Multielement Geochemistry of Three Geothermal Wells, Cove Fort-Sulphurdale Geothermal Area, Utah

Odin D. Christensen, Earth Science Laboratory Division, University of Utah Research Institute



Multielement geochemical analysis of drill cuttings from three geothermal wells, Utah State 42-7, Utah State 31-33 and Forminco #1, in the Cove Fort-Sulphurdale KGRA, Utah, demonstrates that the distributions of different elements are the result of different chemical processes operating throughout the geologic history of the area. Statistical analysis of geochemical-data distributions confirm the presence of several distinct element associations.

Of the 36 elements determined on the samples, 12 (V, Mo, Cd, Ag, Au, Sb, Bi, U, Te, Sn, B and Th) were present in concentrations at or below detection levels. Of the remaining 24 elements, only 3 (Ni, Co and Zr) are lognormally distributed. Distributions for the remaining elements are of aggregate populations which represent background, mineralization of other processes.

Pearson correlation coefficients reveal four elemental groupings:

1) Na-K-Fe-Al-Ti-P-Sr-Ba-Cr-Ni-Li-Be-Zr-La-Ce

2) Ca-Mg

3) Mn-Co-Pb-Zn-As-Hg

4) Cu

Groups 1 and 2 are related to the lithogeochemistry of the host rocks, the first association representing intervals of volcanic and clastic lithologies and the second association representing carbonates. The third group represents elements associated with hydrothermal enrichment. Cu alone does not correlate significantly with any other element. Lithogeochemistry is the most-significant chemical control both in terms of the number of elements and in terms of the magnitude of the resultant variations.

In the Cove Fort-Sulphurdale system, only the distribution of Hg can be related to the location of the present geothermal system. Enrichments in other elements, particularly As, Pb, Zn, Mn and Cu are primarily related to older mineralizing events. Frequent spatial coincidence of enrichments of these elements and of Hg are due to control of sequential hydrothermal events by the same structures.