IODP Proceedings    Volume contents     Search


Data report: diatom and silicoflagellate records of marine isotope Stages 25–27 at IODP Site U1387, Faro Drift1

Cristina Ventura,2, 3 Fatima Abrantes,2, 3, 4 Isabel Loureiro,2 and Antje H.L. Voelker2, 4


During Integrated Ocean Drilling Program Expedition 339, the shipboard micropaleontological studies of Site U1387 core catcher samples revealed the preservation of diatoms and radiolarians in specific depths from early Pleistocene age (900–1000 ka). To evaluate the ecological significance of those diatoms, we analyzed 98 samples from the intervals of 244 to 274 m along the corrected splice, corresponding to marine isotope Stage (MIS) 25 to MIS 29, for the abundance of diatoms and silicoflagellates. In 6 samples, the composition of the diatom assemblage was determined as well. Although most samples were barren of siliceous microfossils, the downcore record revealed two intervals, 249–252 corrected meters composite depth (cmcd) and 263–265 cmcd, where diatoms and silicoflagellates reach their maximum values. These maxima occurred from the MIS 26/25 transition to interglacial MIS 25, and again during early MIS 27. The diatom assemblage includes 27 identified taxa with Chaetoceros (Hyalochaete) resting spores being dominant and Thalassionema nitzschioides and Paralia sulcata significant. The Chaetoceros spores clearly indicate strong influence of seasonal upwelling and associated high primary productivity. Special to the diatom record is, however, the occurrence of the large-diameter (>125 µm) centric diatoms Coscinodiscus asteromphalus, Coscinodiscus apiculatus, and Coscinodiscus cf. gigas that imply incursions of low-nutrient, open-ocean water into the southern Portuguese coast during MIS 25.

1 Ventura, C., Abrantes, F., Loureiro, I., and Voelker, A.H.L., 2017. Data report: diatom and silicoflagellate records of marine isotope Stages 25–27 at IODP Site U1387, Faro Drift. In Stow, D.A.V., Hernández-Molina, F.J., Alvarez Zarikian, C.A., and the Expedition 339 Scientists, Proceedings of the Integrated Ocean Drilling Program, 339: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.339.202.2017

2 Divisão de Geologia e Georecursos Marinhos, Instituto Português do Mar e da Atmosfera (IPMA), Rua Alfredo Magalhães Ramalho 6, 1495-006 Lisboa, Portugal. Correspondence author:

3 CIIMAR, Universidade do Porto, Rua dos Bragas 287, 4050-123 Porto, Portugal.

4 CCMAR, Centro de Ciencias do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.

Initial receipt: 28 January 2016
Acceptance: 18 October 2016
Publication: 7 March 2017
MS 339-202