Major and trace element analyses of drill cores from thermal areas in Yellowstone National Park, Wyoming

Beeson, Melvin; Bargar, Keith

In 1967 and 1968, the U.S. Geological Survey drilled 13 research diamond drill holes in several of the major thermal areas of Yellowstone National Park, Wyoming (Fig. 1). The holes were completed for the purpose of obtaining detailed physical and chemical data on the shallow part of a high temperature geothermal system (White and others, 1975). Two earlier drill holes (C-I and C-II), drilled by the Carnegie Institution of Washington in 1929, are described by Fenner (1936). Depths of the 15 drill holes ranged from 65 to 330 m and averaged about 150 m; maximum temperatures encountered in the drill holes varied from 143.1°C to 237.5°C (White and others, 1975). Nearly continuous drill core was recovered from each of the drill holes. Typically the drill holes penetrated one or more of the following rock units: (1) thin layers of surficial opaline sinter (or travertine) deposited by hot-spring runoff, (2) a mantling of glacial sediments deposited during Pinedale glaciation (about 45,000-14,000 years B.P.; Pierce and others, 1976), and (3) rhyolitic lava flows and pyroclastic rocks of middle and late Pleistocene age (Christiansen and Blank, 1972). Approximately 20-30% of each of the 13 U. S. Geological Survey drill cores was selected for detailed laboratory study, and similar "skeleton" cores from C-I and C-II were obtained from the Carnegie Institution of Washington. These 15 "skeleton" cores were selected as being representative of a drilling interval or contained features of specific interest such as veins, vugs, well-developed secondary mineral relationships, or unusual secondary minerals. Cores from the 13 modern drill holes were studied to identify the hydrothermal alteration mineral phases present. Details of these hydrothermal studies previously were reported for drill holes Y-l (Honda and Muffler, 1970; Honda and Sasaki, 1977), Y-2 (Bargar and Beeson, 1981), Y-3 (Muffler and others, 1971; Bargar and others, 1973), Y-5 (Keith and Muffler, 1978), Y-6 (Bargar and Beeson, in press), Y-7 and Y-8 (Keith and others, 1978b), Y-ll (Muffler and Bargar, 1974; Bargar and Muffler, 1982), and Y-13 (Keith and others, 1978a). Additional reports are planned for drill cores Y-3, Y-4, Y-9, Y-12, and Y-13, and the two Carnegie drill cores. We do not intend to report on the Y-10 drill core, mostly a travertine drill core from Mammoth Hot Springs, although some information on this drill core is given in White and others (1975) and Bargar (1978). The bulk of the 13 drill cores and the "skeleton" cores from drill holes Y-2, Y-5, Y-6, and Y-ll have been placed in a core library operated by the U.S. Geological Survey, Federal Center, Denver, CO, 80225. The remainder of the 1967-1968 "skeleton" drill cores also will be stored at this location upon completion of a few topical studies. The two Carnegie drill cores will be returned to the Carnegie Institution of Washington.

Major and trace element analyses of drill cores from thermal areas in Yellowstone National Park, Wyoming

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