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At least 37 records · Page 2Linked to original sources
USGS2012

Characterization of previously unidentified lunar pyroclastic deposits using Lunar Reconnaissance Orbiter Camera (LROC) data

We used a Lunar Reconnaissance Orbiter Camera (LROC) global monochrome Wide-angle Camera (WAC) mosaic to conduct a survey of the Moon to search for previously unidentified pyroclastic deposits. Promising locations were examined in detail using LROC multispectral WAC mosaics, high-resolution LROC Narrow Angle Camera (NAC) images, and Clementine multispectral (ultraviolet-visible or UVVIS) data. Out of 47 potential deposits chosen for closer examination, 12 were selected as probable newly identified pyroclastic deposits. Potential pyroclastic deposits were generally found in settings similar to previously identified deposits, including areas within or near mare deposits adjacent to highlands, within floor-fractured craters, and along fissures in mare deposits. However, a significant new finding is the discovery of localized pyroclastic deposits within floor-fractured craters Anderson E and F on the lunar farside, isolated from other known similar deposits. Our search confirms that most major regional and localized low-albedo pyroclastic deposits have been identified on the Moon down to ~100 m/pix resolution, and that additional newly identified deposits are likely to be either isolated small deposits or additional portions of discontinuous, patchy deposits.

Journal of Geophysical Research E: Planets↗
USGS1979

Martian channels and the search for extraterrestrial life

The origin of the channels on Mars has been a subject of intense interest since they were first recognized on early Mariner 9 images (Driscoll, 1972; Masursky, 1973). Their presence on the planet, and their striking resemblance to terrestrial flood channels related to glacial outbursts or to dendritic river systems has suggested to most investigators (Baker, 1974, 1977; Nummedal, 1978; Carr, 1979; Masursky et al., 1977) that they were formed by running water. Because life as we know it is dependent on water, the discovery by the 'Mariner cameras', of watercut channels and volcanoes as a source for water, and water ice in the residual north polar cap by Viking, has reaffirmed the choice of Mars as the best target for the search for extraterrestrial life. ?? 1979 Springer-Verlag.

Journal of Molecular Evolution↗
USGS1985

Undiscovered phosphate resources in the Caribbean region and their potential value for agricultural development

The countries of the world's humid tropical regions lack the soil fertility necessary for high agricultural productivity. A recently developed agricultural technology that increases soil fertility can make tropical agriculture highly productive, but the technique requires large inputs into the soil of phosphorus and other fertilizers and soil amendments. Use of fertilizers derived from phosphate rock is increasing greatly throughout the world, and fertilizer raw materials are being produced more and more frequently from phosphate rock deposits close to the areas of use. An increased understanding of the origin of phosphate rock in ancient oceans has enabled exploration geologists to target areas of potential mineral resource value and to search directly for deposits. However, because of the difficulty of prospecting for mineral deposits in forested tropical regions, phosphate rock deposits are not being explored for in the countries of the humid tropics, including most countries of the Caribbean region. As a result, the countries of the Caribbean must import phosphate rock or phosphorus fertilizer products. In the present trade market, imports of phosphate are too low for the initiation of new agricultural technology in the Caribbean and Central American region. A newly proposed program of discovery and development of undiscovered phosphate rock deposits revolves around reconnaissance studies, prospecting by core drilling, and analysis of bulk samples. The program should increase the chance of discovering economic phosphate rock deposits. The search for and evaluation of phosphate rock resources in the countries of the Caribbean region would take about 5 years and cost an average of $15 million per country. The program is designed to begin with high risk-low cost steps and end with low risk-high cost steps. A successful program could improve the foreign exchange positions of countries in the Caribbean region by adding earnings from agricultural product exports and by substituting domestically produced phosphate rock and fertilizer products for imported phosphate fertilizers. A successful program also could provide enough domestically produced phosphorus fertilizer products to allow initiation of new agricultural technology in the region and thus increase domestic food production. Finally, a new phosphorus fertilizer industry would create new jobs in the mining, chemical, and transportation industries of the Caribbean region.

