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USGS2025

Extremophile hotspots linked to containerized industrial waste dumping in a deep-sea basin

Decaying barrels on the seafloor linked to DDT contamination have raised concerns about the public health implications of decades old industrial waste dumped off the coast of Los Angeles. To explore their contents, we collected sediment cores perpendicular to five deep-sea barrels. The concentration of DDT and its breakdown products were highly elevated relative to control sites yet did not vary with distance from the barrels, suggesting that they were not associated with the contamination. Sediment cores collected through white halos surrounding three barrels were enriched in calcite and had elevated pH. The associated microbial communities were low diversity and dominated by alkalophilic bacteria with metagenome-assembled genomes adapted to high pH. A solid concretion sampled between a white halo and barrel was composed of brucite, a magnesium hydroxide mineral that forms at high pH. Based on these findings, we postulate that leakage of containerized alkaline waste triggered the formation of mineral concretions that are slowly dissolving and raising the pH of the surrounding sediment pore water. This selects for taxa adapted to extreme alkalinity and drives the precipitation of “anthropogenic” carbonates forming white halos, which serve as a visual identifier of barrels that contained alkaline waste. Remarkably, containerized alkaline waste discarded >50 years ago represents a persistent pollutant creating localized mineral formations and microbial communities that resemble those observed at some hydrothermal systems. These formations were observed at one-third of the visually identified barrels in the San Pedro Basin and have unforeseen, long-term consequences for benthic communities in the region.

California↗

USGS2024

Analysis of factors affecting plume remediation in a sole-source aquifer system, southeastern Nassau County, New York

Several plumes of dissolved, chlorinated solvents, including trichloroethylene, have been identified in a sole-source aquifer near the former Northrop Grumman Bethpage Facility and Naval Weapons Industrial Reserve Plant sites in southeastern Nassau County, New York. Past investigations have documented that the groundwater contamination originated from this industrial area and now extends to the south, in the direction of groundwater flow. The intermixed plumes are commonly referred to as the “Navy Grumman groundwater plume.” Detailed groundwater-flow modeling was needed for the New York State Department of Environmental Conservation (NYSDEC) to evaluate design options necessary for the construction, operation, optimization, maintenance, and monitoring of a groundwater extraction and treatment cleanup plan selected in a December 2019 Amended Record of Decision by the NYSDEC to comprehensively address these plumes. Consequently, the NYSDEC began a cooperative study with the U.S. Geological Survey in 2020 to better understand the local hydrogeologic framework using two independent approaches to characterize aquifer heterogeneity and update an existing regional groundwater-flow model to provide transient boundary conditions for new inset groundwater-flow models of the plume area. We developed these detailed inset models for the two independent aquifer characterizations using history-matching techniques coupled with a novel approach to risk-based management optimization of the remedial design. We also used the updated regional model to assess this optimized groundwater extraction and treatment design for potential saltwater intrusion. The ensembles of parameters resulting from history matching provided a platform with which to evaluate capture by water-supply and remedial wells using particle-tracking techniques. Using the ensemble to select a risk stance, we performed multiobjective optimization to identify various configurations of remedial pumping that are consistent with external constraints and that favor potentially competing objectives. Multiple solutions provide tradeoffs that NYSDEC can consider. In general, pumping redistribution may help to prevent further contamination migration downgradient. These and other study results are intended to support decisions for the remedial design focused on the local area encompassing the full extent of the Navy Grumman groundwater plume.

New York↗

USGS2024

Framework for implementing damping scaling factors in U.S. Geological Survey National Seismic Hazard Models

Traditionally, probabilistic seismic hazard analysis (PSHA) has focused on calculating ground motion hazard curves for elastic, 5%-damped pseudo spectral accelerations, Sa(T,5%), which are used as the basis for engineering design parameters and targets for ground motion selection and modification. However, structures and geotechnical systems can exhibit a wide range of damping ratios both above and below the 5% level, depending on the construction material, structural system, nonstructural elements, or subsurface soil properties. When spectral parameters at such damping levels are required for certain applications, 5%-damped accelerations have traditionally been extracted from PSHA-based hazard curves and adjusted outside of the hazard integral using damping scaling factors (DSF) such as those from Newmark & Hall (1982). Recent advances in the development of more rigorous and comprehensive damping scaling models (e.g., Rezaeian et al., 2014; Rezaeian et al., 2021) have allowed for the modeling of means and standard deviations of DSFs as functions of earthquake source and path properties for crustal, intraslab, and subduction interface tectonic environments. These DSF models can be applied to ground motion model (GMM) estimates of Sa(T,5%) for a given earthquake rupture scenario to produce a corresponding mean and standard deviation Sa at a specified damping ratio β, Sa(T,β). In this study, the DSF models of Rezaeian et al. (2014) and Rezaeian et al. (2021) are implemented within the U.S. Geological Survey National Seismic Hazard Model (NSHM) PSHA framework to calculate probabilistic hazard curves for spectral accelerations at damping ratios from 0.5% to 30%. The DSF models are applied directly to the mean and standard deviation of Sa(T,5%) predictions from each GMM in the NSHM logic tree. Resulting hazard curves and uniform hazard and risk spectra for Sa(T,β) are presented for several geographic locations and compared with corresponding spectra estimated using current design practices by applying the same DSFs outside of the PSHA calculation. Key differences between the two methods for estimating Sa(T,β) are discussed, and potential strategies are presented for the implementation and usage of the hazard-consistent Sa(T,β) in building codes. Comparing the results to those from DSFs used in current design practices that are mainly based on Newmark & Hall (1982) is not explored in this study.

