IS THE VOLCANIC ERUPTION HIGH THE PRODUCT OF HOTSPOT AND MID-OCEAN RIDGE INTERACTION?

It is found from the high-resolution multibeam data of Segment 27 (Cannat et al. 1999) on the Southwest Indian Ridge (SWIR) that there is an unexpected volcanic eruption high along the axis at 50.5 E, which is somewhat similar to the ridges effected by hotspots. We compared the high with the general characteristics of hotspot-effected mid-ocean ridges, made detailed topographic analysis and studied the topography, geophysical field and geochemical characteristics of the high in order to define whether the Segment 27 is effected by any hotspot nearby. Generally speaking, although there is some sort of similarities to the hotspot-effected ridge, it is not typical. Topographically, there is no off-axis topographical anomaly or asymmetric flanks, and geochemically, the most commonly distributed rocks are still normal basalts. Furthermore, there is actually no obvious record in the historical track of the Crozet hotspot showing any efficacious impact on SWIR. In this regard, we concluded that the Segment 27 was indeed effected by something which led to a substantial increase in magmatic flux, but most probably not the interaction with Crozet hotspot. A more reasonable interpretation is that this unexpected volcanic eruption high was resulted from a robust magmatism caused by local heterogeneity of mantle, just as the three similar ridge segments of MAR (Middle Atlantic Ridge) mentioned in literatures.