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At least 109 records · Page 6Linked to original sources
USGS2025

On the importance of geological and geophysical lunar field work enabled by Artemis Base Camp

We report on six Findings related to the benefit of Artemis Base Camp (ABC) to lunar geoscience (Figure 1). These Findings are on the topics of 1) Repeat field site visits; 2) Geological experiments; 3) Satellite ABC campus(es); 4) Advanced lab equipment; 5) Frequent and resource-intensive EVAs; and 6) Geoscience STEM engagement. Lastly, we consider certain issues and caveats meriting further study in any base camp architecture.

Report↗
USGS2025

lasertram: A Python library for time resolved analysis of laser ablation inductively coupled plasma mass spectrometry data

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) data has a wide variety of uses in the geosciences for in-situ chemical analysis of complex natural materials. Improvements to instrument capabilities and operating software have drastically reduced the time required to generate large volumes of data relative to previous methodologies. Raw data from LA-ICP-MS, however, is in counts per unit time (typically counts per second), not elemental concentrations and converting these count ratesto concentrations requires additional processing. For complex materials where the ablated volume may contain a range of material compositions, a moderate amount of user input is also required if appropriate concentrations are to be accurately calculated. In geologic materials such as glasses and minerals that potentially have numerous heterogeneities (e.g., microlites or other inclusions) within them, this is typically determiningwhether the total ablation signal should be filtered to remove these heterogeneities. This necessitates that the LA-ICP-MS data processing pipeline is one that is not automated, but is also designed to enable rapid and efficient processing of large volumes of data. Here we introduce , a Python library for the time resolved analysis of LA-ICP-MS data. We outline its mathematical theory, code structure, and provide an example of how it can be used to provide the time resolved analysis necessitated by LA-ICP-MS data of complex geologic materials. Throughout the pipeline we show how metadata and data are incrementally added to the objects created such that virtually any aspect of an experiment may be interrogated and its quality assessed. We also show, that when combined with other Python libraries for building graphical user interfaces, it can be utilized outside of a pure scripting environment. can be found at https://doi.org/10.5066/P1DZUR3Z

Applied Computing and Geosciences↗
USGS2007

Statistical analysis of water-quality data containing multiple detection limits II: S-language software for nonparametric distribution modeling and hypothesis testing

Analysis of low concentrations of trace contaminants in environmental media often results in left-censored data that are below some limit of analytical precision. Interpretation of values becomes complicated when there are multiple detection limits in the data-perhaps as a result of changing analytical precision over time. Parametric and semi-parametric methods, such as maximum likelihood estimation and robust regression on order statistics, can be employed to model distributions of multiply censored data and provide estimates of summary statistics. However, these methods are based on assumptions about the underlying distribution of data. Nonparametric methods provide an alternative that does not require such assumptions. A standard nonparametric method for estimating summary statistics of multiply-censored data is the Kaplan-Meier (K-M) method. This method has seen widespread usage in the medical sciences within a general framework termed "survival analysis" where it is employed with right-censored time-to-failure data. However, K-M methods are equally valid for the left-censored data common in the geosciences. Our S-language software provides an analytical framework based on K-M methods that is tailored to the needs of the earth and environmental sciences community. This includes routines for the generation of empirical cumulative distribution functions, prediction or exceedance probabilities, and related confidence limits computation. Additionally, our software contains K-M-based routines for nonparametric hypothesis testing among an unlimited number of grouping variables. A primary characteristic of K-M methods is that they do not perform extrapolation and interpolation. Thus, these routines cannot be used to model statistics beyond the observed data range or when linear interpolation is desired. For such applications, the aforementioned parametric and semi-parametric methods must be used.

