Abstract

The 500-km-long Late Jurassic Independence dike swarm in California extends from the central Sierra Nevada through the Mojave Desert to the Eastern Transverse Range. The dikes are mostly vertical, and their azimuth in the Sierra Nevada is ∼ 315°. However, in the Mojave region, their azimuth varies significantly: 300°–320° in the Argus Range, the Spangler Hills, and the Stoddard Well and Soda Mountain areas, and 340°–350° in the Granite Mountain, Alvord Mountain, and Eagle Mountain areas. Apparently the dikes in the Granite, Alvord, and Eagle mountains areas have rotated ∼ 50° clockwise about vertical axis relative to the Sierra Nevada and the Stoddard Well area. These rotations are remarkably consistent with known post–early Miocene paleomagnetically derived rotations. The clockwise rotations are associated with the east-west–trending left-lateral strike-slip faults in the northeastern Mojave and the Eastern Transverse range regions. In contrast, the data show that little or no rotation occurred in the central Mojave domain, which is characterized by northwest-trending faults.

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