Geology and tectonic evolution of Alaska

Abstract The last major synthesis of the geology of Alaska was Areal Geology of Alaska (P. S. Smith, 1939, U.S. Geological Survey Professional Paper 192). Up to that time, less than half of what was then the Territory of Alaska had been surveyed by geologists, even by the crudest exploratory standards. As a consequence, Professional Paper 192 was concerned primarily with the general spatial distribution, lithology, and relative ages of rock units and Quaternary deposits in Alaska with incidental mention of structure, metallic mineral deposits, and coal resources. Since 1939 there has been a vast increase in the amount and diversity of earth science research in Alaska. The initial impetus was during World War II when expanded studies of mineral resources, surficial deposits, and Aleutian Arc volcanoes were undertaken throughout Alaska. In the post-war years there has been an explosive expansion of geologic and geophysical mapping and research both onshore and offshore. This accelerated effort was spurred on by the emergence of Alaska as a major petroleum producer, by the discovery of major metallic mineral deposits at various localities in the state, and by the extensive systematic helicopter-supported mapping and resource appraisals that have been carried out mainly by government agencies as part of the requirements for Alaska land classifications. In addition, the great 1964 earthquake stimulated intense interest in neotectonic activity and geologic hazards state-wide. As a result of work since 1939, modern geophysical and geologic data are now available for much of Alaska, and few areas remain unexplored.