Early Paleozoic magmatic events in the eastern Klamath Mountains, northern California

Journal Article · Mon Feb 01 00:00:00 EST 1988 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1988)016<0144:EPMEIT>2.3.CO;2· OSTI ID:5237696

Wallin, E T; Mattinson, J M; Potter, A W

New U-Pb zircon ages for nine samples of tonalite and pegmatitic trondhjemite from the Trinity ophiolite and associated melange reveal a complex history of magmatic activity extending back into the earliest Cambrian, much older than previously believed. Earlier investigations, based on limited data, recognized lower Paleozoic crustal elements in the eastern Klamath terrane (EKT) ranging in age from Middle Ordovician to Early to Middle Devonian. The new work in the Yreka-Callahan area of the EKT confirms the Ordovician (440-475 Ma) and younger ages, but reveals for the first time the presence of tonalitic rocks that crystallized during a narrow time interval at about 565-570 Ma. The authors also recognize younger, Late Silurian magmatism at 412 Ma. In the context of available mapping, these ages indicate that the Trinity ophiolite is broadly polygenetic because parts of it yield crystallization ages that span approximately 150 m.y. Superjacent dismembered units of probable early Paleozoic age may be tectonostratigraphically equivalent to the Sierra City melange in the northern Sierra Nevada.

• Research Organization: Univ. of Kansas, Lawrence (USA)
• OSTI ID: 5237696
• Journal Information: Geology; (United States), Vol. 16:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALIFORNIA
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
MAGMATISM
AGE ESTIMATION
ISOTOPE DATING
LEAD
MOUNTAINS
PALEOZOIC ERA
STRATIGRAPHY
TECTONICS
URANIUM
ACTINIDES
ELEMENTS
FEDERAL REGION IX
GEOLOGIC AGES
GEOLOGY
METALS
NORTH AMERICA
USA
580100* - Geology &amp; Hydrology- (-1989)
580202 - Geophysics- Volcanology- (1980-1989)