Publication Date:
2023-11-28
Description:
The climatic deterioration related to the onset of Northern Hemisphere glaciations (circa 2.52 Ma BP) must have lead to reorganization and relocation of species associations and may have enhanced species turnover. The present study investigates how this deterioration affects the dinoflagellate cyst and acritarch assemblages from two locations, DSDP Site 607 (North Atlantic) and the Singa section (southern Italy). The records from these locations cover the interval from 2.8 to 2.2 Ma with at least a 5 ka resolution and they have been correlated to the Milankovitch periodicities on a cycle to cycle basis by means of integrated high resolution stable isotope, calcium carbonate, foraminiferal, palynological and magnetostratigraphical datasets. In the present study this high resolution stratigraphic framework is used for a detailed correlation of events occurring in each of the depositional sequences. It also enables further assessment of the palaeoenvironmental preferences of some dinoflagellate cyst forms. Comparison of the two palynological records reveals a close correspondence in the timing of major assemblage changes and extinction events, confirming their Milankovitch cycle based correlation. A close link between periods of Northern Hemisphere cooling (at oxygen isotope stages 110, 104 and 100-96) and increased dinoflagellate cyst turnover appears to be present for both DSDP Site 607 and the Singa section. The turnover events can also be recognized in the records of planktic foraminifera and calcamous nannoplankton. Comparison of the Singa section with Site 607 and with other time equivalent marine palynological data sets, shows that some oceanic taxa respond similarly over a large area. The biostratigraphical implications are discussed. Notably the last occurrence of Invertocystu lucrymosa appears to be a valuable marker for isotope stage 110 in the Mediterranean and North Atlantic.
Keywords:
94-607_Site; Acritarcha; AGE; Amiculosphaera umbracula; Ataxiodinium choane; Ataxiodinium confusum; Bitectatodinium tepikiense; Calcium carbonate; Cerebrocysta namocensis; COMPCORE; Composite Core; Corrudinium? labradori; Corrudinium harlandii; Cysts; Deep Sea Drilling Project; Density; DEPTH, sediment/rock; Dinoflagellate cyst; Dinoflagellate cyst indeterminata; Dinoflagellate cyst reworked; DSDP; DSDP/ODP/IODP sample designation; Fibrocysta fusiforma; Filisphaera microornata; Glomar Challenger; Gongylodinium serratum; Habibacysta tectata; Impagidinium aculeatum; Impagidinium aliferum; Impagidinium bacatum; Impagidinium pallidum; Impagidinium patulum; Impagidinium plicatum; Impagidinium sp.; Impagidinium strialatum; Impagidinium velorum; Invertocysta lacrymosa; Invertocysta tabulata; Leg94; Lingulodinium machaerophorum; Nematosphaeropsis lativittatus; Nematosphaeropsis lemniscata; Nematosphaeropsis rigida; Nematosphaeropsis sp.; North Atlantic/FLANK; Operculodinium? eirikianum; Operculodinium centrocarpum; Operculodinium israelianum; Operculodinium janduchenei; Pentapharsodinium faeroense; Peridinoid type; Piccoladiniudm fenestratum; Pollen, bisaccate; Pollen and spores, other; Polysphaeridium zoharyi; Pyxidinopsis tuberculata; Sample code/label; Sample mass; Selenopemphix nephroides; Size fraction 〈 0.063 mm, mud, silt+clay; Spiniferites bentori; Spiniferites bulloideus; Spiniferites membranaceus; Spiniferites mirabilis; Spiniferites pseudofurcatus; Spiniferites spp.; Tasmanites; Tectatodinium pellitum; Trinovantedinium capitatum
Type:
Dataset
Format:
text/tab-separated-values, 6611 data points
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