Oceanography and productivity conditions on the Iberian margin: a 150 ky foraminifera record
The main objectives of this thesis were 1) to calibrate the first regional coastal upwelling transfer function for the western Iberian margin and 2) to investigate centennial- to millennial-scale hydrographic and productivity variations along this margin. To improve the knowledge on coastal upwellin...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Universität Bremen
2006
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| Online Access: | https://media.suub.uni-bremen.de/handle/elib/2303 https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000105386 |
| Summary: | The main objectives of this thesis were 1) to calibrate the first regional coastal upwelling transfer function for the western Iberian margin and 2) to investigate centennial- to millennial-scale hydrographic and productivity variations along this margin. To improve the knowledge on coastal upwelling areas like the western Iberian margin is of crucial social and economic importance. Upwelling regions act as high accumulation areas allowing high-resolution reconstructions of past climatic changes, and as sinks for CO2 and thus possible climate regulators.The Present day record and the past oceanographic and productivity conditions on the Iberian margin were investigated through a multi-proxy study (planktonic and benthic foraminifera abundances and stable isotopes, planktonic foraminifera associations, detrital grain abundance (IRD), grain size analysis, carbonate content) of surface sediments and sediment cores.The distribution of the most abundant planktonic foraminifera species on surface sediment samples (134) collected along the Iberian margin clearly mirror the specific hydrographic conditions in this area. Globigerina bulloides and Neogloboquadrina pachyderma (dextral) reflect the seasonal (May to September) coastal upwelling north and south of Lisbonà �à ´s latitude, respectively, evidencing the two sources of upwelled water: subpolar Eastern North Atlantic Central Water (ENACW) in the north, and subtropical ENACW in the south. However, Neogloboquadrina pachyderma (dextral) in association with Globorotalia inflata also seems to mark the descending branch of the North Atlantic Drift (Portugal Current). The tropical-subtropical species Globigerinoides ruber (white), Globigerinoides trilobus trilobus, and Globorotalia inflata are related to the winter-time eastern branch of the Azores Current (Portugal Coastal Countercurrent). This data set and an eighteen year integration of daily satellite SST were used to calibrate and define a regional transfer function, which was then used to compare the results from ... |
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