Volcanic ash production and dispersal at the 14°N segment of the Mid-Atlantic Ridge
Abstract
Volcanic ash, material < 2 mm diameter, has been found along the few mid-ocean ridges (MOR) that have recently been explored for ash, raising the possibility that explosive MOR volcanism is more common than previously believed. The widespread introduction of volcanic ash in the MOR environment has consequences for biogeochemical cycling and the chemical composition of marine sediment. However, it is not known if ash generating MOR eruptions are rare or common events or whether they are linked to the tectonic environment (e.g., magma supply). Here we report the first comprehensive study of ash at a slow spreading ridge segment, including the abundance and composition of volcanic ash from 20 sediment push cores collected within the axial valley and 5 gravity cores from outside the axial valley of the 14°N segment of the Mid-Atlantic Ridge. We find that volcanic ash is present in all the 25 cores assessed to date despite the expectation ash dissemination would be limited. The measured mass fraction of ash within 20 cores define spatial dispersal patterns that help identify sources and test dispersal models. In addition, we analyzed the major element chemistry of 310 ash particles from five axial valley push cores (sampling the upper 30 cm of sediment) and find that the ash exhibits a range of MORB compositions. This ridge segment, like other slow spreading centers, exhibits geochemical diversity that we use to identify the sources of recovered ash. Our initial results suggest that ash within our study area (~50 km2 within the axial valley of the Mid-Atlantic Ridge) was produced during many unique events. By evaluating the types of events that produce and disperse MOR ash, our study results aid in the development of methods for reconstructing MOR volcanic histories and improve estimates of ash delivery to the oceans.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V43H0186F
- Keywords:
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- 8408 Volcano/climate interactions;
- VOLCANOLOGY;
- 8414 Eruption mechanisms and flow emplacement;
- VOLCANOLOGY;
- 8424 Hydrothermal systems;
- VOLCANOLOGY;
- 8427 Subaqueous volcanism;
- VOLCANOLOGY