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The Ring of Fire: Backarc Basins.

Nowhere on our planet is the nature of Earth's real estate in such jeopardy as along the "ring of fire" that defines the margin of the Pacific Ocean. In geologic terms, the ring of fire is characterized by two essential morphotectonic elementsdeep linear trenches and chains of active volcanoes. These features are manifestations of a fundamental planetary process, the convective stirring of hot material at depth; the trenches mark sites where cold slabs, making up Earth's outer shell, converge and one slab sinks beneath another, sliding back into the underlying hot material of Earth's lower mantle. The forces generated by the interactions at, and along, this zone of tectonic suturing produce destructive earthquakes. In addition, as the cold slab sinks into the hot mantle, it is heated and reacts in a variety of ways with the overlying hot mantle wedge to create molten material that buoyantly rises to create the volcanic arcs of the Pacific's fiery ring. Moreover, the temporal and spatial interplay of magmatism and tectonism along this dynamic interface often results in splitting of the volcanic arcs to form rift zones that, through continued extension, subside and lead to the creation of backarc basins. An inspection of the margins of the Pacific reveals an intricate assemblage of volcanic arcs and backarc basins that define a west-facing crescent from the Bering Sea southward through the Western Pacific. An inventory of areal dimensions, terrain architecture, and geologic history of the arc-backarc basin complexes exhibits considerable variation that appears to be age-dependent, suggesting an evolutionary progression. By careful documentation of the geological (distribution, age, and composition of rock bodies) and geophysical (velocity structure, distribution of mass, seismicity, kinematic history) properties of arc-backarc complexes, the evolutionary path (or paths) that these features follow can be resolved and a fundamental aspect of our dynamic planet understood. Backarc Basins is a compilation of 14 papers, each of which summarizes salient geological and geophysical characteristics of a particular backarc basin. As an ensemble it samples backarc basins in different stages of development ranging from the initial rifting phase through mature spreading. No other such compilation exists, and the timing of this one is excellent because in the last decade widespread utilization of swath bathymetry and sidescan imagery, multichannel seismics, manned submersibles and remotely operated vehicles, and deep ocean drilling in the backarc basins of the Pacific has created a wealth of information that has revolutionized our understanding of the dynamic processes occurring in these regions. The book is loaded with new data and observations that collectively provide important new insights into the subject. The backarc basins of the Pacific are natural laboratories where the interplay of magmatic and tectonic processes can be deciphered. Backarc basin processes are particularly significant because they are thought to have been instrumental in the growth and development of this planet's continents through geologic time, as well as the creation of ore deposits of economic importance. Backarc Basins should thus be of interest to Earth scientists with a diverse range of interest including marine geology and geophysics, global tectonics, Precambrian geology, and mineral resource prediction. Students of seafloor tectonics will be somewhat disappointed because the format of the volume does not permit the presentation of high-resolution seafloor imaging data at a scale large enough to retain the high-fidelity record of backarc basin tectonism. But this is a minor weakness when balanced against the strengths of this fine compilation. Paul J. Fox Ocean Drilling Program, Texas A&M University, College Station, TX 77845-9547, USA