@phdthesis{oai:nagoya.repo.nii.ac.jp:00005083,
 author = {Asahara, Yoshihiro and 淺原, 良浩},
 month = {Sep},
 note = {Temporal variations of Sr isotopic compositions in the detrital component of north Pacific sediments have been precisely examined. The Sr isotopic composition is controlled by the flux of eolian material from the Asian continent with a high 87Sr/86Sr ratio (0.724 - 0.726) relative to volcanic material with a low ratio (0.703 - 0.705) from the Izu-Ogasawara-Mariana arc and oceanic islands such as Hawaiian Islands. Assuming that the volcanic flux is constant, the temporal variation in Sr isotopic ratio reflects the amount of eolian input from the continent. The major characteristics of the temporal variations and the interpretation of them are summarized as follows: (1) The 87Sr/86Sr records show cyclic fluctuations of 400 ky and 100 ky periodicities which are associated with the eccentricity of the earth's orbit (Milankovitch Cycle). (2) Between 3 and 0.8 Ma, the 87Sr/86Sr ratio in the north central Pacific sediment increases gradually. This reflects an increased eolian input from the arid region in east Asia. The increase must be related to aridification of the Asian continent. (3) The decreased 87Sr/86Sr ratio during the past 0.8 my implies a decreased eolian input. The age of 0.8 Ma may relate to the climatic event Known as the middle Pleistocene shift. All of these phenomena reflect a fluctuation of the eolian flux corresponding to the paleoclimatic cycle of aridity in the Asian continent. The Sr isotopic composition of pelagic sediment in the north Pacific is sensitive to changes in the eolian input reflecting to the aridity of the Asian continent. keywords: 87Sr/86Sr; Pacific sediment; Milankovitch Cycle; Asian loess; paleoclimate, 名古屋大学博士学位論文 学位の種類:博士(理学) (論文) 学位授与年月日:平成11年9月30日},
 school = {名古屋大学, Nagoya University},
 title = {[87]Sr/[86]Sr variation in north Pacific sediments: A record of the Milankovitch Cycle in the past 3 million years},
 year = {1999}
}