Tahoe-Truckee volcanic field
Tahoe-Truckee volcanic field
early Pleistocene to Pliocene(?)
Consists of basaltic to trachyandesitic lavas extruded in numerous relatively low-volume subaerial and lesser subaqueous eruptions, which produced diverse volcanic features, including lava flows, cinder cones, breccias, pillows, and tuffs (e.g. Kortemeier and others, 2018) distributed along and adjacent to the northwestern shoreline of Lake Tahoe, across the region north of the lake, and along the Truckee River. Chemically similar to the older (underlying/stratigraphically lower) Cascade arc volcanic rocks (map unit aca) but differ by having higher concentrations of high field strength elements and phosphorus, light REE enrichment, as well as other chemical differences (e.g., Cousens and others, 2011, 2012; Kortemeier and others, 2018). The Tahoe-Truckee volcanic field (TTVF; map unit ttv) also differs from the underlying arc volcanics by being generally aphyric and small volume (Cousens and others, 2011, 2012). Depending on how the boundary between earlier arc volcanism and younger TTVF post-arc volcanism is defined, the oldest TTVF rocks could be interpreted to be Pliocene (3.17 ± 0.02 Ma per Cousens and others, 2011) or Quaternary (2.3 ± 0.05 Ma per Kortemeier and others, 2018). The youngest dated eruptive unit is 0.94 ± 0.003 Ma (Kortemeier and others, 2018).