Computers & Geosciences↗
USGS2026

3D semantic mapping of surface geological features

Semantic mapping in 3D is fundamental to a wide range of geoscientific studies and applications, including geomorphology, hazard assessment, and environmental monitoring. However, automatically segmenting geological features from large-scale photogrammetric datasets remains a significant challenge. We present a methodology to address this gap. Using overlapping images collected over environments of interest, Structure-from-Motion (SfM) produces georeferenced point clouds and estimates camera poses. Existing large vision models, such as Segment Anything Model, segment objects in the images, generating pixel-segmentation associations. To produce pixel-point associations, we project the points back onto the camera image planes. As objects are independently segmented across multiple images with different perspectives, we develop a segmentation mosaicking algorithm to build probabilistic point-segmentation associations that combines the pixel-segmentation associations and pixel-point associations. Our methodology is validated using both synthetic data generated by Kubric and real-world UAV-SfM data. The implementation is designed to be compatible with existing SfM software, including Agisoft and OpenDroneMap, for photogrammetry mapping in geoscience studies. As a case study, we apply our method to the semantic mapping of precariously balanced rocks (PBRs), which provide upper-bound constraints on historical ground motion shaking intensity. To support object-level identification of PBRs, we additionally integrated Grounding DINO, enabling text-prompted segmentation of features of interest within UAV imagery. This case study demonstrates the effectiveness of our method in generating a 3D semantic map of PBRs, enabling spatial distribution of PBR fragility for earthquake hazard analysis.

Computers & Geosciences↗
USGS2007

Geologic and anthropogenic factors influencing karst development in the Frederick region of Maryland

Karst features pervade the outcrop belts of Triassic, Ordovician, and Cambrian rocks in the Frederick Valley region of Maryland's western Piedmont. Detailed stratigraphic analysis and geologic and karst mapping demonstrate that individual stratigraphic units have differing susceptibilities of karst feature creation. Although the Triassic Leesburg Member of the Bull Run Formation and Rocky Springs Station Member of the Cambrian Frederick Formation have many surface depressions within their outcrop belts, the Lime Kiln Member of the Frederick Formation and the Ceresville, Fountain Rock, and Woodsboro members of the Ordovician Grove Formation have the greatest potential for development of catastrophic collapse sinkholes. Although these four members have the highest relative susceptibility, human activity can increase the potential for sinkhole activation in all units. Rerouting of surface drainage patterns, unlined drainage, and storm-water management areas and removal of significant overburden deposits significantly increase sinkhole development, but mainly, these units are inherently more susceptible to begin with. Copyright ?? 2007. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗
USGS2010

Application of the surface azimuthal electrical resistivity survey method to determine patterns of regional joint orientation in glacial tills

Joints within unconsolidated material such as glacial till can be primary avenues for the flow of electrical charge, water, and contaminants. To facilitate the siting and design of remediation programs, a need exists to map anisotropic distribution of such pathways within glacial tills by determining the azimuth of the dominant joint set. The azimuthal survey method uses standard resistivity equipment with a Wenner array rotated about a fixed center point at selected degree intervals that yields an apparent resistivity ellipse. From this ellipse, joint set orientation can be determined. Azimuthal surveys were conducted at 21 sites in a 500-km2 (193 mi2) area around Milwaukee, Wisconsin, and more specifically, at sites having more than 30 m (98 ft) of glacial till (to minimize the influence of underlying bedrock joints). The 26 azimuthal surveys revealed a systematic pattern to the trend of the dominant joint set within the tills, which is approximately parallel to ice flow direction during till deposition. The average orientation of the joint set parallel with the ice flow direction is N77??E and N37??E for the Oak Creek and Ozaukee tills, respectively. The mean difference between average direct observation of joint set orientations and average azimuthal resistivity results is 8??, which is one fifth of the difference of ice flow direction between the Ozaukee and Oak Creek tills. The results of this study suggest that the surface azimuthal electrical resistivity survey method used for local in situ studies can be a useful noninvasive method for delineating joint sets within shallow geologic material for regional studies. Copyright ?? 2010 The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗
USGS2009

Characterization of the Helderberg Group as a geologic seal for CO 2 sequestration