Circular↗
USGS2013

Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms

Studies of abundance variations of light stable isotopes in nature have had a tremendous impact on all aspects of geochemistry since the development, in 1947, of a gas source isotope ratio mass spectrometer capable of measuring small variations in stable isotope ratios (Nice, 1947]. Stable isotope geochemistry is now a mature field, as witnessed by the proliferation of commercially available mass spectrometers installed at virtually every major academic, government, and private-sector research geochemistry laboratory. A recent search of a literature database revealed over 3,000 articles that utilized stable isotope geochemistry over the last 20 years. Nonetheless, many exciting new technical developments are leading to exciting new discoveries and applications. In particular, micro-analytical techniques involving new generations of laser- and ion-microprobes are revolutionizing the types of analyses that can be done on spot sizes as small as a few tens of micrometers [Shanks and Criss, 1989]. New generations of conventional gas source and thermal ionization mass spectrometers, with high levels of automation and increased sensitivity and precision, are allowing analyses of large numbers of samples, like those needed for stable isotope stratigraphy in marine sediments, and are enabling the development and application of new isotopic systems.

Book chapter↗
USGS2015

Now hiring! Empirically testing a three-step intervention to increase faculty gender diversity in STEM

Workforce homogeneity limits creativity, discovery, and job satisfaction; nonetheless, the vast majority of university faculty in science, technology, engineering, and mathematics (STEM) fields are men. We conducted a randomized and controlled three-step faculty search intervention based in self-determination theory aimed at increasing the number of women faculty in STEM at one US university where increasing diversity had historically proved elusive. Results show that the numbers of women candidates considered for and offered tenure-track positions were significantly higher in the intervention groups compared with those in controls. Searches in the intervention were 6.3 times more likely to make an offer to a woman candidate, and women who were made an offer were 5.8 times more likely to accept the offer from an intervention search. Although the focus was on increasing women faculty within STEM, the intervention can be adapted to other scientific and academic communities to advance diversity along any dimension.

BioScience↗
USGS1975

Mineral deposits in western Saudi Arabia; a preliminary report

Mineral deposits in Saudi Arabia include a variety of deposits which were formed in many geologic environments. These include magmatic and late magmatic deposits in igneous masses, contact metamorphic deposits along the margins of igneous bodies, and stratiform sulfide deposits and veins. Notable deposits of sedimentary origin include deposits of iron oxides and phosphate. Strata-bound massive sulfide deposits containing copper, zinc, and nickel sulfides associated with pyrite and pyrrhotite in complexly deformed volcanic rocks in Saudi Arabia have been the subject of controversy. They are considered by some geologists to be of syngenetic or volcanogenic origin, and by others to be epigenetic. The principal mineral deposits in western Saudi Arabia are localized in mineral belts within tectonic zones that trend northerly, northeasterly, and northwesterly. These belts contain the exploration target areas most promising for future exploration. Noteworthy among these are: 1) the northerly-trending Bidah copper-zinc belt; 2) the Sayid copper-zinc zone; 3) the northwest-trending Nuqrah copper zinc-silver belt; and 4) the north-northwesterly-trending Al Amar belt. Gold and silver deposits are mainly localized in north-trending structural features of the Hijaz geotectonic cycle and northwest Najd trends. Saudi Arabian metal deposits known thus far contain reserves in the 2 billion dollar range. Further exploration should result in discoveries that could significantly increase this amount; Saudi Arabia may well have workable metallic and nonmetallic mineral resources for industrial developments in many parts of the Kingdom. In order to effectively carry on a search for new mineral deposits, the belts should be mapped in detail, with emphasis on the delineation of stratigraphic and structural features that control metallization. In addition, geochemical and geophysical studies should be made of promising areas to outline exploration targets. These targets could then be systematically explored.

