Geosphere; February 2008; v. 4; no. 1;
p. 1-35; DOI: 10.1130/GES00122.1
© Geological Society of America
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Figure 10. Geologic map of the paleovalley at Nanny Creek, east side of the Pequop Mountains (Brooks et al., 1995b; this study) with 40Ar/39Ar dates from this study (regular type) and Brooks et al. (1995a, 1995b; italics). The paleovalley, which was at least 6 km wide and possibly 1.6 km deep, has basal conglomerate containing rounded boulders up to 6 m in diameter, overlain by the plagioclase-biotite tuff and tuff of Big Cottonwood Canyon, andesite lavas, and a thick megabreccia consisting of angular blocks mostly of the tuff of Big Cottonwood Canyon. That megabreccia consists of reworked blocks is confirmed by petrographic, chemical, 40Ar/39Ar, and paleomagnetic data (this study; M.R. Hudson, in Brooks et al., 1995a; Palmer and MacDonald, 2002).
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