Biostratigraphy of the last 50 kyr in the contourite depositional system of the Gulf of Cádiz

Abstract

This paper proposes a biostratigraphic framework for the last 50kyr in the contourite depositional system (CDS) of the Gulf of Cádiz with a solid and independent age control, and tests the reliability of faunal-based analyses in a bottom current-dominated environment related to high current velocities. The distribution of planktonic foraminifera and pteropods has been studied in twenty-two piston cores of the Holocene and Late Pleistocene age from the Gulf of Cádiz. A detailed correlation between the cores has been made possible by a large radiocarbon and isotopic data set and a high degree of similarity of frequency changes within several species by coiling direction changes of Globorotalia truncatulinoides and Globorotalia hirsuta and by occurrences of the polar species Neogloboquadrina pachyderma and Limacina retroversa. Occurrences of these polar species are clearly related to paleoclimatic oscillations and reflect rapidly changing surface water conditions in the Gulf of Cádiz during the latest Pleistocene that have been observed regardless of sedimentation rates and sedimentary environments (contouritic drifts vs slope without bottom current influence).