Accelerating and spatially-varying crustal uplift and its geomorphic expression, San Andreas Fault zone north of San Francisco, California

作者：Grove Karen^*; Sklar Leonard S; Scherer Anne Marie; Lee Gina; Davis Jerry

来源：Tectonophysics, 2010, 495(3-4): 256-268.

DOI：10.1016/j.tecto.2010.09.034

• Marine terrace
• Luminescence dating
• Hillslope gradient
• Watershed hypsometry
• Point Reyes
• Marin County

Marine terraces that bevel the western flank of the Point Reyes Peninsula were used to measure crustal uplift rates west of the San Andreas Fault segment north of San Francisco. Field measurements of platform inner edges, and luminescence ages from overlying marine sediments, suggest the youngest platform was cut by waves during the similar to 80-ka sea-level high stand (MIS 5a). Since 80 ka, the platform has been uplifted slowly throughout most of the peninsula, but more rapidly in the southern part, where uplift reaches a rate of similar to 1 m/ka. Analyses of the spatial distributions of hillslope gradient and elevation are consistent with the terrace data. Correlations of older terrace levels to high-stand ages suggest that crustal uplift has accelerated in the southern part of the peninsula during the past similar to 300 ky, probably as a result of a contractional zone that has been migrating northward. This study is the first to quantify the rate and style of crustal uplift west of this San Andreas Fault segment. Although the transform motions in this region are well documented, the complex nature of interacting fault strands are only beginning to be understood. These results imply that other faults, with reverse-motions, are also active and potentially contributing to earthquake hazards.

• 出版日期2010-12-3