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Research about Taylor Mountains quadrangle

Source-linked reports with geographic coverage including Taylor Mountains quadrangle.

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Bayesian mapping of regionally grouped, sparse, univariate earth science data

Some earth science data are naturally grouped by region, and it is often desirable to map these data by region. However, if there are only a few samples within each region, then the map should be smoothed in an appropriate way to mitigate the problems that arise from having only a few samples. A smoothing algorithm based on a Bayesian hierarchical model is developed and presented in this report. This algorithm has several features that make it especially suitable for mapping earth science data: it can account for measurements that are censored, it can process multiple datasets with different measurement errors and different censoring thresholds, and it can calculate the uncertainty in any statistic that is mapped. The algorithm is demonstrated by mapping gold concentrations that are measured in streambed sediments in the Taylor Mountains quadrangle in southwestern Alaska.

Alaska↗

Reconnaissance surficial geologic map of the Taylor Mountains quadrangle, southwestern Alaska

This map and accompanying digital files are the result of the interpretation of aerial photographs from the 1950s as well as more modern imagery. The area, long considered a part of Alaska that was largely not glaciated (see Karlstrom, 1964; Coulter and others, 1965; or Péwé, 1975), actually has a long history reflecting local and more distant glaciations. An unpublished photogeologic map of the Taylor Mountains quadrangle from the 1950s by J.N. Platt Jr. was useful in the construction of this map. Limited new field mapping in the area was conducted as part of a mapping project in the Dillingham quadrangle to the south (Wilson and others, 2003); however, extensive aerial photograph interpretation represents the bulk of the mapping effort. The accompanying digital files show the sources for each line and geologic unit shown on the map. I used the Platt and Muller 1950s-era aerial photographic interpretation map as the starting point for the surficial geology; their unpublished data were produced using a reconnaissance quality topographic base map. In addition to transferring their data to a modern base to use as a guide, all of the photographs were re-examined. As result, in a number of areas, the features have been reinterpreted and the linework revised. A major difference between the maps is the recognition of much more extensive glacially dammed lake deposits and reassignment of some glacial deposits to different glacial events.

Alaska↗

Aqueous geochemical data from the analysis of stream-water samples collected in June and July 2005 — Taylor Mountains 1:250,000 scale quadrangle, Alaska

We report on the chemical analysis of water samples collected from the Taylor Mountains 1:250,000-scale quadrangle. Parameters for which data are reported include pH, conductivity, water temperature, major cation and anion concentrations, trace-element concentrations, and dissolved organic-carbon concentrations. Samples were collected as part of a multiyear U.S. Geological Survey project "Geologic and Mineral Deposit Data for Alaskan Economic Development." Data presented here are from samples collected in June and July of 2005. The data are being released at this time with minimal interpretation. This is the second release of aqueous geochemical data from this project; 2004 aqueous geochemical data were published previously ( Wang and others, 2006 ). The data in this report augment but do not duplicate or supersede the previous data release. Site selection was based on a regional sampling strategy that focused on first- and second-order drainages. Water sample site selection was based on landscape parameters that included physiography, wetland extent, lithological changes, and a cursory field review of mineralogy from pan concentrates. Stream water in the Taylor Mountians quadrangle is dominated by bicarbonate (HCO 3- ), though in a few samples more than 50 percent of the anionic charge can be attributed to sulfate (SO 4 2- ). The major-cation chemistry ranges from Ca 2+ /Mg 2+ dominated to a mix of Ca 2+ /Mg 2+ /Na + +K + . In general, good agreement was found between the major cations and anions in the duplicate samples. Many trace elements in these samples were at or near the analytical method detection limit, but good agreement was found between duplicate samples for elements with detectable concentrations. With the exception of a total mercury concentration of 0.33 ng/L detected in a field blank, field blank major-ion and trace-elements concentrations were below detection.

Alaska↗