Inge B. says:
December 14, 2012 at 16:13
Interesting. But I don’t think this is the only place to find rhyolite at ocean spreading ridges.
In Iceland, which is located in the middle of a such, the MAR, there are lots of volcanoes containing rhyolite, the biggest known areas for that being Torfajökull, Lón and Borgarfjördur Eystri.
Also in 2007, scientists discovered a big caldera containing central volcano out on Reykjanes Ridge. [link to news.nationalgeographic.com
] As far as I could get, there has not yet been carried out research re. the petrology of the volcano, but compairing it to volcanoes on Iceland mainland – and it was eg. compaired to Krafla volcano – rhyolite could be expected among others. Around Krafla, you don’t only find basalt (in the fissure system), but also rhyolite, eg. in the lava domes Leirhnjúkur and Námafjall.
[link to commons.wikimedia.org
This is up on the summet of Námafjall, view direction north. In the background at yr. right: Krafla central volcano with the Krafla power station (steam cloud) in front, at yr. left side: the mountain chain of Kinnarfjöll on the western side of Skjálfandi bay (which is covered up by the mountains in the middle ground, all of them part of Krafla volcanic system).
[link to volcanocafe.wordpress.com