期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：28
DOI：10.1073/pnas.2204761119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
We address the hypothesis that changes in Pleistocene sea level have consequences for abyssal-hill bathymetry. A model illustrates how reductions in magma production caused by rising sea level could trigger faults at 100-ky intervals at intermediate spreading-rate ridges (>2.3 cm/y) and at 41-ky intervals at faster spreading-rate ridges (>3.8 cm/y). Analysis of 17 different regional ridge systems gives characteristic length scales that closely align with the predictions from the faulting model. Furthermore, a robust spectral peak is found at the 41-ky obliquity period at fast-spreading ridges. Together, these results constitute strong evidence for a pervasive influence of Pleistocene variations in glaciation and sea level on the pattern of abyssal hills.
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.
