TOC, carbonate, opal composition and trace element concentration from ODP Holes 175-1082A and 175-1084A
Distinctive light-dark color cycles in sediment beneath the Benguela Current Upwelling System indicate repetitive alternations in sediment delivery and deposition. Geochemical proxies for paleoproductivity and for depositional conditions were employed to investigate the paleoceanographic processes i...
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ftpangaea:oai:pangaea.de:doi:10.1594/PANGAEA.744049 2024-09-15T18:36:30+00:00 TOC, carbonate, opal composition and trace element concentration from ODP Holes 175-1082A and 175-1084A Robinson, Rebecca S Meyers, Philip A Murray, Richard W MEDIAN LATITUDE: -23.303910 * MEDIAN LONGITUDE: 12.424175 * SOUTH-BOUND LATITUDE: -25.513880 * WEST-BOUND LONGITUDE: 11.820580 * NORTH-BOUND LATITUDE: -21.093940 * EAST-BOUND LONGITUDE: 13.027770 * DATE/TIME START: 1997-09-13T04:45:00 * DATE/TIME END: 1997-09-24T03:15:00 2002 application/zip, 2 datasets https://doi.pangaea.de/10.1594/PANGAEA.744049 https://doi.org/10.1594/PANGAEA.744049 en eng PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.744049 https://doi.org/10.1594/PANGAEA.744049 CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess Supplement to: Robinson, Rebecca S; Meyers, Philip A; Murray, Richard W (2002): Geochemical evidence for variations in delivery and deposition of sediment in Pleistocene light-dark color cycles under the Benguela Current Upwelling System. Marine Geology, 180(1-4), 249-270, https://doi.org/10.1016/S0025-3227(01)00217-1 175-1082A 175-1084A Benguela Current South Atlantic Ocean DRILL Drilling/drill rig Joides Resolution Leg175 Ocean Drilling Program ODP dataset publication series 2002 ftpangaea https://doi.org/10.1594/PANGAEA.74404910.1016/S0025-3227(01)00217-1 2024-07-24T02:31:20Z Distinctive light-dark color cycles in sediment beneath the Benguela Current Upwelling System indicate repetitive alternations in sediment delivery and deposition. Geochemical proxies for paleoproductivity and for depositional conditions were employed to investigate the paleoceanographic processes involved in creating these cycles in three mid-Pleistocene intervals from ODP Sites 1082 and 1084. Concentrations of total organic carbon (TOC) vary between 3.5 and 17.1%. Concentrations of CaCO3 vary inversely to TOC and Al, which suggests that both carbonate dissolution and terrigenous dilution contribute to the light-dark cycles. Opal concentrations are independent of both TOC and CaCO3, therefore eliminating diatom production and lateral transport of shelf material as causes of the light-dark cycles. d13Corg and d15Ntot values do not vary across light-dark sediment intervals, implying that the extent of relative nutrient utilization did not change. The stable d15Ntot values represent a balanced change in nitrate supply and export production and therefore indicate that productivity was elevated during deposition of the TOC-rich layers. Parallel changes in concentrations of indicator trace elements and TOC imply that changes in organic matter delivery influenced geochemical processes on the seafloor by controlling consumption of pore water oxygen. Cu, Ni, and Zn are enriched in the darker sediment as a consequence of greater organic matter delivery. Redox-sensitive metals vary due to loss (Mn and Ba) or enrichment (Mo) under reducing conditions created by TOC oxidation. Organic matter delivery impacts subsequent geochemical changes such as carbonate dissolution, sulfate reduction and the concentration of metals. Thus, export production is considered ultimately responsible for the generation of the color cycles. Other/Unknown Material South Atlantic Ocean PANGAEA - Data Publisher for Earth & Environmental Science ENVELOPE(11.820580,13.027770,-21.093940,-25.513880) |
institution |
Open Polar |
collection |
PANGAEA - Data Publisher for Earth & Environmental Science |
op_collection_id |
ftpangaea |
language |
English |
topic |
175-1082A 175-1084A Benguela Current South Atlantic Ocean DRILL Drilling/drill rig Joides Resolution Leg175 Ocean Drilling Program ODP |
spellingShingle |
