Publications
Filter Total Items: 1459
Laccoliths of the southwest part of the Little Belt Mountains; their relation to ancestral structures of the Central Montana Uplift Laccoliths of the southwest part of the Little Belt Mountains; their relation to ancestral structures of the Central Montana Uplift
No abstract available.
Authors
Mitchell W. Reynolds
Radiocarbon dating of cores collected from Bear Lake, Utah and Idaho Radiocarbon dating of cores collected from Bear Lake, Utah and Idaho
No abstract available.
Authors
Steven M. Colman, Darrell S. Kaufman, Joseph G. Rosenbaum, John P. McGeehin
40Ar/39Ar and K-Ar geochronology and tectonic significance of the Upper Cretaceous Adel Mountain volcanics and spatially associated Tertiary igneous rocks, northwestern Montana 40Ar/39Ar and K-Ar geochronology and tectonic significance of the Upper Cretaceous Adel Mountain volcanics and spatially associated Tertiary igneous rocks, northwestern Montana
No abstract available.
Authors
Stephen S. Harlan, Lawrence W. Snee, Mitchell W. Reynolds, Harald H. Mehnert, R. G. Schmidt, Steve D. Sheriff, Anthony J. Irving
Contrasting Proterozoic basement complexes near the truncated margin of Laurentia, northwestern Sonora–Arizona international border region Contrasting Proterozoic basement complexes near the truncated margin of Laurentia, northwestern Sonora–Arizona international border region
We utilize new geological mapping, conventional isotope dilution–thermal ionization mass spectrometry (ID-TIMS) and sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon analyses, and whole-rock radiogenic isotope characteristics to distinguish two contrasting Proterozoic basement complexes in the international border region southeast of Yuma, Arizona. Strategically located near...
Authors
Jonathan A. Nourse, Wayne R. Premo, Alexander Iriondo, Eric R. Stahl
Evaluation of groundwater movement in the Frenchman Flat CAU using geochemical and isotopic analysis Evaluation of groundwater movement in the Frenchman Flat CAU using geochemical and isotopic analysis
The principal pathway for radionuclide migration from underground tests in Frenchman Flat, on the Nevada Test Site, to the accessible environment is groundwater flow. Two potential pathways for radionuclide transport via groundwater have been identified from hydrologic data: (1) radionuclide transport downward from the alluvial and volcanic aquifers into the underlying carbonate aquifer...
Authors
R. Hershey, J. Thomas, T. Rose, James B. Paces, I. M. Farnham, F. C. Benedict
Isotopic dating of Meso- and Neoproterozoic mafic magmatism in the southern Tobacco Root Mountains, Southwestern Montana Isotopic dating of Meso- and Neoproterozoic mafic magmatism in the southern Tobacco Root Mountains, Southwestern Montana
New isotopic dating of mafic dikes in the southern Tobacco Root Mountains of southwestern Montana provides evidence for two distinct episodes of subparallel Proterozoic mafic magmatism separated by about 700 m.y. Previously published geochemical data from dikes in the southern Tobacco Root Mountains had identified three geochemical groups (termed groups A, B, and C) with apparent Rb–Sr...
Authors
Stephen S. Harlan, Wayne R. Premo, D. Unruh, J. W. Geissman
Paleoceanographic history of the Guaymas Basin, Gulf of California, during the past 15,000 years based on diatoms, silicoflagellates, and biogenic sediments Paleoceanographic history of the Guaymas Basin, Gulf of California, during the past 15,000 years based on diatoms, silicoflagellates, and biogenic sediments
High-resolution records of calcium carbonate, biogenic opal, diatoms, and silicoflagellates from western Guaymas Basin gravity core GGC55 and piston core JPC56 and eastern Guaymas Basin DSDP Site 480 reveal a complex paleoceanographic history of the central Gulf of California during the past 15,000 years. Prior to ∼ 6.2 ka, the eastern and western Guaymas Basin proxy records were...
Authors
John A. Barron, David Bukry, Walter E. Dean
Topogrid Derived 10 Meter Resolution Digital Elevation Model of Charleston, and Parts of Berkeley, Colleton, Dorchester and Georgetown Counties, South Carolina Topogrid Derived 10 Meter Resolution Digital Elevation Model of Charleston, and Parts of Berkeley, Colleton, Dorchester and Georgetown Counties, South Carolina
EXPLANATION The purpose of developing a new 10m resolution digital elevation model (DEM) of the Charleston Region was to more accurately depict geologic structure, surfical geology, and landforms of the Charleston County Region. Previously, many areas northeast and southwest of Charleston were originally mapped with a 20 foot contour interval. As a result, large areas within the National
Authors
Peter G. Chirico
Validation of abundance estimates from mark–recapture and removal techniques for rainbow trout captured by electrofishing in small streams Validation of abundance estimates from mark–recapture and removal techniques for rainbow trout captured by electrofishing in small streams
Estimation of fish abundance in streams using the removal model or the Lincoln - Peterson mark - recapture model is a common practice in fisheries. These models produce misleading results if their assumptions are violated. We evaluated the assumptions of these two models via electrofishing of rainbow trout Oncorhynchus mykiss in central Idaho streams. For one-, two-, three-, and four...
Authors
Amanda E. Rosenberger, Jason B. Dunham
Mosaic of digital raster Soviet topographic maps of Afghanistan Mosaic of digital raster Soviet topographic maps of Afghanistan
No abstract available.
Authors
Peter G. Chirico, Michael B. Warner
Fabric and texture at Siple Dome, Antarctica Fabric and texture at Siple Dome, Antarctica
Preferred c-axis orientations are present in the firn at Siple Dome, West Antarctica, and recrystallization begins as shallow as 200 m depth in ice below –20°C, based on digital analysis of c-axis fabrics, grain-sizes and other characteristics of 52 vertical thin sections prepared in the field from the kilometer-long Siple Dome ice core. The shallowest section analyzed, from 22 m, shows...
Authors
C. L. Diprinzio, Lawrence A. Wilen, R. B. Alley, J. J. Fitzpatrick, M. K. Spencer, A. J. Gow