Young volcanism and related hydrothermal activity at 5°S on the slow-spreading southern Mid-Atlantic Ridge
| Autor: | Mirjam Perner, J. Mawick, M. Warmuth, Oliver Schmale, Karsten M. Haase, Holger Paulick, Stefan Weber, Andrea Koschinsky, Bernd Melchert, Ulrike Westernströer, Christian Mertens, H. Marbler, Colin W. Devey, Dana R. Yoerger, Sylvia G. Sander, Maren Walter, Robin Keir, Chris German, Timothy M. Shank, Sven Petersen, O. Giere, Harald Strauss, Richard Seifert, Dieter Garbe-Schönberg, J. Süling, Nicole Dubilier, S. Fretzdorff, Klas Lackschewitz, Uwe Stöber, Christian Ostertag-Henning, Frank U. Zielinski, Marc Peters, Jan Kuever, J. Stecher |
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| Rok vydání: | 2007 |
| Předmět: |
geography
Vulcanian eruption geography.geographical_feature_category 010504 meteorology & atmospheric sciences Lava Earth science Geochemistry Mid-ocean ridge Volcanism Mid-Atlantic Ridge 010502 geochemistry & geophysics 01 natural sciences Seafloor spreading Hydrothermal circulation Geophysics Volcano 13. Climate action Geochemistry and Petrology Geology 0105 earth and related environmental sciences |
| Zdroj: | Geochemistry, Geophysics, Geosystems. 8 |
| ISSN: | 1525-2027 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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