TELECONNECTIONS DURING THE LAST 60 KYR: GREENLAND ICE/PRODUCTIVITY AND ANOXIA ON THE MARGINS OF ALTA AND BAJA CALIFORNIA AND IN THE CARIACO BASIN

Correlation of millennial-scale anoxic events in the Santa Barbara Basin with interstadial events recorded in the oxygen-isotope composition of Greenland ice (Dansgaard-Oeschger, DO, cycles) has been well documented for oxygen isotope stage 3 (OIS3; 60-24 cal ka), the Bölling/Alleröd warm interval (B/A; 15-13 cal ka), and the Holocene. This correlation has been extended to the open Alta California margin based on multiple proxies. We report a similar correlation between Greenland DO cycles and low bottom-water oxygen (BWO) conditions on the southern Baja California margin indicated by the presence of laminated sediments with high concentrations and mass accumulation rates (MARs) of organic carbon (OC) during the last 60 kyr. Trace-element proxies for anoxia and productivity, namely elevated concentrations and MARs of molybdenum and cadmium in these same laminated sediments suggest that productivity may be more important than ventilation in producing changes in BWO conditions on open, highly productive continental margins. A similar conclusion based on trace-element data applies to the Alta California margin for OIS3 and the B/A, but not the Holocene. The main conclusion from these proxies is that during the last glacial interval (LGI; 24-15 cal ka) productivity was lower and bottom-water oxygen levels were higher than during OIS3 and the Holocene on all margins of the Californias. The OC and trace-element profiles in the LGI-Holocene transition in the Cariaco Basin on the margin of northern Venezuela are remarkably similar to those in the transition on the northern Alta California margin. Synchronous climate-driven changes as recorded in the sediments on the margins of the Californias and from the Cariaco Basin with those recorded in Greenland ice support the hypothesis that changes in atmospheric dynamics played a major role in abrupt climate change during the last 60 kyr.