Conference Paper↗

USGS1973

Geohydrology of the Cross-Florida Barge Canal area, with special reference to the Ocala vicinity

The Cross-Florida Barge Canal route commences at Palatka on the St. Johns River, about 75 miles upstream from the Atlantic Ocean, and extends 110 miles southwestward across Peninsular Florida into deep water in the Gulf of Mexico near Yankeetown. The canal will be equipped with five locks, each 600 feet long and 84 feet wide, and the channel will be a minimum of 12 feet deep and 150 feet wide. From near Ocala northeastward, the canal channel will replace much of the natural channel of the Oklawaha River, and will be excavated into beds of the so-called shallow sand aquifer of Miocene age and younger, which overlies limestone of the Floridan aquifer. Westward from Ocala, most of the canal will be excavated below the potentiometric surface into limestone and dolomite of the Floridan aquifer. Water levels of Rodman, Eureka, and Inglis Pools will be controlled by dams and spillways with the limited exchange of water between the pools and the aquifers. The water levels in the Summit Pools will fluctuate with the natural changes in the ground-water level of the Floridan aquifer, although the stage of the pool will be controlled partly by the stage held in the Eureka Pool. A dynamic inflow-outflow relationship will exist between the Summit Pool and the Floridan aquifer. The Floridan aquifer in the canal area is 1,000 to 1,200 feet thick and consists of limestone and dolomite of middle Eocene Miocene age, including from older to younger, the Lake City, Avon Park, and Ocala limestones plus permeable sandy, dolomitic limestone in the lower part of the Hawthorn Formation. It is possible that most of the flow to the two major springs in the area occurs in the upper 100 feet or so of the aquifer in the Ocala Limestone. The aquifer is underlain by the Oldsmar limestone of early Eocene age and is overlain by sand, clayey sand, clay and shell beds of Miocene through Holocene age, in thickness from a few feet to 300 feet. The permeable beds overlying the Floridan aquifer constitute the shallow aquifer, while the poorly permeable ones act as confining beds where the Floridan aquifer is under artesian conditions. A north-south line drawn separating the head of Silver Springs on the west from the Oklawaha River on the east marks the approximate western limit of a continuous blanket of materials of Miocene-Pliocene(?) age covering the rocks of the Floridan aquifer. East of the line, much of the aquifer is under artesian conditions, particularly in the Oklawaha River valley, although in some areas east of the valley, direct recharge through thick permeable Miocene-Pliocene(?) sands occurs. West of the line, only scattered remnants of a once continuous Miocene-Pliocene(?) cover remain. Lack of the cover is a result of erosion on the crest and flank of the Ocala Uplift, a broad northwest-southeast trending anticlinal upwarp, the axis of which is crossed by the canal route in the Dunnellon area. Over most of this area the Floridan aquifer is unconfined and receives direct recharge through a cover of a few tens of feet of sand and clayey sand of Quaternary age. Tensional stresses during the structural evolution of the Ocala Uplift produced an intersecting system of fractures and normal faults in rocks of the Floridan aquifer. The fractures and faults are important controls for orientation of solution channels and, therefore, for development of ground-water circulation patterns. When the system surface streams, which once drained the Barge Canal area, eroded the poorly permeable Miocene-Pliocene(?) cover from the flanks of the Ocala Uplift, surface runoff was reduced and precipitation began to directly infiltrate the underlying limestones. Now only principal streams remain, such as the Oklawaha and Withlacoochee Rivers and a few short tributaries, while one of the most highly developed subsurface drainage systems in the world has evolved in cavernous limestone of the Floridan aquifer. Two of the larger freshwater springs in the world now discharge from the Floridan aquifer in the canal area. Silver Springs near Ocala discharges an average 531 mgd (million gallons per day) down the 4-mile long Silver River, which flows on poorly permeable beds to the Oklawaha River. Rainbow Springs near Dunnellon discharges on average 468 mgd from numerous orifices in the bed of the 5-mile-long Rainbow River, which flows into the Withlacoochee River. The heads of the springs have migrated to their present positions partly because of a tendency of ground-water levels to decline as permeability in the aquifer is increased due to removal of limestone by solution, and because of mechanical erosion of the limestone in the vicinity of the spring heads. Also, points of principal spring discharges have shifted in the past due to changes in ground-water levels in response to changes in sea level. The subsurface drainage system is continuing to evolve today, as evidenced in part by frequent occurrence of new sinkholes and by the presence of significant amounts of calcium bicarbonate in the spring waters. Rodman Pool, at the east end of the canal, is separated from the Floridan aquifer by poorly permeable materials. The pool's operating water level will be only a few feet above the potentiometric surface at the downstream end, and at or slightly below the potentiometric surface at the upstream end. Little exchange of water between the Rodman Pool and the Floridan aquifer is expected. Eureka Pool, just upstream from Rodman Pool, will also be separated from the Floridan aquifer by poorly permeable beds. However, the stage of the pool will be about 15 feet higher than the natural potentiometric surface at the pool's downstream end, and some seepage into the Floridan aquifer is anticipated through faults and leaky parts of the poorly permeable beds, with a consequent rise in ground-water levels in areas adjacent to the lower end of the pool. Possibilities for particulate contamination of the aquifer will tend to be minimized because of the filtering capacity of the materials through which water must pass to reach the aquifer, although the natural filter will not preclude movement into the aquifer of contaminants which might become dissolved in the pool waters. No significant interchange of water between the pool and the aquifer is expected at the upstream end of the Eureka Pool. Present construction plans indicate an operating stage for Eureka Pool which will range between 38 and 40 feet above mean sea level, although it is possible to dredge the pool deep enough to permit a range in stage of 36 to 40 feet. A backwater effect extending up Silver River from the Eureka Pool is expected to regulate the stage at the head of Silver Springs between 39 and 44 feet above mean sea level if the pool ranges between 36 and 40 feet. If Eureka Pool ranges only between 38 and 40 feet, the range of stage at the head of the springs should be about 41 to 44 feet above mean sea level. From Inglis Lock west, the canal will have direct connection with the Gulf, and canal stage will fluctuate with the Gulf tide. Since the canal stage will be slightly lower than the adjacent ground-water levels along much of the reach, there will be some ground-water inflow to the canal. No significant changes in the existing ground-water regime are expected in the vicinity of Inglis Pool, the first step up in the canal east of the Gulf. Existing ground-water and surface-water levels in the area will not change appreciable, and the natural stage and flow of Rainbow Springs, which will flow by way of Rainbow River into Inglis Pool, should not be affected by canal operations. A possible adverse effect of the canal on the Inglis Pool area could result if sea water is locked up from the Gulf through Inglis Lock. However, the high step of 25 feet at the lock, flushing action of continuous flow from Inglis Pool to the lower reaches of the Withlacoochee River, and use of possible preventive locking procedures should minimize the problem. The potential for adverse effects on the ground-water regime is greatest in the area of the Summit Pool. Through most of the length of the pool, the canal channel will be excavated into limestone of the Floridan aquifer to depths of 12 to 27 feet below the potentiometric surface. Changes that will take place in the ground-water flow system in the Silver Springs drainage area, once the canal is completed, were estimated by flow-net analysis. Variation in aquifer transmissivity was determined by calculating transmissivity in 25 different flow cells surrounding Silver Springs. Transmissivity in the 25 cells averages about 15,600,000 gpd/ft [2,090,000 ft2/day (feet squared)], but transmissivity in the six cells through which the Summit Pool passes ranges from 9,000,000 to 44,000,000 gpd/ft (1,210,000 to 5,900,000 ft2/day). Transmissivity was used to compute static stage of the Summit Pool under given ground-water level conditions. Had the canal existed in May 1968 and had the stage of Eureka Pool been held at 36 feet at the time, the static stage in Summit Pool would have been about 42.1 feet above mean sea level. Thus, a conceptual model of the changes in the potentiometric surface wrought by the finished canal was drawn, and zones of ground-water inflow and outflow were delineated. Most outflow from the Summit Pool to the aquifer should be limited to one 4-mile-long zone along the north side of the pool, about 5 miles south of Silver Springs. It is estimated that a water volume equivalent to about 8 percent of the daily flow of Silver Springs will enter the Summit Pool each day from the southern one-third of the Silver Springs drainage area. A like amount will reenter the aquifer at the main zone of outflow and move toward Silver Springs at an estimated average velocity of about 200 feet per day, if something close to the natural static stage of the pool is maintained by return pumpage of the lockage losses. At a velocity of 200 feet per day, water from the Summit Pool would discharge at Silver Springs about 140 days later. However, any estimate of velocity in the highly cavernous limestone aquifer in the area should be used with caution, because difficult to measure changes in porosity and thickness of major zones of flow may cause large variations in velocity. If all lockage losses are returned to the Summit Pool by pumping from Eureka Pool, no net loss from the Silver Springs drainage area, except for some evaporation from the water surface in the canal and possible leakage around locks, will result from canal operations. The zone of outflow from the Summit Pool to the aquifer will be in a natural potentiometric trough, and the zone of inflow will be in a potentiometric ridge area. The equilibrium water level in the pool will tend to be about 1 foot higher than the altitude of the lowest level in the pre-canal potentiometric trough, and about 2 feet lower than the highest level on the pre-canal potentiometric ridge. West of the Silver Springs drainage area just east of Dunnellon Lock, in the area of a local potentiometric high, the water level in the Summit Pool is expected to be about 15 feet below the natural potentiometric surface. In most areas 2 to 3 miles away from the Summit Pool, effects of the canal on the natural potentiometric surface should be slight. The stage of the Summit Pool, judging from the 36-year record for ground-water level changes and the anticipated indirect effect of the controlled stage in Eureka Pool, should have a maximum of about 10.5 feet with a maximum water level of about 51.5 feet above mean sea level and a minimum of about 41.0 feet above mean sea level. Of particular importance in the Summit Pool is an implementation of well planned construction and operational procedures designed to minimize risks of ground-water contamination.

