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No abstract available.

","largerWorkType":{"id":24,"text":"Conference Paper"},"largerWorkTitle":"Proceedings: Sagebrush Steppe Ecosystems Symposium","conferenceTitle":"Sagebrush Steppe Ecosystems Symposium","conferenceDate":"Boise State University, Boise, Idaho","conferenceLocation":"June 21-23, 1999","language":"English","publisher":"Boise, ID","publisherLocation":"U.S. Bureau of Land Management","usgsCitation":"Steenhof, K., Kochert, M.N., Carpenter, L., Lehman, R., and Marzluff, J., 1999, Effects of wildfires and military training on raptors, in Proceedings: Sagebrush Steppe Ecosystems Symposium, June 21-23, 1999, Boise State University, Boise, Idaho, p. 100-101.","productDescription":"2 p.","startPage":"100","endPage":"101","costCenters":[{"id":290,"text":"Forest and Rangeland Ecosystem Science Center","active":false,"usgs":true}],"links":[{"id":349818,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5a6124cfe4b06e28e9c25c46","contributors":{"authors":[{"text":"Steenhof, K.","contributorId":98696,"corporation":false,"usgs":true,"family":"Steenhof","given":"K.","affiliations":[],"preferred":false,"id":724601,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kochert, Michael N. 0000-0002-4380-3298 mkochert@usgs.gov","orcid":"https://orcid.org/0000-0002-4380-3298","contributorId":3037,"corporation":false,"usgs":true,"family":"Kochert","given":"Michael","email":"mkochert@usgs.gov","middleInitial":"N.","affiliations":[{"id":289,"text":"Forest and Rangeland Ecosys Science Center","active":true,"usgs":true},{"id":290,"text":"Forest and Rangeland Ecosystem Science Center","active":false,"usgs":true}],"preferred":true,"id":724602,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Carpenter, L.B.","contributorId":49317,"corporation":false,"usgs":true,"family":"Carpenter","given":"L.B.","email":"","affiliations":[],"preferred":false,"id":724603,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Lehman, R.N.","contributorId":49132,"corporation":false,"usgs":true,"family":"Lehman","given":"R.N.","email":"","affiliations":[],"preferred":false,"id":724604,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Marzluff, J.M.","contributorId":15152,"corporation":false,"usgs":true,"family":"Marzluff","given":"J.M.","affiliations":[],"preferred":false,"id":724605,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70194604,"text":"70194604 - 1999 - Structure and function of biological soil crusts","interactions":[],"lastModifiedDate":"2017-12-06T15:02:26","indexId":"70194604","displayToPublicDate":"1999-12-31T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":5,"text":"Book chapter"},"publicationSubtype":{"id":24,"text":"Book Chapter"},"title":"Structure and function of biological soil crusts","docAbstract":"

No abstract available

","largerWorkType":{"id":24,"text":"Conference Paper"},"largerWorkTitle":"Proceedings: Pacific Northwest Forest ad Rengeland Soil Organism Symposium","conferenceTitle":"Pacific Northwest Forest ad Rengeland Soil Organism Symposium","conferenceDate":"March 17-19, 1998","conferenceLocation":"Corvallis, Oregon","language":"English","publisher":"USDA, Forest Service, Pacific Northwest Research Station","publisherLocation":"Portland, OR","usgsCitation":"Belnap, J., 1999, Structure and function of biological soil crusts, chap. of Proceedings: Pacific Northwest Forest ad Rengeland Soil Organism Symposium, p. 161-178.","productDescription":"18 p.","startPage":"161","endPage":"178","costCenters":[{"id":290,"text":"Forest and Rangeland Ecosystem Science Center","active":false,"usgs":true}],"links":[{"id":349826,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5a6124cfe4b06e28e9c25c36","contributors":{"authors":[{"text":"Belnap, Jayne 0000-0001-7471-2279 jayne_belnap@usgs.gov","orcid":"https://orcid.org/0000-0001-7471-2279","contributorId":1332,"corporation":false,"usgs":true,"family":"Belnap","given":"Jayne","email":"jayne_belnap@usgs.gov","affiliations":[{"id":568,"text":"Southwest Biological Science Center","active":true,"usgs":true}],"preferred":true,"id":724629,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70194855,"text":"70194855 - 1999 - Tracing sediment dispersal on nourished beaches: Two case studies","interactions":[],"lastModifiedDate":"2018-01-24T08:03:45","indexId":"70194855","displayToPublicDate":"1999-12-31T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Tracing sediment dispersal on nourished beaches: Two case studies","docAbstract":"

The event- to decade-scale patterns of sediment dispersal on two artificially nourished beaches have been mapped using a combination of geophysical surveys, closely-spaced vibracores, and repeated beach profiles. At both Wrightsville Beach, NC and Folly Island, SC the sediment used for beach nourishment is macroscopically distinct from native sediment and can be used to identify sediment transport pathways and infer mechanisms for across-shelf transport. The data from both sites demonstrate that significant quantities of nourishment sediment are being transported seaward onto the inner continental shelf. The time and space scales of this transport are of engineering interest for the planning, design and long-term maintenance of nourished beaches.

","largerWorkType":{"id":24,"text":"Conference Paper"},"largerWorkTitle":"Coastal Sediments '99","conferenceTitle":"Fourth International Symposium on Coastal Engineering and Science of Coastal Sediment Processes","conferenceDate":"June 21-23, 1999","conferenceLocation":"Long Island, NY","language":"English","publisher":"American Society of Civil Engineers","isbn":"9780784404362","usgsCitation":"Thieler, E.R., Gayes, P.T., Schwab, W.C., and Harris, M., 1999, Tracing sediment dispersal on nourished beaches: Two case studies, in Coastal Sediments '99, Long Island, NY, June 21-23, 1999, p. 2118-2136.","productDescription":"22 p.","startPage":" 2118","endPage":"2136","costCenters":[{"id":678,"text":"Woods Hole Coastal and Marine Science Center","active":true,"usgs":true}],"links":[{"id":350554,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"North Carolina, South Carolina","otherGeospatial":"Folly Island, Wrightsville Beach","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -79.95849609375,\n 32.9257074887604\n ],\n [\n -76.025390625,\n 32.9257074887604\n ],\n [\n -76.025390625,\n 35.191766965947394\n ],\n [\n -79.95849609375,\n 35.191766965947394\n ],\n [\n -79.95849609375,\n 32.9257074887604\n ]\n ]\n ]\n }\n }\n ]\n}","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5a69a95fe4b06e28e9c81a97","contributors":{"authors":[{"text":"Thieler, E. Robert 0000-0003-4311-9717 rthieler@usgs.gov","orcid":"https://orcid.org/0000-0003-4311-9717","contributorId":2488,"corporation":false,"usgs":true,"family":"Thieler","given":"E.","email":"rthieler@usgs.gov","middleInitial":"Robert","affiliations":[{"id":678,"text":"Woods Hole Coastal and Marine Science Center","active":true,"usgs":true}],"preferred":true,"id":725675,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gayes, Paul T.","contributorId":194931,"corporation":false,"usgs":false,"family":"Gayes","given":"Paul","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":725676,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Schwab, William C. 0000-0001-9274-5154 bschwab@usgs.gov","orcid":"https://orcid.org/0000-0001-9274-5154","contributorId":417,"corporation":false,"usgs":true,"family":"Schwab","given":"William","email":"bschwab@usgs.gov","middleInitial":"C.","affiliations":[{"id":678,"text":"Woods Hole Coastal and Marine Science Center","active":true,"usgs":true}],"preferred":true,"id":725677,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Harris, M. Scott","contributorId":7795,"corporation":false,"usgs":true,"family":"Harris","given":"M. Scott","affiliations":[],"preferred":false,"id":725678,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70189487,"text":"70189487 - 1999 - Progress of environmental studies in coal mining areas of western Pennsylvania and central West Virginia","interactions":[],"lastModifiedDate":"2017-07-13T15:33:13","indexId":"70189487","displayToPublicDate":"1999-12-31T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Progress of environmental studies in coal mining areas of western Pennsylvania and central West Virginia","docAbstract":"

Two studies related to the regional environmental effects of coal mining in the Appalachian Plateau were conducted in 1998 as part of the National Water‐Quality Assessment program of the U.S. Geological Survey. The study area of about 20,000 square miles included parts of the Allegheny and Monongahela River basins in the north and the Kanawha River basin in the south. Water in domestic wells downgradient from fully reclaimed surface coal mines was compared to water in similar wells at unmined sites. As expected, pH was lower and the concentration of sulfate was greater at mined sites in both areas, although the pH difference was greater in the southern area. Median concentrations of iron and manganese exceeded federal drinking‐water standards at mined sites in both areas and at unmined sites in the southern area. Median concentrations of radon near reclaimed mines were about half those at unmined sites.

