The main objective of this study is to reconstruct surface water dynamics occurring along the Western Iberian Margin (WIM) relating them to the position of the Subpolar Front and to the dynamics affecting the Subtropical gyre. The study, centred on changes in calcareous nannoplankton paleo-assemblages at IODP Site U1385 (37°34.285′N; 10°7.562′W), allows to reconstruct the regional surface water circulation patterns, as well as the surface paleoproductivity fluctuations and the water column stratification between ̴ 25 and 0 ka. Abrupt changes in calcareous nannoplankton paleo-assemblages occurr at the transition from glacial to interglacial conditions. The glacial conditions (25.3–11.5 ka) are characterized by dominance, of cold calcareous nannoplankton species, suggesting prevalent Portugal Current (PC) influence and a shift southward of the Intertropical Convergence Zone (ITCZ), as consequence of Northern Hemisphere (NH) insolation minima. Whereas opposite conditions verified during the interglacial interval (11.5–0.84 ka), favour the proliferation of warm species because of a strong Iberian Poleward Current (IPC) influence in the entire area. The Last Glacial Maximum (LGM) is characterized by a moderate productivity together with a decreasing mixing and the establishment of a medium-deep nutricline. Subpolar and Subtropical Fronts migration southward during Heinrich stadial 1 (HS1) show low productivity conditions and a water column stratification. The Bølling/Allerød (B/A) is characterized by the northward extension of the Subtropical gyre favouring an increasing productivity that decreases during the Younger Dryas stadial (YD). The latter is characterized by a general cooling although less pronounced of that recorded for HS1. During the entire period, other than the major abundance of warm taxa suggesting a general prevalence of the IPC, a variable productivity and a water column stratification in particular at the beginning of the Holocene is shown.

Reconstructing ocean surface dynamics over the last ̴ 25 kyr at “Shackleton Site” IODP - U1385

Argenio C.;Amore F. O.
2021

Abstract

The main objective of this study is to reconstruct surface water dynamics occurring along the Western Iberian Margin (WIM) relating them to the position of the Subpolar Front and to the dynamics affecting the Subtropical gyre. The study, centred on changes in calcareous nannoplankton paleo-assemblages at IODP Site U1385 (37°34.285′N; 10°7.562′W), allows to reconstruct the regional surface water circulation patterns, as well as the surface paleoproductivity fluctuations and the water column stratification between ̴ 25 and 0 ka. Abrupt changes in calcareous nannoplankton paleo-assemblages occurr at the transition from glacial to interglacial conditions. The glacial conditions (25.3–11.5 ka) are characterized by dominance, of cold calcareous nannoplankton species, suggesting prevalent Portugal Current (PC) influence and a shift southward of the Intertropical Convergence Zone (ITCZ), as consequence of Northern Hemisphere (NH) insolation minima. Whereas opposite conditions verified during the interglacial interval (11.5–0.84 ka), favour the proliferation of warm species because of a strong Iberian Poleward Current (IPC) influence in the entire area. The Last Glacial Maximum (LGM) is characterized by a moderate productivity together with a decreasing mixing and the establishment of a medium-deep nutricline. Subpolar and Subtropical Fronts migration southward during Heinrich stadial 1 (HS1) show low productivity conditions and a water column stratification. The Bølling/Allerød (B/A) is characterized by the northward extension of the Subtropical gyre favouring an increasing productivity that decreases during the Younger Dryas stadial (YD). The latter is characterized by a general cooling although less pronounced of that recorded for HS1. During the entire period, other than the major abundance of warm taxa suggesting a general prevalence of the IPC, a variable productivity and a water column stratification in particular at the beginning of the Holocene is shown.
Calcareous nannofossils
Late Pleistocene-Holocene
MIS 1–2
Western Iberian margin
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12070/52375
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