GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 261-2
Presentation Time: 9:00 AM-6:30 PM


WANG, Bronwen, Alaska Science Center, U.S. Geological Survey, 4210 University Dr, Anchorage, AK 99508 and ELLEFSEN, Karl J., U.S. Geological Survey, Box 25046, Mail Stop 964, Denver Federal Center, Denver, CO 80225

The Taylor Mountains quadrangle, Alaska, encompasses a variety of Au ± Hg and Sn-W mineral system types, geological domains, and Quaternary sediment types. To delineate elemental background concentrations and identify geochemically anomalous areas, a stream sediment geochemical survey (n = 700) was conducted between 2004 and 2008. The geochemical data were analyzed using multivariate statistics, and six geochemical subsets were identified. Initial interpretation relates these geochemical subsets to the major geologic features and mineral systems of the Taylor Mountains quadrangle. Two subsets are enriched in Hg relative to the other subsets and are predominantly found in the Kuskokwim Mountains and the uplands in the northwest; this signature likely reflects the Hg-rich epithermal or intrusion-related mineral systems of the Kuskokwim Mountains. The third and fourth subsets are enriched in As, Bi, Cd, Sb, W and Au relative to other subsets and are principally located near the Shotgun Hills, Sleitat Mountain, and Taylor Mountains. The geochemical signature of these subgroups is interpreted as reflecting the Au and W mineralization in these areas. The fifth and sixth subsets are principally found in the southern portion of the quadrangle, where deposits from early and late Wisconsin glacial episodes are common. One of these subsets predominates in the southeastern portion of the quadrangle and is enriched in Ca, K, La, Na, and Sr relative to the other subsets. The other is predominantly found in the southwestern portion of the quadrangle and is enriched in Ag, Mg, Mn relative to the other subsets. The glacial deposits in the southeast were derived from the western Alaska Range; those in the southwest were derived from glaciers that flowed from the Ahklun Mountains. The geochemical differences noted in stream sediments in these areas may reflect the differing provenance of the glacial deposits. linkages made between the geochemical signatures found in stream sediments and the geology and mineralization can help delineate both background and potentially anomalous elemental concentrations that reflect the geological and metallogenic characteristics of the area.