The morphotectonic features of non-transform discontinuity at 11°S and its hydrothermal activity, Central Indian Ridge

Abstract

Korea Institute of Ocean Science and Technology (KIOST) has surveyed the CentralIndian Ridge (CIR) between 17˚S and 7˚S to delineate segment morphotectonics as well asto identify hydrothermal activity. We found not only 4 prominent non-transformdiscontinuities (NTDs) and 11 ocean core complexes (OCCs), but also severalhydrothermal activities within these off-axis structures. Here we report the one of thelargest NTD3-1 and the associated hydrothermalism in the region. The NTD3-1 is 44 kmin length and 10 km in width. Glass watch-shaped basin floor of the NTD is flanked by isclearly defined by 4000 m isobath. The NTD adjoins the linear escarpments that displays> 1000 m high in relief. The escarpments strike at 035°, approximately 45° oblique in aclockwise direction to the orientation of two adjoining ridge segments. The fracture zonebetween segment 3-1 and 3-2 along the off-axis is able to be traced but through-goingtrends thereof are not clear at the terrain that immediately flanks segment 3-1 to east andwest for a distance of approximately 75 km and 30 km, respectively. Low intensity inbackscatter values, a little positive magnetic anomaly and uncommon seismic activitiesover the NTD3-1 are indicative of that the basin-like NTD3-1 has been riven off byamagmatic and aseimic extension. In particular, strike-slip Centroid-Monent Tensors areremarkable in the southern tips of NTD3-1. The n-transformdiscontinuities (NTDs) and 11 ocean core complexes (OCCs), but also severalhydrothermal activities within these off-axis structures. Here we report the one of thelargest NTD3-1 and the associated hydrothermalism in the region. The NTD3-1 is 44 kmin length and 10 km in width. Glass watch-shaped basin floor of the NTD is flanked by isclearly defined by 4000 m isobath. The NTD adjoins the linear escarpments that displays> 1000 m high in relief. The escarpments strike at 035°, approximately 45° oblique in aclockwise direction to the orientation of two adjoining ridge segments. The fracture zonebetween segment 3-1 and 3-2 along the off-axis is able to be traced but through-goingtrends thereof are not clear at the terrain that immediately flanks segment 3-1 to east andwest for a distance of approximately 75 km and 30 km, respectively. Low intensity inbackscatter values, a little positive magnetic anomaly and uncommon seismic activitiesover the NTD3-1 are indicative of that the basin-like NTD3-1 has been riven off byamagmatic and aseimic extension. In particular, strike-slip Centroid-Monent Tensors areremarkable in the southern tips of NTD3-1. The