Florida↗

USGS2025

Site response and wave propagation effects in the eastern United States

Fourier amplitude spectra from regional earthquakes in the eastern United States are used in a parametric inversion for source, path, and site effects. Five earthquakes are selected for analysis during the installation of the United States National Seismic Network (US), Earthscope’s USArray Transportable Array (TA), and other temporary arrays to maximize station coverage. A global search algorithm is used to solve for site response from 0.1 to 15 Hz, corner frequency, geometrical spreading ( r - γ ), and frequency dependent anelastic attenuation in the form Q(f) = Q o f α . Tradeoff between moment and geometric spreading is handled by fixing the moment. The tradeoff between corner frequency and Q(f) is solved by selecting the value of corner frequency that minimizes an objective function defined over all stations. Values of site response and attenuation parameters show a strong spatial correlation with the physiographic provinces of the eastern United States. Site response for the Atlantic Coastal Plain is consistent with previous work using spectral ratios relative to a reference site, defined by strong resonance peaks correlated with the thickness of sediments. Site response for the other physiographic provinces is markedly different from the coastal plain, with a lack of distinct resonance peaks and a broad moderate high at frequences from 0.1 to 0.5 Hz consistent with the hard-rock geology of the regions. Like site response, Q(f) has a strong correlation with physiographic province, showing lower values on the coastal plain and higher values inland. Geometric spreading exponent, γ, decreases with increasing hypocenter distance from just above 1 at a few tens of kilometers to 0.9 at 500 km. The limited range in geometric spreading values is attributed to starting the Fourier transform window at the S ‐wave arrival for all distances and averaging over multiple wave types.

