Fluid compositions and mineralogy of precipitates from Mid Atlantic Ridge hydrothermal vents at 4°48'S


The effect of volcanic activity on submarine hydrothermal systems has been well documented along fast- and intermediate-spreading centers but not from slow-spreading ridges. Indeed, volcanic eruptions are expected to be rare on slow-spreading axes. Here we report the presence of hydrothermal venting associated with extremely fresh lava flows at an elevated, apparently magmatically robust segment center on the slow-spreading southern Mid-Atlantic Ridge near 5°S. Three high-temperature vent fields have been recognized so far over a strike length of less than 2 km with two fields venting phase-separated, vapor-type fluids. Exit temperatures at one of the fields reach up to 407°C, at conditions of the critical point of seawater, the highest temperatures ever recorded from the seafloor. Fluid and vent field characteristics show a large variability between the vent fields, a variation that is not expected within such a limited area. We conclude from mineralogical investigations of hydrothermal precipitates that vent-fluid compositions have evolved recently from relatively oxidizing to more reducing conditions, a shift that could also be related to renewed magmatic activity in the area. Current high exit temperatures, reducing conditions, low silica contents, and high hydrogen contents in the fluids of two vent sites are consistent with a shallow magmatic source, probably related to a young volcanic eruption event nearby, in which basaltic magma is actively crystallizing. This is the first reported evidence for direct magmatic-hydrothermal interaction on a slow-spreading mid-ocean ridge.

DOI https://doi.org/10.1594/PANGAEA.727454
Related Identifier https://doi.org/10.1029/2006GC001509
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.727454
Creator Haase, Karsten M ORCID logo; Petersen, Sven (ORCID: 0000-0002-5469-105X); Koschinsky, Andrea ORCID logo; Seifert, Richard; Devey, Colin W ORCID logo; Keir, Robin; Lackschewitz, Klas Sven; Melchert, Bernd; Perner, Kerstin ORCID logo; Schmale, Oliver; Süling, J; Dubilier, Nicole (ORCID: 0000-0002-9394-825X); Zielinski, Frank; Fretzdorff, Susanne; Garbe-Schönberg, Dieter ORCID logo; Westernstroer, Ulrike; German, Christopher R; Shank, Timothy M; Yoerger, Dana; Giere, Olav; Küver, Jan; Marbler, Herwig; Mawick, Jule; Mertens, Christian ORCID logo; Stöber, Uwe ORCID logo; Walter, Maren; Ostertag-Henning, Christian ORCID logo; Paulick, Holger; Peters, Michael; Strauss, Harald; Sander, Sylvia; Stecher, Jens; Warmuth, Marco; Weber, Stefan
Publisher PANGAEA
Publication Year 2009
Funding Reference German Research Foundation https://doi.org/10.13039/501100001659 Crossref Funder ID 5471797 https://gepris.dfg.de/gepris/projekt/5471797 From Mantle to Ocean: Energy-, Material- and Life-cycles at Spreading Axes
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Language English
Resource Type Publication Series of Datasets; Collection
Format application/zip
Size 3 datasets
Discipline Earth System Research
Spatial Coverage (-12.377W, -4.815S, -12.372E, -4.792N); Mid-Atlantic Ridge at 4-11°S
Temporal Coverage Begin 2005-04-09T17:13:17Z
Temporal Coverage End 2006-05-14T11:06:00Z