Original paper
Revised and refined age model for the upper Pliocene of IODP Site U1389 (IODP Expedition 339, Gulf of Cádiz)
Grunert, Patrick; Balestra, Barbara; Richter, Carl; Flores, José-Abel; Auer, Gerald; Gallardo, Ángela García; Piller, Werner E.
Newsletters on Stratigraphy Volume 51 Number 3 (2018), p. 261 - 283
published: Jun 1, 2018
published online: Jul 5, 2018
Open Access (paper may be downloaded free of charge)
Abstract
We present a revision and refinement of the age model for upper Pliocene (2.6–3.7 Myrs) sediments recovered from the southern Iberian Margin at IODP Hole U1389E. New biostratigraphic data from discrete samples allow 1) the identification of a distinct increase in abundances of Neogloboquadrina atlantica (sin), dated to 2.72 Ma at sites in the North Atlantic and Mediterranean; and 2) the reconsideration of the last occurrence of Discoaster tamalis (2.8–2.87 Myrs), which is placed at a greater depth than in the original shipboard age model. The revised biostratigraphic framework suggests a considerably deeper location for paleomagnetic subchron C2An.1r (Kaena; 3.032–3.116 Myrs). New paleomagnetic data, however, do not produce credible evidence for reversed polarity. Based on biostratigraphic data from this and other sites under the influence of Mediterranean Outflow Water we attribute the absence of the Kaena subchron to a hiatus between ~ 3.2 and 3 Myrs due to enhanced bottom current strength. A further stratigraphic refinement has been achieved for four well-recovered core intervals through the correlation of the planktic δ18 O record of U1389E to reference records in the Mediterranean. In our revised age model, observed changes in lithology are wellreflected in a long-term trend towards high sediment accumulation rates, contrasting the linear sediment accumulation rates of the original age model.
Keywords
biostratigraphy • discoaster tamalis • stable isotopes • pliocene • neogloboquadrina atlantica • magnetostratigraphy