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At least 829 records · Page 46Linked to original sources
USGS2012

Exploring the Earth's crust: History and results of controlled-source seismology

This volume contains a comprehensive, worldwide history of seismological studies of the Earth’s crust using controlled sources from 1850 to 2005. Essentially all major seismic projects on land and the most important oceanic projects are covered. The time period 1850 to 1939 is presented as a general synthesis, and from 1940 onward the history and results are presented in separate chapters for each decade, with the material organized by geographical region. Each chapter highlights the major advances achieved during that decade in terms of data acquisition, processing technology, and interpretation methods. For all major seismic projects, the authors provide specific details on field observations, interpreted crustal cross sections, and key references. They conclude with global and continental-scale maps of all field measurements and interpreted Moho contours. An accompanying DVD contains important out-of-print publications and an extensive collection of controlled-source data, location maps, and crustal cross sections.

GSA Memoir↗
USGS1976

Exploration for porphyry copper deposits in Pakistan using digital processing of Landsat-1 data

Rock-type classification by digital-computer processing of Landsat-1 (formerly ERTS-1) multispectral scanner data has been used to select 23 prospecting targets in the Chagai District, Pakistan, 5 of which have proved to be large areas of hydrothermally altered porphyry containing pyrite. The known porphyry copper deposit at Saindak was used as a control area. Empirical maximum and minimum apparent reflectance limits were selected for each multispectral scanner band in each rock type classified, and a relatively unrefined classification table was prepared. Where the values for all four bands fitted within the limits designated for a particular class, a symbol for the presumed rock type was printed by the computer at the appropriate location; these symbols formed a classification map. Drainage channels, areas of mineralized quartz diorite, areas of pyrite-rich rock, and the approximate limit of propylitic alteration were very well delineated on the computer-generated map of the test area. The classification method was then used to evaluate 2,100 km 2 in the Mashki Chah region, east of the test area, and a partial check of the results was made in the field. The results of the experiment show that outcrops of hydrothermally altered and mineralized rock can be identified from Landsat-1 data under favorable conditions. The empirical method of digital computer classification of the multispectral scanner data was relatively unrefined and rapid. The five mineralized prospecting sites identified are in locations that I would not have selected as favorable on the basis of geologic knowledge or photogeologic interpretation at the time of the investigation.

Journal of Research of the U.S. Geological Survey↗
USGS1980

Airborne Fraunhofer line discriminator (FLD) luminescence imaging systems and its application to exploration problems

Experiments with an imaging airborne Fraunhofer line discriminator (FLD) are being conducted to establish the feasibility of delineating the areal extent of luminescent materials on the earth's surface from aircraft and spacecraft. All luminescence measurements are related to a standard set of conditions with rhodamine wt dye used as a reference standard. The FLD has a minimum detectable rhodamine wt concentration of 0.1 parts per billion (ppb) at a signal-to-noise ratio of 5.0. Luminescence, when expressed in a signal-to-noise ratio (R) is related to equivalent ppb rhodamine wt through the relationship ppb=(0.1R-0.4). Luminescent materials imaged from an aircraft altitude of approximately 2400 m above terrain include fluorite in association with molybdenum, Pinenut Mountains, Nevada (R=62.0); mineralized playas, Claunch, New Mexico (R=960.0); uranium and vanadium-bearing outcrops, Big Indian Valley, Utah (R=105.0); uranophane sandstones, Sandia Mountains, New Mexico (R=60.0); phosphate outcrops, Pine Mountain, California (R=76.0); and marine oil slicks, Santa Barbara Channel, California (R=24.0). Correlation between the amount of fluorite in the rocks and soils of the Pinenut Mountains and luminescence, measured by the FLD, is as high as 0.88 at the 95 percent confidence level.

Sixth Annual Pecora Symposium and Exposition↗
USGS2007

Survey report of NOAA Ship McArthur II cruises AR-04-04, AR-05-05 and AR-06-03: habitat classification of side scan sonar imagery in support of deep-sea coral/sponge explorations at the Olympic Coast National Marine Sanctuary

