Accumulation of biogenic and lithogenic material in the Pacific sector of the Southern Ocean during the past 40,000 years

Publication Type  Journal Article
Year of Publication  2003
Authors  Chase, Z.; Anderson, R. F.; Fleisher, M. Q.; Kubik, P. W.
Journal Title  Deep-Sea Research Part Ii-Topical Studies in Oceanography
Volume  50
Issue  3-4
Pages  799-832
ISBN Number  0967-0645
Accession Number  ISI:000181922700014
Key Words  last-glacial-maximum; antarctic circumpolar current; atmospheric co2; marine-sediments; deep-sea; biological productivity; terrigenous sediment; interglacial changes; pa-231/th-230 ratio; atlantic sector
Abstract  

The Th-230-normalization technique was applied to surface sediments and down-core records from the Pacific sector of the Southern Ocean between 120degreesW and 170degreesW in order to reconstruct vertical rain rates, corrected for lateral redistribution of sediment. Preserved rain rates of opal, organic carbon and biogenic Ba all indicate that biological productivity south of the Antarctic Polar Front (APF) was much lower than today during the Last Glacial Maximum (LGM), probably in response to increased ice cover. However, by analogy with modern opal fluxes south of the ACC, we show that year-round ice cover is not a prerequisite for very low rates of opal accumulation. Available records from north of the APF indicate little to no change in opal export, in contrast to records from the Indian and Atlantic sectors, which show enhanced opal export north of the APF during the LGM. Glacial records from north of 66degreesS in the Pacific all show lithogenic fluxes that were greater than today, but significantly lower than lithogenic fluxes in the glacial Atlantic and Indian sectors. Together, these new records from the Pacific sector show that during the LGM the three basins of the Southern Ocean were significantly more differentiated than today. The observed inter-basin distribution of lithogenic fluxes and opal burial, and the presumed geographical distribution of increased dust input to the Southern Ocean during the LGM, are consistent with an Atlantic-Indian-Pacific gradient in the degree of iron-stimulated diatom productivity within the zone lying between the APF and the Subantarctic Front. Previous studies, which focused primarily on the Atlantic sector, may have overestimated the glacial increase in the strength of the biological pump in the Southern Ocean. (C) 2002 Elsevier Science Ltd. All rights reserved.

Notes  

662AGTimes Cited:32Cited References Count:86

URL  <Go to ISI>://000181922700014
DOI  Pii S0967-0645(02)00595-7