Surface water was sampled during summer base flow at about 180 sites that drain between 5 and 80 square miles; the sites also were sampled during 1979‐81. Median pH in 1998 was 7.9 in the north and 7.4 in the south, about 0.5 unit higher than in 1980 in both areas. Median concentrations of sulfate increased from 38 mg/L to 56 mg/L in the north and from 46 mg/L to 77 mg/L in the south, in apparent contradiction to the generally lower sulfur content of geologic units in the southern area. Among 52 basins where mining occurred both before and after 1980, the sulfate concentration more than doubled in 13 (25 percent), including greater than five‐fold increases in 5 (10 percent). For 16 mined basins where no mining has occurred since 1980, the median decrease in sulfate concentration was 18 percent, from which the half‐time for oxidation of mining‐related pyrite is estimated to be about 65 years.

","largerWorkType":{"id":24,"text":"Conference Paper"},"largerWorkTitle":"Proceedings Twentieth Annual West Virginia Surface Mine Drainage Task Force Symposium","largerWorkSubtype":{"id":19,"text":"Conference Paper"},"conferenceTitle":"Twentieth Annual West Virginia Surface Mine Drainage Task Force Symposium","conferenceDate":"April 13-14, 1999","conferenceLocation":"Morgantown, WV","language":"English","publisher":"West Virginia Mine Drainage Task Force","publisherLocation":"Morgantown, WV","usgsCitation":"Eychaner, J.H., 1999, Progress of environmental studies in coal mining areas of western Pennsylvania and central West Virginia, in Proceedings Twentieth Annual West Virginia Surface Mine Drainage Task Force Symposium, Morgantown, WV, April 13-14, 1999, 6 p.","productDescription":"6 p.","costCenters":[{"id":532,"text":"Pennsylvania Water Science Center","active":true,"usgs":true}],"links":[{"id":343821,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":343820,"rank":1,"type":{"id":15,"text":"Index Page"},"url":"https://wvmdtaskforce.com/past-symposium-papers/1999-symposium-papers/"}],"country":"United States","state":"Pennsylvania, West Virginia","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"596886a4e4b0d1f9f05f59ed","contributors":{"authors":[{"text":"Eychaner, James H.","contributorId":102050,"corporation":false,"usgs":true,"family":"Eychaner","given":"James","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":704888,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70188274,"text":"70188274 - 1999 - Development of a long-term ecological monitoring program in Denali National Park and Preserve, Alaska (USA)","interactions":[],"lastModifiedDate":"2017-06-07T15:31:52","indexId":"70188274","displayToPublicDate":"1999-12-31T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"seriesNumber":"RMRS-P-12 ","title":"Development of a long-term ecological monitoring program in Denali National Park and Preserve, Alaska (USA)","docAbstract":"

A Long-term Ecological Monitoring (LTEM) program began at Denali National Park and Preserve, Alaska (USA) in 1992, as a prototype for subarctic parks. The early history of the Denali LTEM program provides insight into the challenges that can arise during monitoring program development. The Denali program has thus far taken a watershed approach, involving collocation of study effort for a mix of abiotic and biotic attributes within a small, headwater stream (Rock Creek) which crosses the tundra-taiga boundary. An initial effort at integration and synthesis of meteorological, vegetation, small mammal and passerine bird data for the first 7 years of the program found few correlations, but power was low. We will now attempt to balance the intensive work in Rock Creek by developing a cost-effective sampling design that includes more of the park. We are also working to improve linkages between the monitoring program and park management decision-making and to strengthen data management and reporting mechanisms.

","largerWorkType":{"id":4,"text":"Book"},"largerWorkTitle":"Proceedings: North American science symposium: Toward a unified framework for inventorying and monitoring forest ecosystem resources ","largerWorkSubtype":{"id":12,"text":"Conference publication"},"conferenceTitle":"North American Science Symposium: Toward a unified framework for inventorying and monitoring forest ecosystem resources ","conferenceDate":"November 1-6, 1998","conferenceLocation":"Guadalajara, Jalisco, Mexico","language":"English","publisher":"U.S. Department of Agriculture","usgsCitation":"Oakley, K.L., Debevec, E.M., and Rexstad, E.A., 1999, Development of a long-term ecological monitoring program in Denali National Park and Preserve, Alaska (USA), in Proceedings: North American science symposium: Toward a unified framework for inventorying and monitoring forest ecosystem resources , Guadalajara, Jalisco, Mexico, November 1-6, 1998, p. 307-314.","productDescription":"8 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koakley@usgs.gov","contributorId":747,"corporation":false,"usgs":true,"family":"Oakley","given":"Karen","email":"koakley@usgs.gov","middleInitial":"L.","affiliations":[{"id":116,"text":"Alaska Science Center Biology MFEB","active":true,"usgs":true}],"preferred":true,"id":697053,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Debevec, Edward M.","contributorId":192613,"corporation":false,"usgs":false,"family":"Debevec","given":"Edward","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":697054,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Rexstad, Eric A.","contributorId":55701,"corporation":false,"usgs":true,"family":"Rexstad","given":"Eric","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":697055,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70194592,"text":"70194592 - 1999 - Ecosystem sustainability and condition","interactions":[],"lastModifiedDate":"2017-12-06T14:07:07","indexId":"70194592","displayToPublicDate":"1999-12-31T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":5,"text":"Book chapter"},"publicationSubtype":{"id":24,"text":"Book Chapter"},"title":"Ecosystem sustainability and condition","docAbstract":"

No abstract available.

","largerWorkType":{"id":4,"text":"Book"},"largerWorkTitle":"Ecological stewardship: A common reference for ecosystem management","language":"English","publisher":"Elsevier Science","publisherLocation":"New York, NY","usgsCitation":"Carroll, C., Belnap, J., and Meffe, G.K., 1999, Ecosystem sustainability and condition, chap. of Ecological stewardship: A common reference for ecosystem management, p. 583-598.","productDescription":"16 p.","startPage":"583","endPage":"598","costCenters":[{"id":289,"text":"Forest and Rangeland Ecosys Science Center","active":true,"usgs":true}],"links":[{"id":349816,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5a6124cfe4b06e28e9c25c48","contributors":{"authors":[{"text":"Carroll, C.Ronald","contributorId":111540,"corporation":false,"usgs":false,"family":"Carroll","given":"C.Ronald","email":"","affiliations":[],"preferred":false,"id":724589,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Belnap, Jayne 0000-0001-7471-2279 jayne_belnap@usgs.gov","orcid":"https://orcid.org/0000-0001-7471-2279","contributorId":1332,"corporation":false,"usgs":true,"family":"Belnap","given":"Jayne","email":"jayne_belnap@usgs.gov","affiliations":[{"id":568,"text":"Southwest Biological Science Center","active":true,"usgs":true}],"preferred":true,"id":724590,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Meffe, Gary K.","contributorId":111690,"corporation":false,"usgs":false,"family":"Meffe","given":"Gary","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":724591,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70244056,"text":"70244056 - 1999 - Chapter 7: Studies of short-lived radionuclides in Santorini volcanics","interactions":[],"lastModifiedDate":"2023-05-31T16:53:17.527913","indexId":"70244056","displayToPublicDate":"1999-12-08T11:48:01","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Chapter 7: Studies of short-lived radionuclides in Santorini volcanics","docAbstract":"

Disequilibria between the short-lived radioactive nuclides 226Ra, 230Th and 238U in young volcanic rocks can be used both for dating the time of crystallisation of a rock, and as isotopic tracers of the sources of magmas and the chemical evolution of volcanic systems. The principles of these methods have been reviewed extensively elsewhere (Condomines et al. 1988; Gill et al. 1992; Gill & Condomines 1992; Macdougall 1995). In this chapter, we present new 238U-230Th-226Ra disequilibria data for the Thera pyroclastics and for selected lavas. These data complement the radiogenic isotopic data presented in Chapter 6 on the compositional evolution through time of the pyroclastic ejecta. In particular, we find that the (230Th/232Th) isotopic ratio corrected to the time of eruption varies in a systematic way with time through the second cycle of the Thera pyroclastics and variations in this ratio are correlated with the variations of 87Sr/86Sr, 143Nd/144Nd and Pb isotopes.