The Midwest Regional Carbon Sequestration Partnership recognizes that both the Devonian Oriskany Sandstone and the Silurian Salina Group offer potential for subsurface carbon dioxide storage in northern West Virginia. The Silurian-Devonian Helderberg Group lies stratigraphically between these two units, and consequendy, its potential as a geologic seal must be evaluated. Predominantly a carbonate interval with minor interbedded siliciclastics and chert, the Helderberg Group was deposited in an ancient epeiric sea. Although most previous investigations of this unit have concentrated on outcrops in eastern West Virginia, new information is available from an injection well drilled along the Ohio River at First Energy's R. E. Burger electric power plant near Shadyside, Ohio. Geophysical, seismic, and core data from this well have been combined with existing outcrop information to evaluate the Helderberg Group's potential as a seal. The data collected suggest that only secondary porosity remains, and permeability, if it exists, most likely occurs along faults or within fractures. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗
USGS2009

Assessing spatial uncertainty in reservoir characterization for carbon sequestration planning using public well-log data: A case study

Mapping and characterization of potential geologic reservoirs are key components in planning carbon dioxide (CO 2 ) injection projects. The geometry of target and confining layers is vital to ensure that the injected CO 2 remains in a supercritical state and is confined to the target layer. Also, maps of injection volume (porosity) are necessary to estimate sequestration capacity at undrilled locations. Our study uses publicly filed geophysical logs and geostatistical modeling methods to investigate the reliability of spatial prediction for oil and gas plays in the Medina Group (sandstone and shale facies) in northwestern Pennsylvania. Specifically, the modeling focused on two targets: the Grimsby Formation and Whirlpool Sandstone. For each layer, thousands of data points were available to model structure and thickness but only hundreds were available to support volumetric modeling because of the rarity of density-porosity logs in the public records. Geostatistical analysis based on this data resulted in accurate structure models, less accurate isopach models, and inconsistent models of pore volume. Of the two layers studied, only the Whirlpool Sandstone data provided for a useful spatial model of pore volume. Where reliable models for spatial prediction are absent, the best predictor available for unsampled locations is the mean value of the data, and potential sequestration sites should be planned as close as possible to existing wells with volumetric data. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗
USGS2009

Reservoir uncertainty, Precambrian topography, and carbon sequestration in the Mt. Simon Sandstone, Illinois Basin

Sequestration sites are evaluated by studying the local geological structure and confirming the presence of both a reservoir facies and an impermeable seal not breached by significant faulting. The Cambrian Mt. Simon Sandstone is a blanket sandstone that underlies large parts of Midwest United States and is this region's most significant carbon sequestration reservoir. An assessment of the geological structure of any Mt. Simon sequestration site must also include knowledge of the paleotopography prior to deposition. Understanding Precambrian paleotopography is critical in estimating reservoir thickness and quality. Regional outcrop and borehole mapping of the Mt. Simon in conjunction with mapping seismic reflection data can facilitate the prediction of basement highs. Any potential site must, at the minimum, have seismic reflection data, calibrated with drill-hole information, to evaluate the presence of Precambrian topography and alleviate some of the uncertainty surrounding the thickness or possible absence of the Mt. Simon at a particular sequestration site. The Mt. Simon is thought to commonly overlie Precambrian basement granitic or rhyolitic rocks. In places, at least about 549 m (1800 ft) of topographic relief on the top of the basement surface prior to Mt. Simon deposition was observed. The Mt. Simon reservoir sandstone is thin or not present where basement is topographically high, whereas the low areas can have thick Mt. Simon. The paleotopography on the basement and its correlation to Mt. Simon thickness have been observed at both outcrops and in the subsurface from the states of Illinois, Ohio, Wisconsin, and Missouri. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗
USGS2007

Geologic characteristics of the central stretch of the Ticona Channel, north-central Illinois