Habitat mapping and characterization has been defined as a high-priority management issue for the Olympic Coast National Marine Sanctuary (OCNMS), especially for poorly known deep-sea habitats that may be sensitive to anthropogenic disturbance. As a result, a team of scientists from OCNMS, National Centers for Coastal Ocean Science (NCCOS), and other partnering institutions initiated a series of surveys to assess the distribution of deep-sea coral/sponge assemblages within the sanctuary and to look for evidence of potential anthropogenic impacts in these critical habitats. Initial results indicated that remotely delineating areas of hard bottom substrate through acoustic sensing could be a useful tool to increase the efficiency and success of subsequent ROV-based surveys of the associated deep-sea fauna. Accordingly, side scan sonar surveys were conducted in May 2004, June 2005, and April 2006 aboard the NOAA Ship McArthur II to: (1) obtain additional imagery of the seafloor for broader habitat-mapping coverage of sanctuary waters, and (2) help delineate suitable deep-sea coral-sponge habitat, in areas of both high and low commercial-fishing activities, to serve as sites for surveying-in more detail using an ROV on subsequent cruises, Several regions of the sea floor throughout the OCNMS were surveyed and mosaicked at 1-meter pixel resolution. Imagery from the side scan sonar mapping efforts was integrated with other complementary data from a towed camera sled, ROVs, sedentary samples, and bathymetry records to describe geological and biological (where possible) aspects of habitat. Using a hierarchical deep-water marine benthic classification scheme (Greene et al. 1999), we created a preliminary map of various habitat polygon features for use in a geographical information system (GIS). This report provides a description of the mapping and groundtruthing efforts as well as results of the image classification procedure for each of the areas surveyed.

Washington↗
USGS2011

Exploring life history characteristics of naturalized versus stocked chinook

Naturalization of stocked populations can result in divergence of life-history traits from domestic stocks. Lake Michigan supports popular Chinook (Oncorhynchus tshawytscha) Salmon fisheries that have been sustained by stocking since the late 1960s. Natural recruitment of Chinook Salmon in Lake Michigan has increased in the last few decades and currently contributes over 50% of Chinook Salmon recruits. Samples collected as part of a lakewide mass-marking of Lake Michigan Chinook Salmon, starting with the 2006 year class, indicated hatchery fish average 30-mm longer and 130 grams heavier than naturalized fish at age-1. We hypothesized that selective forces differ for naturalized and hatchery populations resulting in divergent life-history characteristics with implications for Chinook Salmon population production and the Lake Michigan fishery. Specific life-history metrics of interest include: age- and size- at maturity, spawning run timing, fecundity, and sex ratio. Objectives: We evaluated life history characteristics between naturally recruited and stocked Chinook Salmon in Lake Michigan to help discern potential changes resulting from naturalization and implications for fisheries. A. Conduct an analysis of historical data to determine if life-history parameters changed through time as the Chinook Salmon population became increasingly naturalized. B. Conduct a two-year field study of naturalized and hatchery stocked Chinook Salmon spawning populations to quantify differences in life-history metrics of adults. C. Determine if reproductive potential differs between naturalized and hatchery stocked Chinook salmon by measuring egg thiamine levels.

Michigan↗
USGS2012

Exploring the erodibility of sediments and harmful algal blooms in the Gulf of Maine

Investigators at the U.S. Geological Survey (USGS) are cooperating with scientists at Woods Hole Oceanographic Institution (WHOI) to investigate harmful algal blooms along the New England coast in the Gulf of Maine. These blooms are caused by cysts of the dinoflagellate Alexandrium fundyense that overwinter in the bottom sediments and germinate in spring. Depending on conditions such as temperature, light, nutrient levels, and currents, these single-celled organismscan create a bloom along the coast, called ‘red tides.’Shellfish that have ingested these cells in sufficient concentration can become toxic to humans and require that the shellfisheries be closed. After the spring bloom, the organisms form cysts that sink to the sea floor and are sequestered in the bottom sediments over the winter.

EcoSystem Indicator Partnership Journal↗
USGS2002

A model project for exploring the role of sustainability science in a citizen-centered, collaborative decision-making process

The role of science in society is evolving as we enter the 21st century. The report, Science — The Endless Frontier (Bush 1990[1945]), outlined a model of national scientific research that served the country for 50 years. The contract between science and society established in that report stipulated that science is essential and that basic research meets national needs (Pielke and Byerly 1998). This stipulation and the abundant — seemingly unlimited and unquestioned — funding for research during the Cold War caused many scientists to come to believe that funding for science was an entitlement independent of societal needs. Implicit in this belief is that science alone can solve society’s problems. We now are learning that many policy issues that involve science involve diverse economic, political, social, and aesthetic values as well, and rarely, if ever, is scientific information alone the basis of public policy (e.g., see Sarewitz 1996a, 1996b; Frodeman 1997). Moreover, resources are increasingly more limited and many in society are questioning the value of public-supported science.

Human Ecology Review↗