","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.07","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D., Sparks, R.S., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Chapter 7: Studies of short-lived radionuclides in Santorini volcanics: Geological Society, London, Memoirs, v. 19, no. 1, p. 118-128, https://doi.org/10.1144/GSL.MEM.1999.019.01.07.","productDescription":"11 p.","startPage":"118","endPage":"128","costCenters":[],"links":[{"id":417609,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Greece","otherGeospatial":"Santorini","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 25.353444,36.332103 ], [ 25.353444,36.482241 ], [ 25.488055,36.482241 ], [ 25.488055,36.332103 ], [ 25.353444,36.332103 ] ] ] } } ] }","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874331,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874332,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874333,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":106007,"corporation":false,"usgs":false,"family":"Pyle","given":"D. M.","affiliations":[],"preferred":false,"id":874334,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R. S. J.","contributorId":46686,"corporation":false,"usgs":false,"family":"Sparks","given":"R.","email":"","middleInitial":"S. J.","affiliations":[],"preferred":false,"id":874335,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874336,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874337,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874338,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244055,"text":"70244055 - 1999 - Chapter 8: The evolution of Santorini","interactions":[],"lastModifiedDate":"2023-05-31T16:47:16.431998","indexId":"70244055","displayToPublicDate":"1999-12-08T11:34:10","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Chapter 8: The evolution of Santorini","docAbstract":"

There now follows a synthesis of the main results of this study. We interpret the observations in terms of the interplay between magmatic, tectonic and volcanic processes and place these processes within a global context. Santorini has displayed a wide variety of igneous and volcanic phenomena over a period of at least 650 000 years of almost continuous and focused volcanism. Perhaps the most intriguing issues are the causes of volcanic and magmatic cyclicity, the secular variations in magma composition and the way in which magmatic processes have influenced the style of volcanism.

","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.08","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D.M., Sparks, R.S., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Chapter 8: The evolution of Santorini: Geological Society, London, Memoirs, v. 19, no. 1, p. 129-133, https://doi.org/10.1144/GSL.MEM.1999.019.01.08.","productDescription":"5 p.","startPage":"129","endPage":"133","costCenters":[],"links":[{"id":417608,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Greece","otherGeospatial":"Santorini","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 25.353444,36.332103 ], [ 25.353444,36.482241 ], [ 25.488055,36.482241 ], [ 25.488055,36.332103 ], [ 25.353444,36.332103 ] ] ] } } ] }","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874323,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874324,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874325,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":172256,"corporation":false,"usgs":false,"family":"Pyle","given":"D.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874326,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R. S. J.","contributorId":46686,"corporation":false,"usgs":false,"family":"Sparks","given":"R.","email":"","middleInitial":"S. J.","affiliations":[],"preferred":false,"id":874327,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874328,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874329,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874330,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244054,"text":"70244054 - 1999 - Chapter 4: Compositional zoning and petrology of the Thera pyroclastics","interactions":[],"lastModifiedDate":"2023-05-31T16:27:10.404252","indexId":"70244054","displayToPublicDate":"1999-12-08T11:23:11","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Chapter 4: Compositional zoning and petrology of the Thera pyroclastics","docAbstract":"

Compositional zoning is a common feature of pyroclastic deposits erupted from calderas worldwide (Smith 1979; Hildreth 1981; Bacon & Druitt 1988; De Silva 1991; Feeley & Davidson 1994). Compositionally zoned tuffs provide a geologically instantaneous snapshot of the vertical stratigraphy and density stratification in the chamber immediately before eruption. Magma bodies are commonly zoned in density, with light, relatively cool, silicic magma overlying hotter, more mafic magma. Vertical zonation can arise by a number of processes, including crystallization and convective fractionation on the chamber.

","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.04","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D., Sparks, R.S., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Chapter 4: Compositional zoning and petrology of the Thera pyroclastics: Geological Society, London, Memoirs, v. 19, no. 1, p. 58-78, https://doi.org/10.1144/GSL.MEM.1999.019.01.04.","productDescription":"21 p.","startPage":"58","endPage":"78","costCenters":[],"links":[{"id":417607,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Greece","otherGeospatial":"Santorini","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 25.353444,36.332103 ], [ 25.353444,36.482241 ], [ 25.488055,36.482241 ], [ 25.488055,36.332103 ], [ 25.353444,36.332103 ] ] ] } } ] }","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874315,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874316,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874317,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":106007,"corporation":false,"usgs":false,"family":"Pyle","given":"D. M.","affiliations":[],"preferred":false,"id":874318,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R. S. J.","contributorId":46686,"corporation":false,"usgs":false,"family":"Sparks","given":"R.","email":"","middleInitial":"S. J.","affiliations":[],"preferred":false,"id":874319,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874320,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874321,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874322,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244053,"text":"70244053 - 1999 - Chapter 2: Geological and tectonic setting of Santorini","interactions":[],"lastModifiedDate":"2023-05-31T16:21:37.18906","indexId":"70244053","displayToPublicDate":"1999-12-08T11:14:30","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Chapter 2: Geological and tectonic setting of Santorini","docAbstract":"

Santorini lies in an area of complex extensional and subduction-related tectonics in a continental environment (Jackson 1994). The region has had a long geological history with large changes occurring during the Alpine orogeny and in the Late Tertiary as a consequence of post-collisional extension and major re-adjustments of the plate boundaries. The Aegean region is thought to be moving towards the southwest where the Aegean microplate overrides the Eastern Mediterranean sea floor. The collision has created the Hellenic trench to the south of Crete where the eastern Mediterranean sea floor is subducting beneath the Aegean Sea at 5-6 cm a-1. Santorini is one of several Quaternary volcanoes that define the present day active volcanic arc related to this subduction zone (Fig. 2.1). We here provide a synopsis of the broader geological and tectonic context of Santorini within the Aegean area. The geology, isotope geochemistry and geochronology of the crystalline basement of the southern Aegean is of particular relevance as it is likely that the Santorini magmas have interacted extensively with the continental crust. Geochemical evidence presented in Chapters 6 and 7 confirms this prediction. We also give a synopsis of the Quaternary Aegean Island Arc, of which Santorini is the most active centre.

","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.02","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D.M., Sparks, R., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Chapter 2: Geological and tectonic setting of Santorini: Geological Society, London, Memoirs, v. 19, no. 1, p. 5-12, https://doi.org/10.1144/GSL.MEM.1999.019.01.02.","productDescription":"8 p.","startPage":"5","endPage":"12","costCenters":[],"links":[{"id":417606,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Greece","otherGeospatial":"Santorini","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 25.353444,36.332103 ], [ 25.353444,36.482241 ], [ 25.488055,36.482241 ], [ 25.488055,36.332103 ], [ 25.353444,36.332103 ] ] ] } } ] }","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874307,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874308,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874309,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":172256,"corporation":false,"usgs":false,"family":"Pyle","given":"D.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874310,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R.S.J.","contributorId":149550,"corporation":false,"usgs":false,"family":"Sparks","given":"R.S.J.","email":"","affiliations":[],"preferred":false,"id":874311,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874312,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874313,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874314,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244052,"text":"70244052 - 1999 - Chapter 6 Geochemistry, isotopic composition and petrogenetic modelling of the Thera pyroclastics","interactions":[],"lastModifiedDate":"2023-05-31T16:22:39.930277","indexId":"70244052","displayToPublicDate":"1999-12-08T10:57:22","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Chapter 6 Geochemistry, isotopic composition and petrogenetic modelling of the Thera pyroclastics","docAbstract":"

This chapter examines the major element, trace element, and isotope geochemistry of the Thera pyroclastics, and places it in the context of the geochemical evolution of the whole volcanic field. Geochemical studies to date have been undertaken predominantly on the lavas, and the pyroclastic succession has been relatively neglected. The data on the pyroclastics are taken from Druitt (1983), Mellors (1988), Pyle (19906), and Edwards (1994). Wholerock analyses and sample descriptions are given in Appendix 2. Most analyses are of a single pumice or scoria lump, although some are combinations of several small clasts and a few are compositionally banded. The rock classification scheme used throughout the memoir is shown in Fig. 6.1. Previous isotopic studies on Santorini are also largely confined to the lavas, and no detailed studies had been carried out on the pyroclastic rocks. In this chapter we present new 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb and δ18О isotopic data on 40 samples of the Thera pyroclastics. We also include some measurements of hydrogen isotopes. Methods of geochemical and isotopic analysis are described in Appendix 1. This chapter also presents some quantitative models of fractional crystallization and assimilation of crustal rocks. The geochemical data and models point towards the importance of crystal fractionation, magma mixing and assimilation of continental crust in magma genesis at Santorini. The chapter also documents temporal changes in geochemical features of Santorini magmas.

