Progress report on the study of radioactive quartz-pebble conglomerate of the Medicine Bow Mountains and Sierra Madre, southeastern Wyoming

Abstract

in 1978. GEOLOGIC BACKGROUND Precambrian miogeosynclinal metasedimentary rocks were first recognized in the Medicine Bow Mountains by Hague (Hague and Emmons, 1877), who gave a relatively good description of these rocks, located in the north-central Medicine Bow Mountains. They were later described in more detail by Van Hise (Van Hise and Leith, 1909) and Blackwelder (1926). Blackwelder (1926) gave the first complete description of these rocks and named various units in the upper part of the succession. Of particular interest is the fact that in a later paper Blackwelder (1935) noted that these miogeosynclinal rocks strongly resembled the Huronian rocks of the Great Lakes region. The first description of miogeosynclinal metasedimentary rocks in the Sierra Madre was by Spencer (1904), who made a superb reconnaissance study of almost the entire area.

New stratigraphic subdivisions and redefinition of subdivisions of late Archean and early Proterozoic metasedimentary and metavolcanic rocks of the Sierra Madre and Medicine Bow Mountains, southern Wyoming

“…Rocks of the Deep Lake and Libby Creek Groups have been described in detail previously (Houston and others, 1968;Karlstrom andHouston, 1979a, 1979b;Lanthier, 1979;Graff, 1979), so it is not necessary to repeat rock descriptions in this report. However, that terminology is adopted with the changes shown in table 16, made necessary by recent mapping.…”

“…Furthermore, even if these two glacial units cannot be considered to be broadly timeequivalent units, there are indications that the Libby Creek Group is younger than the Deep Lake Group. Houston, Karlstrom, and Graff (1979) and Houston and Karlstrom (1980) suggested a correlation between the Deep Lake and Libby Creek Groups of the Medicine Bow Mountains and the Huronian Supergroup of southern Ontario (fig. 21).…”

“…A tentative definition of a succession of rocks referred to as the Phantom Lake Metamorphic Suite was made by Karlstrom andHouston (1979a, 1979b) for the Medicine Bow Mountains and by Graff (1979) for the Sierra Madre. The term was applied to a sequence of metasedimentary and metavolcanic rocks exposed in the vicinity of Phantom Lake in sec.…”

“…The stratigraphy of the Proterozoic rocks of the Sierra Madre was described by Divis (1976) and Graff (1979), and except for the newly named Bottle Creek Formation, the detailed lithologic descriptions are not repeated here. However, recent mapping has necessitated several terminology changes: (1) some of the rocks assigned to the Vagner Formation in the Sierra Madre by Graff (1979) are reassigned in this report to the Bottle Creek Formation; (2) the Copperton Quartzite is called the Copperton Formation from Karlstrom and others (1983); (3) the Singer Peak Formation includes both the Singer Peak Formation and rocks assigned to the Campbell Lake Formation by Graff (1979); and (4) the entire Proterozoic succession is referred to as the Snowy Pass Group lower, middle, and upper parts for reasons discussed below (figs. 9, 21).…”

Precambrian petrochemistry of the northern Park Range, Colorado, and its implications for studies of crustal derivation

“…Detailed geologic maps and cross sections of the area have been published (Snyder, 1980a(Snyder, , 1980b(Snyder, , 1980c. Adjoining areas of Precambrian rocks have been mapped by Steven (1954), Houston and others (1968), and Karlstrom (1977) to the northeast, and by Divis (1976), Houston and Ebbett (1977), Houston, Karlstrom, and Graff (1979), and Graff (1978) to the north. The Colorado geologic setting is shown on the summary maps of Ogden Tweto (1976aTweto ( and b, 1978Tweto ( , 1979.…”