Age of Lassen Peak, California, and implications for the ages of late Pleistocene glaciations in the southern Cascade Range
Turrin BD, Christiansen RL, Clynne MA, Champion DE, Gerstel WJ, Muffler LJ, Trimble DA. 1998. Age of Lassen Peak, California, and implications for the ages of late Pleistocene glaciations in the southern Cascade Range. Geological Society of America Bulletin. 110(7):931-945
Lassen Peak is a large volcanic dome of late Pleistocene age at the southern end of the Cascades arc. This dacitic dome has a complex phenocryst assemblage of mixed-magma origin and has been effectively dated for the first time using the 40Ar/39Ar technique. Emplacement of the dome occurred after an advance of late Pleistocene glaciers from an older volcanic cone to the southwest and from a large volcanic plateau to the east. Emplacement of the Lassen Peak dome before the latest major Pleistocene glaciation—correlated by previous workers with the Tioga glaciation of the Sierra Nevada—formed a high peak that intercepted some of the precipitation that previously had fed the plateau ice cap, forming a 10-km-long glacier from a cirque on the northeast side of the peak. The weighted mean 40Ar/39Ar age of the dacite of Lassen Peak is 28.3 ± 2.7 ka. Comparison of its remnanent magnetic direction to that of sedimentary deposits at Mono Lake, California, indicates a correlation to strata of 27 ± 1 ka. The dacite of Kings Creek, which erupted from the site of Lassen Peak before a glacial advance that predated the Lassen Peak dome, overlies peat that has a U-Th-calibrated 14C age of 37.6 ± 0.2 ka. The dacite of Kings Creek yielded a 40Ar/39Ar age of 32 ± 17 ka. The paleomagnetism of this dacite is similar to that of Mono Lake sediments of 35 ± 1 ka age. Thus, a late Pleistocene glacial advance probably began in the Lassen region between about 35 and 27 ka.
- Type
- Journal Article
- Authors
- Turrin, Brent; Christiansen, Robert; Clynne, Michael; Champion, Duane; Gerstel, Wendy; Muffler, L; Trimble, Deborah
- Units
- LAVO
- Keywords
- age, Lassen Peak, Physical Sciences, pleistocene glaciations, southern Cascade Range, stratigraphy, volcanos