Search results for "Gephyrocapsa"
showing 3 items of 3 documents
Primary productivity variability on the Atlantic Iberian Margin over the last 70,000 years: Evidence from coccolithophores and fossil organic compoun…
2010
[1] This study analyzes coccolithophore abundance fluctuations (e.g., Emiliania huxleyi, Gephyrocapsa specimens, and Florisphaera profunda) in core MD01-2444 sediment strata retrieved at the Iberian Margin, northeastern Atlantic Ocean. Coccolithophores are calcareous nannofossils, a major component of the oceanic phytoplankton, which provide information about past ecological and climatological variability. Results are supported by data on fossil organic compounds (sea surface temperatures, alkenones, and n-hexacosan-1-ol index) and geochemical analyses (benthic δ13Ccc and planktonic δ18Occ isotopes). Three scenarios are taken into account for this location at centennial-scale resolution ove…
Size variations in the genus Gephyrocapsa during the Early Plaeistocene in the eastern Mediterranean
2014
The genus Gephyrocapsa, belonging to coccolithophores, hasoften been used in biostratigraphic and paleoceanographic studies ofthe late Cenozoic. This taxon exhibits a gradual increase in sizeduring the Early Pleistocene which has been ascribed to evolutiveand/or environmental processes and has been used for biostratigraphicpurposes.Here we show both biometric and relative abundance data ofspecimens of this genus between about 2.0 and 0.9 Ma, from sedimentsof the Ionian Sea (eastern Mediterranean). Measurements onthe long axis of placoliths highlight a gradual size increase betweenthe upper part of MNN 19a and the top of MNN 19d biozones. Onthe basis of the comparison with paleoenvironmental…
Mediterranean coccolith ecobiostratigraphy since the penultimate Glacial (the last 145,000years) and ecobioevent traceability
2015
The Mediterranean Sea is a miniature ocean ideal to test the response of marine ecosystems to amplified orbital and suborbital climate changes. Here we present coccolith data from a Sardinia Channel gravity core (Arcose C_33) analysed over the last 145,000 years, with a mean resolution of about 900 years. The study highlights that regional phytoplankton assemblages underwent significant modifications between the penultimate glacial and the last interglacial, as well as between the last glacial and the Holocene. The N ratio palaeoproductivity index suggests reduced productivity levels and the development of a deep nutricline during the last interglacial and the Holocene. Within the last glac…