The potential hydrothermal systems unexplored in the Southwest Indian Ocean

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ORIGINAL RESEARCH PAPER

The potential hydrothermal systems unexplored in the Southwest Indian Ocean Yanhui Suo1 · Sanzhong Li1,2 · Xiyao Li1 · Zhen Zhang1 · Dong Ding1 

Received: 13 July 2016 / Accepted: 19 December 2016 © Springer Science+Business Media Dordrecht 2017

Abstract Deep-sea hydrothermal vents possess complex ecosystems and abundant metallic mineral deposits valuable to human being. On-axial vents along tectonic plate boundaries have achieved prominent results and obtained huge resources, while nearly 90% of the global mid-ocean ridge and the majority of the off-axial vents buried by thick oceanic sediments within plates remain as relatively undiscovered domains. Based on previous detailed investigations, hydrothermal vents have been mapped along five sections along the Southwest Indian Ridge (SWIR) with different bathymetry, spreading rates, and gravity features, two at the western end (10°–16°E Section B and 16°–25°E Section C) and three at the eastern end (49°–52°E Section D, 52°–61°E Section E and 61°–70°E Section F). Hydrothermal vents along the Sections B, C, E and F with thin oceanic crust are hosted by ultramafic rocks under tectoniccontrolled magmatic-starved settings, and hydrothermal vents along the Section D are associated with exceed magmatism. Limited coverage of investigations is provided along the 35°–47°E SWIR (between Marion and Indomed fracture zones) and a lot of research has been done around the Bouvet Island, while no hydrothermal vents has been reported. Analyzing bathymetry, gravity and geochemical data, magmatism settings are favourable for the occurrence of hydrothermal systems along these two sections. An off-axial hydrothermal system in the southern flank of * Sanzhong Li [email protected] 1

Submarine Geosciences and Prospecting Techniques, MOE and College of Marine Geosciences, Ocean University of China, Qingdao 266100, China

2

Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China

the SWIR that exhibits ultra-thin oceanic crust associated with an oceanic continental transition is postulated to exist along the 100-Ma slow-spreading isochron in the Enderby Basin. A discrete, denser enriched or less depleted mantle beneath the Antarctic Plate is an alternative explanation for the large scale thin oceanic crust concentrated on the southern flank of the SWIR. Keywords Hydrothermal vents · Magmatism · Tectonic · Hotspot · Ocean–continent transition

Introduction Deep-sea hydrothermal vents possess complex ecosystems and are rich in metallic mineral deposits. Research into these vents has driven progress in our understanding of the transfer of heat, chemicals and organisms from the Earth’s hot interior into the ocean. Of the 597 observed global hydrothermal vents (InterRidge Vents Database Version 3.2), 590 (99%) are distributed along or near active plate boundaries and are associated with mid-ocean ridges, back-arc spreading centres or arc volcanoes, while 7 (1%) are distributed along intra-plate volcanoes. Ext