eastern United States↗

USGS2025

Timing of hydrothermal alteration and Au-Sb-W mineralization, Stibnite-Yellow Pine district, Idaho

The Stibnite-Yellow Pine district of central Idaho was mined from the early 1900s until the 1990s, extracting gold, antimony, tungsten, and mercury from veins and disseminated and replacement ores in mountainous terrain along the headwaters of the Salmon River. Mining during the two World Wars supplied critical antimony and tungsten to the war efforts. Recent exploration has delineated mineral resources of over 187 metric tons Au, 274 metric tons Ag, and 93,000 metric tons Sb. Mineralization is hosted in Cretaceous Idaho batholith granitic rocks and a sequence of Neoproterozoic to Paleozoic metasedimentary strata of carbonate and siliciclastic compositions. Historical studies outlined some of the complex paragenesis but debated the absolute age of mineralization. New petrographic and geochronologic work documents a sequence of five hydrothermal events in the Stibnite-Yellow Pine district. Event 1 is related to Cretaceous magmatic and hydrothermal activity and includes events ranging in age from 86 to 75 Ma, including sparse quartz-molybdenite veins dated at 86 Ma. Disseminated gold mineralization of event 2 is associated with sericitic alteration and sulfidation of igneous biotite and replacement of plagioclase by potassium feldspar, largely in granodiorite. Gold is present in zoned arsenian pyrite in both disseminated ores and in crosscutting carbonate-quartz veins containing pyrite and arsenopyrite. The large Yellow Pine deposit, localized at a dilatant bend in the Meadow Creek fault, hosts such disseminated and vein gold. Event 2 is interpreted as the major gold-forming event; 40 Ar/ 39 Ar ages of sericite and potassium feldspar alteration range, respectively, from 70 to 59 and 66 to 56 Ma. The long span is interpreted to reflect the age of gold mineralization and local overprinting by event 3. A narrower range from 66 to 61 Ma is interpreted to date the peak of gold mineralization and alteration. Event 3, tungsten mineralization with scheelite, is texturally later than event 2 gold and localized along the Meadow Creek structure. Event 3 scheelite has been dated by isotope dilution-thermal ionization mass spectrometry (ID-TIMS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb methods at 57 Ma. Event 4, best developed in the West End area, includes gold-silver–bearing quartz-carbonate-pyrite veins and breccias with epithermal textures and potassium feldspar alteration envelopes. Adularia from event 4 yields 40 Ar/ 39 Ar plateau ages of 52 to 51 Ma. Event 5 antimony and mercury mineralization consists of stibnite veins and breccia cements at the Yellow Pine and Hangar Flat deposits as well as cinnabar veins and replacements at the peripheral Fern and Hermes deposits; it is constrained by an LA-ICP-MS U-Pb date on scheelite (ca. 47 Ma) intergrown with stibnite. Minor propylitic and argillic alteration is evident in 47 Ma igneous dikes, which do not contain economic mineralization. The Au-Sb-W ores in the Stibnite-Yellow Pine mining district formed over an extended time period from about 70 to 45 Ma in multiple pulses that were localized along the Meadow Creek fault zone. Each event corresponds to episodes of magmatism and/or hydrothermal activity in the region. Insignificant event 1 skarn and molybdenum mineralization is similar in age to the Thompson Creek porphyry molybdenum deposit in central Idaho. Event 2 gold mineralization occurred during a magmatic gap in central Idaho but was synchronous with magmatism in the Bitterroot lobe further north; event 2 is similar in age to orogenic gold-arsenic mineralization at the Beartrack mine in eastern Idaho. Event 3 scheelite mineralization coincides with tungsten mineralization at the Quartz Creek deposit, late magmatism in the Bitterroot lobe, and rapid exhumation of the Atlanta lobe of the Idaho batholith. Event 4 gold mineralization is coincident with the onset of regional Challis magmatism and extension. Event 5 antimony and mercury mineralization is time-equivalent to epithermal gold mineralization in the nearby Thunder Mountain volcanic field and the peak of Challis magmatism.

Idaho↗

USGS2026

Modeling future groundwater depletion to evaluate sustainability goals set under the Sustainable Groundwater Management Act in the critically overdrafted basins of the Central Valley, California, USA (2020–2070)

In 2014, California's Sustainable Groundwater Management Act (SGMA) mandated local agencies to devise and implement groundwater sustainability plans to address critically overdrafted conditions throughout the state's aquifers. However, the feasibility of these agencies' sustainability goals has not previously been assessed through a regional-scale, integrative lens. Here, we develop and analyze a novel, basin-wide database of 936 sustainability indicator wells located within Central Valley subbasins designated as critically overdrafted, most of which lie in the San Joaquin Valley. Our database shows 2040 groundwater elevation goals vary widely from 60 m above to 80 m below 2020 levels, with variability within and between adjacent subbasins. To evaluate the feasibility of achieving these goals, we coupled the database with a regional hydrologic model (Central Valley Hydrologic Model version 2) and simulated multiple future pumping scenarios. Results show that under increased groundwater demand, 60%–70% of indicator wells may fail to meet their 2040 goals. Even a 50% reduction from 2020 demand levels leaves nearly 40% of wells failing to meet their sustainability thresholds by 2040. Baseline models show that by 2070, up to 70% of wells could fail to meet their goals due to large-scale, spatially connected regions of groundwater depletion. This integrated framework, linking the first region-wide compilation of SGMA indicator wells with a regional groundwater model, demonstrates that many local sustainability goals may be unattainable with substantial (up to 50%) reductions in pumping. Additional management interventions, such as expanded recharge or coordinated demand reductions, may help achieve sustainability goals.

