Explosive Volcanism in the Deep

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Can a volcano be explosive in the deep sea? What about violent? What about mildly aggravated?

Historically, we’ve assumed the answer to be no. Explosive eruptions were thought to be absent at depths below the critical point for seawater around 3000m. Combine this with the lack of evidence for a pyroclastic deposit [rock materials formed by fragmentation as a result of volcanic action] below 3,000m. On top of that add the hypothesis that mid-ocean-ridge basalts do not possess the volatility to produce impressive eruptions at high pressures.

A group of researchers report this week in Nature provide evidence of pyroclastic deposits on the Gakkel ridge in the Arctic Basin at 4000m. In the abstract the authors note a large area “blanketed” with deposits including bubble wall fragments.

Well…that raises some questions.


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Figure 2: a, Frame grab from a high-definition video camera taken on the south side of Duque’s hill (see Fig. 1 for location). About 10 cm (visually estimated and confirmed during sampling) of pyroclastic material is piled atop a high-standing, weathered, pillow feature. The exoskeleton of an as yet unidentified species of hexactinellid sponge23 is visible in the foreground. b, High-definition video frame grab of talus blocks possibly representing ejecta from a vulcanian explosion on Oden volcano (see Fig. 1 for location). c, Glassy, granular, pyroclastic material. d, Bubble wall fragment from pyroclastic deposit.

Dr. M (1605 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, created to facilitate research to address fundamental questions in evolutionary science. He has conducted deep-sea research for 11 years and published over 40 papers in the area. He has participated in dozens of expeditions taking him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses mainly on marine systems and particularly the biology of body size, biodiversity, and energy flow. He focuses often on deep-sea systems as a natural test of the consequences of energy limitation on biological systems. He is the author and chief editor of Deep-Sea News, a popular deep-sea themed blog, rated the number one ocean blog on the web and winner of numerous awards. Craig’s popular writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.





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