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This report consists of geochemical data for rock samples collected in the Sleetmute 1:250,000-scale quadrangle by the U.S. Geological Survey between 1993 and 1999. Data were primarily used to conduct a mineral resource assessment of this quadrangle. The analytical results are presented here as digital tabular data with no interpretation.
Introduction The Kuskokwim mineral belt of Bundtzen and Miller (1997) forms an important metallogenic region in southwestern Alaska that has yielded more than 3.22 million ounces of gold and 400,000 ounces of silver. Precious-metal and related deposits in this region associated with Late Cretaceous to early Tertiary igneous complexes extend into the Taylor Mountains 1:250,000-scale quadrangle. The U.S. Geological Survey is in the process of conducting a mineral resource assessment of this region. This report presents analytical data collected during the third year of this multiyear study. A total of 138 rock geochemistry samples collected during the 2006 field season were analyzed using the ICP-AES/MS42, ICP-AES10, fire assay, and cold vapor atomic absorption methods described in more detail below. Analytical values are provided in percent (% or pct: 1 gram per 100 grams), parts per million (ppm: 1 gram per 1,000,000 grams), or parts per billion (ppb: 1 gram per 1,000,000,000 grams) as indicated in the column heading of the data table. Data are provided for download in Excel (*.xls), comma delimited (*.csv), dBase 4 (*.dbf) and as a point coverage in ArcInfo interchange (*.e00) formats available at http://pubs.usgs.gov/of/2007/1386/.
Obduction of an ophiolite complex onto the northwestern continental margin of the India plate occurred during the Late Cretaceous to early Paleocene, followed by collision of the ophiolitic complex of the India plate with the Eurasia plate in the Eocene. Lower Eocene marine strata overlie the ophiolitic complex suggesting that suturing was completed by early Eocene time. The Quetta-Muslim Bagh-Sibi region is a structurally complex area within west-central Pakistan characterized by broad and tight folds, and reverse, thrust, and strike-slip faults. In order to understand this complex deformation, we have divided this region into five structural domains which are separated by four major boundary faults formed during four major periods of deformation related to oblique convergence of the India and Eurasia plates. The five structural domains are (1) a foredeep, (2) a foreland fold-and-thrust belt, (3) a major deep trough that formed within the foreland fold-and-thrust belt and filled with collision molasse, (4) a thick flysch deposit, and (5) a subduction-obduction and related igneous rock terrane on the margin of the Eurasia plate (Afghan block). The four major faults that bound the structural terrane are the Frontal (F), Ghazaband-Zhob (GZ), Gwal-Bagh (GB), and Chaman (C) faults. Four major periods of deformation are recognized: (1) emplacement of ophiolitic rocks onto the continental margin of the India plate; (2) convergence of the India-Eurasia plates; (3) deposition of Tertiary-Quaternary molasse units followed by major folding and thrusting, and formation of strike-slip faults; and (4) deposition of Pleistocene molasse units with subsequent folding, thrusting, and strike-slip motion that continues to the present.
This assessment focused on five zinc-bearing minerals. The minerals were subjected to a number of analyses including quantitative X-ray diffraction, optical microscopy, leaching tests, and bioaccessibility and toxicity studies. Like a previous comprehensive assessment of five copper-bearing minerals, the purpose of this assessment was to obtain structural and chemical information and to characterize the reactivity of each mineral to various simulated environmental and biological conditions. As in the copper minerals study, analyses were conducted consistent with widely accepted methods. Unless otherwise noted, analytical methods used for this study were identical to those described in the investigation of copper-bearing minerals. Two sphalerite specimens were included in the zinc-minerals set. One sphalerite was recovered from a mine in Balmat, New York; the second came from a mine in Creede, Colorado. The location and conditions of origin are significant because, as analyses confirmed, the two sphalerite specimens are quite different. For example, data acquired from a simulated gastric fluid (SGF) study indicate that the hydrothermally formed Creede sphalerite contains orders of magnitude higher arsenic, cadmium, manganese, and lead than the much older metamorphic Balmat sphalerite. The SGF and other experimental results contained in this report suggest that crystallizing conditions such as temperature, pressure, fluidization, or alteration processes significantly affect mineral properties—properties that, in turn, influence reactivity, solubility, and toxicity. The three remaining minerals analyzed for this report—smithsonite, hemimorphite, and hydrozincite—are all secondary minerals or alteration products of zinc-ore deposits. In addition, all share physical characteristics such as tenacity, density, streak, and cleavage. Similarities end there. The chemical composition, unit-cell parameters, acid-neutralizing potential, and other observable and quantifiable properties indicate very different minerals. Only one of each of these minerals was studied. Had this assessment included multiples of these minerals, geochemical and mineralogical distinctions would have emerged, similar to the results for the two sphalerite specimens.
This report presents electron microprobe data on glasses and selected crystalline phases from Kīlauea Iki lava lake and glasses from the 1959 summit eruption of Kīlauea Volcano, Hawaii. Some of these data have been published previously, but the complete set has not been published before. In addition, this report includes electron microprobe data for phases in melting experiments reported earlier, which form the basis for using many of the glass compositions reported here to estimate quenching temperatures of the samples. Finally, because of the latter application, this report includes all useful field determinations of temperature taken in Kīlauea Iki boreholes from 1967 to 1988. These field measurements have been merged with geothermometry based on glass and Fe-Ti oxide compositions to produce a comprehensive review of all available thermal information for Kīlauea Iki. Making these datasets available completes documentation of field and chemical information on Kīlauea Iki lava lake, supplementing six previous U.S. Geological Survey Open-File Reports listed in the References Cited.
Preface In anticipation for increased funding made possible by the Water Resources Development Act of 2020, the Upper Mississippi River Restoration (UMRR) Program identified a need to conduct river-wide assessments of floodplain vegetation. In January 2025, we assembled a group of subject matter experts to perform the following tasks: Review Upper Mississippi River Restoration’s current floodplain vegetation research portfolio, Identify important features and goals for long-term floodplain vegetation monitoring, Evaluate the suitability of existing datasets for system-wide vegetation assessments, and Discuss emerging opportunities to learn about floodplain vegetation dynamics from local-scale restoration and management projects. This document is a summarization of what occurred at the meeting and provides suggested next steps toward developing the capacity to conduct routine long-term monitoring and assessment of floodplain vegetation as part of the Upper Mississippi River Restoration Program.
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Analyses for barium, beryllium, boron, calcium, cobalt, chromium, copper, iron, lanthanum, magnesium, manganese, molybdenum, niobium, nickel, lead, scandium, tin, strontium, titanium, vanadium, yttrium, zinc, and zirconium were performed on 1,304 sediment samples from the continental shelf and slope of the northern Gulf of Mexico. Approximately 40 percent of the samples were collected in two relatively small regions, one seaward of Galveston, Texas, between long. 94° and 95° W. and the other around the Dry Tortugas on the south Florida shelf. The is remaining samples represent a broad reconnaissance survey extending from the Rio Grande to the Florida Keys.
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