Municipal GIS database of El Salvador: Volume 3, La Palma, El Salvador
No abstract available.
La Palma↗
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Results for “Journal of Hydrology, Regional Studies”
Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
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High-resolution magnetic survey using an unoccupied aerial vehicle to constrain buried lava flow geometry, volume, and eruptive history of Little Cones, Crater Flat, Nevada
Magnetic surveys are an important tool used to augment geologic mapping in distributed volcanic fields. Using magnetic anomalies, it is possible to model the geometry of shallowly buried volcanic features, such as conduits, sills, and lava flows. This subsurface mapping is important for understanding eruption dynamics and emplacement of lava flows, and it sometimes reveals buried volcanoes no longer visible at the surface. These data are critical to better interpret the numbers, styles, and magnitudes of eruptions in distributed volcanic fields and their associated volcanic hazards. New advances in unoccupied aerial vehicles (UAVs) offer an attractive middle range of resolution and aerial coverage between ground-based magnetic surveys and aeromagnetic surveys. Here, we present the results of a UAV fluxgate magnetic survey of the Little Cones, Nevada, scoria cones, which have been the target of previous ground and aeromagnetic surveys. The magnetic anomalies at Little Cones are of interest because the surrounding alluvium conceals lava flows that erupted from Little Cones, making it very difficult to understand the volume and morphology of lava flows from geologic mapping alone. Nonlinear inversion of UAV-collected magnetic data were used to model the thickness and morphology of buried Little Cones’ lava flows with higher precision than achieved previously. The sequence of events and calculated flow characteristics are then interpreted. The total volume of Little Cones, including concealed lava flows, is approximately 0.016 cubic kilometer, and the initial sheet flow erupted in less than 24 hours. The findings presented herein demonstrate that UAV-based magnetic surveys are a reliable method of data collection and an efficient alternative to other survey methods, facilitating development of a three-dimensional perspective of distributed volcanic fields.
Nevada↗
U-Pb scheelite ages of tungsten and antimony mineralization in the Stibnite-Yellow Pine district, central Idaho
The Stibnite-Yellow Pine district contains the largest antimony resource in the United States, as well as significant gold, and is a historic producer of tungsten. Application of in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) direct dating of scheelite from two Au-Sb-W ore deposits, Yellow Pine and Hangar Flats, yielded an older group of U-Pb ages in the range of 60.0 ± 2.8 to 57.0 ± 1.1 Ma and a younger U-Pb age for scheelite intergrown with stibnite of 47.4 ± 1.1 Ma. These in situ analyses were calibrated by isotope dilution-thermal ionization mass spectrometry (ID-TIMS) U-Pb lower intercept ages of two coarsely crystalline scheelite samples that yielded ages of 57.52 ± 0.22 and 56.62 ± 0.16 Ma. Scheelite of the latter age is of sufficient quality to serve as a primary reference material for LA-ICP-MS scheelite U-Pb geochronology. The group of older U-Pb scheelite ages agrees with 40 Ar/ 39 Ar ages of 56.9 ± 1.2 to 56.38 ± 0.54 Ma on adularia from Yellow Pine and Hangar Flats, whereas the younger U-Pb scheelite age is similar to an 40 Ar/ 39 Ar age of 46.00 ± 0.40 Ma on adularia from an epithermal gold-silver deposit in the adjacent Thunder Mountain caldera. Our results indicate that the main stage of tungsten mineralization occurred at ca. 57 Ma, whereas the main stage of antimony mineralization occurred at ca. 47 Ma—thereby providing first-time age constraints for antimony and tungsten mineralization in the Stibnite-Yellow Pine district.
Idaho↗
The effects of line simplification on planform geometry
Data on maps should retain accuracy regardless of scale. Yet, as cartographic lines are generalized, there can be impacts on properties such as topology, density, and planform geometry. Here, we investigate the use of the Scale Specific Sinuosity (S3) metric (Stanislawski et al., 2023) to evaluate the effects of line simplification on planform geometry, which is the bends of streams in map view. We employ an open-source Python S3 workflow to characterize the geometry of five diverse stream channels in the United States. The original data are extracted from the U.S. Geological Survey National Hydrography Dataset 1:24,000-scale vector data (U.S. Geological Survey, 2000) (Table 1), and the simplification is done using the Visvalingam and Whyatt method (2017) with a simplification tolerance of 0.5, 1.0, 1.5, and 2.0 km. The S3 analysis is calculated at each level of simplification and S3 derivatives are generated. Derivatives include measures of sinuosity, fractal dimension, and the dominant bend wavelength. The findings show that the change in planform geometry is scale-dependent, though simplification will have little effect on straighter lines. The change becomes more apparent in complex lines as the degree of simplification aligns with the scale of the dominant bend geometries. These logical conclusions are evidence that the S3 is a useful metric for automated characterization of bend geometry regardless of line complexity.
