01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-06-0089 |
| Title of Abstract | Hydrothermal Activity along the Southwest Indian Ridge: Capturing a Massive Volcanic-Hydrothermal Episode at an Ultraslow-Spreading Ridge (67.7°E) |
| Authors | Srinivas Rao Arvapalli*, Sunil Sunil Vadakkepuliyambatta |
| Organisation | National Centre for Polar and Ocean Research |
| Address | NCPOR, Headland sada vasco-da-gama, Goa, India Pincode: 403804 E-mail: srinivas@ncpor.res.in |
| Country | India |
| Presentation | Oral |
| Abstract | Ultraslow-spreading ridges (full spreading rate <20mm/year) have traditionally been regarded as magma-starved systems, characterized by limited, discontinuous, and spatially localized volcanic activity. However, recent evidence from the Indian Ocean reveals that large-scale magmatic and hydrothermal events can also occur along these slowest-spreading ridge systems. Water column surveys were conducted along a ~600km segment of the eastern Southwest Indian Ridge (SWIR) between 63°E and 69°E from 2014 to 2020. Using conductivity-temperature-depth (CTD) profilers equipped with turbidity and oxidation reduction potential (ORP) sensors, multiple hydrothermal plumes were identified, including an unusual large and anomalous event near 67.7°E, located directly above an axial volcanic ridge. This site showed evidence of a major magmatic - hydrothermal episode between 2017 and 2020, temporally linked to a seismic swarm event during September-October 2018. Post surveys revealed a thick, vertically stratified hydrothermal plume spanning 2300⿿4600m water depth. The plume exhibited strong turbidity anomalies (up to 0.35 οNTU), temperature-salinity deviations, and coherent ORP anomalies indicative of intense hydrothermal discharge likely driven by lava eruption and subsequent cooling. The vertical thickness of the plume (~2km), with distinct layering centered near 3300m, and an along-axis dispersion exceeding 160km, highlights the exceptional scale of this event - comparable to rare, large hydrothermal plumes observed over mid-ocean ridges since 1987. The spatial and temporal correlation between the seismic activity and the plume supports a magmatic origin, involving lava effusion rather than diking alone. These findings demonstrate that significant volcanic and hydrothermal processes can occur even at ultraslow-spreading ridges, with broad implications for seafloor accretion, chemical fluxes, and hydrothermal ecosystems. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Ultraslow spreading ridge, water column anomalies, hydrothermal event plume, earthquakes |
| For Awards | no |