Pliocene sediment and silicon isotope record of ODP Site 145-882

• Main Authors: Bailey, Ian, Liu, Qingsong, Swann, George E A, Jiang, Zhaoxia, Sun, Youbin, Zhao, Xiang, Roberts, Andrew P
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2011
• Subjects: 145-882; 145-882A; COMPCORE; Composite Core; DRILL; Drilling/drill rig; Joides Resolution; Leg145; North Pacific Ocean; Ocean Drilling Program; ODP; Arctic; Magnetic susceptibility
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.772036; https://doi.org/10.1594/PANGAEA.772036

Increases in the low-field mass-specific magnetic susceptibility (chi), dropstones and the terrigenous sediment component from Ocean Drilling Program (ODP) Site 882 (~45°N) have been interpreted to indicate a major onset of ice-rafting to the sub-Arctic northwest Pacific Ocean during marine isotope stage (MIS) G6 (from ~2.75 Ma). In contrast, studies of the terrigenous content of sediments cored downwind of ODP Site 882 indicate that dust and disseminated volcanic ash deposition in the sub-Arctic Pacific increased markedly during MIS G6. To investigate the relative contribution of dust, volcanic ash and ice rafting to the Pliocene chi increase, we present new high-resolution environmental magnetic and ice-rafted debris records from ODP Sites 882 and 885. Our results demonstrate that the chi increase at both sites across MIS G6 is predominantly controlled by a previously overlooked mixture of aeolian dust and volcanic ash. Our findings call into question the reliability of chi as a proxy for ice-rafting to the North Pacific. They also highlight a previously undocumented link between iron fertilisation and biogeochemical cycling in the North Pacific at a key stage during intensification of late Pliocene northern hemisphere glaciation.