Neogene Volcaniclastic Sediments from Atka Basin, Aleutian Ridge

摘要: Atka basin is a major depression in the Aleutian Terrace, south of Andreanof Islands chain (174°W). Sediments flooring were recovered at Site 186 Deep Sea Drilling Project on southern edge basin. Most sedimentary fill diatomaceous silty clay. Interbedded clay are numerous layers turbidite sand and vitric volcanic ash. The mostly volcanic-rock fragments glass, although some feldspar quartzose debris, including chert, present. sediment must have originated by erosion eruptions adjacent central arc. Neogene sedimentation rates exceeded 180 m/m.y. early Pliocene may been more than 300 These high caused extensive shelf perhaps associated with extensional rifting volcanism late Miocene Pliocene. sediments structurally temporally part "late series" Ridge probably representative vast volumes Tertiary debris that has accumulated ridge parts Bering Sea. reactive nature suggests other basins along not be particularly favorable locations for hydrocarbon accumulation.