Sediment magnetic and paleomagnetic studies were conducted on a core from Buck Lake, Klamath County, Oregon, that was collected as part of an investigation into the Quaternary climate history of the western United States. This report documents the methods used to obtain paleomagnetic directions, magnetic properties, and ancillary data, and presents these data in tabular form. Adam (1993) and Adam and others (1994) describe the site, the drilling methods, and lithology of the lacustrine sediments. Rosenbaum and others (1994) present preliminary interpretations of the sediment magnetic data and show that variations in magnetic properties closely reflect changes in climate as interpreted from the pollen record.
Although small arms ranges are known to be contaminated with lead, the full extent of metal contamination has not been described, nor has the oral bioavailability of lead in these soils. In this work, soil samples from ranges with diverse geochemical backgrounds were sieved to <250 μm and analyzed for total metal content. Soils had consistently high levels of lead and copper, ranging from 4549 to 24 484 μg/g and 223 to 2936 μg/g, respectively, while arsenic, antimony, nickel, and zinc concentrations were 100-fold lower. For lead bioavailability measurements, two widely accepted methods were used: an in vivo juvenile swine relative bioavailability method measuring lead absorption from ingested soils relative to equivalent lead acetate concentrations and an in vitro bioaccessibility procedure which measured acid-extractable lead as a percent of total lead in the soil. For eight samples, the mean relative bioavailability and bioaccessibility of lead for the eight soils was about 100% (108 ± 18% and 95 ± 6%, respectively) showing good agreement between both methods. Risk assessment and/or remediation of small arms ranges should therefore assume high bioavailability of lead.
Research Article| August 01, 1980 Icelandite and aenigmatite-bearing pantellerite from the McDermitt caldera complex, Nevada-Oregon Andy B. Wallace; Andy B. Wallace 1Cordex Exploration Company, 573 East Second Street, Reno, Nevada 89502 Search for other works by this author on: GSW Google Scholar John W. Drexler; John W. Drexler 2Department of Geology & Geological Engineering, Michigan Technological University, Houghton, Michigan 49931 Search for other works by this author on: GSW Google Scholar Norman K. Grant; Norman K. Grant 3Department of Geology, Miami University, Oxford, Ohio 45056 Search for other works by this author on: GSW Google Scholar Donald C. Noble Donald C. Noble 4Department of Geology & Geological Engineering, Michigan Technological University, Houghton, Michigan 49931 Search for other works by this author on: GSW Google Scholar Author and Article Information Andy B. Wallace 1Cordex Exploration Company, 573 East Second Street, Reno, Nevada 89502 John W. Drexler 2Department of Geology & Geological Engineering, Michigan Technological University, Houghton, Michigan 49931 Norman K. Grant 3Department of Geology, Miami University, Oxford, Ohio 45056 Donald C. Noble 4Department of Geology & Geological Engineering, Michigan Technological University, Houghton, Michigan 49931 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1980) 8 (8): 380–384. https://doi.org/10.1130/0091-7613(1980)8<380:IAAPFT>2.0.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Andy B. Wallace, John W. Drexler, Norman K. Grant, Donald C. Noble; Icelandite and aenigmatite-bearing pantellerite from the McDermitt caldera complex, Nevada-Oregon. Geology 1980;; 8 (8): 380–384. doi: https://doi.org/10.1130/0091-7613(1980)8<380:IAAPFT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Intermediate lavas from the middle Miocene McDermitt caldera complex, Nevada-Oregon, have very high FeO* (= total Fe as FeO; 9.1 to 10.2 wt %) and low MgO (0.4 to 2.1 wt %) contents at SiO2 contents of 59.5 to 62 wt %. With the exception of significantly higher K2O contents (3.1 to 4.7 wt %), these lavas are compositionally very similar to icelandite (“tholeiitic andesite”) from oceanic areas. In addition to the voluminous comendite tuffs of the complex, a thin unit of densely welded crystal-rich pantellerite tuff of probable air-fall origin is exposed on the northern wall of the McDermitt caldera. The pantellerite tuff contains 1.5% aenigmatite phenocrysts. The high FeO*/MgO ratios of the icelandites and the peralkaline nature of the silicic rocks suggest differentiation under conditions of low fO2 and fH2O. The existence at McDermitt of a continuous series of rocks ranging from potassic icelandite to comendite and pantellerite is consistent—as are other geologic, geochemical, and geophysical data—with the derivation of the icelandites and ultimately of the voluminous peralkaline silicic rocks of the complex from mafic magma generated from upwelling mantle material. Labile U released during the crystallization of late subvolcanic bodies of peralkaline silicic magma may have provided an appreciable proportion of the epigenetic U now present in the upper part of the caldera complex. Reducing conditions produced by the very Fe-rich glassy icelandites may have contributed to the fixation of U at the Aurora and Bretz prospects. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Using stable isotope dilution, we determined the bioavailability of soilborne lead (Pb) in human adult volunteers. Soil from a residential yard at a mining-impacted federal Superfund site that had negligible amounts of other priority pollutants was dried and screened through a 25-micron mesh sieve. The < 250-micron fraction, which likely represents that ingested via hand-to-mouth activity, was then sterilized by exposure to radiation. Ten replicate samples yielded a mean (SD) soil Pb concentration of 2924 +/- 36 ppm, and a mean 206Pb/207Pb ratio of 1.1083 +/- 0.0002, indicating remarkable soil homogeneity. Six adults with 206Pb/207Pb ratios of > 1.190 were admitted to the clinical research center and fasted overnight prior to dosing with 250 micrograms Pb/70 kg bw (i.e., 85.5 mg soil/70 kg) in a gelatin capsule. Blood for Pb and 206Pb/207Pb ratios was obtained at 14 time points through 30 hr. Results of the isotopic analyses from these subjects indicate that on average 26.2% +/- 8.1 of the administered dose was absorbed. Six additional subjects were subsequently studied but ingested soil immediately after a standardized breakfast. Bioavailability in this group was only 2.52% +/- 1.7. Collectively, this study provides the first experimental estimates of soil Pb absorption in humans, and should allow for more precise estimates of health risks due to Pb-contaminated soil.
