Hydrothermal systems at mid-ocean ridges (MOR) transfer heat, metals, and carbon from Earth’s interior to the deep ocean, influencing pathways of chemical elements and compounds as they move between living and nonliving parts of Earth, including atmosphere, water, and soil.
Director, CSIR-National Institute of Oceanography (NIO), Dona-Paula, Goa, Prof Sunil Kumar Singh, says about his path-breaking research that establishes the role of glaciation on volcanism: “Increased volcanism along the hydrothermal ridges during the glacial period increased the hydrothermal activity that further increased carbon dioxide flux.”
Singh, along with two other researchers – Sayantan De and Robin John, from CSIR-NIO, Goa – examined a 49,000-year sediment record recovered from the Carlsberg Ridge (CR) in the Indian Ocean to investigate links among glacial-interglacial sea-level changes, volcanism and hydrothermal activity.
“We reconstructed the hydrothermal variability using trace element and Pb isotope analyses of Ferro-Manganese (Fe–Mn) oxyhydroxide coatings from sediment cores. The study presents the first lead (Pb) isotope record of Fe–Mn coatings from an active mid-ocean ridge in the Indian Ocean, offering new insights into how sea-level modulates hydrothermal regimes at slow-spreading ridges over millennial timescales,” says Singh. “The geochemical diversity of deep-sea sediments along MORs is controlled by inputs of hydrothermal materials and fluids, volcanic fragments, and lithogenic debris.”
The team analyzed trace metal concentrations – Cobalt, Nickel, Chromium (Co, Ni, Cr) and Pb isotope ratios in authigenic (minerals formed in sediment or sedimentary rocks) Fe–Mn (Ferro-Manganese) oxyhydroxide coatings, which preserve chemical signals of link between glaciation and volcanism.
Their findings reveal that slow-spreading MOR hydrothermal systems respond dynamically to climate-driven sea-level change and impact long-term ocean chemistry. Glacial sea-level drop decreases hydrostatic pressure, which exerts an important external control on MOR and enhances volcanism and hydrothermal activity.
Elevated hydrothermal fluxes during glacial lows have been documented at a few other ocean ridges, including East Pacific Rise, Juan de Fuca Ridge, Mid-Atlantic Ridge, Central Indian Ridge, and Tianxiu Vent Field of the Carlsberg Ridge, he says.
