Previous   |   Next

doi:10.2204/iodp.proc.323.110.2011

Description of basement volcanic sequences in Holes U1342A and U1342D on Bowers Ridge in the Bering Sea¹

H. Kawabata,² K. Sato,² Y. Tatsumi,² D.W. Scholl,^{3, 4} K. Takahashi,⁵ and the Expedition 323 Scientists⁶

Abstract

At Ulm Plateau, near the eastern end of the crestal area of Bowers Ridge, basement of lithified volcaniclastic sediment (~42 m) was recovered at Integrated Ocean Drilling Program (IODP) Site U1342 beneath a thin cover (~49 m) of surface sediment. Recovery of basement rock provided an unprecedented opportunity to address the origin and evolution of this enigmatic appendage of the Aleutian arc massif. Contrasting hypotheses have been proposed for the formation of the arc massif of Bowers Ridge, either in the Cretaceous North Pacific Ocean exotic to the Bering Sea or within the Bering Sea during the Eocene formation of the Aleutian arc.

The volcanic sequence recovered from Site U1342 was divided into six major lithologic units: Unit I, vesiculated andesitic lava flow; Unit II, interbedded volcanic sandstone and polymict volcanic conglomerate; Unit III, monomict volcanic conglomerate; Unit IV, interbedded volcanic sandstone and polymict volcanic conglomerate; Unit V, monomict volcanic conglomerate; and Unit VI, polymict volcanic conglomerate. Units III and IV represent hydroclastic volcaniclastic deposits, whereas Units II, IV, and VI are epiclastic volcaniclastic strata.

¹Kawabata, H., Sato, K., Tatsumi, Y., Scholl, D.W., Takahashi, K., and the Expedition 323 Scientists, 2011. Description of basement volcanic sequences in Holes U1342A and U1342D on Bowers Ridge in the Bering Sea. In Takahashi, K., Ravelo, A.C., Alvarez Zarikian, C.A., and the Expedition 323 Scientists, Proc. IODP, 323: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.323.110.2011

²Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan. Correspondence author: hiroshik@jamstec.go.jp

³Department of Geology and Geophysics, University of Alaska Fairbanks, Fairbanks AK 99775, USA.

⁴Contact address: MS 999, U.S. Geological Survey, Menlo Park CA 90425, USA.

⁵Department of Earth and Planetary Sciences, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.

⁶Expedition 323 Scientists' addresses.

Publication: 15 March 2011
MS 323-110

Top of page   |   Previous   |   Next