","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.06","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D., Sparks, R.S., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Chapter 6 Geochemistry, isotopic composition and petrogenetic modelling of the Thera pyroclastics: Geological Society, London, Memoirs, v. 19, no. 1, p. 89-116, https://doi.org/10.1144/GSL.MEM.1999.019.01.06.","productDescription":"28 p.","startPage":"89","endPage":"116","costCenters":[],"links":[{"id":417605,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Greece","otherGeospatial":"Santorini","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 25.353444,36.332103 ], [ 25.353444,36.482241 ], [ 25.488055,36.482241 ], [ 25.488055,36.332103 ], [ 25.353444,36.332103 ] ] ] } } ] }","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874299,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874300,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874301,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":106007,"corporation":false,"usgs":false,"family":"Pyle","given":"D. M.","affiliations":[],"preferred":false,"id":874302,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R. S. J.","contributorId":46686,"corporation":false,"usgs":false,"family":"Sparks","given":"R.","email":"","middleInitial":"S. J.","affiliations":[],"preferred":false,"id":874303,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874304,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874305,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874306,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244051,"text":"70244051 - 1999 - Chapter 3: Development of the Santorini volcanic field in space and time","interactions":[],"lastModifiedDate":"2023-05-31T16:21:56.655686","indexId":"70244051","displayToPublicDate":"1999-12-08T10:32:08","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Chapter 3: Development of the Santorini volcanic field in space and time","docAbstract":"

Santorini is one of the largest Quaternary volcanic centres of the Aegean Region. The caldera cliffs preserve well-exposed sequences of lavas and pyroclastic deposits, which record the long development of the volcano in space and time. These include the products of 12 major explosive eruptions and the dissected remains of several ancient lava shields, stratovolcanoes, and lava-dome complexes. The former existence of multiple eruptive centres scattered over the present-day islands shows that Santorini is best considered as a volcanic field, which probably also continues under the sea (Heiken & McCoy 1984). Santorini is best known for the Minoan eruption of the late Bronze Age (Bond & Sparks 1976; Heiken & McCoy 1984; Sparks & Wilson 1990), but some of the previous explosive eruptions may have been as large (Druitt et al. 1989). The occurrence of repeated explosive eruptions has triggered formation of at least four large calderas, such that the present-day caldera is a composite structure (Druitt & Francaviglia 1992). Santorini is potentially one of the most dangerous volcanoes in Europe, having had numerous eruptions in historic times, some of them with significant explosive components (Fytikas et al. 1990a).

","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.03","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D.M., Sparks, R.S., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Chapter 3: Development of the Santorini volcanic field in space and time: Geological Society, London, Memoirs, v. 19, no. 1, p. 13-59, https://doi.org/10.1144/GSL.MEM.1999.019.01.03.","productDescription":"47 p.","startPage":"13","endPage":"59","costCenters":[],"links":[{"id":417604,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Greece","otherGeospatial":"Santorini","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 25.353444,36.332103 ], [ 25.353444,36.482241 ], [ 25.488055,36.482241 ], [ 25.488055,36.332103 ], [ 25.353444,36.332103 ] ] ] } } ] }","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874291,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874292,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874293,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":172256,"corporation":false,"usgs":false,"family":"Pyle","given":"D.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874294,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R. S. J.","contributorId":46686,"corporation":false,"usgs":false,"family":"Sparks","given":"R.","email":"","middleInitial":"S. J.","affiliations":[],"preferred":false,"id":874295,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874296,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874297,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874298,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244050,"text":"70244050 - 1999 - Chapter 5: Cumulate nodules in the Thera pyroclastics","interactions":[],"lastModifiedDate":"2023-05-31T16:22:17.069304","indexId":"70244050","displayToPublicDate":"1999-12-08T10:11:19","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Chapter 5: Cumulate nodules in the Thera pyroclastics","docAbstract":"

Gabbroic and dioritic nodules are common in some horizons of the Thera pyroclastics. These nodules contain pyroxene as the main ferromagnesian phase in contrast to the early Akrotiri centre, which contain nodules with abundant hornblende (Nicholls 1971a; Pichler & Kussmaul 1972). Calcsilicate nodules and gabbroic nodules have also been recognized in Santorini lavas (Fouqu6 1879; Nicholls 1971a). Previous studies of Santorini volcanic rocks indicate that crystal fractionation has played an important role in generating the compositional range basalt-andesite-dacite-rhyodacite (Nicholls 1971a; Mann 1983; Huijsmans 1985; Barton & Huijsmans 1986). This interpretation is also consistent with much of the petrological data presented in Chapter 4 and the geochemical data and models presented in Chapter 6. However, disequilibrium phenocryst assemblages in some lavas (Huijsmans 1985; Chapter 4), banded pumice clasts in many pyroclastic deposits (Druitt et al. 1989; Chapters 4), isotopic disequilibria in phenocrysts (Pyle et al. 1988; Chapters 6 and 7) and complex zoning patterns in plagioclase crystals (Stamatelopoulou-Seymour et al. 1990) indicate that magma mixing has also occurred. In addition, trace element and isotopic abundances can be interpreted in terms of assimilation of continental crust during fractionation (Barton et al. 1983; Stamatelopoulou-Seymour et al. 1990; Chapter 6). The nodules provide information on petrogenetic processes that have influenced the evolution of Santorini magmas. Their petrology is documented in this chapter and compared with that of associated juvenile ejecta. The nodules are identified as cumulates from andesitic and dacitic magmas, con- firming the importance of fractional crystallization in the petrogenesis of Santorini magmas. They also demonstrate that mafic plutonic rocks can be formed from intermediate to silicic magmas.

","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.05","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D., Sparks, R.S., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Chapter 5: Cumulate nodules in the Thera pyroclastics: Geological Society, London, Memoirs, v. 19, no. 1, p. 79-88, https://doi.org/10.1144/GSL.MEM.1999.019.01.05.","productDescription":"10 p.","startPage":"79","endPage":"88","costCenters":[],"links":[{"id":417583,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Greece","otherGeospatial":"Santorini","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 25.353444,36.332103 ], [ 25.353444,36.482241 ], [ 25.488055,36.482241 ], [ 25.488055,36.332103 ], [ 25.353444,36.332103 ] ] ] } } ] }","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874283,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874284,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874285,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":106007,"corporation":false,"usgs":false,"family":"Pyle","given":"D. M.","affiliations":[],"preferred":false,"id":874286,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R. S. J.","contributorId":46686,"corporation":false,"usgs":false,"family":"Sparks","given":"R.","email":"","middleInitial":"S. J.","affiliations":[],"preferred":false,"id":874287,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874288,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874289,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874290,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244049,"text":"70244049 - 1999 - Chapter 1: Previous research","interactions":[],"lastModifiedDate":"2023-05-31T16:21:16.017041","indexId":"70244049","displayToPublicDate":"1999-12-08T10:02:30","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Chapter 1: Previous research","docAbstract":"

Santorini has fascinated and stimulated explorers and scholars since ancient times. Jason and the Argonauts were apparently visitors to the islands and described a giant called Talos. Molten metal flowed from his feet and he threw stones at them. The island is perhaps best known for the paroxysmal eruption that took place in the Late Bronze Age at the height of the Minoan civilization that dominated Crete and the Aegean region. The legend of Atlantis, in which a whole city sank beneath the sea in a single day and night, is plausibly based on the effects of this eruption on the Minoan Civilization.

The geographer Strabo described the eruption of 197 bc in the following way:
... for midway between Thera and Therasia fires broke forth from the sea and continued for four days, so that the whole sea boiled and blazed, and the fires cast up an island which was gradually elevated as though by levers and consisted of burning masses...

This introduction gives a brief synopsis of research on the volcano since this dramatic chronicle was written. Research on Santorini has contributed substantial advances not only in the understanding of Santorini itself but to general principles in volcanology and petrology. three centres for lava eruptions on Therasia and northern Thera: the Peristeria, Simandiri and Skaros-Therasia Volcanoes.
","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.01","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D., Sparks, R.S., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Chapter 1: Previous research: Geological Society, London, Memoirs, v. 19, no. 1, p. 1-4, https://doi.org/10.1144/GSL.MEM.1999.019.01.01.","productDescription":"4 p.","startPage":"1","endPage":"4","costCenters":[],"links":[{"id":417582,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Greece","otherGeospatial":"Santorini","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ 25.353444,36.332103 ], [ 25.353444,36.482241 ], [ 25.488055,36.482241 ], [ 25.488055,36.332103 ], [ 25.353444,36.332103 ] ] ] } } ] }","volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874275,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874276,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874277,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":106007,"corporation":false,"usgs":false,"family":"Pyle","given":"D. M.","affiliations":[],"preferred":false,"id":874278,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R. S. J.","contributorId":46686,"corporation":false,"usgs":false,"family":"Sparks","given":"R.","email":"","middleInitial":"S. J.","affiliations":[],"preferred":false,"id":874279,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874280,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874281,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874282,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244048,"text":"70244048 - 1999 - Appendix 2: Tabulated analytical data","interactions":[],"lastModifiedDate":"2023-05-31T15:01:22.646222","indexId":"70244048","displayToPublicDate":"1999-12-08T09:54:35","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Appendix 2: Tabulated analytical data","docAbstract":"

Details of analytical methods and errors are given in Appendix 1. bd means below detection and na not analysed. Samples numbers which begin with the letter S are from Druitt (1983) and those that begin with LS are from Edwards (1994). Sample numbers which begin with the number 8 are either from Mellors (1988) or Pyle (1990b). Subunits of each major tuff of the Thera pyroclastics are denoted by upper case letters (A to D). These are listed in Table 3.4. In the case of the minor sequences (Appendix 2.3), the sequence abbreviations (M6 to M8) are shown in Fig. 3.17 and the individual unit abbreviations (CD1 to CD10) are from Edwards (1994).