California↗

USGS1998

Water resources of Mellette and Todd counties, South Dakota

Mellette and Todd Counties are located in south-central South Dakota and have a combined area of 2,694 square miles. The White River and its tributaries, which include the Little White River, drain Mellette County and about one-half of Todd County. Tributaries to the Niobrara River, which include the Keya Paha River, drain the other one-half of Todd County. The average discharge of the Little White River is about 56 cubic feet per second as the river enters Todd County and is about 131 cubic feet per second as it discharges to the White River in northern Mellette County. The average discharge of the Keya Paha River just outside Todd County is about 39 cubic feet per second. The average annual runoff for Mellette and Todd Counties ranges from 0.94 to 2.36 inches based on records from nine streamflow-gaging stations in and near the counties. The average annual runoff is 1.62 inches, which compares with the average annual precipitation of about 19 inches. In Todd County, shallow wells completed in the alluvial, Ogallala, Arikaree, and White River aquifers generally can supply water that has low concentrations of dissolved solids, is fresh, and is soft to moderately hard. Ground water from shallow aquifers is limited in Mellette County; therefore, deep wells, often greater than 1,000 feet, are sometimes installed. The Pierre Shale often is used to supply rural domestic and stock wells in Mellette County even though well yields are low and the water has high dissolved solids, is moderately saline, and is very hard. Alluvial aquifers are present in both counties and store an estimated 1.6 million acre-feet of water. The water quality of the alluvial aquifers is dependent on the underlying deposits, and generally the water has low concentrations of dissolved solids, is fresh, and is soft to moderately hard where underlain by the Ogallala and Arikaree Formations; has moderate concentrations of dissolved solids, is slightly saline, and is hard where underlain by the White River Group; and has high concentrations of dissolved solids, is saline, and is very hard where underlain by the Pierre Shale. Also, yields often are lower where the alluvial aquifers are underlain by the Pierre Shale. The Ogallala aquifer is present in only Todd County, and the Arikaree aquifer is present throughout most of Todd County and southwestern and south-central Mellette County. The Ogallala aquifer contains an estimated 17 million acre-feet of water in storage, and the Arikaree aquifer contains an estimated 50 million acre-feet of water in storage. Both aquifers generally are suitable for irrigation, and yields from these aquifers are sometimes greater than 1,000 gallons per minute. Nitrate concentrations in 13 out of 92 water samples collected from the Ogallala aquifer exceeded the Primary Drinking Water Maximum Contaminant Level (MCL) of 10 milligrams per liter. In 11 out of 46 samples collected from the Arikaree aquifer, arsenic concentrations exceeded the MCL of 50 micrograms per liter. The White River aquifer, where present, is usually the shallowest source of ground water in Mellette County. The White River aquifer also is used in northern Todd County where the Ogallala and Arikaree aquifers are not present. The White River aquifer contains an estimated 50 million acre-feet of water in storage. Reported yields from the aquifer range from 1 to 30 gallons per minute, which generally is insufficient to support irrigation in most areas. However, yields are sufficient for livestock-watering and rural-domestic purposes. In both counties, the Pierre Shale is the shallowest bedrock aquifer and is exposed at the land surface throughout most of Mellette County. This aquifer is used primarily in Mellette County. Although the aquifer contains an estimated maximum of 1.5 million acre-feet of water in storage, it is not a viable source of ground water because the aquifer is relatively impermeable, yields are low, and water usually can be obtained from shallower sources, especially in Todd County. Reported yields from the Pierre Shale aquifer range from 1 to 8 gallons per minute. Because few test holes and wells penetrate below the Pierre Shale, little is known about the extent of the deeper bedrock aquifers. All wells completed in the Dakota Sandstone, Inyan Kara, and Minnelusa and Madison aquifers in the counties are used for stock-watering purposes. High concentrations of dissolved solids and hard water are characteristic of the water quality in the bedrock aquifers. Depths to the top of the deeper bedrock aquifers range from 1,270 feet to greater than 2,000 feet below land surface.

South Dakota↗

USGS2026

Diverging mineral chemistry of iron and nickel throughout Earth’s changing redox conditions reveals foundation for their evolution as protein cofactors

