This award will support Dr. Sager of Texas A & M university to participate in a study of the morphology, sediment history, and geochemistry of guyots which are located between the Japan Trench and the Hawaiian Islands. This area of the Pacific Ocean is known to be unique and is characterized by numerous seamount chains, atolls and guyot groups which began forming during a Cretaceous period of extensive volcanism. Data to be collected during a field program aboard the Thomas Washington include reflection seismic profiles, gravity and magnetics across individual guyots as well as sampling of these features. These data will be used to examine questions on the age sequences of volcanism, Cretaceous Pacific Plate motions, lithosphere flexuring and elastic/thermal thickness, geochemical affinities and mantle sources of volcanics, seamount paleolatitudes, thickness and internal stratigraphy of guyot reef caps, and the timing and causes of reef drowning. These data will be used to examine the hypothesis that the older northwest end of this "Darwin Belt" of seamount chains was underlain in Cretaceous times by the type of mantle and thin, hot lithosphere that now underlies the active, southeast part of the belt. This is a cooperative project involving scientist at Scripps Institution, Texas A & M University and the Massachusetts Institute of Technology. Data from this project will be important in planning future ocean drilling in this region.
