The Dansgaard-Oeschger cycles discovered in the up stream source region of the North Pacific Intermediate Water formation

Millennial-scale oceanographic oscillations were identified in the southern Okhotsk Sea based on high-resolution measurements of total organic carbon (TOC), C/N ratios, and biogenic opal, employing Core MD01-2412 (53 m) with the bottom age of 115 ka. The oscillations are linked with the Dansgaard-Oeschger (D-O) climatic cycles. Inadequate data existed in the source regions of the North Pacific Intermediate Water (NPIW) formation thus far. We report the first decisive documentation of the D-O cycles in the up stream source region of the NPIW, illustrating that the D-O cycles observed in the down stream regions (e.g., Santa Barbara Basin) due to expansion of the NPIW were in part governed by the climatic variations occurred in the Okhotsk Sea. Increases in TOC and C/N ratios reflect abrupt sea level rises associated with 14 interstadial events over the past 115 kyrs, attributing to the downward transport of eroded continental shelf sediments.