首页|Transform Faults and Non-Transform Discontinuities of the Western Southwest Indian Ridge: Experimental Modeling
Transform Faults and Non-Transform Discontinuities of the Western Southwest Indian Ridge: Experimental Modeling
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NSTL
Pleiades Publishing Inc
The paper considers the segment of the Southwest Indian Ridge located between the Du Toit-Andrew Bain-Prince Edward fault zone and the Bouvet Triple Junction. Two areas are distinguished within the boundaries of this segment, which differ in the structure of the seafloor topography and in their evolution. In the eastern area (from 9° E to 25° E), there are no transform faults and significant thermal anomalies in the mantle. The western segment of the studied part of the ridge (from the Bouvet Triple Junction to 9° E) is crosscut by several large transform faults and develops under the noticeable influence of the thermal anomaly of the Bouvet plume. Such a relationship between the segmentation of the seafloor topography and thermal anomalies in the mantle is not typical of slow and ultraslow spreading ridges. Here the ridge is crosscut by transform faults. Within the areas with a noticeable thermal influence of mantle thermal anomalies these faults disappear. We conducted physical modeling and analysis of temperature field profiles in the model developed to evaluate the influence of the melt accumulation depth on the segmentation of the Southwest Indian Ridge. It has been found that the depth of melt accumulation has a significant effect on the segmentation of mid-ocean ridge (MOR) bathymetry. However, this is not the only major influencing factor. The segmentation of the MOR can be affected by the serpentinization process as well. A decrease in the spreading rate is accompanied by an increase in the depth of the magma chamber, or the area of the focused mantle upwelling. This leads to widespread serpentinization along the extension axis, due to relatively low-intensity magmatism and a high degree of fracturing of the rocks. As a consequence, this leads to the reorganization of the structural segmentation of the MOR due to the disappearance of transform faults with a decrease in the lithosphere strength. The combined effect of the depth of the melt accumulation and serpentinization on the segment of the Southwest Indian Ridge, which has no significant thermal anomaly in the mantle, can lead not only to the disappearance of transform faults but also maintain this setting over a long period. In the western part of the Southwest Indian Ridge, which is influenced by the mantle thermal anomaly, conditions for serpentinization are less favorable. As a result, transform faults are well developed in this area.
NETL
NSTL
Pleiades Publishing Inc