Open-File Report↗
USGS2012

Structural equation modeling and the analysis of long-term monitoring data

The analysis of long-term monitoring data is increasingly important; not only for the discovery and documentation of changes in environmental systems, but also as an enterprise whose fruits validate the allocation of effort and scarce funds to monitoring. In simple terms, we may distinguish between the detection of change in some ecosystem attribute versus the investigation of causes and consequences associated with that change. The statistical framework known as structural equation modeling (SEM) can contribute to both detection of changes and the search for causes. This chapter summarizes some of the capabilities of SEM and shows a few ways it can be used to model temporal change. Because of its ability to test hypotheses about whether rates of change are zero or nonzero, it can be used for change detection with repeated-measures data. As more of the capabilities of SEM are presented, its capacity for evaluating causal networks is highlighted. Here is where its potential for making a unique contribution to the analysis of long-term monitoring data is revealed. Thus, one?s primary motivation for using SEM with monitoring data will be to investigate hypotheses about what factors may be driving change. In this chapter, it will be necessary to first introduce notation to describe the elements of structural equation models (SE models) so as to permit an unambiguous presentation of their various forms. The first part of the chapter works through the fundamental features of models of increasing complexity, while the second part of the chapter illustrates several of these possibilities using a real example.

Book chapter↗
USGS1977

Preliminary data on some Precambrian deposits of zinc-copper-lead sulfides and zinc spinel (granite) in Colorado

Precambrian sulfide deposits in the Southern Rocky Mountains in Colorado are being studied and re-evaluated according to geologic concepts which were developed in recent years in other parts of the world during successful research regarding economic massive sulfide deposits. These studies, initiated in 1974 in Colorado by the U.S. Geological Survey, have indicated that a new look at areas containing long dormant mines and prospects may well lead to the discovery of minable Precambrian sulfide deposits. The zinc, copper, and lead contents of ores investigated to date, supplemented by silver and gold contents, indicate that many long-forgotten deposits are minable in terms of grade. The deposits occur in Precambrian rocks metamorphosed to the lower amphibolite facies in one major region and to the upper amphibolite facies in other regions. Field studies have provided ample evidence indicating that the search for commercial tonnages can he facilitated by using newer concepts of economic geology regarding ore-host rock associations as prospecting guides and by using structural considerations aimed toward learning how metamorphism and folding have modified the shapes and distribution of the ore bodies. A newly recognized concept, originating from the current studies by the U.S. Geological Survey in Colorado, concerns the potential economic significance of gahnite, a zinc spinel. The field and laboratory data indicate that gahnite can be used by geologists as a prospector's guide to ore and can be considerd by mining engineers as a potential major ore mineral, contributing significant amounts of zinc to the sulfide ores in many of the deposits. Studies to date indicate that the Gunnison area, the Salida area, and the Guffey area are particularly favorable to the search for minable deposits, and the potential is equally present in many other areas.

Colorado↗
USGS1958

The next decade in geochemistry

The purpose, associations, functions; and activities of the Geochmical Society are reviewed briefly. Work on the Colorado Plateau uranium deposits is described as an example of what geochemical research, in conjunction with detailed field work, mineralogical studies, and related techniques can contribute to the understanding of a type of deposit. It is pointed out that not only have these studies given a great deal of information about the origin of the ores, but they have brought about directly a manifold increase in production and reserves of uranium in the United States. Indirectly, they aided the discovery of the tremendous deposits of the Blind River area in Ontario. It is suggested that similar broad cooperative attacks could not only yield comparable results with other types of mineral deposits, such as laterites and Mississippi Valley type lead-zinc deposits, but could also advance our knowledge and understanding of such diverse problems of geology and cosmology as the origin of granites, origin and geologic implications of meteorites (including tektites), origin and search for petroleum, and geochemical relations and interpretations of natural waters. For each of these problems methods of approach are outlined and for some of them, specific projects and correlative problems are mentioned. It is further suggested that the broad cooperative attack needed for most of these problems might be fostered most effectively by a programme comparable to that of the I.G.Y., even though for most types of geochemical research synoptic sampling and observations are not as important as they are for many projects in geophysics.

