Age model, stable isotopes, major element proportions and endmember unmixing results from four western tropical Atlantic cores
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| Format: | Dataset Open Access |
| Langue: | en |
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PANGAEA
2014
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| _version_ | 1867171367064961024 |
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| author | Govin, Aline Chiessi, Cristiano Mazur Zabel, Matthias Sawakuchi, André Oliveira Heslop, David Hörner, Tanja Zhang, Yancheng Mulitza, Stefan |
| author_facet | Govin, Aline Chiessi, Cristiano Mazur Zabel, Matthias Sawakuchi, André Oliveira Heslop, David Hörner, Tanja Zhang, Yancheng Mulitza, Stefan |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | We investigate changes in the delivery and oceanic transport of Amazon sediments related to terrestrial climate variations over the last 250 ka. We present high-resolution geochemical records from four marine sediment cores located between 5 and 12° N along the northern South American margin. The Amazon River is the sole source of terrigenous material for sites at 5 and 9° N, while the core at 12° N receives a mixture of Amazon and Orinoco detrital particles. Using an endmember unmixing model, we estimated the relative proportions of Amazon Andean material ("%-Andes", at 5 and 9° N) and of Amazon material ("%-Amazon", at 12° N) within the terrigenous fraction. The %-Andes and %-Amazon records exhibit significant precessional variations over the last 250 ka that are more pronounced during interglacials in comparison to glacial periods. High %-Andes values observed during periods of high austral summer insolation reflect the increased delivery of suspended sediments by Andean tributaries and enhanced Amazonian precipitation, in agreement with western Amazonian speleothem records. Increased Amazonian rainfall reflects the intensification of the South American monsoon in response to enhanced land-ocean thermal gradient and moisture convergence. However, low %-Amazon values obtained at 12° N during the same periods seem to contradict the increased delivery of Amazon sediments. We propose that reorganizations in surface ocean currents modulate the northwestward transport of Amazon material. In agreement with published records, the seasonal North Brazil Current retroflection is intensified (or prolonged in duration) during cold substages of the last 250 ka (which correspond to intervals of high DJF or low JJA insolation) and deflects eastward the Amazon sediment and freshwater plume. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_831553 |
| institution | PANGAEA |
| language | en |
| publishDate | 2014 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Age model, stable isotopes, major element proportions and endmember unmixing results from four western tropical Atlantic cores Govin, Aline Chiessi, Cristiano Mazur Zabel, Matthias Sawakuchi, André Oliveira Heslop, David Hörner, Tanja Zhang, Yancheng Mulitza, Stefan Center for Marine Environmental Sciences; Integrierte Analyse zwischeneiszeitlicher Klimadynamik; INTERDYNAMIK; MARUM We investigate changes in the delivery and oceanic transport of Amazon sediments related to terrestrial climate variations over the last 250 ka. We present high-resolution geochemical records from four marine sediment cores located between 5 and 12° N along the northern South American margin. The Amazon River is the sole source of terrigenous material for sites at 5 and 9° N, while the core at 12° N receives a mixture of Amazon and Orinoco detrital particles. Using an endmember unmixing model, we estimated the relative proportions of Amazon Andean material ("%-Andes", at 5 and 9° N) and of Amazon material ("%-Amazon", at 12° N) within the terrigenous fraction. The %-Andes and %-Amazon records exhibit significant precessional variations over the last 250 ka that are more pronounced during interglacials in comparison to glacial periods. High %-Andes values observed during periods of high austral summer insolation reflect the increased delivery of suspended sediments by Andean tributaries and enhanced Amazonian precipitation, in agreement with western Amazonian speleothem records. Increased Amazonian rainfall reflects the intensification of the South American monsoon in response to enhanced land-ocean thermal gradient and moisture convergence. However, low %-Amazon values obtained at 12° N during the same periods seem to contradict the increased delivery of Amazon sediments. We propose that reorganizations in surface ocean currents modulate the northwestward transport of Amazon material. In agreement with published records, the seasonal North Brazil Current retroflection is intensified (or prolonged in duration) during cold substages of the last 250 ka (which correspond to intervals of high DJF or low JJA insolation) and deflects eastward the Amazon sediment and freshwater plume. |
| title | Age model, stable isotopes, major element proportions and endmember unmixing results from four western tropical Atlantic cores |
| topic | Center for Marine Environmental Sciences; Integrierte Analyse zwischeneiszeitlicher Klimadynamik; INTERDYNAMIK; MARUM |
| url | https://doi.org/10.1594/PANGAEA.831553 |