175-1082A 175-1084A Benguela Current South Atlantic Ocean DRILL Drilling/drill rig Joides Resolution Leg175 Ocean Drilling Program ODP Robinson, Rebecca S Meyers, Philip A Murray, Richard W TOC, carbonate, opal composition and trace element concentration from ODP Holes 175-1082A and 175-1084A |
topic_facet |
175-1082A 175-1084A Benguela Current South Atlantic Ocean DRILL Drilling/drill rig Joides Resolution Leg175 Ocean Drilling Program ODP |
description |
Distinctive light-dark color cycles in sediment beneath the Benguela Current Upwelling System indicate repetitive alternations in sediment delivery and deposition. Geochemical proxies for paleoproductivity and for depositional conditions were employed to investigate the paleoceanographic processes involved in creating these cycles in three mid-Pleistocene intervals from ODP Sites 1082 and 1084. Concentrations of total organic carbon (TOC) vary between 3.5 and 17.1%. Concentrations of CaCO3 vary inversely to TOC and Al, which suggests that both carbonate dissolution and terrigenous dilution contribute to the light-dark cycles. Opal concentrations are independent of both TOC and CaCO3, therefore eliminating diatom production and lateral transport of shelf material as causes of the light-dark cycles. d13Corg and d15Ntot values do not vary across light-dark sediment intervals, implying that the extent of relative nutrient utilization did not change. The stable d15Ntot values represent a balanced change in nitrate supply and export production and therefore indicate that productivity was elevated during deposition of the TOC-rich layers. Parallel changes in concentrations of indicator trace elements and TOC imply that changes in organic matter delivery influenced geochemical processes on the seafloor by controlling consumption of pore water oxygen. Cu, Ni, and Zn are enriched in the darker sediment as a consequence of greater organic matter delivery. Redox-sensitive metals vary due to loss (Mn and Ba) or enrichment (Mo) under reducing conditions created by TOC oxidation. Organic matter delivery impacts subsequent geochemical changes such as carbonate dissolution, sulfate reduction and the concentration of metals. Thus, export production is considered ultimately responsible for the generation of the color cycles. |
format |
Other/Unknown Material |
author |
Robinson, Rebecca S Meyers, Philip A Murray, Richard W |
author_facet |
Robinson, Rebecca S Meyers, Philip A Murray, Richard W |
author_sort |
Robinson, Rebecca S |
title |
TOC, carbonate, opal composition and trace element concentration from ODP Holes 175-1082A and 175-1084A |
title_short |
TOC, carbonate, opal composition and trace element concentration from ODP Holes 175-1082A and 175-1084A |
title_full |
TOC, carbonate, opal composition and trace element concentration from ODP Holes 175-1082A and 175-1084A |
title_fullStr |
TOC, carbonate, opal composition and trace element concentration from ODP Holes 175-1082A and 175-1084A |
title_full_unstemmed |
TOC, carbonate, opal composition and trace element concentration from ODP Holes 175-1082A and 175-1084A |
title_sort |
toc, carbonate, opal composition and trace element concentration from odp holes 175-1082a and 175-1084a |
publisher |
PANGAEA |
publishDate |
2002 |
url |
https://doi.pangaea.de/10.1594/PANGAEA.744049 https://doi.org/10.1594/PANGAEA.744049 |
op_coverage |
MEDIAN LATITUDE: -23.303910 * MEDIAN LONGITUDE: 12.424175 * SOUTH-BOUND LATITUDE: -25.513880 * WEST-BOUND LONGITUDE: 11.820580 * NORTH-BOUND LATITUDE: -21.093940 * EAST-BOUND LONGITUDE: 13.027770 * DATE/TIME START: 1997-09-13T04:45:00 * DATE/TIME END: 1997-09-24T03:15:00 |
long_lat |
ENVELOPE(11.820580,13.027770,-21.093940,-25.513880) |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
Supplement to: Robinson, Rebecca S; Meyers, Philip A; Murray, Richard W (2002): Geochemical evidence for variations in delivery and deposition of sediment in Pleistocene light-dark color cycles under the Benguela Current Upwelling System. Marine Geology, 180(1-4), 249-270, https://doi.org/10.1016/S0025-3227(01)00217-1 |
op_relation |
https://doi.pangaea.de/10.1594/PANGAEA.744049 https://doi.org/10.1594/PANGAEA.744049 |
op_rights |
CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1594/PANGAEA.74404910.1016/S0025-3227(01)00217-1 |
_version_ |
1810480169354264576 |