Inyo Mountains fanglomerate
Inyo Mountains fanglomerate
late to middle Miocene
Fanglomerate occurring on the southern and southwestern flanks of the Inyo Mountains east of Owens Lake. Consists of weakly consolidated to well-cemented, massive to bedded pebble to cobble conglomerate, locally with boulders up to 1-3 m (Conrad, 1993; Stone and others, 2004). Deeply dissected; clast composition consists of limestone, dolomite, siliceous sedimentary and minor plutonic lithologies all reflecting derivation from Paleozoic to Mesozoic basement units of the Inyo Mountains (Conrad, 1993; Stone and others, 2004). Locally (in northeastern area of occurrence) includes coarse strata composed almost entirely of quartz monzonite (Stone and others, 2004). Ash bed near base of unit is 13.62 Ma based on average of four Ar-Ar measurements (Conrad, 1993) and tephra in upper section is estimated to be 9-6 Ma based on tephrochronology (Stone and others, 2004). Inferred to stratigraphically underlie the ~7.7 to 4.2 Ma Darwin Plateau Basalts (map unit dpb; Conrad, 1993; Swanson, 1996; Stone and others, 2004). Includes the fanglomerate of Slate Canyon and fanglomerate of Bonham Canyon of Stone and others (2004). May be partially correlative with the Coso Formation (map unit cos) that occurs to the south.