This award supports cooperative research in geology and geochemistry between Dr. John F. Lewis of George Washington University and co-investigators in the Dominican Republic Ing. Salvador Brouwer of Falconbridge Dominicana and Dr. Richard Moore of Falconbridge Ltd., Canada. A unique opportunity exists to make a detailed study of the Maimon Formation, a unit of metamorphosed volcanic and minor sedimentary rocks of apparent Late Jurassic or Early Cretaceous age located in the Median Belt of the Dominican Republic. This study will be directed towards (1) an understanding of the early tectonic position of the Maimon-Amina Formations in the evolution of Hispaniola, (2) magmatic affinities of the Maimon-Amina volcanic rocks and studies of their metamorphism and alteration, (3) the genesis of the exhalative volcanogenic massive sulfides within the Maimon Formation. The program will involve mapping, detailed petrographic work, detailed structural analysis, an extensive program of major and trace element geochemical analyses of rocks, age dating and isotopic geochemistry of rocks and sulfides. The program provides the stimulus and opportunity for well- trained Dominican geologists to participate at a level of scientific work not normally available to them. The work also provides for the training of U.S. graduate students. Dominican students participate as field assistants giving them the opportunity to learn and practice good techniques. This type of research provides for the rapid exchange and dissemination of knowledge. In these ways, the project will fulfill the goals of the Science in Developing Countries Program.