Tracing hydrological millennial-scale cycles in the late Quaternary of the Cariaco Basin and the southern Gulf of Cádiz using coccoliths and dinoflagellate cysts

• Main Author: Mertens, Kenneth
• Other Authors: Louwye, Stephen
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universiteit Gent 2009
• Subjects: Earth and Environmental Sciences; dinoflagellate cysts; millennial-scale; Cariaco Basin; Gulf of Cádiz; North Atlantic Oscillation; Intertropical Convergence Zone; hydrological cycles; late Quaternary; coccoliths; Lingulodinium machaerophorum; North Atlantic; North Atlantic oscillation
• Online Access: https://biblio.ugent.be/publication/592743; http://hdl.handle.net/1854/LU-592743; https://biblio.ugent.be/publication/592743/file/4334946

Climate fluctuations in tropical to subtropical regions are coupled to hydrological changes. The reconstruction of these hydrological changes during rapid late Quaternary climate oscillations is crucial for climate change study. The present study demonstrates that coccoliths and dinoflagellate cysts are very useful as paleoclimatological indicators for the elucidation or a better understanding of the late Quaternary regional and global palaeoclimate. This study also reveals new insights in coccolithophore and dinoflagellate palaeoecology. At the outset, two fundamental studies were undertaken to strengthen dinoflagellate cysts as a proxy for paleoecological studies. Since so-called ‘standard’ palynological processing methods are still very variable and inflict damage on organic-walled microfossils to a certain extent, the effect on the determination of dinoflagellate cyst concentrations needed to be sorted out. Furthermore, since there were indications that process length variation of Lingulodinium machaerophorum is related to salinity, there was a need to assess its use for quantitative palaeosalinity reconstruction, which is of critical importance for better understanding of global climate change. Two locations were chosen for a high-resolution micropalaeontological study of hydrological millennial-scale cycles during Late Quaternary times: the Cariaco Basin, an anoxic basin offshore Venezuela and the Southern Gulf of Cádiz, offshore Morocco. Because of the high sedimentation rates, both sites contain a relatively undisturbed Late Quaternary climate record. Both record rapid, large climatic oscillations related to major hydrological changes caused by respectively the intertropical convergence zone (ITCZ) and the North Atlantic Oscillation (NAO). Results of the micropalaeontological analysis indicate that the changes in the dominance of river influx or upwelling cause important variations in plankton productivity in both locations. These variations are reflected in both assemblage changes and absolute abundance ...