Geochimica et Cosmochimica Acta↗
USGS1979

The corrosive well waters of Egypt's western desert

The discovery that ground waters of Egypt's Western Desert are highly corrosive is lost in antiquity. Inhabitants of the oases have been aware of the troublesome property for many decades and early investigators mention it in their reports concerning the area. Introduction of modern well-drilling techniques and replacements of native wood casing with steel during the 20th century increased corrosion problems and, in what is called the New Valley Project, led to an intense search for causes and corrective treatments. This revealed that extreme corrosiveness results from combined effects of relatively acidic waters with significant concentrations of destructive sulfide ion; unfavorable ratios of sulfate and chloride to less aggressive ions; mineral equilibria and electrode potential which hinder formation of protective films; relative high chemical reaction rates because of abnormal temperatures, and high surface velocities related to well design. There is general agreement among investigators that conventional corrosion control methods such as coating metal surfaces, chemical treatment of the water, and electrolytic protection with impressed current and sacrificial electrodes are ineffective or impracticable for wells in the Western Desert's New Valley. Thus, control must be sought through the use of materials more resistant to corrosion than plain carbon steel wherever well screens and casings are necessary. Of the alternatives considered, stainless steel appears to. be the most promising where high strength and long-term services are required and the alloy's relatively high cost is acceptable. Epoxy resin-bonded fiberglass and wood appear to be practicable, relatively inexpensive alternatives for installations which do. not exceed their strength limitations. Other materials such as high strength aluminum and Monel Metal have shown sufficient promise to. merit their consideration in particular locations and uses. The limited experience with pumping in these desert wells leaves uncertainties concerning the durability of conventional pump designs. Egypt's New Valley Project provides an excellent opportunity for continuing study of the corrosion problems that concern ground-water developers in many parts of the world.

Water Supply Paper↗
USGS2020

Some approaches to accounting for incidental carcass discoveries in non-monitored years using the Evidence of Absence model

Executive Summary We evaluate three approaches to accounting for incidental carcasses when estimating an upper bound on total mortality (𝑀) as 𝑀 ∗ using the Evidence of Absence model (EoA; Dalthorp and others, 2017) to assess compliance with an Incidental Take Permit (ITP) (Dalthorp & Huso, 2015) under a monitoring protocol that includes formal, dedicated carcass surveys that achieve an overall detection probability of 𝑔 𝑠 =0.15 in the first year, followed by 4 years with no formal monitoring but with carcasses potentially discovered incidentally by operations and maintenance crews in their normal course of activity or otherwise discovered outside the formal searches. We refer to carcasses discovered incidentally as “incidentals” and define 𝑥 𝑖 as the count of incidentals. Similarly, we define 𝑥 𝑠 as the number of carcasses found during the formal searches conducted the first year.

Open-File Report↗
USGS1904

The copper deposits of the Encampment District, Wyoming

During the last few years prospecting in the Medicine Bow and Park ranges in northern Colorado and southern Wyoming has proved that copper-bearing minerals occur frequently and are very generally distributed over a wide region in this portion of the Rocky Mountains. This has gradually become known through the discovery of several more or less promising copper deposits and also through the exploitation of a few properties which have produced ore on a commercial scale. The increase in the number of prospectors has kept pace with the increasing interest in the region, until now every part of it has been at least cursorily examined. In spite of this activity and of a considerable amount of development work at several localities, the productive mines in actual operation are few, but the search for valuable deposits continues, and it is to be expected that other mines will eventually be discovered.

Wyoming↗
USGS2009

Evaluation of trap capture in a geographically closed population of brown treesnakes on Guam

