1 Ma paleoclimatic record from the Eastern Mediterranean - Marflux project: first results of a micropaleontological and sedimentological investigation of a long piston core from the Calabrian Ridge

Abstract

The main purpose of the paper is the reconstruction of the paleoclimatic record of the longest (37.04 m) deep-sea core so far recorded in the eastern Mediterranea sea. Core KC01B was raised from the Calabrian Ridge in the framework of the European MAST-Marflux Project. Quantitative calcium carbonate, grain size, planktonic foraminifer and calcareous nannofossil investigations were carried out on 337 samples (about 1 sample/10 cm) taken throughout the core (with the exception of the disturbed 231 uppermost cm). The core bottom has been dated at about 1100 ka, on the basis of the recognition of the Jaramillo magnetic event and the small Gephyrocapsa nannofossil Zone. The upward decreasing calcium carbonate content and average grain size, combined with the upward increasing sedimentation rate, witness the much higher clay mineral supply characterizing the upper 10-12 m of the core. The study of planktonic foraminifer assemblages allowed the reconstruction of climatic fluctuations which affected the Mediterranean area during early to late Pleistocene times. In the upper part of the core, the well known climatic stages recorded in several other Mediterranean core have been clearly recognized. Below about 22.7 m from core top, corresponding to climatic stage 14, the short term trend of the climatic curve changes from lower to higher frequency climatic cycles. At the same level, the long term trend of the curve leads from a mean value of -15.3 (above 22.7 m) to +3.3 (below that level). Correlation of sapropel layers with respect to the climatic curve allowed to recognize the presence of sapropels S11 and S12, to demonstrate the lack of sapropel S10 and to correlate three pre-S12 sapropel layers with relatively cold climatic intervals. The study of calcareous nannofossils resulted in the following calibrations: the top of the small Gephyrocapsa Zone with the first warm fluctuations following the top of the Jaramillo magnetic event; the LAD of Gephyrocapsa sp. 3 with climatic stage 15; the LAD of P. lacunosa with the higher part of climatic stage 13; an abundance increase of small with respect to medium sized Gephyrocapsa with climatic stage 8; the base of the E. huxleyi Acme Zone with the boundary between climatic stages 4 and 3.