","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.10","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D., Sparks, R.S., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Appendix 2: Tabulated analytical data: Geological Society, London, Memoirs, v. 19, no. 1, p. 138-163, https://doi.org/10.1144/GSL.MEM.1999.019.01.10.","productDescription":"26 p.","startPage":"138","endPage":"163","costCenters":[],"links":[{"id":417581,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874267,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874268,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874269,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":106007,"corporation":false,"usgs":false,"family":"Pyle","given":"D. M.","affiliations":[],"preferred":false,"id":874270,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R. S. J.","contributorId":46686,"corporation":false,"usgs":false,"family":"Sparks","given":"R.","email":"","middleInitial":"S. J.","affiliations":[],"preferred":false,"id":874271,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874272,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874273,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874274,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70244047,"text":"70244047 - 1999 - Appendix 1: Analytical methods and errors","interactions":[],"lastModifiedDate":"2023-05-31T14:43:22.95092","indexId":"70244047","displayToPublicDate":"1999-12-08T09:38:08","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1790,"text":"Geological Society, London, Memoirs","active":true,"publicationSubtype":{"id":10}},"title":"Appendix 1: Analytical methods and errors","docAbstract":"
Thirty eight K-Ar and eight 40Ar/39Ar high-precision age determinations were made at the US Geological Survey, Menlo Park, on a total of 22 rocks from the entire volcanic field. Duplicate or triplicate determinations were carried out on 14 samples in order to improve analytical precision. All ages were measured on whole-rock samples selected after thin-section examination. Most of the samples meet the usual criteria for whole-rock dating (Mankinen © Dal-rymple 1972), but some contain minor amounts of glass and a few samples are very glassy. The samples selected for dating were crushed to 0.5-lmm (-18 to +35 mesh). For K-Ar dating aliquots weighing c. 25 g were used for the Ar measurements. A 10 g aliquot was ground to -200 mesh and splits of the powder were used for K20 measurements, which were made in duplicate on each of two separate splits of sample powder by flame photometry after lithium metaborate fusion and dissolution (Ingamells 1970). Ar analyses were by isotope-dilution mass spectrometry using a high-purity (>99.9%) 38Ar tracer and techniques and equipment described previously (Dalrymple & Lanphere 1969). All samples for Ar extraction were baked overnight at 280°C. Mass analyses were done on a 22.68 cm radius, multiple-collector mass spectrometer with a nominal 90° sector magnet, using automated data collection (Stacey etal 1981).

Errors given for the calculated K-Ar ages of individual measurements are estimates of the standard deviation of analytical precision. The errors were calculated using formulae derived by Cox & Dalrymple (1967) and Dalrymple & Lanphere (1969).
","language":"English","publisher":"Geological Society of London","doi":"10.1144/GSL.MEM.1999.019.01.09","usgsCitation":"Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D.M., Sparks, R., Lanphere, M.A., Davies, M., and Barreirio, B., 1999, Appendix 1: Analytical methods and errors: Geological Society, London, Memoirs, v. 19, no. 1, p. 134-137, https://doi.org/10.1144/GSL.MEM.1999.019.01.09.","productDescription":"4 p.","startPage":"134","endPage":"137","costCenters":[],"links":[{"id":417580,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"19","issue":"1","noUsgsAuthors":false,"publicationDate":"1999-12-09","publicationStatus":"PW","contributors":{"authors":[{"text":"Druitt, T. H.","contributorId":60662,"corporation":false,"usgs":true,"family":"Druitt","given":"T.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":874259,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Edwards, L.","contributorId":91976,"corporation":false,"usgs":true,"family":"Edwards","given":"L.","affiliations":[],"preferred":false,"id":874260,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mellors, R. M.","contributorId":30542,"corporation":false,"usgs":false,"family":"Mellors","given":"R.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874261,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Pyle, D. M.","contributorId":172256,"corporation":false,"usgs":false,"family":"Pyle","given":"D.","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":874262,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Sparks, R.S.J.","contributorId":149550,"corporation":false,"usgs":false,"family":"Sparks","given":"R.S.J.","email":"","affiliations":[],"preferred":false,"id":874263,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Lanphere, Marvin A. alder@usgs.gov","contributorId":2696,"corporation":false,"usgs":true,"family":"Lanphere","given":"Marvin","email":"alder@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":874264,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Davies, M.","contributorId":54726,"corporation":false,"usgs":true,"family":"Davies","given":"M.","affiliations":[],"preferred":false,"id":874265,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Barreirio, B.","contributorId":11113,"corporation":false,"usgs":true,"family":"Barreirio","given":"B.","email":"","affiliations":[],"preferred":false,"id":874266,"contributorType":{"id":1,"text":"Authors"},"rank":8}]}} ,{"id":70162419,"text":"70162419 - 1999 - Invasive nonindigenous species: a major threat to freshwater biodiversity","interactions":[],"lastModifiedDate":"2016-01-25T09:19:32","indexId":"70162419","displayToPublicDate":"1999-12-02T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":5,"text":"Book chapter"},"publicationSubtype":{"id":24,"text":"Book Chapter"},"title":"Invasive nonindigenous species: a major threat to freshwater biodiversity","docAbstract":"

No abstract available.

","largerWorkType":{"id":4,"text":"Book"},"largerWorkTitle":"Freshwater ecoregions of North America: A conservation assessment","largerWorkSubtype":{"id":15,"text":"Monograph"},"language":"English","publisher":"Island press","usgsCitation":"Williams, J., and Meffe, G.K., 1999, Invasive nonindigenous species: a major threat to freshwater biodiversity, chap. of Freshwater ecoregions of North America: A conservation assessment, p. 67-73.","productDescription":"7 p.","startPage":"67","endPage":"73","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":566,"text":"Southeast Ecological Science Center","active":true,"usgs":true}],"links":[{"id":314723,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":314722,"rank":1,"type":{"id":15,"text":"Index Page"},"url":"https://islandpress.org/book/freshwater-ecoregions-of-north-america"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"56a75562e4b0b28f1184d858","contributors":{"authors":[{"text":"Williams, J.D.","contributorId":74701,"corporation":false,"usgs":true,"family":"Williams","given":"J.D.","email":"","affiliations":[],"preferred":false,"id":589513,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Meffe, Gary K.","contributorId":111690,"corporation":false,"usgs":false,"family":"Meffe","given":"Gary","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":589514,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70169433,"text":"70169433 - 1999 - Role of brown bears (Ursus arctos) in the flow of marine nitrogen into a terrestrial ecosystem","interactions":[],"lastModifiedDate":"2018-05-20T18:35:23","indexId":"70169433","displayToPublicDate":"1999-12-01T17:15:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2932,"text":"Oecologia","active":true,"publicationSubtype":{"id":10}},"title":"Role of brown bears (Ursus arctos) in the flow of marine nitrogen into a terrestrial ecosystem","docAbstract":"

We quantified the amount, spatial distribution, and importance of salmon (Oncorhynchus spp.)-derived nitrogen (N) by brown bears (Ursus arctos) on the Kenai Peninsula, Alaska. We tested and confirmed the hypothesis that the stable isotope signature (δ15N) of N in foliage of white spruce (Picea glauca) was inversely proportional to the distance from salmon-spawning streams (r=–0.99 and P<0.05 in two separate watersheds). Locations of radio-collared brown bears, relative to their distance from a stream, were highly correlated with δ15N depletion of foliage across the same gradient (r=–0.98 and –0.96 and P<0.05 in the same two separate watersheds). Mean rates of redistribution of salmon-derived N by adult female brown bears were 37.2±2.9 kg/year per bear (range 23.1–56.3), of which 96% (35.7±2.7 kg/year per bear) was excreted in urine, 3% (1.1±0.1 kg/year per bear) was excreted in feces, and <1% (0.3± 0.1 kg/year per bear) was retained in the body. On an area basis, salmon-N redistribution rates were as high as 5.1±0.7 mg/m2 per year per bear within 500 m of the stream but dropped off greatly with increasing distance. We estimated that 15.5–17.8% of the total N in spruce foliage within 500 m of the stream was derived from salmon. Of that, bears had distributed 83–84%. Thus, brown bears can be an important vector of salmon-derived N into riparian ecosystems, but their effects are highly variable spatially and a function of bear density.

