The Active Yakutat （Kula？） Plate and Its Southcentral Alaska Megathrust and Intraplate Earthquakes  

作　　者：John W. Reeder 

机构地区：[1]Terra International, 6005 Calle Maggioni, Cannaregio, Venice 30121, Italy

出　　处：《Journal of Earth Science and Engineering》2016年第1期18-58,共41页地球科学与工程（英文版）

摘　　要：Alaska geology and plate tectonics have not been well understood due to an active Yakutat plate, believed to be part of the remains of an ancient Kula plate, not being acknowledged to exist in Alaska. It is positioned throughout most of southcentral Alaska beneath the North American plate and above the NNW subducting Pacific plate. The Kula？ plate and its eastern spreading ridge were partially ＂captured＂ by the North American plate in the Paleocene. Between 63 Ma and 32 Ma, large volumes of volcanics erupted from its subducted N-S striking spreading ridge through a slab window. The eruptions stopped at 32 Ma, likely due to the Pacific plate fiat-slab subducting from the south beneath this spreading ridge. At 28 Ma, magmatism started again to the east; indicating a major shift to the east of this ＂refusing to die＂ spreading ridge. The captured Yakutat plate has also been subducting since 63 Ma to the WSW. It started to change to WSW fiat-slab subduction at 32 Ma, which stopped all subduction magmatism in W and SW Alaska by 22 Ma. The Yakutat plate subduction has again increased with the impact/joining of the coastal Yakutat terrane from the ESE about 5 Ma, resulting in the Cook Inlet Quaternary volcanism of southcentral Alaska. During the 1964 Alaska earthquake, sudden movements along the southcentral Alaska thrust faults between the Yakutat plate and the Pacific plate occurred. Specifically, the movements consisted of the Pacific plate moving NNW under the buried Yakutat plate and of the coastal Yakutat terrane, which is considered part of the Yakutat plate, thrusting WSW onto the Pacific plate. These were the two main sources of energy release for the E part of this earthquake. Only limited movement between the Yakutat plate and the North American plate occurred during this 1964 earthquake event. Buried paleopeat age dates indicate the thrust boundary between the Yakutat plate and North American plate will move in about 230 years, resulting in a more ＂continental＂ type megathrust earthquake for sou

关 键 词：1964 Alaska earthquake oceanic and continental types of megathrust earthquakes WSW subducting Yakutat plate large active WSW striking slice faults Alaska geology and tectonics oil and gas resources. 

分 类 号：P583[天文地球—岩石学] P315.2[天文地球—地质学]