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Fission‐track geochronologic evidence for Late Cretaceous mylonitization and Early Paleocene uplift of the northeastern Peninsular Ranges, California
Author(s) -
Dokka Roy K.
Publication year - 1984
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl011i001p00046
Subject(s) - batholith , geology , cretaceous , mylonite , thermochronology , fission track dating , paleontology , mesozoic , zircon , geochemistry , tectonics , shear zone , structural basin
Fission‐track dating of minerals from the Santa Rosa Mylonite Belt and adjoining rocks of the northeastern Peninsular Ranges batholith indicates that the area was affected by a brief, but intense cooling event approximately 61 m.y. ago. Concordant ages from different mineral species suggest a minimum temperature drop of ∼120°C during this event. This rapid cooling event probably reflects major uplift and unroofing of the batholith at the beginning of the Paleocene. These new data coupled with other published isotopic data, firmly establishes that the Santa Rosa Mylonite Belt formed during the Late Cretaceous.