Volcanic ash deposits in the Gulf of Alaska and problems of correlation of deep-sea ash deposits

摘要: Abstract The study of sediment cores from the Gulf Alaska reveals occurrence three distinct ash layers or intervals abundant in volcanic ash. refractive index glass fragments upper layer is 1.485 ± 0.002. composed 95% with an approximate silica content 74%. Katmai eruption 1912 considered to be source which more widespread than previously described. middle dark brown and basaltic composition a 1.565. It occurs some areas as others, mixed non-volcanic sediment. physical properties, stratigraphic relationships suggest that this unit derived common but unknown source. lower ash, approximately andesitic composition, recorded two cores. age layer, determined by radiocarbon dating carbonate sediments above below inferred older 25,000 years. petrography these deposits discussed. Included are brief discussions deep-sea north Atlantic Ocean, Mediterranean Sea, Mexico equatorial Pacific Ocean (Worzel ash). Some famous eruptions historic record briefly reviewed such Tambora East Indies, Volcan Quizapu Chile, Hekla 1947 Iceland, Glacier Peak 6,700 years ago northern Cascades, U.S.A. problems correlation possible world-wide Worzel ( Ewing et al., 1959) cometary origin discounted.