There are less well-known types of volcanism that don't involve magma: mud volcanism is one. Mud volcanoes come in two types. On land, hundreds of them occur in areas where hydrocarbons are abundant, like Trinidad or Azerbaijan (see this one in the Image Gallery). Under the sea, thousands of them occur near subduction trenches, where serpentinite mud is abundant (about serpentinization).
Another newly discovered form of volcanism involves asphalt. Asphalt flows were first documented on the floor of the Gulf of Mexico in 2003. No one knows how many of these tar volcanoes there are.A few more references: Supercritical water and Hydrothermal Chimneys
Carbon Degassing from the Lithosphere [and upper mantle]
2 comments:
I don't think that anybody disagrees that serpentine plays a major role in volatile circulation and state along the Moho. When -osphere is added, however, there is a different message - that a continuous layer of serpentine exists. I have to agree with a comment on the previous post - the existence of an -osphere is testable by seismic velocity, and there is evidence against it.
As to whether the authors of "The Serpentosphere" are trying to imply a continuous layer of serpentine minerals or are trying to facilitate a discussion about a concept with their use of a - *gasp* - new word, it is now quite easy to contact two of the authors from links on this post to find out, if one is really interested.
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