Evolution of the Southwest Indian Ridge from 55°45′E to 62°E: Changes in plate-boundary geometry since 26 Ma
From 55°45′E to 58°45′E and from 60°30′E to 62°00′E, the ultraslow‐spreading Southwest Indian Ridge (SWIR) consists of magmatic spreading segments separated by oblique amagmatic spreading segments, transform faults, and nontransform discontinuities. Off‐axis magnetic and multibeam bathymetric data p...
Saved in:
Published in | Geochemistry, geophysics, geosystems : G3 Vol. 8; no. 6; pp. Q06022 - n/a |
---|---|
Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
American Geophysical Union
01.06.2007
Blackwell Publishing Ltd |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | From 55°45′E to 58°45′E and from 60°30′E to 62°00′E, the ultraslow‐spreading Southwest Indian Ridge (SWIR) consists of magmatic spreading segments separated by oblique amagmatic spreading segments, transform faults, and nontransform discontinuities. Off‐axis magnetic and multibeam bathymetric data permit investigation of the evolution of this part of the SWIR. Individual magmatic segments show varying magnitudes and directions of asymmetric spreading, which requires that the shape of the plate boundary has changed significantly over time. In particular, since 26 Ma the Atlantis II transform fault grew by 90 km to reach 199 km, while a 45‐km‐long transform fault at 56°30′E shrank to become an 11 km offset nontransform discontinuity. Conversely, an oblique amagmatic segment at the center of a first‐order spreading segment shows little change in orientation with time. These changes are consistent with the clockwise rotation of two ∼450‐km‐wide first‐order spreading segments between the Gallieni and Melville transform faults (52–60°E) to become more orthogonal to spreading. We suggest that suborthogonal first‐order spreading segments reflect a stable configuration for mid‐ocean ridges that maximizes upwelling rates in the asthenospheric mantle and results in a hotter and weaker ridge‐axis that can more easily accommodate seafloor spreading. |
---|---|
Bibliography: | ArticleID:2006GC001559 istex:1E0D66C3EE29FCE53AE9E7B0A3FE37B53E3237D4 ark:/67375/WNG-NCJ9JTV0-8 |
ISSN: | 1525-2027 1525-2027 |
DOI: | 10.1029/2006GC001559 |