UC San Diego
Tectonic and Stratigraphic Controls of the Continental Shelf and Slope, Southern California
- Author(s): Holmes, James John
- Advisor(s): Driscoll, Neal W
- et al.
Understanding the tectonic and geomorphic processes that shape continental margins has both scientific and societal relevance. This dissertation uses state-of-the-art 3D seismic reflection, CHIRP, and piston core analysis to investigate the architecture, character, and attendant deformation of the Newport-Inglewood Rose Canyon fault system, San Onofre trend fault system, and San Mateo trend fault system, where all three systems interact off the coast of San Onofre, California.
Using these data, we first describe the fault geometry and subsurface deformation of the Newport-Inglewood Rose Canyon system on the continental shelf based on our analysis of high-resolution 3D P-Cable multichannel seismic reflection data and CHIRP data. We organize fault segments into three zones based on fault character and describe each zone. We then discuss in detail structures that we observe throughout the survey and propose alternative kinematic models of transpression and then transtension to explain the formation and bisection of a 2 km wide subsurface antiformal dome structure.
Next, using piston core analysis, we compare the grain size and timing of turbidite emplacement from two local off-shelf canyon systems. We describe our models of activity for each canyon system and discuss the tectonic and geomorphic controls that impact sand supply to one of the canyons. The results of this study question the use of turbidites as seismothems because their emplacement history is controlled by numerous other processes (e.g., shelf width, eustasy, storms, and earthquakes).
Finally, we use high-resolution 3D P-Cable multichannel seismic reflection data and piston core analysis to investigate and categorize the segments of the San Onofre and San Mateo trend fault systems. Using these data, we illuminate structural details observed in both the seismic data and at the seafloor. The structural deformation along this portion of the Californian margin is more consistent with transpression at step overs along strike slip fault systems than compression associated with a regional blind thrust.