Hydrogeochemical Exploration: A Reconnaissance Study on Northeastern Seward Peninsula, Alaska

Professional Paper 1814- A
By: , and 
Edited by: Julie A. Dumoulin

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Abstract

A reconnaissance hydrogeochemical study employing high-resolution/high-sensitivity inductively coupled plasma mass spectrometry analysis of stream and seep water samples (n= 171) was conducted in an area of limited bedrock exposure on the northeastern Seward Peninsula, Alaska. Sampling was focused in drainages around four main areas—at the Anugi Pb-Zn-Ag occurrence and in streams upstream of historically and currently mined placer gold deposits in the Candle Creek, Utica, and Monument Mountain areas. The objective of the study was to determine whether distribution of elevated metal concentrations in water samples could “see” through sediment cover and provide evidence of bedrock sources for base metals and gold. Some observations include (1) elevated Ag, As, Pb, and Zn concentrations relative to the study area as a whole in stream and seep samples from over and downstream of part of the Anugi Pb-Zn-Ag prospect; (2) abrupt downstream increases in Tl and Sb ± Au concentrations coincident with the upstream termination of productive placer deposits in the Inmachuk and Old Glory Creek drainages near Utica; (3) high K, Mo, Sb, and F throughout much of the Inmachuk River drainage near Utica; and (4) elevated As ± base metals and Au at two sites along Patterson Creek near the town of Candle and three additional contiguous sites identified when an 85th percentile cut-off was employed. Molybdenum ± gold concentrations (>90th percentile) were also measured in samples from three sites on Glacier Creek near Monument Mountain. The hydrogeochemistry in some areas is consistent with limited stream-sediment data from the region, including high Pb-Zn-Ag-As concentrations associated with Anugi, as well as historical reports of arsenopyrite-bearing veins upstream of placer operations in Patterson Creek. Chemistry of samples in the Inmachuk River-Old Glory Creek area also suggest more laterally extensive stibnite- (and gold-?) bearing veining than is currently known in the Old Glory Creek drainage. Our results indicate that hydrogeochemistry can be a useful method of geochemical exploration and offer targets for follow-up rock, soil, and subsurface sampling to ascertain the presence of mineralized bedrock.

Suggested Citation

Graham, G.E., Taylor, R.D., and Buckley, S., 2015, Hydrogeochemical exploration—A reconnaissance study on northeastern Seward Peninsula, Alaska, in Dumoulin, J.A., ed., Studies by the U.S. Geological Survey in Alaska, vol. 15: U.S. Geological Survey Professional Paper 1814–A, 16 p., http://dx.doi.org/10.3133/pp1814A.

ISSN: 2330-7102 (online)

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Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Hydrogeochemical exploration: a reconnaissance study on northeastern Seward Peninsula, Alaska
Series title Professional Paper
Series number 1814
Chapter A
DOI 10.3133/pp1814A
Year Published 2015
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Alaska Science Center Geology Minerals
Description v, 16 p.
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title Studies by the U.S. Geological Survey in Alaska, vol. 15 (Professional Paper 1814)
Country United States
State Alaska
Other Geospatial Seward Peninsula
Online Only (Y/N) Y
Additional Online Files (Y/N) N