Magma- induced tectonics at the East Pacific Rise 9°50'N: Evidence from high- resolution characterization of seafloor and subseafloor

• 成果类型: Article
• 署名作者: Marjanovic, Milena; Chen, Jie; Escartin, Javier; Parnell-Turner, Ross; Wu, Jyun-Nai
• 署名单位: Universite Paris Cite; Centre National de la Recherche Scientifique (CNRS); CNRS - National Institute for Earth Sciences & Astronomy (INSU); University of California System; University of California San Diego; Scripps Institution of Oceanography; Centre National de la Recherche Scientifique (CNRS); CNRS - National Institute for Earth Sciences & Astronomy (INSU); Universite PSL; Ecole Normale Superieure (ENS)
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14420
• DOI: 10.1073/pnas.2401440121
• 发表日期: 2024-06-18
• 关键词: midocean ridge; EVOLUTION; eruption; beneath; segmentation; insights; systems; faults; GROWTH; axis

摘要

At fast - spreading centers, faults develop within the axial summit trough (AST; 0 to 250 m around the axis) primarily by diking - induced deformation originating from the axial magma lens (AML). The formation of the prominent abyssal - hill - bounding faults beyond the axial high (>2,000 m) is typically associated with the unbending of the lithosphere as it cools and spreads away from the AST. The presence of faults is rarely mapped between these two thermally distinct zones, where the lithosphere is still too hot for the faults to be linked with the process of thermal cooling and outside of the AST where the accretional diking process dominates the ridge axis. Here, we reveal a remarkable vertical alignment between the distinct morphological features of the magma body and the orientation of these faults, by comparison of 3 - D seismic imagery and bathymetry data collected at the East Pacific Rise (EPR) 9 degrees 50'N. The spatial coincidence and asymmetric nucleation mode of the mapped faults represent the most direct evidence for magmatically induced faulting near the ridge axis, providing pathways for hydrothermalism and magma emplacement, helping to build the crust outside of the AST. The high - resolution seafloor and subsurface images also enable revised tectonic strain estimates, which shows that the near - axis tectonic component of seafloor spreading at the EPR is an order of magnitude smaller than previously thought with close to negligible contribution of lava buried faults to spreading.