Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 119, Issue 28, Pages -Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.2204761119
Keywords
volcanism; midocean ridges; sea level; Milankovitch forcing
Categories
Funding
- NSF [1338832]
- European Research Council [772255]
- European Research Council (ERC) [772255] Funding Source: European Research Council (ERC)
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It is found that changes in sea level can influence the pattern of bathymetry flanking midocean ridges, and this influence is related to the periodic variations in melt supply. The analysis of bathymetry across different midocean ridge regions supports the predictions from the faulting model, and also reveals a connection between the sea floor fabric and the periods of Pleistocene sea-level variability and Earth's variations in axial tilt.
It is established that changes in sea level influence melt production at midocean ridges, but whether changes in melt production influence the pattern of bathymetry flanking midocean ridges has been debated on both theoretical and empirical grounds. To explore the dynamics that may give rise to a sea-level influence on bathymetry, we simulate abyssal hills using a faulting model with periodic variations in melt supply. For 100-ky melt-supply cycles, model results show that faults initiate during periods of amagmatic spreading at half-rates >2.3 cm/y and for 41-ky melt-supply cycles at half-rates >3.8 cm/y. Analysis of bathymetry across 17 midocean ridge regions shows characteristic wavelengths that closely align with the predictions from the faulting model. At intermediate-spreading ridges (half-rates >2.3 cm/y and <= 3.8 cm/y) abyssal hill spacing increases with spreading rate at 0.99 km/(cm/y) or 99 ky (n = 12; 95% CI, 87 to 110 ky), and at fast-spreading ridges (half-rates >3.8 cm/y) spacing increases at 38 ky (n = 5; 95% CI, 29 to 47 ky). Including previously published analyses of abyssal-hill spacing gives a more precise alignment with the primary periods of Pleistocene sea-level variability. Furthermore, analysis of bathymetry from fast-spreading ridges shows a highly statistically significant spectral peak (P < 0.01) at the 1/(41-ky) period of Earth's variations in axial tilt. Faulting models and observations both support a linkage between glacially induced sea-level change and the fabric of the sea floor over the late Pleistocene.
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