Offset of Latest Pleistocene Shoreface Reveals Slip Rate on the Hosgri Strike-Slip Fault, Offshore Central California

Johnson, Samuel Y.; Hartwell, Stephen R.; Dartnell, Peter

doi:10.1785/0120130257

Cited by 16 publications

(4 citation statements)

References 33 publications

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“…North of San Luis Obispo, the Santa Lucia Range is being lifted at 0.8 mm/yr due to slip on steeply dipping reverse faults that bound the mountain range (Ducea et al, 2003). These reverse faults are likely the result of plate boundary transpression and a restraining step geometry, where right-lateral displacement on faults southeast of the range is transferred westward to the Hosgri fault (Clark et al, 1994;Titus et al, 2007;Johnson et al, 2014).…”

Section: Implications For Regional Active Tectonicsmentioning

confidence: 99%

Late Pleistocene rates of rock uplift and faulting at the boundary between the southern Coast Ranges and the western Transverse Ranges in California from reconstruction and luminescence dating of the Orcutt Formation

McGregor

Onderdonk

2021

Geosphere

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The western Transverse Ranges and southern Coast Ranges of California are lithologically similar but have very different styles and rates of Quaternary deformation. The western Transverse Ranges are deformed by west-trending folds and reverse faults with fast rates of Quaternary fault slip (1–11 mm/yr) and uplift (1–7 mm/yr). The southern Coast Ranges, however, are primarily deformed by northwest-trending folds and right-lateral strike-slip faults with much slower slip rates (3 mm/yr or less) and uplift rates (<1 mm/yr). Faults and folds at the boundary between these two structural domains exhibit geometric and kinematic characteristics of both domains, but little is known about the rate of Quaternary deformation along the boundary. We used a late Pleistocene sedimentary deposit, the Orcutt Formation, as a marker to characterize deformation within the boundary zone over the past 120 k.y. The Orcutt Formation is a fluvial deposit in the Santa Maria Basin that formed during regional planation by a broad fluvial system that graded into a shoreline platform at the coast. We used post-infrared–infrared-stimulated luminescence (pIR-IRSL) dating to determine that the Orcutt Formation was deposited between 119 ± 8 and 85 ± 6 ka, coincident with oxygen isotope stages 5e-a paleo–sea-level highstands and regional depositional events. The deformed Orcutt basal surface closely follows the present-day topography of the Santa Maria Basin and is folded by northwest-trending anticlines that are a combination of fault-propagation and fault-bend-folding controlled by deeper thrust faults. Reconstructions of the Orcutt basal surface and forward modeling of balanced cross sections across the study area allowed us to measure rock uplift rates and fault slip rates. Rock uplift rates at the crests of two major anticlinoria are 0.9–4.9 mm/yr, and the dip-slip rate along the blind fault system that underlies these folds is 5.6–6.7 mm/yr. These rates are similar to those reported from the Ventura area to the southeast and indicate that the relatively high rates of deformation in the western Transverse Ranges are also present along the northern boundary zone. The deformation style and rates are consistent with models that attribute shortening across the Santa Maria Basin to accommodation of clockwise rotation of the western Transverse Ranges and suggest that rotation has continued into late Quaternary time.

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Section: Implications For Regional Active Tectonicsmentioning

confidence: 99%

Late Pleistocene rates of rock uplift and faulting at the boundary between the southern Coast Ranges and the western Transverse Ranges in California from reconstruction and luminescence dating of the Orcutt Formation

McGregor

Onderdonk

2021

Geosphere

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“…A significant challenge for paleoseismology is obtaining primary, near‐field evidence for coseismic offset with accurate age constraints. For subaqueous studies, high‐resolution marine geophysical methods are capable of imaging vertically offset stratigraphy and evidence for punctuated fault growth [ Barnes and Pondard , ; Bartholomew et al , ; Brothers et al , , ; Pondard and Barnes , ], as well as offset seabed/lakefloor morphology that can be dated to constrain late Pleistocene and Holocene slip rates [ Dingler et al , ; Johnson et al , ; Kent et al , ; Ryan et al , ]. However, stratigraphic evidence for recent displacement along strike‐slip faults is difficult to resolve in deep‐water settings (>200 m) and two‐dimensional cross sections are most practical for imaging vertical displacement.…”

