Geology, environmental hazards, and petroleum resources for 1982 OCS lease sale 73, offshore central and northern California

McCulloch, David S.; Clarke, Samuel H.; Dolton, G.L.; Field, Michael E.; Scott, Edward W.; Utter, P.A.

doi:10.3133/ofr821000

Cited by 3 publications

References 37 publications

(18 reference statements)

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Deep crustal reflection profiling offshore southern central California

Meltzer¹,

Levander²

1991

J. Geophys. Res.

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Deep crustal reflection profiling offshore southern central California shows that the offshore Santa Maria Basin and adjacent shelf and slope are underlain by oceanic crust which underthrusts the margin. On common‐midpoint (CMP) sections the top of the oceanic crust appears as a strong coherent reflection occurring at 6 s two‐way time (twt). The reflection can be traced continuously more than 50 km from the deep ocean basin eastward beneath the continental shelf. Depth conversion places the top of oceanic crust at 6–16 km depth with a dip of 8° toward the coast. Beneath the Santa Lucia High the crustal reflection breaks up into several east dipping segments. Above the oceanic crust an accretionary wedge increases in thickness from 3 km at the base of the slope to over 12 km beneath the Santa Lucia High. The Neogene sedimentary section above the accretionary prism exhibits relatively little deformation, implying that most of the accretion occurred during pre‐Neogene convergence between the North American plate and oceanic plates located to the west. The offshore Santa Maria Basin exhibits at least two periods of Neogene deformation: an early extensional phase, accompanied by strike‐slip faulting, occurred in the lower to middle Miocene followed by compression and basin inversion in the upper Miocene‐lower Pliocene. The development of structures in the basin began in the northwest and is progressively younger to the southeast. Faults identified in the offshore sedimentary column offset acoustic basement but are not imaged in the Franciscan basement material below 2–3 s twt and do not extend to, or offset, the deep reflections. We suggest that the oceanic crust served as a detachment surface above which the shallow deformation occurred. Neogene sediments in the offshore basins show only 1–3 km of shortening. This implies that shortening, due to Neogene oblique plate motion between the Pacific and North American plates, extends east of the offshore Santa Maria Basin and is distributed across the entire transform margin.

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Deep crustal reflection profiling offshore southern central California

Meltzer¹,

Levander²

1991

J. Geophys. Res.

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Installability of a Multiline Ring Anchor System in a Seabed under Severe Environmental Conditions

Lee

Hong

Aubeny

et al. 2021

OCEANS 2021: San Diego – Porto

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Effect of Shared Anchor System for a Floating Offshore Wind Project on Reductions in CO2 Emissions

Lee

Aubeny

2023

Day 1 Mon, May 01, 2023

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The trend of the offshore wind industry is expected to shift from fixed towers in shallow water to floating platforms in deeper water due to factors such as wind resource consistency and local seafloor bathymetry. The floating offshore wind industry requires cost-effective anchor alternatives suitable to a range of mooring types, water depths, geological locations, and environmental conditions. One attractive and cost-effective anchor solution can be the shared anchor system, with multiple mooring lines attached to a single anchor. Previous preliminary studies indicate that the shared anchor system provides significant capital cost savings due to its multiline potential resulting in reductions in required anchor footprints and logistic efforts. While they provide valuable insights into anchor performance and its cost-saving effect, these studies did not address the environmental impact in view of greenhouse gas emissions. This spurs the current study to estimate the effect of the shared anchor systems on reductions in CO2 emission. Firstly, this paper compares envisioned shared anchor systems, such as a suction anchor, a deeply embedded ring anchor (DERA), and a skirt, from optimal design standpoints. Secondly, embodied carbon in steel-based anchor alternatives is computed using a carbon calculator tool based on standardized data and compared to each solution. Lastly, the study carries out a comparative study on how anchor transportation from the factory to the construction site affects CO2 emission. The findings from the study provide a platform to select the shared anchor system considering cost reductions and estimate the environmental effects, which is a key consideration to Green Construction. The results show that the DERA is a cost-effective and environmental-friendly alternative for the floating offshore wind project.

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Geology, environmental hazards, and petroleum resources for 1982 OCS lease sale 73, offshore central and northern California

Cited by 3 publications

References 37 publications

Deep crustal reflection profiling offshore southern central California

Deep crustal reflection profiling offshore southern central California

Installability of a Multiline Ring Anchor System in a Seabed under Severe Environmental Conditions

Effect of Shared Anchor System for a Floating Offshore Wind Project on Reductions in CO2 Emissions

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