Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion

Davy, R.; Morgan, Joanna; Minshull, T. A.; Bayrakci, Gaye; Bull, Jonathan M.; Klaeschen, Dirk; Reston, T. J.; Sawyer, Dale S.; Lymer, Gaël; Cresswell, Derren

doi:10.1093/gji/ggx415

Cited by 26 publications

(21 citation statements)

References 47 publications

(67 reference statements)

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“…The improved spatial resolution provided by the 3D volume ( Supplementary Figure S1) reveals the internal structure of the fault blocks, showing that S developed late in the rifting evolution and slipped at low-angle ( Figure 7). Crystalline basement, sampled by submersible and identified more widely from seismic velocities (Bayrakci et al, 2016;Davy et al, 2018), is overlain by a thin internally poorly reflective package (A), that we interpret as predating the current fault blocks (Figures 5 and 7). Overlying A is a thicker, more ubiquitous and reflective series of sediments (B); small offsets in the fine layering of package B show that this unit is intensely fractured and faulted.…”

Section: Timing and Angle Of Slip On Smentioning

confidence: 91%

3D development of detachment faulting during continental breakup

Lymer

Cresswell

Reston

et al. 2019

Earth and Planetary Science Letters

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The developing asymmetry of rifting and continental breakup to form rifted margins has been much debated, as has the formation, mechanics and role of extensional detachments. Bespoke 3D seismic reflection data across the Galicia margin, west of Spain, image in unprecedented detail an asymmetric detachment (the S reflector). Mapping S in 3D reveals its surface is corrugated, proving that the overlying crustal blocks slipped on S surface during the rifting. Crucially, the 3D data show that the corrugations on S perfectly match the corrugations observed on the present-day block-bounding faults, demonstrating that S is a composite surface, comprising the juxtaposed rotated roots of block-bounding faults as in a rolling hinge system with each new fault propagation moving rifting oceanward; changes in the orientation of the corrugations record the same oceanward migration. However, in contrast to previous rolling hinge models, the slip of the crustal blocks on S occurred at angles as low as ~20°, requiring that S was unusually weak, consistent with the hydration of the underlying mantle

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Section: Timing and Angle Of Slip On Smentioning

confidence: 91%

3D development of detachment faulting during continental breakup

Lymer

Cresswell

Reston

et al. 2019

Earth and Planetary Science Letters

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“…Recently, by using full waveform information of seismic data, full waveform inversion (FWI) is now one of S. Li, B. Liu, Y. Ren, S. yang, Y. Wang the most appealing methods to reconstruct the velocity model with high accuracy and resolution [1]- [3]. FWI was firstly proposed in the early 1980s.…”

Section: Introductionmentioning

confidence: 99%

Deep-Learning Inversion of Seismic Data

Liu

Ren

et al. 2020

IEEE Trans. Geosci. Remote Sensing

249

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In this paper, we propose a new method to tackle the mapping challenge from time-series data to spatial image in the field of seismic exploration, i.e., reconstructing the velocity model directly from seismic data by deep neural networks (DNNs). The conventional way to address this ill-posed seismic inversion problem is through iterative algorithms, which suffer from poor nonlinear mapping and strong non-uniqueness. Other attempts may either import human intervention errors or underuse seismic data. The challenge for DNNs mainly lies in the weak spatial correspondence, the uncertain reflection-reception relationship between seismic data and velocity model as well as the timevarying property of seismic data. To approach these challenges, we propose an end-to-end Seismic Inversion Networks (SeisInvNet for short) with novel components to make the best use of all seismic data. Specifically, we start with every seismic trace and enhance it with its neighborhood information, its observation setup and global context of its corresponding seismic profile. Then from enhanced seismic traces, the spatially aligned feature maps can be learned and further concatenated to reconstruct velocity model. In general, we let every seismic trace contribute to the reconstruction of the whole velocity model by finding spatial correspondence. The proposed SeisInvNet consistently produces improvements over the baselines and achieves promising performance on our proposed SeisInv dataset according to various evaluation metrics, and the inversion results are more consistent with the target from the aspects of velocity value, subsurface structure and geological interface. In addition to the superior performance, the mechanism is also carefully discussed, and some potential problems are identified for further study. Index Terms-Seismic inversion, Deep neural networks.

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“…The northeastern Nova Scotia continental offshore is widely classified as a magma-poor rifted margin (e.g., Funck et al, 2004;Keen & Cordsen, 1981;Keen et al, 1991;Lau et al, 2018;Sibuet et al, 2012;Wu et al, 2006) with crustal structures similar to the extensively investigated Newfoundland-Grand Banks margin (e.g., Funck et al, 2003;Lau et al, 2006;Shillington et al, 2006;van Avendonk et al, 2006) to the north and its Iberia conjugate margin (e.g., Clark et al, 2007;Davy et al, 2016;Davy et al, 2018;Dean et al, 2015). Along all these margins, a continent-ocean transition (COT) is commonly characterized by a layer of transitional crust that overlies a serpentinized mantle layer, as interpreted based on modeled seismic velocities that are lower (<8.0 km/s) than for unaltered peridotites, with some areas having exhumed serpentinized mantle (ESM) overlain directly by sediments.…”

Section: Introductionmentioning

confidence: 99%

Along‐Strike Variations in Structure of the Continent‐Ocean Transition at the Northeastern Nova Scotia Margin From Wide‐Angle Seismic Observations

2019

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Our 2‐D‐layered velocity model along strike northeastern Nova Scotian margin, constrained by wide‐angle seismic Profile OCTOPUS and coincident 9‐km streamer Profile GXT‐5100, displays highly variable basement structures interpreted to define four distinct zones within the continent‐ocean transition: Zone I, with thin (1–2 km) and laterally uniform upper crust (5.2–5.5 km/s) and high‐velocity lower crust (6.5–7.7 km/s); Zone II, with velocities of 5.5–7.5 km/s and a high vertical velocity gradient (∼1.1/s) characteristic of exhumed serpentinized (up to 90%) mantle (ESM) above ∼3.5‐km‐thick slightly (<30%) serpentinized mantle layer of reduced mantle velocities (7.5–8.0 km/s); Zone III, with 1‐ to 2‐km‐thick upper crust and velocity of ∼5.2 km/s above a ∼6‐km‐thick, moderately (<60%) serpentinized mantle layer (velocity ∼6.4–7.9 km/s); and Zone IV, with lower crust (∼0.7–3.0 km thick and with velocity of 6.1–6.6 km/s) between upper crust (velocity ∼5.0–5.4 km/s) and a slightly serpentinized mantle layer (<40%; velocity ∼7.3–8.0 km/s). These continent‐ocean transition structures represent embryonic oceanic or rifted continental crust, and ESM. By combining our results with those from two dip‐oriented crossing profiles, we map a regional track of non‐ESM landward of Profile OCTOPUS with mostly uniform along‐dip width, but a limited extent and variable width section of ESM seaward. Our results indicate that there can be a remarkable amount of short‐wavelength (e.g., 50 km) lateral structural variability within individual rifted margin segments but that mapping it requires a grid of modern wide‐angle profiles.

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Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion

Cited by 26 publications

References 47 publications

3D development of detachment faulting during continental breakup

3D development of detachment faulting during continental breakup

Deep-Learning Inversion of Seismic Data

Along‐Strike Variations in Structure of the Continent‐Ocean Transition at the Northeastern Nova Scotia Margin From Wide‐Angle Seismic Observations

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