1. Open population mark-recapture analysis of unbounded populations accommodates some types of closure violations (e.g. emigration, immigration). In contrast, closed population analysis of such populations readily allows estimation of capture heterogeneity and behavioural response, but requires crucial assumptions about closure (e.g. no permanent emigration) that are suspect and rarely tested empirically. 2. In 2003, we erected a double-sided barrier to prevent movement of snakes in or out of a 5-ha semi-forested study site in northern Guam. This geographically closed population of >100 snakes was monitored using a series of transects for visual searches and a 13 ?? 13 trapping array, with the aim of marking all snakes within the site. Forty-five marked snakes were also supplemented into the resident population to quantify the efficacy of our sampling methods. We used the program mark to analyse trap captures (101 occasions), referenced to census data from visual surveys, and quantified heterogeneity, behavioural response, and size bias in trappability. Analytical inclusion of untrapped individuals greatly improved precision in the estimation of some covariate effects. 3. A novel discovery was that trap captures for individual snakes consisted of asynchronous bouts of high capture probability lasting about 7 days (ephemeral behavioural effect). There was modest behavioural response (trap happiness) and significant latent (unexplained) heterogeneity, with small influences on capture success of date, gender, residency status (translocated or not), and body condition. 4. Trapping was shown to be an effective tool for eradicating large brown treesnakes Boiga irregularis (>900 mm snout-vent length, SVL). 5. Synthesis and applications. Mark-recapture modelling is commonly used by ecological managers to estimate populations. However, existing models involve making assumptions about either closure violations or response to capture. Physical closure of our population on a landscape scale allowed us to determine the relative importance of covariates influencing capture probability (body size, trappability periods, and latent heterogeneity). This information was used to develop models in which different segments of the population could be assigned different probabilities of capture, and suggests that modelling of open populations should incorporate easily measured, but potentially overlooked, parameters such as body size or condition. ?? 2008 The Authors.

Journal of Applied Ecology↗
USGS1991

Element dispersion in alluvium covering gold deposits east of the Osgood Mountains, Getchell Trend, Humboldt County, Nevada: slides and text of a talk given at the Association of Exploration Geochemists' 15th International Geochemical Exploration Symposium, Reno, Nevada

The current trend in mineral exploration is to search for covered deposits. In the Great Basin, this translates into searching for ore bodies buried by alluvial cover. The exploration techniques used range from random drilling to the use of new and exciting geochemical sampling media and analytical methods. But we have a problem. Many of our geochemical techniques lack a conceptual basis (We tried it and it worked) or the original conceptual basis is now suspect (The method also works when it shouldn't). What we need is a basic understanding of what is going on in the alluvium -- the third dimension. The discovery and development of the alluvium-covered, disseminated gold deposits at Rabbit Creek, Chimney Creek, and Pinson provides us with an opportunity to gain some knowledge of the dispersion of elements in the third dimension. The work presented here is one part of a larger multi-disciplinary study of the Kelly Creek Valley by the U.S. Geological Survey in cooperation with FirstMiss Gold, Inc., Gold Fields Mining Corporation, Pinson Mining Company, and Santa Fe Pacific Mining, Inc.

Nevada↗
USGS2023

Seafloor observations eliminate a landslide as the source of the 1918 Puerto Rico Tsunami

The 11 October 1918 devastating tsunami in northwest Puerto Rico had been used as an example for earthquake‐induced landslide tsunami hazard. Three pieces of evidence pointed to a landslide as the origin of the tsunami: the discovery of a large submarine landslide scar from bathymetry data collected by shipboard high‐resolution multibeam sonar, reported breaks of submarine cable within the scar, and the fit of tsunami models to flooding observations. Newly processed seafloor imagery collected by remotely operated vehicle (ROV) show, however, pervasive Fe–Mn crust (patina) on the landslide walls and floor, indicating that the landslide scar is at least several hundred years old. C 14 "> 14 C dates of sediment covering the landslide floor verify this interpretation. Although we have not searched the region systematically for an alternative tsunami source, we propose a possible source—a two‐segment normal‐fault rupture along the eastern wall of Mona rift. The proposed fault location matches the published normal faults with steep bathymetry and is close to the International Seismological Center–Global Earthquake Model catalog locations of the 1918 mainshock and aftershocks. The ROV observations further show fresh vertical slickensides and rock exposure along the proposed fault trace. Hydrodynamic models from an M w "> M w 7.2 earthquake rupture along the eastern wall of the rift faithfully reproduce the reported tsunami amplitudes, polarities, and arrival times. Our analysis emphasizes the value of close‐up observations and physical samples to augment remote sensing data in natural hazard studies.

