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J.A. Barron

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During the late Neogene, North Pacific diatom sedimentation underwent major changes in response to high-latitude cooling and changes in surface and deep water circulation. At 9 Ma diatom mass accumulation rates (MARs) increased in the NW Pacific and off northeast Japan, possibly due to shoaling of the Isthmus of Panama, which lead to an enrichment of nutrients in North Pacific deep waters. During the latest Miocene, diatom MARs increased progressively off southern California (6.5 Ma), at high latitudes of the North Pacific (6.2 Ma), and off northeastern Japan (5.5 Ma), presumably in response to high latitude cooling. At about 4.5 Ma diatom sedimentation abruptly increased in the NW Pacific but declined off Japan...
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Age determinations are reported for microfossils from 56 dart-cores collected in 1978 from the Kodiak shelf. The ages suggest that rocks cropping out along Albatross Bank, at the shelf edge, are as old as middle or late Miocene, and that the anticline forming Albatross Bank, previously defined with multi- and single-channel seismic records, plunges northeastward in the sampled area. Foraminiferal paleobathymetry further suggests that m.ajor tectonic activity has occurred on the Kodiak shelf since the early or middle Pliocene, including two episodes of vertical movement--first subsidence on the order of 2000 m, then uplift of at least 3000 m. Microfossil ages and paleobathymetric determinations indicate an average...
Categories: Publication; Types: Citation; Tags: Open-File Report
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Pacific climate is known to have varied during the Holocene, but spatial patterns remain poorly defined. This paper compiles terrestrial and marine proxy data from sites along the northeastern Pacific margins and proposes that they indicate 1) suppressed ENSO conditions during the middle Holocene between ~8000 and 4000 cal BP with a North Pacific that generally resembled a La Ni??a-like or more negative PDO phase and 2) a climate transition between ~4200 and 3000 cal BP that appears to be the teleconnected expression to a more modern-like ENSO Pacific. Compared to modern day conditions, the compiled data suggest that during the middle Holocene, the Aleutian Low was generally weaker during the winter and/or located...
Categories: Publication; Types: Citation; Tags: Quaternary International
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