Holocene millennial‐scale productivity variations in the Sicily Channel (Mediterranean Sea)

Abstract

[1] The calcareous nannofossil assemblages of Ocean Drilling Program Hole 963D from the central Mediterranean Sea have been investigated to document oceanographic changes in surface waters. The studied site is located in an area sensitive to large-scale atmospheric and climatic systems and to high-and low-latitude climate connection. It is characterized by a high sedimentation rate (the achieved mean sampling resolution is <70 years) that allowed the Sicily Channel environmental changes to be examined in great detail over the last 12 ka BP. We focused on the species Florisphaera profunda that lives in the lower photic zone. Its distribution pattern shows repeated abundance fluctuations of about 10-15%. Such variations could be related to different primary production levels, given that the study of the distribution of this species on the Sicily Channel seafloor demonstrates the significant correlation to productivity changes as provided by satellite imagery. Productivity variations were quantitatively estimated and were interpreted on the basis of the relocation of the nutricline within the photic zone, led by the dynamics of the summer thermocline. Productivity changes were compared with oceanographic, atmospheric, and cosmogenic nuclide proxies. The good match with Holocene master records, as with ice-rafted detritus in the subpolar North Atlantic, and the near-1500-year periodicity suggest that the Sicily Channel environment responded to worldwide climate anomalies. Enhanced Northern Hemisphere atmospheric circulation, which has been reported as one of the most important forcing mechanisms for Holocene coolings in previous Mediterranean studies, had a remarkable impact on the water column dynamics of the Sicily Channel.

Orbital variations in planktonic foraminifera assemblages from the Ionian Sea during the Middle Pleistocene Transition

“…Teleconnection phenomena between the Mediterranean and the Greenland/North Atlantic region are documented for the late Quaternary (e.g. Rohling et al, 1998;Cacho et al, 1999;Sbaffi et al, 2001;Rohling et al, 2002b;Sprovieri et al, 2003;Martrat et al, 2004;Pérez-Folgado et al, 2004;Sprovieri et al, 2006;Incarbona et al, 2008a). This connection has been explained by variations in North Atlantic Deep Water formation rate, as modelling experiments suggest that this mechanism is able to cause coherent temperature changes in the two regions (e.g.…”

“…Lourens et al, 1996;Martrat et al, 2004;Sprovieri et al, 2006;Incarbona et al, 2008a). The Mediterranean basin climate is characterized by global scale connections.…”

Ten Years of Paleoceanographic Studies at ODP Site 963 (Central Mediterranean Sea)

“…The chronological framework here presented follows Sprovieri et al [14] for the MIS 5 interval (130-70 kiloyears ago -ka), Sprovieri et al [16] for the last glacial (70-20 ka) and Incarbona et al [15] for the Holocene (11.6-0 ka). The age model is complemented by the correlation between the planktonic foraminifera paleoclimatic curve from data of Sprovieri et al [13] and the Greenland ice core 18 O curve [50] along the last deglaciation, thus including the BollingAllerød and the Younger Dryas base.…”

“…Calcareous nannofossil analysis was carried out on 1121 samples [13][14][15][16][37][38][39] by observation with a polarized microscope at about 1250 X magnification. Rippled smear slides were prepared following the standard procedure [40].…”

“…This area is nowadays very sensitive to modifications in the Mediterranean thermohaline circulation [11,12] and, for many reasons, suitable for paleoceanographic research: the very high-sedimentation rate of Site 963, specifically between 18.0 and 50.0 cm/kyr over the last 130 kyr [13][14][15][16]; the flow of Levantine Intermediate Water (LIW) at the sea floor, a key water mass for understanding Mediterranean oceanographic dynamics; the middle-latitude location, suitable to provide information on the interaction among different climatic systems.…”