Iron (Fe) and nickel (Ni) were both foundational to early metabolism, yet their biological trajectories diverged as Earth’s surface redox state changed. Here, we integrate mineral chemistry network analysis, protein metal-site coordination-sphere analysis, and curated redox comparisons to test how geochemistry and metalloprotein architecture co-evolved. Mineral network analyses show broader electronegativity variation and network diversity for Fe-bearing minerals through time relative to Ni-bearing minerals. In structural analyses of protein metal centers in a combined Fe/Ni protein structure set, it is shown that Fe- and Ni-associated environments differ in amino-acid composition, hydropathy structure, and cysteine representation. The greater chemical diversity and electronegativity variation in Fe minerals mirror the higher redox and structural versatility of Fe-binding proteins. The presence of Fe in a broader range of mineral and protein environments demonstrates the chemical adaptability of the metal, from the anoxic Archean to oxidative Earth surface conditions following the Great Oxidation Event. Iron, with its broad redox potential range in Fe-oxidoreductases, has a central role in both anaerobic and aerobic metabolisms. Nickel, by contrast, is less widespread in biology. Today, Ni is predominantly employed in deeply branching anaerobic pathways and by proteins with narrower redox potential ranges. Our results show that evolutionary processes, constrained by metal chemistry, habitually utilize Fe as a redox generalist while retaining Ni in specialized roles. The divergent paths of Ni and Fe, from rocks to proteins, demonstrate the intimate relationship between planetary geochemistry and metabolic origins on Earth and suggest that Fe/Ni geochemistry may inform habitability assessments in extraterrestrial environments when interpreted within specific planetary environmental contexts.

Life↗

USGS2025

A comprehensive geologic framework of the National Crustal Model for seismic hazard studies in the conterminous United States

A three-dimensional (3D) geologic framework has been developed for the conterminous United States (U.S.) as part of the U.S. Geological Survey National Crustal Model to enhance seismic hazard modeling. The geologic framework is created from geologic maps and multiple subsurface geologic unit boundaries including the base of the Miocene, Cenozoic, Phanerozoic, and the Mohorovičić discontinuity. Modifications are made to surficial geologic maps to remove discontinuities across state and country borders. The subsurface distribution of rock type and age is extrapolated from the surface, seeded with subsurface geologic information, and constrained by a map of basement geology. The framework provides the basis for estimates of subsurface seismic velocity and density that is needed to improve estimates of earthquake ground shaking and seismic hazard. The present framework greatly expands and updates a previously published 3D geologic framework of the western part of the U.S. that was itself a first-of-its-kind digital 3D portrayal of the nation.

conterminous United States↗

USGS2025

The impact of burial diagenesis on soil-formed minerals in paleosols using stable isotopes of phyllosilicates and carbonate clumped isotopes

To understand the effects of burial diagenesis on the stable isotope geochemistry of soil-formed clay and carbonate minerals in paleosols, samples were collected from seven cores, spanning middle- to upper-Pennsylvanian strata of the Illinois Basin, with varied maximum burial depths of 1–3 km. Mixed-layer illite-smectite and kaolinite mixtures give δ 2 H and δ 18 O values of −83 ‰ to −36 ‰ and 11.9 ‰ to 21.1 ‰ (VSMOW), respectively. After carbonates were screened petrographically for diagenetic textures using transmitted light and cathodoluminescence, measured clumped isotope Δ 47 values range from 0.504 to 0.563 ‰ (I-CDES). Resulting mineral formation temperatures for phyllosilicate mineral mixtures are 28 to 66 °C (mean = 47 °C), whereas T(Δ 47 ) estimates for calcites are 36 to 61 °C (mean = 45 °C). Calculated δ 18 O water values from which phyllosilicate minerals and calcites precipitated under isotopic equilibrium ranges from −7.1 to −1.2 ‰ and − 1.4 to +4.9 ‰, respectively. Closed and open-system phyllosilicate-fluid exchange modeling indicates that phyllosilicate alteration occurred in the presence of a low temperature brine or meteoric water and is interpreted to occur in a layer-by-layer illitization transformation. Due to the lack of diagenetic textures and positively correlated T(Δ 47 ) and δ 18 O water , calcites are interpreted to have undergone solid-state bond reordering. Despite low to moderate temperatures (<125 °C) and varying depths of shallow burial (1–3 km), solid-state transformation of phyllosilicates and calcites indicates paleosols had prolonged exposure to burial conditions which has implications for the use of paleosol minerals for paleoenvironmental reconstructions.

Illinois, Indiana, Kentucky↗

USGS2025

Chemostratigraphy of the Cretaceous Hue Shale in Arctic Alaska: Exploring paleoceanographic controls on trace element enrichment, organic matter accumulation, and source-rock evolution

We document chemostratigraphy in an outcrop of late Albian to early Campanian (∼103–82 Ma) marine source rocks to better understand paleoenvironmental controls on trace element (TE) enrichment and organic matter accumulation in the distal Colville foreland basin of Arctic Alaska and how those drivers are linked to arc volcanism and successions of Cretaceous oceanographic and climatic biogeochemical events. This unique, 113-m-thick section of Cretaceous Hue Shale deposited during a series of previously undocumented Arctic Cretaceous oceanic anoxic events (Lease et al., 2024) is the only known exposure of thermally immature (0.48–0.52% R o , random vitrinite reflectance) Hue Shale in Arctic Alaska. Strata comprise mainly clay-rich mudstone with elevated total organic carbon (TOC) and hydrogen index values reaching 26.3 wt% (mean = 7.5 wt%) and 689 mg hydrocarbon (HC)/g TOC (mean = 385 mg HC/g TOC), respectively. Maceral composition consists predominantly of fluorescent amorphous organic matter, with abundant brightly fluorescent alginite, including Tasmanites , acritarchs, and Leiosphaeridia . Discrete layers of volcanic ash (preserved as bentonite) are present throughout the section and provide quantitative age control based on U–Pb dates. Chemostratigraphic trends are investigated to advance our understanding of local oceanographic conditions and controls on stratigraphic and temporal heterogeneity of Brookian source rocks. Concurrent sedimentary enrichment in Mo, U, V, Pb, and Cu across the Albian–Cenomanian boundary of the exposed basal gamma-ray zone, may reflect anoxic to euxinic benthic redox conditions favoring organic matter accumulation and preservation. Fluctuating degrees of anoxia-euxinia are inferred throughout the overlying Hue Shale succession, reflected by varying patterns of TE enrichment and TE–TOC covariation. Elevated C org /P molar ratios (>250) across most of the section, with several values exceeding 690, signify that enhanced biological productivity is sustained throughout deposition. Enhanced productivity, recorded by both C org /P and excess Ba, also parallels increases in source rock richness (elevated TOC and S 2 values) during the late Albian–early Cenomanian and late Cenomanian – Turonian. Enhanced productivity and variations in oceanic circulation/stratification likely both drove changes in benthic redox conditions that favored organic carbon accumulation and preservation. Increased continental arc volcanism (e.g., Okhotsk–Chukotka volcanic belt) and High Arctic Large Igneous Province magmatic eruptions throughout the Cretaceous, inferred to have influenced nutrient cycling and local aqueous nutrient availability, also have been invoked as potential drivers of organic carbon burial and source-rock development across the sedimentary sequence. Results presented here document the organic-rich and oil-prone source-rock quality of the Hue Shale in the distal part of the Colville foreland basin and bolster the potential for a Cretaceous petroleum system beneath the eastern North Slope.

