Enhanced and Asymmetric Melting Beneath the Southern Mariana Back‐Arc Spreading Center Under the Influence of Pacific Plate Subduction

Matsuno, Takeshi; Seama, Nobukazu; Shindo, Haruka; Nogi, Yoshifumi; Okino, Kyoko

doi:10.1029/2021jb022374

Cited by 2 publications

(1 citation statement)

References 92 publications

(191 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Through nonlinear regularized inversion, smooth two-dimensional anisotropic electrical models were reconstructed from the measured data. The electrical resistivity of the upper mantle is primarily influenced by factors such as temperature, the extent of partial melting, and the presence of water (or hydrogen) dissolved in the solid mantle (particularly olivine) and melts (Matsuno et al, 2022;McKenzie et al, 2005). The study also included preliminary rock physics analysis and geological interpretations to assess the thermal structure, melt distribution, and the occurrence of water.…”

Section: Introductionmentioning

confidence: 99%

Deep electrical imaging of the extinct oceanic ridge in the southwestern sub-basin of the South China Sea

Gao,

Li,

et al. 2023

Front. Mar. Sci.

View full text Add to dashboard Cite

The resistivity structure of an extinct mid-ocean ridge is significant in understanding the evolution of a mid-ocean ridge from its spreading phase to its dying phase. The magnetotelluric (MT) method is a crucial tool in studying the deep resistivity structure as it is sensitive to resistivity which is affected by heat and allows for imaging of the electrical properties of the mantle. While modern electromagnetic data has enhanced our understanding of the deep structure of rapidly expanding and ultra-slow expanding mid-ocean ridges, the deep electrical structure below extinct mid-ocean ridges has not been studied extensively.In July 2020, marine MT instruments were deployed in the southwest subbasin of the South China Sea to study the resistivity structure below a stalled mid-ocean ridge. The study found that the imaged thickness of the lithospheric lid (>100Ωm) varies between 20 and 90 km, exhibiting a positive correlation with its age. The melt ascent channel is closed below the stalled mid-ocean ridge, and the melt falls back and forms a small melt trap below the dead mid-ocean ridge. In the northwest survey line of oceanic ridge, huge low-resistivity anomalies (<1Ωm), located between 80km and 160 km depth. In the southeast survey line of oceanic ridge, there is a slightly smaller low-resistivity anomalies (<1Ωm). These results indicate that partial melt continues to exist after the cessation of spreading at the mid-ocean ridge. The lithosphere-asthenosphere boundary (LAB) and the ocean basin of the South China Sea experienced a certain magmatic transformation during the cooling and falling process. According to the resistivity, temperature, pressure, and SEO3 model, the melt content is estimated to be approximately 1-12%. The electrical structure of the mantle in the South China Sea is an important basis for studying the current state beneath the ceased spreading mid-ocean ridge.

show abstract

Section: Introductionmentioning

confidence: 99%

Deep electrical imaging of the extinct oceanic ridge in the southwestern sub-basin of the South China Sea

Gao,

Li,

et al. 2023

Front. Mar. Sci.

View full text Add to dashboard Cite

show abstract

Inversion of marine magnetotelluric and controlled source electromagnetic data with site gap and low signal-to-noise ratio

Jiang,

Yang,

Sun

et al. 2024

Geophysical Journal International

View full text Add to dashboard Cite

Summary Marine magnetotelluric (MT) and controlled source electromagnetic (CSEM) methods have been routinely applied to survey the crustal and upper mantle electrical resistivity structures beneath the sea floor. In practice, there are inevitably site gaps and contamination by noises in the collected data because of lost ocean bottom electromagnetic (OBEM) receivers, unusable data, and difficulties in deploying instruments near deep trenches. So far, it remains unclear to what degree those factors will lower the resolution and the credibility of marine MT and CSEM inversion models. In this paper, we investigate the individual and combined effects of site gaps and data noises on the inversion models through synthetic analyses based on a simple block resistivity model and a realistic resistivity structure derived from the Mariana Trench. The results suggest that data with a sufficiently high signal-to-noise ratio can reasonably recover the sub-seafloor structures in the area of data gap. The transverse electric (TE) mode and tipper data from the MT method are much more sensitive to the structure near the site gap. The joint inversion of MT and CSEM data would improve the model's resolution at the site gap area. The inversion of data with a relatively low signal-to-noise ratio, for example, 10 per cent, can recover the structures with few artifacts if there is no site gap. But if the site gap and noisy data are combined, even a joint inversion cannot correctly recover the burial depths and geometries of the anomalous bodies beneath the site gap where vertical strips are likely present. To improve the model's resolution and suppress inversion artifacts, we propose constraining part of the model with as much a prior information as possible. Specifically, for a survey in the subduction zone, we could reduce the penalties on the model's smoothness at the upper and low interfaces of the resistive subduction slab, or even fix the resistivity of the resistive slab with the help of other information, if any. The inversion models shown in this paper provide valuable references for the site design before marine MT and CSEM surveys as well as for interpreting real data inversion models that may be subject to the same biases introduced by the site gap and noise.

show abstract

Enhanced and Asymmetric Melting Beneath the Southern Mariana Back‐Arc Spreading Center Under the Influence of Pacific Plate Subduction

Cited by 2 publications

References 92 publications

Deep electrical imaging of the extinct oceanic ridge in the southwestern sub-basin of the South China Sea

Deep electrical imaging of the extinct oceanic ridge in the southwestern sub-basin of the South China Sea

Inversion of marine magnetotelluric and controlled source electromagnetic data with site gap and low signal-to-noise ratio

Contact Info

Product

Resources

About