Geometry and Late Pleistocene Displacement of the Shoreline and Oceano Fault Zones, San Luis Obispo Bay, California

Nishenko, Stuart P.; Greene, H. Gary; Hogan, Phillip; Bergkamp, Bryan

doi:10.1785/0120160177

Cited by 4 publications

(2 citation statements)

References 33 publications

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“…Advances in high-resolution geophysical imaging provide higher resolution of offshore deformation and fault architecture; such technological developments allow for improved imaging of near-vertical fault segments, offsets at step-overs, and fault recency (Kluesner and Brothers, 2016;Nishenko et al, 2018). Near-vertical faults can be imaged in three-dimensional seismic data because the offset is projected onto the time-slice (i.e., map view).…”

Section: Introduction Geologic Background and Motivationmentioning

confidence: 99%

High-Resolution 3D Seismic Imaging of Fault Interaction and Deformation Offshore San Onofre, California

2021

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The Inner California Borderland (ICB) records a middle Oligocene transition from subduction to microplate capture along the southern California and Baja coast. The closest nearshore fault system, the Newport-Inglewood/Rose Canyon (NIRC) fault complex is a dextral strike-slip system that extends primarily offshore approximately 120 km from San Diego to Newport Beach, California. Holocene slip rates along the NIRC are 1.5–2.0 mm/year in the south and 0.5 mm/year along its northern extent based on trenching and well data. High-resolution 3D seismic surveys of the NIRC fault system offshore of San Onofre were acquired to define fault interaction across a prominent strike-slip step-over. The step-over deformation results in transpression that structurally controls the width of the continental shelf in this region. Shallow coring on the shelf yields a range of sedimentation rates from 0.27–0.28 mm/year. Additionally, a series of smaller anticlines and synclines record subtle changes in fault trends along with small step-overs and secondary splay faults. Finally, sedimentary units onlapping and dammed by the anticline, place constraints on the onset of deformation of this section of the NIRC fault system. Thickness estimates and radiocarbon dating yield ages of 560,000 to 575,000 years before present for the onset of deformation.

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Section: Introduction Geologic Background and Motivationmentioning

confidence: 99%

High-Resolution 3D Seismic Imaging of Fault Interaction and Deformation Offshore San Onofre, California

2021

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“…Good documentation of bedrock incision by San Luis Obispo Creek and subsequent repeat erosion of channels within San Luis Obispo Bay indicates that it formed as early as MIS 12 (~330-350 ka) or earlier and as late as MIS 2 (~20 ka). The later dates were provided using recently collected 3D seismic-reflection profile data for the evaluation of the seismic hazards probability at the Diablo Canyon Power Plant (PG&E 2012, Nishenko et al in 2018. These buried channels indicate that there is a fairly long history of river migration across the San Luis Obispo Bay shelf.…”

Section: Arguello Canyon System Headmentioning

confidence: 99%

Tracing the Arguello Submarine Canyon System from Shelf Origins to an Abyssal Sink

Marsaglia¹,

Rodriguez²,

Weeraratne³

et al. 2019

From the Mountains to the Abyss: The California Borderland as an Archive of Southern California Geologic Evolution

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The Arguello submarine canyon/channel system extends over 300 km from the continental shelf off Point Arguello and Point Conception in southern California westward onto the oceanic crust of the Pacific plate. In the northernmost reaches where the canyon system originates, all stages in the evolution of seafloor morphologic fluid flow features—from pockmarks to gullies to converging rills—are observed, similar to what has been described for the Ascension slope, north of Monterey Bay. These features appear to be active today and are linked to fluid leakage from the underlying hydrocarbon basin. The channel dissects a continental slope that exhibits features consistent with large-scale mass wasting. Upslope scarps may be the source of the morphological feature at the base of the slope previously referred to as the “Arguello submarine fan,” with topographic expressions (e.g., large channel meanders, ridges) that are more consistent with mass transport deposits than with deep-sea fan depositional lobes. The modern canyon crosscuts these deposits and parallels an older, meandering channel/canyon to the west. Modern seismicity along the shelf and slope may have, and potentially still can, trigger landslides on the slope. Seismicity associated with seamount volcanism, past subduction, and Borderland transrotational and extensional processes most likely played a role in stimulating mass wasting. The presence of abundant nearby petroleum suggests that gas venting and hydrate dissociation cannot be ruled out as a triggering mechanism for the slope destabilization occurring today. The canyon/channel continues due south on a path possibly determined by the structural grain of north–south-aligned abyssal hills underlying oceanic basement. At latitude 33°18′N, the channel makes a 90° turn (bend) to the west at the E–W-striking Arguello transform fault wall and develops into a meandering channel system that crosses over abyssal hill crustal fabric. The system ultimately straightens as it continues west before veering north, curving around a thickened crustal bulge at a corner offset in the Arguello fracture zone in complex basement structure, and then finally empties into an 800-m-deep basin depocenter.

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Subaqueous clinoforms created by sandy wave-supported gravity flows: Lessons from the Central California shelf

et al. 2023

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Geometry and Late Pleistocene Displacement of the Shoreline and Oceano Fault Zones, San Luis Obispo Bay, California

Cited by 4 publications

References 33 publications

High-Resolution 3D Seismic Imaging of Fault Interaction and Deformation Offshore San Onofre, California

High-Resolution 3D Seismic Imaging of Fault Interaction and Deformation Offshore San Onofre, California

Tracing the Arguello Submarine Canyon System from Shelf Origins to an Abyssal Sink

Subaqueous clinoforms created by sandy wave-supported gravity flows: Lessons from the Central California shelf

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