Quaternary faulting of basalt flows on the Melones and Almanor fault zones, North Fork Feather River, northeastern California

Conference · Thu Apr 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5130328

Wakabayashi, J ^[1]; Page, W D ^[2]

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1. Wakabayashi (John), Hayward, CA (United States)
2. Pacific Gas and Electric Co., San Francisco, CA (United States). Geosciences Dept.

Field relations indicate multiple sequences of late Cenozoic basalt flowed down the canyon of the North Fork Feather River from the Modoc Plateau during the Pliocene and early Quaternary. Remnants of at least three flow sequences are exposed in the canyon, the intermediate one yielding a K/Ar plagioclase date of 1.8 Ma. Topographic profiling of the remnants allows identification of Quaternary tectonic deformation along the northern Plumas trench, which separates the Sierra Nevada from the Diamond Mountains. The authors have identified several vertical displacements of the 1.8-Ma unit in the North Fork canyon and the area NE of Lake Almanor. NE of the lake, three NW-striking faults, each having down-to-the-west displacements of up to 35 m, are related to faulting along the east side of the Almanor tectonic depression. Analysis of the displaced basalt flows suggests that uplift of the Sierra Nevada occurred with canyon development prior to 2 Ma, and has continued coincident with several subsequent episodes of basalt deposition. Quaternary faulting of the basalt is associated with the Melones fault zone and the Plumas trench where they extend northward from the northern Sierra Nevada into the Modoc Plateau and southern Cascades. In contrast to the Mohawk Valley area, where the Plumas trench forms a 5-km-wide graben, faulting in the Almanor region is distributed over a 15-km-wide zone. A change in the strike of faulting occurs at Lake Almanor, from N50W along the Plumas trench to N20W north of the lake. The right-slip component on the fault of the Plums trench may result in a releasing bend at the change in strike and explain the origin of the Almanor depression.

• OSTI ID: 5130328
• Report Number(s): CONF-9305259-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALIFORNIA
GEOLOGIC FAULTS
GEOLOGY
TECTONICS
ARGON ISOTOPES
BASALT
GEOMETRY
ISOTOPE DATING
POTASSIUM ISOTOPES
QUATERNARY PERIOD
AGE ESTIMATION
ALKALI METAL ISOTOPES
CENOZOIC ERA
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
IGNEOUS ROCKS
ISOTOPES
MATHEMATICS
NORTH AMERICA
ROCKS
USA
VOLCANIC ROCKS
580000* - Geosciences