- Economic Geology
Explosive Subaqueous Volcanism. James D.L. White, John L. Smellie, and David A. Clague, Editors. 379 Pp. American Geophysical Union Geophysical Monograph 140. 2003. Price $90.00; members $63.00.
In the first sentence of the introductory chapter to this book, the editors state that "the role of explosive subaqueous eruptions has long been considered unimportant." This chapter and the remainder of the book then go on to reassess this statement, concluding that explosive subaqueous volcanism is, in fact, an important process, with the possibility that "a quarter of the earth’s explosive activity occurs under water." These conclusions have become possible only because deep-sea submersibles have given volcanologists access to underwater, active volcanic provinces, in a similar manner to the way this technology has given economic geologists access to submarine black smokers. Although a deep submarine explosive volcanic event has not yet been directly witnessed, examination of the products of such events suggests that explosive volcanisms can occur in water depths as great as 4,300 m.
Why should economic geologists be concerned about the importance of subaqueous explosive volcanism? A large part of our resources of copper, zinc, lead, silver, and gold are closely tied to volcanism, and many of these resources form underwater. The most obvious examples of deposits formed in submarine volcanic provinces are volcanic-hosted massive sulfide (VHMS) deposits. However, it is likely that some deposits in the porphyry-epithermal mineral system also formed underwater.
Although the main intent of this book is to document environments, processes, and products of explosive subaqueous volcanism, several papers explicitly address the economic significance of such eruptions. After the introduction, the book is divided into six sections covering (1) subaqueous eruption dynamics, (2) explosive eruptions in the modern deep sea, (3) explosive shallow-marine (Surtseyan) eruptions and their kin, (4) pumiceous subsea silicic eruptions from the modern …