Puerto Rico↗
USGS1984

Offshore exploration and industry change: The case of the Gulf of Mexico

This paper considers industry structure and the exploration performance (by size class of operator) of firms searching for oil and gas in the U.S. Gulf of Mexico. It also tracks the changes in industry structure that have occurred in response to a decline in the quality of remaining prospects in the area. Data presented indicate that because vertically integrated majors dominated in exploration in the early years of the Gulf of Mexico exploration history, they were able to discover 86% of the total hydrocarbons discovered through 1975. However, the data also show a dynamic relationship between the structure of the industry operating in an area and the quality of remaining prospects. The relative share of both credited discoveries and wildcat wells of nonmajor operators has increased as exploration in the gulf proceeded. For example, in state-owned waters from 1951 to 1955, major inns accounted for 85% of all wildcat wells drilled, whereas from 1971 to 1975 these firms accounted for only 30% of the wildcat wells. During these same two periods in the federal Gulf of Mexico, the majors' share of wildcats fell from 98% to 70%.

Journal of Petroleum Technology↗
USGS2011

Data sharing by scientists: Practices and perceptions

Background Scientific research in the 21st century is more data intensive and collaborative than in the past. It is important to study the data practices of researchers – data accessibility, discovery, re-use, preservation and, particularly, data sharing. Data sharing is a valuable part of the scientific method allowing for verification of results and extending research from prior results. Methodology/Principal Findings A total of 1329 scientists participated in this survey exploring current data sharing practices and perceptions of the barriers and enablers of data sharing. Scientists do not make their data electronically available to others for various reasons, including insufficient time and lack of funding. Most respondents are satisfied with their current processes for the initial and short-term parts of the data or research lifecycle (collecting their research data; searching for, describing or cataloging, analyzing, and short-term storage of their data) but are not satisfied with long-term data preservation. Many organizations do not provide support to their researchers for data management both in the short- and long-term. If certain conditions are met (such as formal citation and sharing reprints) respondents agree they are willing to share their data. There are also significant differences and approaches in data management practices based on primary funding agency, subject discipline, age, work focus, and world region. Conclusions/Significance Barriers to effective data sharing and preservation are deeply rooted in the practices and culture of the research process as well as the researchers themselves. New mandates for data management plans from NSF and other federal agencies and world-wide attention to the need to share and preserve data could lead to changes. Large scale programs, such as the NSF-sponsored DataNET (including projects like DataONE) will both bring attention and resources to the issue and make it easier for scientists to apply sound data management principles.

PLoS ONE↗
USGS2017

Efforts to eradicate yellow crazy ants on Johnston Atoll: Results from crazy ant strike teams X, XI and XII (June 2015–December 2016)

Efforts to eradicate invasive yellow crazy ants (Anoplolepis gracilipes; YCA) on Johnston Atoll have been continuous since their discovery in 2010. Through 2014, a variety of commercial and novel formicidal baits were tested against the ant, but none proved capable of eradication. More recently, polyacrylamide crystals (“hydrogel”) saturated with a sucrose solution containing the insecticide dinotefuran has been shown to be effective over large areas when applied against YCA alone or sequentially with a protein-based cat food bait. During June 2015–December 2016, Crazy Ant Strike Teams (CASTs) conducted treatment and monitoring efforts across an infestation of about 57 ha on Johnston Atoll. Following three infestation-wide treatments (primarily using hydrogel) during 2015, YCA were reduced 98% and surviving nests became difficult to find. Subsequently, a protocol designed to detect ants at low abundance that combined hand searching with a high density of baited monitoring stations (12 stations/0.25 ha; HST protocol) was employed within a network of 50 x 50 m cells that subdivided the infestation. During 2016 YCA were found at numerous locations using this method and standard grid-based bait monitoring surveys. Overall, 65 cells where YCA were detected, or cells adjacent to detections, were treated with hydrogel or cat food bait. YCA were not detected during four monitoring events each separated by at least one week, on 85% of these cells after 1–3 treatments, but it was necessary to treat several cells 4–7 times before YCA were eliminated. Results from HST searches allowed us to estimate the probability that YCA were detected when present in an area when searched using that method. Based on this probability, it was determined that areas would have to be searched three times without YCA being detected to allow 93% certainty that the ants were absent. The level of certainty increased to 99% when the search was conducted four times and YCA were not found. Overall, the likelihood of eradicating YCA on Johnston Atoll appears high using existing protocols.

Hawai'i↗