Changes in diatom productivity and upwelling intensity off Peru since the Last Glacial Maximum: Response to basin-scale atmospheric and oceanic forcing
Doering, K.; Erdem, Z.; Ehlert, C.; Fleury, S.; Frank, M.; Schneider, R. (2016). Changes in diatom productivity and upwelling intensity off Peru since the Last Glacial Maximum: Response to basin-scale atmospheric and oceanic forcing. Paleoceanography 31: 1453–1473. dx.doi.org/10.1002/2016PA002936 In: Paleoceanography. American Geophysical Union: Washington, DC. ISSN 0883-8305; e-ISSN 1944-9186, more |   |
| Authors | | Top | - Doering, K.
- Erdem, Z., more
- Ehlert, C.
| - Fleury, S.
- Frank, M.
- Schneider, R.
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| Abstract | New records of stable silicon isotope signatures (δ30Si) together with concentrations of biogenicopal and organic carbon from the central (9°S) and northern (5°S) Peruvian margin reveal changes indiatom productivity and nutrient utilization during the past 20,000 years. The findings are based on a newapproach using the difference between the δ30Si signatures of small (11–32 μm) and large (>150 μm)diatom fractions (Δ30SiCoscino-bSi) in combination with the variance in diatom assemblages for reconstructionof past upwelling intensity. Combination of our records with two previously published records from thesouthern upwelling area off Peru (12–15°S) shows a general decoupling of the environmental conditions atthe central and southern shelf mainly caused by a northward shift of the main upwelling cell from its modernposition (12–15°S) toward 9°S during Termination 1. At this time only moderate upwelling intensity andproductivity levels prevailed between 9°S and 12°S interpreted by a more northerly position of SouthernWesterly Winds and the South Pacific Subtropical High. Furthermore, a marked decrease in productivity at12–15°S during Heinrich Stadial 1 coincided with enhanced biogenic opal production in the EasternEquatorial Pacific, which was induced by a southward shift of the Intertropical Convergence Zone andenhanced northeasterly trade winds. Modern conditions were only established at the onset of the Holocene.Past changes in preformed δ30Si signatures of subsurface waters reaching the Peruvian Upwelling Systemdid not significantly affect the preserved δ30Si signatures. |
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