The geology of offshore central California records a history of accretion and subduction modified by the presently active transform motion between the Pacific and North American Plates. Understanding the older accretionary history lies in establishing the identity and boundaries of basement blocks or terrains. The younger history is recorded in the stratigraphy and deformation of the late Tertiary basins that lie on the continental shelf and slope. The geologic history is complicated by overprinting of old structures during younger tectonic events and by slivering and redistribution during transform motion. The major tectonic events appear to be related both in their timing and sense (transtension and transpression) to changes in relative motion between the Pacific and North American Plates as inferred from changes in the hot-spot trends.
Figures & Tables
The Eastern Pacific Ocean and Hawaii
This new synthesis includes a section on plate kinematics, documenting the basis for a new interpretation of the magnetic anomaly patterns. It also includes: six chapters on various aspects of tectonics, petrologic characteristics, and hydrothermal processes of active ridges from the Galapagos Rift to the Juan de Fuca Ridge; a section on mid-plate volcanism, including the Hawaii-Emperor chain; five chapters on various aspects of northeastern Pacific sedimentary regimes; and nine chapters on the geology of the Pacific continental margin from the Aleutians to Guatemala, seen from the perspective of marine geology. Three separate oversize plates illustrate the bathymetry of the northeast Pacific; two more on the same base show distribution of sediment samples and types and magnetic anomaly data and tectonic interpretations; and others include a synthesis of the geology and bathymetry of the Hawaiian Islands, details of bathymetry along parts of the East Pacific Rise, and a major seismic profile across the Pacific margin of Guatemala.