Since the geological expedition of R.W. Bunsen to Iceland in the mid 19th century, scientists have been puzzled by the frequent co-occurrence of basalt and rhyolite at many volcanoes. Bunsen, who also invented of the Bunsen burner, was the first to describe this phenomenon of “bimodal volcanism”, but these fundamentally different lava types have by now been found together at sites across the planet.
Crucially, the mixing of basalt and rhyolite in a volcano’s magma chamber is a major cause of violently explosive eruptions, but in the 160 years since Bunsen’s observations, no consensus has been reached on how bimodal volcanism actually originates. A new article in “Nature Communications” now re-ignites the debate and offers a fresh perspective on bimodal volcanism at continental volcanoes. Using detailed chemical analyses of rocks from the Carlingford Igneous Centre, the roots of a large, extinct volcano in northeast Ireland, an international team of scientists suggests that the key control on bimodal volcanism could, in fact, be the crustal rocks that lie below the erupting volcano.
This new article, offers a fresh perspective on bimodal volcanism using detailed chemical analyses of rocks from the Carlingford Igneous Centre, Ireland. We suggest that a key control could, in fact, be the crustal rocks that lie deep below the erupting volcano.
The paper, entitled “Bimodal magmatism produced by progressively inhibited crustal assimilation” will be published online by Nature Communications on Friday, 20th June. The attached press release and images are strictly embargoed and the information contained cannot be published until 1000 Dublin time on Friday 20/6/14.
This research was initiated when the two lead authors were at Trinity College Dublin, and was funded by both Science Foundation Ireland and the Irish Research Council for Science, Engineering and Technology.