Paleogeographic evolution of the United States Pacific Northwest during Paleogene time

摘要: Paleogeographic reconstructions for Oregon and Washington during Paleogene time illustrate a major transition from dominantly compressional (prior to middle Eocene time) an extensional tectonic regime. This resulted in the development of three phases basin evolution United States Pacific Northwest. During initial phase, basins formed along continental margin collision oceanic islands. Sediments these were derived nearby orogenic highlands. The second phase began consisted rapid subsidence individual that within broad forearc region. Nonmarine this caused by extension possibly associated with transcurrent faulting. Rapid sedimentation both marine nonmarine sandstone Cretaceous plutonic sources far east. final stage was modification ...