Abstract

Elevated productivity in the northwest Pacific is suggested as a new possible control driving past intervals of low-O2 intermediate water along the western continental margin of North America. According to this mechanism, O2 consumption would occur near the site of formation of North Pacific Intermediate Water (NPIW), due to increased respiration of organic carbon in response to a high-productivity event. Evidence is provided for such a productivity increase during the Bølling-Ållerød interval (14.7–12.9 ka), a time when laminated sediments were deposited along the northern California margin. By this mechanism, low-O2 events in intermediate waters off the western North American margin could occur without significant changes in the rate of NPIW ventilation.

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