Skip to Main content Skip to Navigation
Journal articles

Magmato-Tectonic Cyclicity at the Ultra-Slow Spreading Southwest Indian Ridge: Evidence from Variations of Axial Volcanic Ridge Morphology and Abyssal Hills Pattern

Abstract : On-axis deep tow side scan sonar data are used together with off-axis bathymetric data to investigate the temporal variations of the accretion processes at the ultra-slow spreading Southwest Indian Ridge. Differences in the length and height of the axial volcanic ridges and various degrees of deformation of these volcanic constructions are observed in side scan sonar images of the ridge segments. We interpret these differences as stages in an evolutionary life cycle of axial volcanic ridge development, including periods of volcanic construction and periods of tectonic dismemberment. Using off-axis bathymetric data, we identify numerous abyssal hills with a homogeneous size for each segment. These abyssal hills all display an asymmetric shape, with a steep faulted scarp facing toward the axis and a gentle dipping volcanic slope facing away. We suggest that these hills are remnants of old split axial volcanic ridges that have been transported onto the flanks and that they result from successive periods of magmatic construction and tectonic dismemberment, i.e., a magmato-tectonic cycle. We observe that large abyssal hills are in ridge sections of thicker crust, whereas smaller abyssal hills are in ridge sections of thinner crust. This suggests that the magma supply controls the size of abyssal hills. The abyssal hills in ridge sections of thinner crust are regularly spaced, indicating that the magmato-tectonic cycle is a pseudoperiodic process that lasts ∼0.4 m.y., about 4 to 6 times shorter than in ridge sections of thicker crust. We suggest that the regularity of the abyssal hills pattern is related to the persistence of a nearly constant magma supply beneath long-lived segments. By contrast, when magma supply strongly decreases and becomes highly discontinuous, regular abyssal hills patterns are no longer observed.
Document type :
Journal articles
Complete list of metadatas

Cited literature [42 references]  Display  Hide  Download

https://hal.archives-ouvertes.fr/hal-00104244
Contributor : Daniel Sauter <>
Submitted on : Friday, June 9, 2017 - 9:19:31 AM
Last modification on : Thursday, December 10, 2020 - 3:05:53 AM
Long-term archiving on: : Sunday, September 10, 2017 - 12:47:57 PM

File

Mendel_et_al-2003-Geochemistry...
Publisher files allowed on an open archive

Identifiers

Citation

Véronique Mendel, Daniel Sauter, Céline Rommevaux-Jestin, Philippe Patriat, F. Lefebvre, et al.. Magmato-Tectonic Cyclicity at the Ultra-Slow Spreading Southwest Indian Ridge: Evidence from Variations of Axial Volcanic Ridge Morphology and Abyssal Hills Pattern. Geochemistry, Geophysics, Geosystems, AGU and the Geochemical Society, 2003, 4 (5), ⟨10.1029/2002GC000417⟩. ⟨hal-00104244⟩

Share

Metrics

Record views

471

Files downloads

876