Lake Tahoe intrusive suite
Lake Tahoe intrusive suite
Cretaceous, ~90-126 Ma
Occurs around Lake Tahoe from northwest of Reno south to Highway 4. Chiefly granodiorite, granite, and adamellite. Major plutons: Bryan Meadow Granodiorite, Ebbetts Pass Granodiorite, Carson Pass Tonalite, Castle Valley plutonic assemblage, Freel Peak Granodiorite, granodiorite of Kingsbury Grade, Stanislaus Meadow Adamellite, Burnside Lake Adamellite, granodiorite of Deadwood Lake, Keiths Dome quartz monzonite. Zircon U-Pb and feldspar Pb-Pb ages from this unit range from ~90-126 Ma (Kulow and others, 1997; Wooden and others 1999; Rotberg, 2008; Cecil and others, 2012; Langenheim and others, 2025). Also includes outcrops too small to show at map scale east of French Meadows Reservoir, one of which has yielded a zircon U-Pb age of ~109 Ma (Langenheim and others, 2025). In addition, this unit has yielded K-Ar hornblende and biotite ages of ~91-100 Ma and ~87-102 Ma, respectively, as well as plagioclase K-Ar age of ~93 Ma, K-feldspar K-Ar age of ~100 Ma, and quartz K-Ar age of ~109 Ma (Evernden and Kistler, 1970).