Controls on melt migration and extraction at the ultraslow Southwest Indian Ridge 10°–16°E
Montesi, Laurent G. J.
Behn, Mark D.
Hebert, Laura B.
Barry, Jennifer L.
MetadataShow full item record
KeywordMid-ocean ridges; Southwest Indian Ridge; Crustal accretion; Melt migration; Serpentinization
Crustal thickness variations at the ultraslow spreading 10–16°E region of the Southwest Indian Ridge are used to constrain melt migration processes. In the study area, ridge morphology correlates with the obliquity of the ridge axis with respect to the spreading direction. A long oblique “supersegment”, nearly devoid of magmatism, is flanked at either end by robust magmatic centers (Joseph Mayes Seamount and Narrowgate segment) of much lesser obliquity. Plate-driven mantle flow and temperature structure are calculated in 3-D based on the observed ridge segmentation. Melt extraction is assumed to occur in three steps: (1) vertical migration out of the melting region, (2) focusing along an inclined permeability barrier, and (3) extraction when the melt enters a region shallower than ∼35 km within 5 km of the ridge axis. No crust is predicted in our model along the oblique supersegment. The formation of Joseph Mayes Seamount is consistent with an on-axis melt anomaly induced by the local orthogonal spreading. The crustal thickness anomaly at Narrowgate results from melt extracted at a tectonic damage zone as it travels along the axis toward regions of lesser obliquity. Orthogonal spreading enhances the Narrowgate crustal thickness anomaly but is not necessary for it. The lack of a residual mantle Bouguer gravity high along the oblique supersegment can be explained by deep serpentization of the upper mantle permissible by the thermal structure of this ridge segment. Buoyancy-driven upwelling and/or mantle heterogeneities are not required to explain the extreme focusing of melt in the study area.
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): B10102, doi:10.1029/2011JB008259.
Showing items related by title, author, creator and subject.
Evolution of the Southwest Indian Ridge from 55°45′E to 62°E : changes in plate-boundary geometry since 26 Ma Baines, A. Graham; Cheadle, Michael J.; Dick, Henry J. B.; Scheirer, Allegra Hosford; John, Barbara E.; Kusznir, Nick J.; Matsumoto, Takeshi (American Geophysical Union, 2007-06-23)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 ...
Mineralogical and geochemical features of sulfide chimneys from the 49°39′E hydrothermal field on the Southwest Indian Ridge and their geological inferences Tao, Chunhui; Li, Huaiming; Huang, Wei; Han, XiQiu; Wu, GuangHai; Su, Xin; Zhou, Ning; Lin, Jian; He, YongHua; Zhou, JianPing (Springer, 2011-08-24)During January–May in 2007, the Chinese research cruise DY115-19 discovered an active hydrothermal field at 49°39′E/37°47′S on the ultraslow spreading Southwest Indian Ridge (SWIR). This was also the first active hydrothermal ...
The influence of ridge geometry at the ultraslow-spreading Southwest Indian Ridge (9º-25ºE) : basalt composition sensitivity to variations in source and process Standish, Jared J. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2006-02)Between 9º-25º E on the ultraslow-spreading Southwest Indian Ridge lie two sharply contrasting supersegments. One 630 km long supersegment erupts N-MORB that is progressively enriched in incompatible element concentrations ...