Section: Introductionmentioning

confidence: 99%

The Palos Verdes Fault offshore Southern California: Late Pleistocene to present tectonic geomorphology, seascape evolution, and slip rate estimate based on AUV and ROV surveys

et al. 2015

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The Palos Verdes Fault (PVF) is one of few active faults in Southern California that crosses the shoreline and can be studied using both terrestrial and subaqueous methodologies. To characterize the near‐seafloor fault morphology, tectonic influences on continental slope sedimentary processes and late Pleistocene to present slip rate, a grid of high‐resolution multibeam bathymetric data, and chirp subbottom profiles were acquired with an autonomous underwater vehicle (AUV) along the main trace of PVF in water depths between 250 and 600 m. Radiocarbon dates were obtained from vibracores collected using a remotely operated vehicle (ROV) and ship‐based gravity cores. The PVF is expressed as a well‐defined seafloor lineation marked by subtle along‐strike bends. Right‐stepping transtensional bends exert first‐order control on sediment flow dynamics and the spatial distribution of Holocene depocenters; deformed strata within a small pull‐apart basin record punctuated growth faulting associated with at least three Holocene surface ruptures. An upper (shallower) landslide scarp, a buried sedimentary mound, and a deeper scarp have been right‐laterally offset across the PVF by 55 ± 5, 52 ± 4 , and 39 ± 8 m, respectively. The ages of the upper scarp and buried mound are approximately 31 ka; the age of the deeper scarp is bracketed to 17–24 ka. These three piercing points bracket the late Pleistocene to present slip rate to 1.3–2.8 mm/yr and provide a best estimate of 1.6–1.9 mm/yr. The deformation observed along the PVF is characteristic of strike‐slip faulting and accounts for 20–30% of the total right‐lateral slip budget accommodated offshore Southern California.

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“…Due to the lack of high resolution data, difficulties in carrying out direct observations and dating of underwater landforms, the submerged parts of the coastal sequences are totally neglected and studies dealing with submerged marine terraces are rather scarce (e.g. Passaro et al, 2011;Johnson et al, 2014;Jara-Muñoz et al, 2017;Ricchi et al, 2018). The analysis of submerged marine terraces and sea stacks, combined with sea level variations and tectonic settings, helps us to elucidate the Quaternary coastal evolution of the SE Bay of Biscay.…”

Section: Submerged Marine Terracesmentioning

confidence: 99%

Submerged Marine Terraces Identification and an Approach for Numerical Modeling the Sequence Formation in the Bay of Biscay (Northeastern Iberian Peninsula)

et al. 2020

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Submerged sequences of marine terraces potentially provide crucial information of past sea-level positions. However, the distribution and characteristics of drowned marine terrace sequences are poorly known at a global scale. Using bathymetric data and novel mapping and modeling techniques, we studied a submerged sequence of marine terraces in the Bay of Biscay with the objective to identify the distribution and morphologies of submerged marine terraces and the timing and conditions that allowed their formation and preservation. To accomplish the objectives a highresolution bathymetry (5 m) was analyzed using Geographic Information Systems and TerraceM R . The successive submerged terraces were identified using a Surface Classification Model, which linearly combines the slope and the roughness of the surface to extract fossil sea-cliffs and fossil rocky shore platforms. For that purpose, contour and hillshaded maps were also analyzed. Then, shoreline angles, a geomorphic marker located at the intersection between the fossil sea-cliff and platform, were mapped analyzing swath profiles perpendicular to the isobaths. Most of the submerged strandlines are irregularly preserved throughout the continental shelf. In summary, 12 submerged terraces with their shoreline angles between approximately: −13 m (T1), −30 and −32 m (T2), −34 and 41 m (T3), −44 and −47 m (T4), −49 and 53 m (T5), −55 and 58 m (T6), −59 and 62 m (T7), −65 and 67 m (T8), −68 and 70 m (T9), −74 and −77 m (T10), −83 and −86 m (T11) and −89 and 92 m (T12).Nevertheless, the ones showing the best lateral continuity and preservation in the central part of the shelf are T3, T4, T5, T7, T8, and T10. The age of the terraces has been estimated using a landscape evolution model. To simulate the formation and preservation of submerged terraces three different scenarios: (i) 20-0 ka; (ii) 128-0 ka; and (iii) 128-20 ka, were compared. The best scenario for terrace generation was between 128 and 20 Ka, where T3, T5, and T7 could have been formed.

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Offset of Latest Pleistocene Shoreface Reveals Slip Rate on the Hosgri Strike-Slip Fault, Offshore Central California

Cited by 16 publications

References 33 publications

Late Pleistocene rates of rock uplift and faulting at the boundary between the southern Coast Ranges and the western Transverse Ranges in California from reconstruction and luminescence dating of the Orcutt Formation

Late Pleistocene rates of rock uplift and faulting at the boundary between the southern Coast Ranges and the western Transverse Ranges in California from reconstruction and luminescence dating of the Orcutt Formation

The Palos Verdes Fault offshore Southern California: Late Pleistocene to present tectonic geomorphology, seascape evolution, and slip rate estimate based on AUV and ROV surveys

Submerged Marine Terraces Identification and an Approach for Numerical Modeling the Sequence Formation in the Bay of Biscay (Northeastern Iberian Peninsula)

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