This comparative geochemical study of jasperoid in the northern Great Basin is based on 65 samples from 10 Carlin-type gold deposits and 22 similar but apparently barren hydro-thermal systems. Multielement geochemistry coupled with oxygen isotope data indicate that hydrothermal fluids in barren and mineralized systems evolved in different ways, and that there are fundamental geochemical differences among the various gold-producing deposits of the area.

Much of the variation in the jasperoid geochemical data can be explained in terms of seven abstract end-member components obtained through factor analysis. Three of these components (factors) dominate the results and are related to common products of alteration and mineralization in epithermal systems of the northern Great Basin. Element associations for these factors are: factor 1: Ti02, Al203, La, K20, Sr, Fe203, Th; factor 2: Au, Ag, Sb, Si02> As, Pb; and factor 3: W, B, V, Zn, Co, Au, CaO, Ni, Mn, Cu.

The regional distribution of arsenic and 20 other elements in stream-sediment samples in northern Nevada and southeastern Oregon was studied in order to gain new insights about the geologic framework and patterns of hydrothermal mineralization in the area. Data were used from 10,261 samples that were originally collected during the National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program in the 1970s. The data are available as U.S. Geological Survey Open-File Report 02-0227.