","language":"English","publisher":"Springer","publisherLocation":"Berlin","doi":"10.1007/s004420050961","usgsCitation":"Hilderbrand, G., Hanley, T.A., Robbins, C.T., and Schwartz, C., 1999, Role of brown bears (Ursus arctos) in the flow of marine nitrogen into a terrestrial ecosystem: Oecologia, v. 121, no. 4, p. 546-550, https://doi.org/10.1007/s004420050961.","productDescription":"5 p.","startPage":"546","endPage":"550","numberOfPages":"5","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":481,"text":"Northern Rocky Mountain Science Center","active":true,"usgs":true}],"links":[{"id":319430,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alaska","otherGeospatial":"Kenai Peninsula","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n 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Box 644236, Pullman, WA 99164","active":true,"usgs":false}],"preferred":false,"id":624117,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Schwartz, C.C.","contributorId":33658,"corporation":false,"usgs":true,"family":"Schwartz","given":"C.C.","email":"","affiliations":[],"preferred":false,"id":624118,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":5223872,"text":"5223872 - 1999 - Robustness of closed capture-recapture methods to violations of the closure assumption","interactions":[],"lastModifiedDate":"2023-12-14T15:00:57.397339","indexId":"5223872","displayToPublicDate":"1999-12-01T12:18:53","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1465,"text":"Ecology","active":true,"publicationSubtype":{"id":10}},"title":"Robustness of closed capture-recapture methods to violations of the closure assumption","docAbstract":"

Closed-population capture–recapture methods have been used extensively in animal ecology, both by themselves and within the context of Pollock’s robust design and multistate models, to estimate various parameters of population and community dynamics. The defining assumption of geographic and demographic closure (i.e., no births, deaths, immigration, or emigration) for the duration of sampling is restrictive and is likely to be violated in many field situations. I evaluated several types of violations of the closure assumption and found that completely random movement in and out of a study area does not introduce bias to estimators from closed-population methods, although it decreases precision. In addition, if capture probabilities vary only with time, the closed-population Lincoln-Petersen estimator is unbiased for the size of the superpopulation when there are only births/immigration or only deaths/emigration. However, for other cases of nonrandom movement, closed-population estimators were biased when movement was Markovian (dependent on the presence/absence of the animal in the previous time period), when an animal was allowed one entry to and one exit from the study area, or when there was trap response or heterogeneity among animals in capture probability. In addition, the probability that an animal is present and available for capture (e.g., breeding propensity) can be estimated using Pollock’s robust design only when movement occurs at a broader temporal scale than that of sampling.

","language":"English","publisher":"Ecological Society of America","doi":"10.1890/0012-9658(1999)080[2517:ROCCRM]2.0.CO;2","usgsCitation":"Kendall, W.L., 1999, Robustness of closed capture-recapture methods to violations of the closure assumption: Ecology, v. 80, no. 8, p. 2517-2525, https://doi.org/10.1890/0012-9658(1999)080[2517:ROCCRM]2.0.CO;2.","productDescription":"9 p.","startPage":"2517","endPage":"2525","numberOfPages":"9","costCenters":[{"id":531,"text":"Patuxent Wildlife Research Center","active":true,"usgs":true}],"links":[{"id":503484,"rank":2,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://zotero.org/groups/5435545/items/XLX9JJ77","text":"External Repository"},{"id":202011,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"80","issue":"8","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4a0fe4b07f02db5fea2d","contributors":{"authors":[{"text":"Kendall, William L. wkendall@usgs.gov","contributorId":406,"corporation":false,"usgs":true,"family":"Kendall","given":"William","email":"wkendall@usgs.gov","middleInitial":"L.","affiliations":[{"id":531,"text":"Patuxent Wildlife Research Center","active":true,"usgs":true}],"preferred":false,"id":339781,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70260453,"text":"70260453 - 1999 - Evaluation of weights of evidence to predict epithermal-gold deposits in the Great Basin of the western United States","interactions":[],"lastModifiedDate":"2024-11-01T16:37:47.092931","indexId":"70260453","displayToPublicDate":"1999-12-01T11:32:32","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2832,"text":"Natural Resources Research","onlineIssn":"1573-8981","printIssn":"1520-7439","active":true,"publicationSubtype":{"id":10}},"title":"Evaluation of weights of evidence to predict epithermal-gold deposits in the Great Basin of the western United States","docAbstract":"

The weights-of-evidence method provides a simple approach to the integration of diverse geologic information. The application addressed is to construct a model that predicts the locations of epithermal-gold mineral deposits in the Great Basin of the western United States. Weights of evidence is a data-driven method requiring known deposits and occurrences that are used as training sites in the evaluated area. Four hundred and fifteen known hot spring gold–silver, Comstock vein, hot spring mercury, epithermal manganese, and volcanogenic uranium deposits and occurrences in Nevada were used to define an area of 327.4 km2 as training sites to develop the model. The model consists of nine weighted-map patterns that are combined to produce a favorability map predicting the distribution of epithermal-gold deposits. Using a measure of the association of training sites with predictor features (or patterns), the patterns can be ranked from best to worst predictors. Based on proximity analysis, the strongest predictor is the area within 8 km of volcanic rocks younger than 43 Ma. Being close to volcanic rocks is not highly weighted, but being far from volcanic rocks causes a strong negative weight. These weights suggest that proximity to volcanic rocks define where deposits do not occur. The second best pattern is the area within 1 km of hydrothermally altered areas. The next best pattern is the area within 1 km of known placer-gold sites. The proximity analysis for gold placers weights this pattern as useful when close to known placer sites, but unimportant where placers do not exist. The remaining patterns are significantly weaker predictors. In order of decreasing correlation, they are: proximity to volcanic vents, proximity to east-west to northwest faults, elevated airborne radiometric uranium, proximity to northwest to west and north-northwest linear features, elevated aeromagnetics, and anomalous geochemistry. This ordering of the patterns is a function of the quality, applicability, and use of the data. The nine-pattern favorability map can be evaluated by comparison with the USGS National Assessment for hot spring gold–silver deposits. The Spearman's ranked correlation coefficient between the favorability and the National Assessment permissive tracts is 0.5. Tabulations of the areas of agreement and disagreement between the two maps show 74% agreement for the Great Basin. The posterior probabilities for 51 significant deposits in the Great Basin, both used and not used in the model, show the following: 26 classified as favorable; 25 classified as permissive; and 1, Florida Canyon, classified as nonpermissive.The Florida Canyon deposit has a low favorability because there are no volcanic rocks near the deposit on the Nevada geologic map used. The largest areas of disagreement are caused by the USGS National Assessment team concluding that volcanic rocks older than 27 Ma in Nevada are not permissive, which was not assumed in this model. The weights-of-evidence model is evaluated as reasonable and delineates permissive areas for epithermal deposits comparable to expert's delineation. The weights-of-evidence model has the additional characteristics that it is well defined, reproducible, objective, and provides a quantitative measure of confidence.