Alaska↗

USGS2024

The advantages of electric-grade heat storage in long closed-loop wells

Though long (e.g., tens of kilometers) closed-loop geothermal wells are under consideration for the extraction of subsurface heat, these wells might also serve as an efficient energy storage mechanism for electricity generation. Using a semi-analytic model solution, the potential for electric-grade heat storage as a function of ambient temperature (e.g., corresponds to depth of loop), well length, well diameter, and flow rate is evaluated. The following simplified cases for comparison of standard closed loop operation with energy storage operation were considered: [1] constant flow rate and constant temperature (90 °C) injection to represent the standard closed-loop base-case; and [2] constant flow rate and annual cycle sinusoidal temperature (90-150 °C) to represent seasonal (summer) charging while solar resources are peak. Initial temperatures for all scenarios considered herein are a uniform 175 °C. Electric-grade heat is assumed to be delivered whenever temperatures at the extraction point exceed 90 °C. For calculation purposes only, if temperature falls below 100 °C, it is assumed that heat delivered is sub-economic, so no electricity would be produced. For all scenarios, temperatures at the extraction well asymptotically approach the flow-weighted average injection temperature, but energy storage scenarios exhibited a damped time-varying signal that diminishes in magnitude with length of the loop. The asymptotic approach depends on initial temperatures in the rock and the heat extraction rate (a function of well diameter and flowrate). This analysis demonstrates that shorter closed loops can produce more electricity over time than longer closed-loops previously proposed for electricity production over typical engineering design lifetimes (e.g., 30 years). Although only a high-temperature scenario is considered herein, rock that is initially below boiling temperature would not host a standard closed-loop resource, but injection of hot water seasonally would asymptotically heat this low-temperature system to temperatures capable of electricity production. In other words, regardless of initial temperatures, closed loops could be used to store electricity with no critical minerals in the geothermal battery.

Conference Paper↗

USGS2025

Low-sulfidation epithermal deposits of the central Basin and Range Province, USA

The Basin and Range Province is host to many important low-sulfidation epithermal deposits. Within this broad zone of extension, epithermal deposits are hosted by specific areas of Miocene and younger bimodal volcanism. In northern Nevada, rifting and related volcanic activity occurred in response to thermal bulging during the development of the Yellowstone hotspot. The Colorado River Extensional Corridor in southern Nevada, adjoining eastern California and northwestern Arizona, is a major zone of Miocene crustal extension formed during the transformation of the western margin of North America from a convergent to a transform plate boundary. The style of mineralization in the low-sulfidation epithermal deposits in these areas is strongly controlled by the nature of the volcanic successions. Highgrade, low-tonnage deposits are commonly found in flow-dominated volcanic successions where ore deposition occurred through short-lived periods of fluid flashing. In contrast, low-grade, large-tonnage deposits are more commonly located in clastic-dominated successions where fluid infiltration of the permeable hosts and cooling predominated.

Arizona, California, Nevada, Oregon↗

USGS2025

Evidence of mineral alteration in a salt marsh subterranean estuary: Implications for carbon and trace element cycling

Subterranean estuaries (STE) in salt marshes are biogeochemically active zones where interactions between terrestrial groundwater and seawater drive complex cycling of carbon and trace elements, influenced by mineral dissolution. These systems, characterized by fine-grained organic-rich peat overlying permeable coastal aquifers, play a crucial role as a blue carbon sink, yet their geochemical dynamics remain poorly understood. We investigated dissolved trace elements, carbon, silica, and radium isotopes in a salt marsh STE (Sage Lot Pond, Waquoit Bay, MA) over seasonal and annual cycles. Our results reveal that groundwater and estuarine water circulation through marsh peat and aquifer sediments leads to enrichments of dissolved organic and inorganic carbon (DOC and DIC), Si, Ba, and Mn, with variable source/sink behavior of Fe and net removal of U. Submarine groundwater discharge dominated Ba fluxes, whereas pore water drainage from marsh peat acted as the main sink for U and source of Si. Fe cycling was variable, with terrestrial Fe largely removed as groundwater passed through the STE, consistent with Fe-sulfide and amorphous phase formation. Radium isotope ratios identified two distinct subsurface flow pathways, influenced by metal-oxide cycling and organic matter breakdown. Si production was decoupled from DIC, suggesting Si originates from mineral alteration, whereas DIC results from both mineral weathering and microbial respiration. Silicate mineral alteration, coupled with marsh pore water drainage, accounts for up to 16% of annual DIC exports (66 g C m −2 y −1 ), highlighting the importance of STEs in coastal carbon and trace element cycling, especially as marshes face environmental change.