Conference Paper↗
Geochemistry and thermometry of magnetite veins and replacements in iron ore deposits from the Iron Springs district, SW Utah, USA: Relation to magmatic and hydrothermal processes
Ore-genesis, texture, chemical compositions, and thermometry of magnetite were used to better evaluate the origins of iron ore deposits across the Iron Spring district, Utah. Trace element compositions, determined by LA-ICP-MS, were used to calculate temperatures based on X Mg numbers and characterize the trace element signatures of magmatic and hydrothermal magnetite. Magnetite occurs as coarser crystalline grains within veins, breccias, and cavities along with finer crystalline replacements. Magnetite is most commonly intergrown with apatite, phlogopite, and carbonate in veins, breccias, and cavities where apatite occurs separately from the other gangue minerals. The results using empirical trace element discrimination diagrams generally suggest that the magnetite is overall of hydrothermal origin regardless of textural variations or field relationships. The X Mg numbers of the magnetite in the magnetite-apatite ores, however, are suggestive of high temperature magmatic conditions; whereas those of vein, breccia, and replacement occurrences containing other gangue minerals are suggestive of lower temperature hydrothermal processes.
Utah↗
Update of the 2008 provisional Enhanced Geothermal Systems (EGS) assessment for the Great Basin, USA
In response to the Energy Act of 2020, the U.S. Geological Survey (USGS) is updating the Enhanced Geothermal Systems (EGS) resource assessment for the Great Basin, USA. The previous 2008 provisional assessment estimated how much electricity could be generated from EGS resources of the western United States using models of electric-grade heat, models of heat extraction over time, and estimates of how much rock might be stimulated to produce viable amounts of heat. Herein, a similar conceptual strategy is applied, using updated models of heat extraction as a function of fracture spacing and well distance. Previously used reservoir heat delivery models are updated to have a dependence on fracture and well spacing, potentially improving future estimates of EGS resources as ongoing research provides a better understanding about the success of reservoir stimulation as a function of geology and location. For a range of well distances (250-1000 m) and fracture spacings (1-50 m), heat extraction efficiency ranges from 25-62%, demonstrating the importance of accounting for the most likely results of proven viable fracturing technologies. Although fracturing is important, the biggest uncertainty by far in estimating the EGS resource for the Great Basin is estimating which geologic units at what depths can be stimulated sufficiently to produce geothermal energy economically and efficiently. Uncertainties in these factors yield estimates that range over two orders of magnitude with an upper limit of ~174 terawatts-thermal (TWth) produced for 30 years from the upper 7 km of the crust. This upper limit would require significant technological advances to access most of the electric-grade resource across the Great Basin. Assuming that 1% of this estimate will be accessible in the next few decades gives a resource estimate similar to that made in the 2008 provisional assessment. These estimated EGS heat extraction rates far exceed ( greater than 100x) the natural geothermal heat production rate, thus geothermal electricity production at these rates might not be sustainable unless heat is also recharged from other sources (e.g., excess solar energy when supply exceeds demand). In addition to assessment maps and cumulative estimates, the new models of fractured reservoirs developed herein can be used to estimate steady power production given a set of fractures and well spacing, and estimates can be made for setback distances to ensure no thermal interference with nearby powerplants.