The Ticona Channel is located in north-central Illinois and occurs in Grundy, LaSalle, and Putnam counties. It is a buried bedrock valley that served as the principal paleodrainage system in north-central Illinois during the Illinoian and pre-Illinoian. This study focused on the part of the Ticona Channel within the Leonore 7.5??? Quadrangle. The geometry and stratigraphy of sediments that fill the Ticona Channel were investigated using high-resolution, shallow seismic reflection profiling, traditional field geologic mapping techniques, borehole data, and water-well-log data. The valley is about 2 km (1 mi) wide and approximately 60 m (200 ft) deep. The U-shape channel is straight, trends east-west, and has only one mappable tributary. The valley is carved into the Pennsylvanian Carbondale Formation in the eastern part of the study area; it has incised into the Ordovician Prairie du Chien Group in the west. At its base, the Ticona Channel is filled with the Pearl Formation, which is coarse-grained sand and gravel that was deposited during the Illinoian glaciation. The Pearl Formation is overlain by Illinoian till of the Glasford Formation and is capped by Wedron Group sediments from the Wisconsinan stage. Copyright ?? 2007. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗
USGS2010

Use of the azimuthal resistivity technique for determination of regional azimuth of transmissivity

Many bedrock units contain joint sets that commonly act as preferred paths for the movement of water, electrical charge, and possible contaminants associated with production or transit of crude oil or refined products. To facilitate the development of remediation programs, a need exists to reliably determine regional-scale properties of these joint sets: azimuth of transmissivity ellipse, dominant set, and trend(s). The surface azimuthal electrical resistivity survey method used for local in situ studies can be a noninvasive, reliable, efficient, and relatively cost-effective method for regional studies. The azimuthal resistivity survey method combines the use of standard resistivity equipment with a Wenner array rotated about a fixed center point, at selected degree intervals, which yields an apparent resistivity ellipse from which joint-set orientation can be determined. Regional application of the azimuthal survey method was tested at 17 sites in an approximately 500 km2 (193 mi2) area around Milwaukee, Wisconsin, with less than 15m (50 ft) overburden above the dolomite. Results of 26 azimuthal surveys were compared and determined to be consistent with the results of two other methods: direct observation of joint-set orientation and transmissivity ellipses from multiple-well-aquifer tests. The average of joint-set trend determined by azimuthal surveys is within 2.5?? of the average of joint-set trend determined by direct observation of major joint sets at 24 sites. The average of maximum of transmissivity trend determined by azimuthal surveys is within 5.7?? of the average of maximum of transmissivity trend determined for 14 multiple-well-aquifer tests. Copyright ?? 2010 The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗
USGS2008

Citronelle Dome: A giant opportunity for multizone carbon storage and enhanced oil recovery in the Mississippi Interior Salt Basin of Alabama

The Citronelle Dome is a giant, salt-cored anticline in the eastern Mississippi Interior Salt Basin of southern Alabama that is located near several large-scale, stationary, carbon-emitting sources in the greater Mobile area. The dome forms an elliptical, four-way structural closure containing opportunities for CO2-enhanced oil recovery (CO2-EOR) and large-capacity saline reservoir CO2 sequestration. The Citronelle oil field, located on the crest of the dome, has produced more than 169 million bbl of 42-46?? API gravity oil from sandstone bodies in the Lower Cretaceous Rodessa Formation. The top seal for the oil accumulation is a thick succession of shale and anhydrite, and the reservoir is underfilled such that oil-water contacts are typically elevated 30-60 m (100-200 ft) above the structural spill point. Approximately 31-34% of the original oil in place has been recovered by primary and secondary methods, and CO2-EOR has the potential to increase reserves by up to 20%. Structural contour maps of the dome demonstrate that the area of structural closure increases upward in section. Sandstone units providing prospective carbon sinks include the Massive and Pilot sands of the lower Tuscaloosa Group, as well as several sandstone units in the upper Tuscaloosa Group and the Eutaw Formation. Many of these sandstone units are characterized by high porosity and permeability with low heterogeneity. The Tuscaloosa-Eutaw interval is capped by up to 610 m (2000 ft) of chalk and marine shale that are proven reservoir seals in nearby oil fields. Therefore, the Citronelle Dome can be considered a major geologic sink where CO2 can be safely stored while realizing the economic benefits associated with CO2-EOR. Copyright ?? 2008. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Environmental Geosciences↗
USGS2018

