Physico-chemical properties of newly discovered hydrothermal plumes above the Southern Mid-Atlantic Ridge (13°-33°S).

Schmid, Florian , Peters, Maike, Walter, Maren, Devey, Colin , Petersen, Sven , Yeo, Isobel, Köhler, Janna, Jamieson, John William, Walker, Sharon and Sültenfuß, Jürgen (2019) Physico-chemical properties of newly discovered hydrothermal plumes above the Southern Mid-Atlantic Ridge (13°-33°S). Deep Sea Research Part I: Oceanographic Research Papers, 148 . pp. 34-52. DOI 10.1016/j.dsr.2019.04.010.

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Supplementary data:

Abstract

Highlights

• Hydrothermal survey in the 13°-33°S region of the Mid-Atlantic Ridge based on hydrographic casts, noble gas observations and AUV dives.
• Discovery of hydrothermal plumes above ten ridge segments pointing to 14 unknown active vent sites.
• Rio de Janeiro Transform (22°S) likely represents a barrier separating different vent endemic faunal communities to the north and south.

Abstract

The oceanic crust is initially cooled and deep-sea chemosynthetic ecosystems are largely fed by hydrothermal circulation and venting on the seafloor. Much of this venting takes place at mid-ocean ridges and in order to make realistic models of the crust's thermal budget and to understand chemosynthetic biogeography it is important to have a detailed inventory of vent sites. Until recently, a major gap in this inventory was the Mid-Atlantic Ridge south of 13°S, a key region for vent fauna biogeography as it is the corridor linking the Atlantic to the Indian and Pacific Oceans. In spring 2013 we systematically surveyed the axial region between 13°S and 33°S for hydrothermal signals in the water column, using turbidity, oxidation-reduction-potential (ORP) and noble gases as indicators. Standard conductivity-temperature-depth (CTD) rosette water-sampler deployments were complimented by a novel autonomous underwater vehicle (AUV) deployment strategy, in which the AUV made single-pass, segment-scale (up to 100 km long) dives close to the seafloor to detect small vents. The ca. 2100 km-long survey covered 16 ridge segments and we identified previously unknown hydrothermal plumes above ten segments that point to 14 new hydrothermal vent fields. The majority of plumes are located at high-relief segment centers, where magmatism is robust. A wide gap in the distribution of vents in the 19°S-23°S region coincides with the Rio de Janeiro Transform, the maximum southward progression of North Atlantic Deep Waters and the maximum northwards extent of 3He-enriched waters with Pacific origins. Crossflowing currents in the transform and the large gap between adjacent vents may prevent a meridional connection between the vent fauna communities in the North Atlantic and along the Antarctic Ridges. This makes the region a prime target for future biogeographical studies.

Document Type: Article
Additional Information: All data presented in this paper will be available via the PANGAEA earth data publisher (https://pangaea.de).
Keywords: Southern mid-atlantic ridge, Mid-ocean ridges, Hydrothermal plumes, Helium-3, Vent fauna biogeography
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS > Marine Mineralische Rohstoffe
MARUM
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
NOC
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.dsr.2019.04.010
ISSN: 0967-0637
Projects: Ocean in the Earth System
Expeditions/Models/Experiments:
Date Deposited: 29 Apr 2019 11:55
Last Modified: 23 Sep 2019 22:16
URI: http://oceanrep.geomar.de/id/eprint/46511

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