Arizona, California, Idaho, Nevada, Oregon, Utah↗
Comparative properties of saponitic fault gouge and serpentinite muds cored from mud volcanoes of the Mariana subduction zone
We obtained 12 core samples for physical and chemical characterization from three serpentinite mud volcanoes (Yinazao, Asùt Tesoru, and Fantangisña) located on the forearc of the Mariana subduction system, that were drilled during International Ocean Discovery Program Expedition 366. Two samples from the Fantangisña mud volcano are interpreted to be clay-rich fault gouges derived from the subduction channel. Their bulk compositions are intermediate between the serpentinites and oceanic basalts. The oceanic crustal materials in the gouges have been thoroughly metasomatized and the serpentinites extensively altered to the trioctahedral, Mg-rich smectite clays saponite and corrensite. The only relict phases in clasts of crustal rock are accessory Ti- and P-bearing minerals. The two fault gouge samples have lower frictional strengths ( μ < 0.2) than the serpentinites ( μ = 0.2–0.4), and their measured permeabilities are also somewhat lower. Their physical and compositional properties correspond to saponitic gouges from other faults that juxtapose serpentinite against crustal rocks, in particular gouges from the two creeping traces of the San Andreas Fault recovered in the core from the San Andreas Fault Observatory at Depth. The décollement beneath Fantangisña mud volcano is thus expected to be very weak and likely characterized by stable slip.
Geophysics, Geochemistry, Geosystems↗
The impact of source time function complexity on stress drop estimates
Earthquake stress drop—a key parameter for describing the energetics of earthquake rupture—can be estimated in several different, but theoretically equivalent, ways. However, independent estimates for the same earthquakes sometimes differ significantly. We find that earthquake source complexity plays a significant role in why theoretically (for simple rupture models) equivalent methods produce different estimates. We apply time‐ and frequency‐domain methods to estimate stress drops for real earthquakes in the SCARDEC (Seismic source ChAracteristics Retrieved from DEConvolving teleseismic body waves, Vallée and Douet, 2016 ) source time function (STF) database and analyze how rupture complexity drives stress‐drop estimate discrepancies. Specifically, we identify two complexity metrics—Brune relative energy (BRE) and spectral decay—that parameterize an earthquake’s complexity relative to the standard Brune model and strongly correlate with the estimate discrepancies. We find that the observed systematic magnitude–stress‐drop trends may reflect underlying changes in STF complexity, not necessarily trends in actual stress drop. Both the decay and BRE parameters vary systematically with magnitude, but whether this magnitude–complexity relationship is real remains unresolved.
Bulletin of the Seismological Society of America↗
Geologic map of the Yabucoa and Punta Tuna quadrangles, Puerto Rico
No abstract available.
Open-File Report↗
Estimation of magnitude and frequency of floods for streams in Puerto Rico: New empirical models
Flood-peak discharges and frequencies are presented for 57 gaged sites in Puerto Rico for recurrence intervals ranging from 2 to 500 years. The log-Pearson Type III distribution, the methodology recommended by the United States Interagency Committee on Water Data, was used to determine the magnitude and frequency of floods at the gaged sites having 10 to 43 years of record. A technique is presented for estimating flood-peak discharges at recurrence intervals ranging from 2 to 500 years for unregulated streams in Puerto Rico with contributing drainage areas ranging from 0.83 to 208 square miles. Loglinear multiple regression analyses, using climatic and basin characteristics and peak-discharge data from the 57 gaged sites, were used to construct regression equations to transfer the magnitude and frequency information from gaged to ungaged sites. The equations have contributing drainage area, depth-to-rock, and mean annual rainfall as the basin and climatic characteristics in estimating flood peak discharges. Examples are given to show a step-by-step procedure in calculating a 100-year flood at a gaged site, an ungaged site, a site near a gaged location, and a site between two gaged sites.
Puerto Rico↗
Kiloyear cycles of carbonate and Mg-silicate replacement at Von Damm hydrothermal vent field
The Von Damm vent field (VDVF) on the Mid-Cayman Rise in the Caribbean Sea is unique among modern hydrothermal systems in that the chimneys and mounds are almost entirely composed of talc. We analyzed samples collected in 2020 and report that in addition to disordered talc of variable crystallinity, carbonates are a major class of mineral at VDVF. The carbonate minerals include aragonite, calcite, magnesium-rich calcite, and dolomite. Talc and carbonate mineral textures indicate that, rather than replacing volcanic host rock, they precipitate from the mixing of hydrothermal fluids and seawater at the seafloor, occurring in chimneys and surrounding rubble. Alternating precipitation of this mineral assemblage is pervasive, with carbonate minerals typically being succeeded by talc, and with indications that in some cases talc and carbonate minerals replace one another. Stable carbon isotopic data indicate the carbonate minerals originate from the mixing of seawater and hydrothermal fluid, which is supported by U-Th data. Radiocarbon calcite ages and talc 234 U- 230 Th isochron ages indicate mineral ages spanning over thousands to tens of thousands of years. Analyses of these samples illustrate a dynamic system that transitions from carbonate-dominated to Mg-silicate−dominated precipitation over time scales of thousands of years. Our observations raise questions regarding the eventual fate of seafloor precipitates and whether carbonate and silicate minerals in such settings are sequestered and represented in the rock record.
