0.251 to 0.782 m. The greater root mean square errors for the latter data are the result of complex hydrogeomorphic environments within the streams, such as submerged aquatic macrophytes and air bubble entrainment; and those along the banks, such as boulders, woody debris, and steep slopes. These complex environments reduce the accuracy of EAARL bathymetric and topographic measurements. Steep banks emphasize the horizontal location discrepancies between the EAARL and ground-survey data and may not be good representations of vertical accuracy. The EAARL point to ground-survey comparisons produced results with slightly higher but similar root mean square errors than those for the EAARL raster to ground-survey comparisons, emphasizing the minimized horizontal offset by using interpolated values from the raster dataset at the exact location of the ground-survey point as opposed to an actual EAARL point within a 1-meter distance. The average error for the wetted stream channel surface areas was -0.5 percent, while the average error for the wetted stream channel volume was -8.3 percent. The volume of the wetted river channel was underestimated by an average of 31 percent in half of the survey areas, and overestimated by an average of 14 percent in the remainder of the survey areas. The EAARL system is an efficient way to obtain topographic and bathymetric data in large areas of remote terrain. The elevation accuracy of the EAARL system varies throughout the area depending upon the hydrogeomorphic setting, preventing the use of a single accuracy value to describe the EAARL system. The elevation accuracy variations should be kept in mind when using the data, such as for hydraulic modeling or aquatic habitat assessments.

Idaho↗

USGS2017

Spatial variability of harmful algal blooms in Milford Lake, Kansas, July and August 2015

Cyanobacterial harmful algal blooms (CyanoHABs) tend to be spatially variable vertically in the water column and horizontally across the lake surface because of in-lake and weather-driven processes and can vary by orders of magnitude in concentration across relatively short distances (meters or less). Extreme spatial variability in cyanobacteria and associated compounds poses unique challenges to collecting representative samples for scientific study and public-health protection. The objective of this study was to assess the spatial variability of cyanobacteria and microcystin in Milford Lake, Kansas, using data collected on July 27 and August 31, 2015. Spatially dense near-surface data were collected by the U.S. Geological Survey, nearshore data were collected by the Kansas Department of Health and Environment, and open-water data were collected by U.S. Army Corps of Engineers. CyanoHABs are known to be spatially variable, but that variability is rarely quantified. A better understanding of the spatial variability of cyanobacteria and microcystin will inform sampling and management strategies for Milford Lake and for other lakes with CyanoHAB issues throughout the Nation. The CyanoHABs in Milford Lake during July and August 2015 displayed the extreme spatial variability characteristic of cyanobacterial blooms. The phytoplankton community was almost exclusively cyanobacteria (greater than 90 percent) during July and August. Cyanobacteria (measured directly by cell counts and indirectly by regression-estimated chlorophyll) and microcystin (measured directly by enzyme-linked immunosorbent assay [ELISA] and indirectly by regression estimates) concentrations varied by orders of magnitude throughout the lake. During July and August 2015, cyanobacteria and microcystin concentrations decreased in the downlake (towards the outlet) direction. Nearshore and open-water surface grabs were collected and analyzed for microcystin as part of this study. Samples were collected in the uplake (Zone C), midlake (Zone B), and downlake (Zone A) parts of the lake. Overall, no consistent pattern was indicated as to which sample location (nearshore or open water) had the highest microcystin concentrations. In July, the maximum microcystin concentration observed in each zone was detected at a nearshore site, and in August, maximum microcystin concentrations in each zone were detected at an open-water site. The Kansas Department of Health and Environment uses two guidance levels (a watch and a warning level) to issue recreational public-health advisories for CyanoHABs in Kansas lakes. The levels are based on concentrations of microcystin and numbers of cyanobacteria. In July and August, discrete water-quality samples were predominantly indicative of warning status in Zone C, watch status in Zone B, and no advisories in Zone A. Regression-estimated microcystin concentrations, which provided more thorough coverage of Milford Lake ( n =683–720) than discrete samples ( n =21–24), generally indicated the same overall pattern. Regardless of the individual agencies sampling approach, the overall public-health advisory status of each zone in Milford Lake was similar according to the Kansas Department of Health and Environment guidance levels.

Kansas↗