Tuttle intrusive complex
Tuttle intrusive complex
Early Cretaceous to Middle Jurassic, ~136-164 Ma
Chiefly diorite and gabbro, and local mafic intrusive breccia, and local anorthosite west of Lake Tahoe. This unit has yielded zircon U-Pb ages of ~136 and ~164 Ma (Wooden and others, 1999; Sabine, 1992), as well as biotite K-Ar ages of ~103 and ~105 Ma (Sabine, 1992). Unit includes Pyramid Peak granite and the small Azure Lake quartz diorite southwest of Lake Tahoe, as well as a small body northwest of Lake Tahoe. Unit mainly intrudes Sailor Canyon and Tuttle Lake Formations (units NSTS, NSTT), as well as Devonian Sutter Butte formation (part of unit NSSB) in the northwest. Local dikes associated with this unit interpreted as feeders for, and coeval with volcanic rocks of Tuttle Lake Formation (unit NSTT). Unit occurs mainly in Mount Tallac area in southwest part of Fallen Leaf Lake roof pendant. Unit forms plutonic part of the Tuttle igneous arc that includes volcanic and associated rocks of Tuttle Lake Formation (unit NSTT). Unit magmatically linked to coeval mafic units of the Emigrant Gap intrusive suite, unit Gegm.