Massachusetts↗

USGS1983

Base flow and ground water in upper Sweetwater Valley, Tennessee

The upper Sweetwater Valley area has a flow system with complex interaction between surface and ground water. A water budget study indicated that during dry years approximately three-fourths of the annual flow to Sweetwater Creek may be derived from ground-water sources. Hydrograph analysis showed seasonal variation of recharge to the ground-water flow system. Streamflow records were analyzed to estimate the frequency of low flow of Sweetwater Creek at river mile 16.7, and indicated the lowest average flow for 1 day in 20 years to be about 5.1 cubic feet per second. Two periods of base-flow measurements of Sweetwater Creek identified channel reaches with significant gains and losses of streamflow. Base flow measurements also showed interbasin transfer of water among sub-basins of the valley. Major flow surpluses were associated with areas in which the majority of flow originated at a spring. Topographically low areas adjacent to the main stem of Sweetwater Creek generally have surplus flow. Topographically higher areas generally have deficient surface outflow unless significant spring flow occurs in the basin. Ground-water recharge occurs by water draining into sinkholes, faults, and fractures. Ground-water flow is regionally diffused across formation strikes from the topographically low areas unless the water is exposed to highly permeable formations or impervious formations. Ground water infiltrates the highly permeable formations and flows along strike. Ground water encountering impervious formations may discharge at small springs at the contact, or may reroute along the contact if the upgradient rock is sufficiently permeable or has well developed secondary porosity. Groundwater discharges to streams at innumerable seeps and at a few large springs. Areas of ground-water flow up-gradient of large springs are hypothesized as likely areas of significant ground-water reservoirs.

Tennessee↗

USGS2025

Solution-collapse breccia pipe uranium deposits of the southern Colorado Plateau, northwestern Arizona, USA

Some of the highest-grade uranium deposits in the United States occur in breccia pipes that formed by solution and collapse of sedimentary strata, which occur in the southern portion of the Colorado Plateau in northwestern Arizona. The host breccia pipes are up to 1200 m in vertical extent, average about 90 m in diameter, and can cross-cut strata from their base in the Mississippian Redwall Limestone to as stratigraphically high on some plateaus as the Triassic Chinle Formation. These uranium-base metal deposits are up to 600 m thick and formed within the breccia pipes where they transect the Permian Coconino Sandstone, Hermit Formation, and the Esplanade Sandstone. Of the hundreds of breccia pipes identified across this region, only a small percentage are known to contain mineralization. The main uranium ore mineral is uraninite that is intergrown with at least 20 base-metal sulfide minerals, which contribute Fe, Cu, Co, As, Pb, Zn, Ni, and Ag to the deposits. This study considered regional stratigraphy, sulfur isotope systematics, mineralogy, in situ dating, and compilation and analysis of previous work on the deposits. A comprehensive deposit model has not been published for these deposits. This analysis identified new additions to update the deposit model for these unusual, possibly unique deposits. Proposed modifications to the model include: (1) the source, mechanisms, timing of the base-metal sulfide mineral assemblages, and (2) the source, mechanism, and timing of the uranium mineralization. Sulfide and uranium deposition are shown to be separate mineralization events. The study proposes the possible role of gypsum as a source of sulfur for the sulfide minerals in the deposits. Groundwaters carrying uranium encountered the preexisting sulfides in breccia pipes, reducing the uranyl ions, and precipitating U oxide (as uraninite). Analysis of the regional stratigraphy recognized that numerous beds of gypsum are in the strata that lie only tens of meters above the breccia pipe deposits. In the breccia pipe region, if these stratigraphic units (Toroweap and Kaibab Formations) do not contain gypsum layers then the underlying pipes are not mineralized; where these Permian gypsum layers do occur, breccia pipes can host mineralization. This new understanding should be useful in identifying the prospective region for mineralized pipes.

Arizona↗

USGS2025

Sand provenance boundary in the Mu Us Sandy Land of northern China

Desert dunes are often assumed to have uniform mineral compositions due to extensive mixing during lateral transport, which complicates provenance studies. The Mu Us Sandy Land in north-central China, near the East Asian summer monsoon precipitation boundary, experiences a wetter climate than most deserts. Climate wetting as a result of a warming climate, and the ‘Sand Control Project’ implemented by the Chinese government to decrease the lateral movement of sand dunes in this area provide an opportunity to study surface processes of sand production and transport. Previous studies using zircon U Pb geochronology and heavy mineral composition indicate distinct sand sources for the Mu Us Sandy Land: local basement-derived middle Yellow River sediments and recycled dried-up lacustrine sediments for the eastern part, and northeastern Tibetan Plateau-derived upper Yellow River sediments for the western part. However, zircons and heavy minerals only represent trace amounts of the bulk mineralogy within a sand dune, so broader provenance analysis targeting common minerals is essential. We focus on the area near the proposed provenance difference boundary between the western and eastern Mu Us Sandy Land, using comprehensive sampling and provenance techniques to confirm distinct provenance characteristics and delineate the provenance boundary. Our findings reveal that sand from most of the Mu Us Sandy Land originated from the erosion of local basement by the middle Yellow River and recycled local dried-up lacustrine sediments, whereas the southwestern corner and the neighboring western-central Chinese Loess Plateau received sediments from the distal northeastern Tibetan Plateau.

Mu Us Sandy Land↗