","language":"English","publisher":"Springer Nature","doi":"10.1023/A:1021602316101","usgsCitation":"Raines, G.L., 1999, Evaluation of weights of evidence to predict epithermal-gold deposits in the Great Basin of the western United States: Natural Resources Research, v. 8, p. 257-276, https://doi.org/10.1023/A:1021602316101.","productDescription":"20 p.","startPage":"257","endPage":"276","costCenters":[],"links":[{"id":463551,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California, Nevada","otherGeospatial":"Great Basin","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -116.17371584886055,\n 36.273382491792404\n ],\n [\n -114.04169884465318,\n 36.75188401988002\n ],\n [\n -114.03910682052589,\n 42.01392037172616\n ],\n [\n -120.09328767290734,\n 41.95091532528593\n ],\n [\n -120.3038484479028,\n 39.282649293195846\n ],\n [\n -116.17371584886055,\n 36.273382491792404\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"8","noUsgsAuthors":false,"publicationStatus":"PW","contributors":{"authors":[{"text":"Raines, Gary L.","contributorId":48162,"corporation":false,"usgs":true,"family":"Raines","given":"Gary","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":917725,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":23937,"text":"ofr99335 - 1999 - Delineation of background laboratory contamination in the analysis of trace concentrations of extractable organic materials in crystalline rocks by Soxhlet extraction, column chromotography, and gas chromatography","interactions":[],"lastModifiedDate":"2012-02-02T00:08:00","indexId":"ofr99335","displayToPublicDate":"1999-12-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"99-335","title":"Delineation of background laboratory contamination in the analysis of trace concentrations of extractable organic materials in crystalline rocks by Soxhlet extraction, column chromotography, and gas chromatography","language":"ENGLISH","publisher":"U.S. Dept. of the Interior, U.S. Geological Survey,","doi":"10.3133/ofr99335","issn":"0094-9140","usgsCitation":"Mimura, K., and Price, L., 1999, Delineation of background laboratory contamination in the analysis of trace concentrations of extractable organic materials in crystalline rocks by Soxhlet extraction, column chromotography, and gas chromatography: U.S. Geological Survey Open-File Report 99-335, 43 p. ill. ;28 cm., https://doi.org/10.3133/ofr99335.","productDescription":"43 p. ill. ;28 cm.","costCenters":[],"links":[{"id":154907,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/of/1999/0335/report-thumb.jpg"},{"id":53143,"rank":300,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/1999/0335/report.pdf","linkFileType":{"id":1,"text":"pdf"}}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4abae4b07f02db671c69","contributors":{"authors":[{"text":"Mimura, Koichi","contributorId":70794,"corporation":false,"usgs":true,"family":"Mimura","given":"Koichi","email":"","affiliations":[],"preferred":false,"id":191006,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Price, L.C.","contributorId":48575,"corporation":false,"usgs":true,"family":"Price","given":"L.C.","email":"","affiliations":[],"preferred":false,"id":191005,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":28965,"text":"wri974224 - 1999 - Evaluation of factors that influence estimated zones of transport for six municipal wells in Clark County, Washington","interactions":[],"lastModifiedDate":"2017-02-07T09:05:15","indexId":"wri974224","displayToPublicDate":"1999-12-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":342,"text":"Water-Resources Investigations Report","code":"WRI","active":false,"publicationSubtype":{"id":5}},"seriesNumber":"97-4224","title":"Evaluation of factors that influence estimated zones of transport for six municipal wells in Clark County, Washington","docAbstract":"

A ground-water flow model was used in conjunction with particle tracking to estimate zones of transport for six municipal well sites in Clark County, Washington. A zone of transport for a well is a three-dimensional volume within a ground-water system that contains all of the ground water that will discharge from that well within a specified time period. All of the zones of transport for a well compose the zone of contribution for the well. Zones of transport and contribution are important considerations in the delineation of wellhead-protection areas. Hydrogeologic factors, such as hydraulic conductivity and porosity, influence the shape and size of the zones of transport, and, therefore, uncertainty in these and other factors can lead to uncertainty in the delineation of the zones of transport. The sensitivity of the zones of transport to uncertainty in selected hydrogeologic factors was evaluated for the six wells. Estimates of the zones of transport were delineated by the U.S. Geological Survey program MODTOOLS from three-dimensional pathlines computed by the U.S. Geological Survey program MODPATH. Input to MODPATH came from steady-state simulations calculated by the U.S. Geological Survey modular three-dimensional finite-difference ground-water flow model, MODFLOW. Three-dimensional modeling is the best method for delineating zones of transport within stratigraphically complex, heterogeneous, anisotropic aquifers that have complex boundary conditions such as streams and multiple, simultaneously discharging wells.

\n

In this study, zones of transport were delineated by using simulated particle locations computed from the results of a three-dimensional steady-state regional model for 0-0.5, 0.5-1, 1-5, 5-10, 10-20, and 20-50 year travel times to the selected wells. Zones of transport for a well were delineated by tracking particles along pathlines in the reverse direction of ground-water flow.

\n

Sensitivity of the zones of transport to change in the discharge rate of the selected well, porosity, and hydraulic conductivity, as well as to the presence or absence of interfering wells, was evaluated at six well sites to evaluate the effect of uncertainties in these factors on the size and shape of zones of transport. Uncertainty in porosity contributed the most to the uncertainty in delineating the zones of transport. Uncertainty in other factors, such as well discharge rate and horizontal hydraulic conductivity, had measurable effects on the zones of transport, but errors introduced through these factors were less significant. Insight into the causes of the changes in the size and shape of the zones of transport to varying conditions was gained by evaluating the simulated water budget and ground-water levels in the vicinity of the well. Changes in the simulated water budget and ground-water levels provided information to better understand the effects of uncertainties in the data on simulation results.The results of this study suggest that ground-water velocity is the underlying control on the size of the zones of transport. The regional hydraulic gradient is the most significant factor controlling the shape and orientation of the zones of transport. Spatial variation in recharge, discharge, and hydraulic properties can also affect the shape of the zones of transport, however. Underestimation of porosity or overestimation of horizontal hydraulic conductivity leads to overestimation of ground-water velocity and overestimation of the size of zones of transport. Overestimation of porosity or underestimation of horizontal hydraulic conductivity leads to underestimation of ground-water velocity and underestimation of the size of zones of transport. Well discharge rate affects ground-water velocities near the well. Underestimation of discharge (and therefore velocities) will result in underestimation of the size of the zones of transport. The sensitivity of estimated zones of transport to uncertainty in parameters such as porosity and horizontal hydraulic conductivity is a function of the well discharge rate and the proximity of the well to boundaries, such as streams and rivers.

","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Portland, OR","doi":"10.3133/wri974224","collaboration":"Prepared in cooperation with Intergovernmental Resource Center, Clark County, Washington","usgsCitation":"Orzol, L., and Truini, M., 1999, Evaluation of factors that influence estimated zones of transport for six municipal wells in Clark County, Washington: U.S. Geological Survey Water-Resources Investigations Report 97-4224, iv, 65 p., https://doi.org/10.3133/wri974224.","productDescription":"iv, 65 p.","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":518,"text":"Oregon Water Science Center","active":true,"usgs":true}],"links":[{"id":120074,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/wri/1997/4224/report-thumb.jpg"},{"id":57840,"rank":300,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/wri/1997/4224/report.pdf","text":"Report","size":"746.16 KB","linkFileType":{"id":1,"text":"pdf"},"description":"Report"}],"country":"United States","state":"Washington","county":"Clark 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L.L.","contributorId":63419,"corporation":false,"usgs":true,"family":"Orzol","given":"L.L.","affiliations":[],"preferred":false,"id":200702,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Truini, Margot mtruini@usgs.gov","contributorId":599,"corporation":false,"usgs":true,"family":"Truini","given":"Margot","email":"mtruini@usgs.gov","affiliations":[{"id":128,"text":"Arizona Water Science Center","active":true,"usgs":true}],"preferred":true,"id":200701,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":24023,"text":"ofr99323 - 1999 - Geochemical investigations and interim recommendations for priority abandoned mine sites, BLM lands, upper Animas River watershed, San Juan County, Colorado","interactions":[],"lastModifiedDate":"2012-02-02T00:08:15","indexId":"ofr99323","displayToPublicDate":"1999-12-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"99-323","title":"Geochemical investigations and interim recommendations for priority abandoned mine sites, BLM lands, upper Animas River watershed, San Juan County, Colorado","docAbstract":"Field observations, sampling of mine dumps and mine drainage waters, and\r\nlaboratory studies of dump materials have been made at mining areas deemed to be on\r\npublic lands administered by the U. S. Bureau of Land Management (BLM) in the Upper\r\nAnimas River watershed. Results of chemical analyses of dump materials, leachates of\r\nthose materials, and surface waters draining mines or dumps provide indications of where\r\nacid is generated or consumed, and metal concentrations below mines or dumps.\r\nInformation on sites previously identified as needing reclamation is reviewed and\r\navailable geochemical information is used to rank 26 sites into four classes of priority for\r\nreclamation.\r\nAlthough there are more than a thousand mining sites (productive mines and\r\nprospects) on BLM lands in the Upper Animas River watershed study area, the majority\r\nare very small (less than about 70 cubic yards of dump material), are more than 2 miles\r\nfrom a major stream, or so inaccessible as to prohibit reclamation. In the summers of\r\n1997 and 1998 approximately 200 sites were observed and more than 100 of these that\r\nappeared to have the potential to geochemically impact the watershed were examined\r\nmore carefully and sampled. Building upon the prior work of the BLM and associated\r\nagencies, this work attempted to identify the most significant sources of mine-related\r\ncontamination and to rank those sites as to priority for reclamation. These most\r\nsignificant mining areas have been examined within a geologic framework and were\r\nevaluated by multiple criteria, including tendency to generate acid and release toxic\r\nmetals, observed damage to vegetation, potential to release metals based on leach tests,\r\nand likelihood of transport into streams of the watershed. No single measurable\r\nparameter, such as metal concentration, can be used to rank the sites. Rather, subjective\r\nestimates are required to evaluate combinations or interactions among several parameters.\r\nThe most subjective estimate, while ranking feasibility of reclamation, is the relative\r\namounts of naturally occurring metals and acidity and mine-related contamination at each\r\nmining area. Mitigation of natural contributions at mines or unmined areas is beyond the\r\nscope of my studies, but should be considered when planning reclamation. Available\r\ninformation for the 26 priority sites is adequate for ranking, but at some sites additional\r\ninformation on groundwater conditions is needed for a more complete site evaluation.","language":"ENGLISH","publisher":"U.S. Dept. of the Interior, U.S. Geological Survey,","doi":"10.3133/ofr99323","issn":"0094-9140","usgsCitation":"Nash, J.T., 1999, Geochemical investigations and interim recommendations for priority abandoned mine sites, BLM lands, upper Animas River watershed, San Juan County, Colorado: U.S. Geological Survey Open-File Report 99-323, 43 p., 2 p. of plates :ill. (some col.), maps ;28 cm., https://doi.org/10.3133/ofr99323.","productDescription":"43 p., 2 p. of plates :ill. (some col.), maps ;28 cm.","costCenters":[],"links":[{"id":156746,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":1705,"rank":100,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.usgs.gov/of/1999/ofr-99-0323/","linkFileType":{"id":5,"text":"html"}}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4b23e4b07f02db6ae256","contributors":{"authors":[{"text":"Nash, J. Thomas","contributorId":26306,"corporation":false,"usgs":true,"family":"Nash","given":"J.","email":"","middleInitial":"Thomas","affiliations":[],"preferred":false,"id":191179,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70020958,"text":"70020958 - 1999 - Fungi from geothermal soils in Yellowstone National Park","interactions":[],"lastModifiedDate":"2023-01-12T20:01:56.636079","indexId":"70020958","displayToPublicDate":"1999-12-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":850,"text":"Applied and Environmental Microbiology","active":true,"publicationSubtype":{"id":10}},"title":"Fungi from geothermal soils in Yellowstone National Park","docAbstract":"