Calibrated peer review assignments for the earth sciences

Calibrated Peer Review ™ (CPR), a web-based instructional tool developed as part of the National Science Foundation reform initiatives in undergraduate science education, allows instructors to incorporate multiple writing assignments in large courses without overwhelming the instructor. This study reports successful implementation of CPR in a large, introductory geology course and student learning of geoscience content. For each CPR assignment in this study, students studied web-based and paper resources, wrote an essay, and reviewed seven essays (three from the instructor, three from peers, and their own) on the topic. Although many students expressed negative attitudes and concerns, particularly about the peer review process of this innovative instructional approach, they also recognized the learning potential of completing CPR assignments. Comparing instruction on earthquakes and plate boundaries using a CPR assignment vs. an instructional video lecture and homework essay with extensive instructor feedback, students mastered more content via CPR instruction.

Journal of Geoscience Education↗
USGS2001

Some suggested future directions of quantitative resource assessments

Future quantitative assessments will be expected to estimate quantities, values, and locations of undiscovered mineral resources in a form that conveys both economic viability and uncertainty associated with the resources. Historically, declining metal prices point to the need for larger deposits over time. Sensitivity analysis demonstrates that the greatest opportunity for reducing uncertainty in assessments lies in lowering uncertainty associated with tonnage estimates. Of all errors possible in assessments, those affecting tonnage estimates are by far the most important. Selecting the correct deposit model is the most important way of controlling errors because the dominance of tonnage-deposit models are the best known predictor of tonnage. Much of the surface is covered with apparently barren rocks and sediments in many large regions. Because many exposed mineral deposits are believed to have been found, a prime concern is the presence of possible mineralized rock under cover. Assessments of areas with resources under cover must rely on extrapolation from surrounding areas, new geologic maps of rocks under cover, or analogy with other well-explored areas that can be considered training tracts. Cover has a profound effect on uncertainty and on methods and procedures of assessments because geology is seldom known and geophysical methods typically have attenuated responses. Many earlier assessment methods were based on relationships of geochemical and geophysical variables to deposits learned from deposits exposed on the surface-these will need to be relearned based on covered deposits. Mineral-deposit models are important in quantitative resource assessments for two reasons: (1) grades and tonnages of most deposit types are significantly different, and (2) deposit types are present in different geologic settings that can be identified from geologic maps. Mineral-deposit models are the keystone in combining the diverse geoscience information on geology, mineral occurrences, geophysics, and geochemistry used in resource assessments and mineral exploration. Grade and tonnage models and development of quantitative descriptive, economic, and deposit density models will help reduce the uncertainty of these new assessments.

Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Sc↗
USGS2005

Environmental issues of petroleum exploration and production: Introduction

Energy is the lifeblood of our planet Earth, an essential commod- ity that powers the expanding global economy. Starting in the 1950s, oil and natural gas became the main sources of primary energy for the increasing world population, and this dominance is expected to continue for several more decades (Edwards, 1997; Energy Information Administration (EIA), 2004). In the United States, petroleum production started in 1859 when Drake's well was drilled near Titusville, Pennsylvania, and oil and natural gas currently supply approximately 63% of the energy consumption; forecasts indicate that by 2025, their use will increase by about 40% to 28.3 million bbl/day and to 31.4 tcf/yr (EIA, 2004). The clear benefits of petroleum consumption, however, can carry major environmental impacts that may be regional or global in scale, in- cluding air pollution, global climate change, and oil spills. This vol- ume of Environmental Geosciences, covering environmental impacts of petroleum exploration and production, does not address these major impacts directly because air pollution and global warming are issues related primarily to petroleum and coal uses, and major oil spills are generally attributed to marine petroleum transportation, such as the Exxon Valdez's 1989 spill of 260,000 bbl of oil into Prince William Sound, Alaska. Exploration for and production of petroleum, however, have caused local detrimental impacts to soils, surface and groundwa- ters, and ecosystems in the 36 producing states in the United States (Richter and Kreitler, 1993; Kharaka and Hanor, 2003). These im- pacts arose primarily from the improper disposal of some of the large volumes (presently estimated at 20 billion bbl/yr total pro- duced) of saline water produced with oil and gas, from accidental hydrocarbon and produced-water releases, and from abandoned oil wells that were orphaned or not correctly plugged (Kharaka et al., 1995; Veil et al., 2004). Impacts and ground-surface disturbances, in the order of several acres per well, can also arise from related activities such as site clearance, construction of roads, tank bat- teries, brine pits and pipelines, and other land modifications nec- essary for the drilling of exploration and production wells and construction of production facilities. The cumulative impacts from these operations are high, because a total of about 3.5 million oil.

