Role of syn-magmatic strain localization in oceanic detachment faulting at ultraslow-spreading ridges

Ma, Qiang1; Zhou, Huaiyang1,2; Dick, Henry J. B.1,3

2024-10-01

10.1016/j.epsl.2024.118892

EARTH AND PLANETARY SCIENCE LETTERS   影响因子和分区

0012-821X

1385-013X

Tectonic extension at slow- to ultraslow-spreading mid-ocean ridges is predominantly accommodated by large- offset detachment faults. Nonetheless, the interplay between these detachment faults and melt supply remains an area of active research. In our study, we undertook a comprehensive analysis of a narrow shear zone and its wall rock, both retrieved from the International Ocean Discovery Program (IODP) Hole U1473A at the Atlantis Bank Oceanic Core Complex (OCC) on the Southwest Indian Ridge. Our methodology encompassed microstructural observations, electron probe analysis, and electron backscatter diffraction. Our findings indicate that an oxide- saturated melt permeated the semi-brittle lithosphere and the fault plane, acting as a lubricant and significantly diminishing the fault's frictional strength. Subsequent deformation-triggered melt segregation led to a 3-4-fold reduction in the viscosity of the footwall gabbros. This reduction likely induced a listric geometry, driven by the reorientation of local stress fields and unusually elevated melt pressure. In contrast to numerical model predictions, our results suggest that the development of oceanic detachment faults is chiefly controlled by synmagmatic strain localization, potentially linked to the rate of melt emplacement and the thickness of the axial lithosphere.

Seafloor spreading Slow and ultraslow mid-ocean ridges Detachment faults Syn-magmatic strain localization Melt supply

SCI ; EI

英语

通讯

Chinese National Key Basic Research Program[2012CB417300]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:001283815400001

ELSEVIER

20243016766314

Faulting ; Strain rate ; Structural geology

Oceanography, General:471.1 ; Geology:481.1 ; Earthquake Measurements and Analysis:484.1

GEOSCIENCES

Web of Science

1.Tongji Univ, State Key Lab Marine Geol, Shanghai 200092, Peoples R China
2.Southern Univ Sci & Technol, Dept Ocean Sci & Engn, Shenzhen 518055, Peoples R China
3.Woods Hole Oceanog Inst, Dept Geol & Geophys, Woods Hole, MA 02543 USA

Ma, Qiang,Zhou, Huaiyang,Dick, Henry J. B.. Role of syn-magmatic strain localization in oceanic detachment faulting at ultraslow-spreading ridges[J]. EARTH AND PLANETARY SCIENCE LETTERS,2024,643.

Ma, Qiang,Zhou, Huaiyang,&Dick, Henry J. B..(2024).Role of syn-magmatic strain localization in oceanic detachment faulting at ultraslow-spreading ridges.EARTH AND PLANETARY SCIENCE LETTERS,643.

Ma, Qiang,et al."Role of syn-magmatic strain localization in oceanic detachment faulting at ultraslow-spreading ridges".EARTH AND PLANETARY SCIENCE LETTERS 643(2024).