Planktonic foraminiferal assemblages were studied at high-resolution in core KC01B from the Ionian Sea. Quantitative analysis allowed us to distinguish the main climatic features and associated ...paleoceanographic changes, that occurred between Marine Isotopic Stages (MIS) 13 and 9 (~500–300ka).
MIS 12 and MIS 10 are characterized by relatively temperate conditions and an oligotrophic oceanographic regime in the early part and by colder conditions and nutrient supply in the sub-surface water masses in the upper part. During these intervals, small but distinct peaks of Neogloboquadrina pachyderma sinistral (sin) are detected at times of extremely negative values of the planktonic foraminifera paleoclimatic curve. Their co-occurrence with similar episodes in the Atlantic suggests that the climate in the Central Mediterranean was associated with north-Atlantic millennial-scale climate instability. MIS 11 and MIS 9 are dominated by surficial warm-water taxa. The climate optimum is reached in the middle part of each of these stages, as denoted by the presence of Globigerinoides sacculifer, and persists for approximately 20 and 6ka during MIS 11 and MIS 9 respectively. This warming is not constant but is characterized by three distinct intervals with elevated winter temperatures and/or weak winter mixing.
Distribution of Globigerina bulloides, Turborotalita quinqueloba and N. pachyderma dextral (dex) indicates that significant environmental changes occur across the transitions from glacial to interglacial MIS 12/MIS 11 (Termination V) and MIS 10/MIS 9 (Termination IV).
The studied record documents a close linkage between Mediterranean climate evolution and higher- and lower-latitude climate change throughout MIS 13–9.
•High-resolution Mid-Pleistocene climate reconstruction in the Central Mediterranean•Significant changes in temperature and productivity occurred during MISs 12 and 10.•The climatic optimum during MIS 11c shows three warmest phases.•T-V and T-IV are characterized by complex paleoceanographic changes.
Integrated data of calcareous plankton and benthic foraminifers from the pre-evaporitic interval of Trave section (Central Italy) allowed the reconstruction of surface and bottom-water conditions in ...the Central Mediterranean during the interval from 7.61 to 6.33
Ma, preceding the Messinian Salinity Crisis.
Our data point out a three-step paleoenvironmental evolution. During the first stage (7.61–7.02
Ma) benthic foraminiferal assemblages depict stable, well-oxygenated and ventilated bottom-water conditions, while the surface water records variable temperature and high nutrient conditions, probably associated with strong seasonality. The second stage (7.02–6.70
Ma) points to unfavourable bottom-water condition, triggered by deep-sea stagnation. This is witnessed by a significant decrease in oxygen concentration and biotic diversity, and by the presence of stress-tolerant taxa. A general warming of the surface water and a strongly stratified water column, characterized by an expanded mixed layer, are also recorded.
From 6.70
Ma onwards (third stage), a prominent change to more restricted, low-oxygenated, hypersaline conditions at the sea floor is testified by the total disappearance of deep-dwelling planktonic foraminifers and the increasing abundance of stress-tolerant species. Calcareous plankton reflects high instability of the surface water in terms of nutrients, temperature and salinity. During this stage the environmental deterioration reaches intermediate depths in the water column.
The initial change toward a step-wise isolation of the Central Mediterranean bottom-waters is probably related to a general warming, responsible for a first slowing-down of the vertical circulation, favouring stratification of surface and intermediate waters and stagnation of bottom-waters. This warming is related to the restricted connection between the Mediterranean Sea and the Atlantic Ocean, which occurred since 7.146
Ma.
In the Trave section, the isolation of bottom-waters most likely occurred at the same time as in other Mediterranean sections. However, due to the presence of a hiatus it cannot be excluded that it occurred with a delay of ~
100
kyr, probably related to the shallower paleodepth of the basin.