Environmental Geosciences↗
USGS2017

On extracting sediment transport information from measurements of luminescence in river sediment

Accurately quantifying sediment transport rates in rivers remains an important goal for geomorphologists, hydraulic engineers, and environmental scientists. However, current techniques for measuring long-time scale (102–106 years) transport rates are laborious, and formulae to predict transport are notoriously inaccurate. Here we attempt to estimate sediment transport rates by using luminescence, a property of common sedimentary minerals that is used by the geoscience community for geochronology. This method is advantageous because of the ease of measurement on ubiquitous quartz and feldspar sand. We develop a model from first principles by using conservation of energy and sediment mass to explain the downstream pattern of luminescence in river channel sediment. We show that the model can accurately reproduce the luminescence observed in previously published field measurements from two rivers with very different sediment transport styles. The model demonstrates that the downstream pattern of river sand luminescence should show exponential-like decay in the headwaters which asymptotes to a constant value with further downstream distance. The parameters from the model can then be used to estimate the time-averaged virtual velocity, characteristic transport lengthscale, storage time scale, and floodplain exchange rate of fine sand-sized sediment in a fluvial system. The sediment transport values predicted from the luminescence method show a broader range than those reported in the literature, but the results are nonetheless encouraging and suggest that luminescence demonstrates potential as a sediment transport indicator. However, caution is warranted when applying the model as the complex nature of sediment transport can sometimes invalidate underlying simplifications.

Journal of Geophysical Research F: Earth Surface↗
USGS2015

“Points requiring elucidation” about Hawaiian volcanism

Hawaiian volcanoes, which are easily accessed and observed at close range, are among the most studied on the planet and have spurred great advances in the geosciences, from understanding deep Earth processes to forecasting volcanic eruptions. More than a century of continuous observation and study of Hawai‘i's volcanoes has also sharpened focus on those questions that remain unanswered. Although there is good evidence that volcanism in Hawai‘i is the result of a high-temperature upwelling plume from the mantle, the source composition and dynamics of the plume are controversial. Eruptions at the surface build the volcanoes of Hawai‘i, but important topics, including how the volcanoes grow and collapse and how magma is stored and transported, continue to be subjects of intense research. Forecasting volcanic activity is based mostly on pattern recognition, but determining and predicting the nature of eruptions, especially in serving the critical needs of hazards mitigation, require more realistic models and a greater understanding of what drives eruptive activity. These needs may be addressed by better integration among disciplines as well as by developing dynamic physics- and chemistry-based models that more thoroughly relate the physiochemical behavior of Hawaiian volcanism, from the deep Earth to the surface, to geological, geochemical, and geophysical data.

Hawaii↗
USGS2021

Random forest

This entry defines and discusses the random forest machine learning algorithm. The algorithm is used to predict class or quantities for target variables using values of a set of predictor variables. It uses decision trees that are generated from bootstrap sampling of the training data set to create a "forest". The entry discusses the algorithm steps, the interpretative tools of the resulting model, current areas of research, and its limitations. Applications to the quantitative geosciences are reviewed as well as availability of software to implement the algorithm.

Book chapter↗