Geology↗
Lithochronologic units and mineral deposits of the Appalachian Orogen from Maine to Alabama
No abstract available.
Appalachian Orogen↗
Velocity-independent dry friction on mica: A realization of ideal Amontons-Coulomb friction
The Amontons-Coulomb friction law assumes that the frictional force between materials is independent of sliding velocity. However, as Coulomb noted, this is a rough approximation, and a second-order dependence of friction on the logarithm of sliding velocity is incorporated in a commonly used ‘rate- and state-dependent’ friction representation. Here we conduct shear experiments on mica, a layer-structured mineral, at temperatures ranging from 25 to 200ºC and under normal stress of 100 MPa. The friction coefficient clearly depends on the logarithmic sliding velocity at 25ºC, but rate sensitivity decreases with increasing temperature until at 200ºC, the friction coefficient is independent of sliding velocity. Our findings could initiate the development of velocity-independent frictional materials, realizing the ideal Amontons-Coulomb friction.
Physical Review Letters↗
Triggering the 2022 eruption of Mauna Loa
Distinguishing periods of intermittent unrest from the run-up to eruption is a major challenge at volcanoes around the globe. Comparing multidisciplinary monitoring data with mineral chemistry that records the physical and spatio-temporal evolution of magmas fundamentally advances our ability to forecast eruptions. The recent eruption of Mauna Loa, Earth’s largest active volcano, provides a unique opportunity to differentiate unrest from run-up and improve forecasting of future eruptions. After decades of intermittent seismic and geodetic activity over 38 years of repose, Mauna Loa began erupting on 27 November 2022. Here we present a multidisciplinary synthesis that tracks the spatio-temporal evolution of precursory activity by integrating mineral and melt chemistry, fluid inclusion barometry, numerical modeling of mineral zoning, syn-eruptive gas plume measurements, the distribution and frequency of earthquake hypocenters, seismic velocity changes, and ground deformation. These diverse data indicate that the eruption occurred following a 2-month period of sustained magma intrusion from depths of 3–5 km up to 1–2 km beneath the summit caldera, providing a new model of the plumbing system at this very high threat volcano. Careful correlation of both the geochemistry and instrumental monitoring data improves our ability to distinguish unrest from the run-up to eruption by providing deeper understanding of the both the monitoring data and the magmatic system—an approach that could be applied at other volcanic systems worldwide.
Hawaii↗
Estimating the hypothetical endowment of critical minerals and other commodities in porphyry copper mine waste in the Four Corners states, USA
Society is fundamentally dependent upon commodities that are used in end-use products for the aerospace, defense, energy, telecommunication, and transportation sectors, resulting in centuries of mining to supply these commodities and materials. Waste from these mining operations can remain on the landscape indefinitely, but there is a lack of national understanding of the distribution and scale of such waste features. The renewable energy transition will continue to increase demand for critical minerals and will result in increasing volumes of mine waste on the Earth’s surface. Reprocessing mine waste can reduce environmental risks and recover needed commodities to match growing demand for societal growth. Therefore, understanding the approximate abundance of commodities that may be available for recovery within mine waste features can be an important piece of domestic critical mineral supply.
Arizona, Colorado, New Mexico, Utah↗
The water quality of Livingston Reservoir on the Trinity River, Southeastern Texas
The concentrations of dissolved solids, chloride, and sulfate in Livingstone Reservoir on the Trinity River in southeastern Texas usually average less than 250 mg/1 (milligrams per litre), 40 mg/1, and 50 mg/1, respectively. The water is usually hard or moderately hard (61 to 180 mg/1 as calcium carbonate). The concentrations of principal dissolved constituents in the reservoir are usually maximum during summer and fall when evaporation is high and inflow is low. Thermal stratification of the reservoir usually begins in March and persists until September or October. Neither the seasonal variation of dissolved constituents in inflow to the reservoir nor thermal stratification has resulted in significant stratification of the principal dissolved constituents. However, thermal stratification has resulted in significant seasonal and areal variations of dissolved oxygen, which results in higher concentration of dissolved iron, dissolved manganese, total phosphorus, and total inorganic nitrogen.
Texas↗