Geothermal soils near Amphitheater Springs in Yellowstone National Park were characterized by high temperatures (up to 70°C), high heavy metal content, low pH values (down to pH 2.7), sparse vegetation, and limited organic carbon. From these soils we cultured 16 fungal species. Two of these species were thermophilic, and six were thermotolerant. We cultured only three of these species from nearby cool (0 to 22°C) soils. Transect studies revealed that higher numbers of CFUs occurred in and below the root zone of the perennial plant Dichanthelium lanuginosum (hot springs panic grass). The dynamics of fungal CFUs in geothermal soil and nearby nongeothermal soil were investigated for 12 months by examining soil cores and in situ mesocosms. For all of the fungal species studied, the temperature of the soil from which the organisms were cultured corresponded with their optimum axenic growth temperature.

","language":"English","publisher":"American Society for Microbiology","doi":"10.1128/AEM.65.12.5193-5197.1999","issn":"00992240","usgsCitation":"Redman, R.S., Litvintseva, A., Sheehan, K., Henson, J., and Rodriguez, R.J., 1999, Fungi from geothermal soils in Yellowstone National Park: Applied and Environmental Microbiology, v. 65, no. 12, p. 5193-5197, https://doi.org/10.1128/AEM.65.12.5193-5197.1999.","productDescription":"5 p.","startPage":"5193","endPage":"5197","costCenters":[{"id":654,"text":"Western Fisheries Research Center","active":true,"usgs":true}],"links":[{"id":479410,"rank":2,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://doi.org/10.1128/aem.65.12.5193-5197.1999","text":"External Repository"},{"id":229649,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Wyoming","otherGeospatial":"Yellowstone National Park","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -111.03881835937499,\n 43.75522505306928\n ],\n [\n -111.03881835937499,\n 44.96479793033104\n ],\n [\n -109.16015624999999,\n 44.96479793033104\n ],\n [\n -109.16015624999999,\n 43.75522505306928\n ],\n [\n -111.03881835937499,\n 43.75522505306928\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"65","issue":"12","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a141be4b0c8380cd548f2","contributors":{"authors":[{"text":"Redman, R. S.","contributorId":26094,"corporation":false,"usgs":true,"family":"Redman","given":"R.","email":"","middleInitial":"S.","affiliations":[],"preferred":false,"id":388106,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Litvintseva, A.","contributorId":74897,"corporation":false,"usgs":true,"family":"Litvintseva","given":"A.","affiliations":[],"preferred":false,"id":388108,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Sheehan, K.B.","contributorId":80447,"corporation":false,"usgs":true,"family":"Sheehan","given":"K.B.","email":"","affiliations":[],"preferred":false,"id":388109,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Henson, J.M.","contributorId":8247,"corporation":false,"usgs":true,"family":"Henson","given":"J.M.","email":"","affiliations":[],"preferred":false,"id":388105,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Rodriguez, R. J.","contributorId":53107,"corporation":false,"usgs":false,"family":"Rodriguez","given":"R.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":388107,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70197197,"text":"70197197 - 1999 - A comparison of the weights-of-evidence method and probabilistic neural networks","interactions":[],"lastModifiedDate":"2018-05-21T16:45:10","indexId":"70197197","displayToPublicDate":"1999-12-01T00:00:00","publicationYear":"1999","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2832,"text":"Natural Resources Research","onlineIssn":"1573-8981","printIssn":"1520-7439","active":true,"publicationSubtype":{"id":10}},"title":"A comparison of the weights-of-evidence method and probabilistic neural networks","docAbstract":"

The need to integrate large quantities of digital geoscience information to classify locations as mineral deposits or nondeposits has been met by the weights-of-evidence method in many situations. Widespread selection of this method may be more the result of its ease of use and interpretation rather than comparisons with alternative methods. A comparison of the weights-of-evidence method to probabilistic neural networks is performed here with data from Chisel Lake-Andeson Lake, Manitoba, Canada. Each method is designed to estimate the probability of belonging to learned classes where the estimated probabilities are used to classify the unknowns. Using these data, significantly lower classification error rates were observed for the neural network, not only when test and training data were the same (0.02 versus 23%), but also when validation data, not used in any training, were used to test the efficiency of classification (0.7 versus 17%). Despite these data containing too few deposits, these tests of this set of data demonstrate the neural network's ability at making unbiased probability estimates and lower error rates when measured by number of polygons or by the area of land misclassified. For both methods, independent validation tests are required to ensure that estimates are representative of real-world results. Results from the weights-of-evidence method demonstrate a strong bias where most errors are barren areas misclassified as deposits. The weights-of-evidence method is based on Bayes rule, which requires independent variables in order to make unbiased estimates. The chi-square test for independence indicates no significant correlations among the variables in the Chisel Lake–Andeson Lake data. However, the expected number of deposits test clearly demonstrates that these data violate the independence assumption. Other, independent simulations with three variables show that using variables with correlations of 1.0 can double the expected number of deposits as can correlations of −1.0. Studies done in the 1970s on methods that use Bayes rule show that moderate correlations among attributes seriously affect estimates and even small correlations lead to increases in misclassifications. Adverse effects have been observed with small to moderate correlations when only six to eight variables were used. Consistent evidence of upward biased probability estimates from multivariate methods founded on Bayes rule must be of considerable concern to institutions and governmental agencies where unbiased estimates are required. In addition to increasing the misclassification rate, biased probability estimates make classification into deposit and nondeposit classes an arbitrary subjective decision. The probabilistic neural network has no problem dealing with correlated variables—its performance depends strongly on having a thoroughly representative training set. Probabilistic neural networks or logistic regression should receive serious consideration where unbiased estimates are required. The weights-of-evidence method would serve to estimate thresholds between anomalies and background and for exploratory data analysis.

","language":"English","publisher":"Springer","doi":"10.1023/A:1021606417010","usgsCitation":"Singer, D.A., and Kouda, R., 1999, A comparison of the weights-of-evidence method and probabilistic neural networks: Natural Resources Research, v. 8, no. 4, p. 287-298, https://doi.org/10.1023/A:1021606417010.","productDescription":"12 p.","startPage":"287","endPage":"298","costCenters":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"links":[{"id":354373,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"8","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5b15919ae4b092d9651e21f2","contributors":{"authors":[{"text":"Singer, Donald A. dsinger@usgs.gov","contributorId":5601,"corporation":false,"usgs":true,"family":"Singer","given":"Donald","email":"dsinger@usgs.gov","middleInitial":"A.","affiliations":[],"preferred":true,"id":735969,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kouda, Ryoichi","contributorId":198036,"corporation":false,"usgs":false,"family":"Kouda","given":"Ryoichi","email":"","affiliations":[],"preferred":false,"id":735970,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ]}