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Report On The Mapping Of The Coyote Mountains, Salton Trough, Southern California


Since 2001 we have been mapping the Coyote Mountains at a 1:2000 scale. The mapping completed to date indicates that the complex geology of the Coyote Mountains includes: 1) Active left- and right-lateral faults and reactivation of older faults; 2) Landslides and terraces related to the recent uplift of the Coyote Mountains; 3) Cenozoic thrust and detachment faults; 4) Miocene (17.1 ± 0.4 Ma) volcanic plugs, cinder cones, tuffs, lahars and flows; 5) To date no Cretaceous igneous rocks have been found; 6) Dated Jurassic igneous rocks: Jwc (gneiss)157 and 164 Ma, Jt (tonalite) 160.2 Ma, Jg (gabbro) 163 Ma, Jd (diorite) 162 Ma; 7) Folded and metamorphosed Paleozoic(?) marbles, quartzites, schists, and amphibolites; 8) Additional evidence for upper Miocene to Pliocene Imperial Group 9+ marine transgressional-regressional sequences intermingled with non-marine sediments; 9) A freshwater limestone and Garnet Formation (fanglomerates) between two of 8+ Imperial Group transgressional-regressional sequences, which implies deposition in an extensional basin near sea level; 10) Difficulty correlating units in the Salton Trough; and 11) Interfingerng of an Imperial Group sediment with volcanic flows of the Alverson Formation. Additional features include meta-pillow basalts, outlier (klippe?), mullion structures, hooddoos, horsts and grabens.