Search results for "Accumulation rates"
showing 2 items of 2 documents
The Valanginian isotope event: a complex suite of palaeoenvironmental perturbations.
2011
17 pages; International audience; The Valanginian records a severe crisis of carbonate systems, both on platforms and in the pelagic realm. This crisis is roughly concomitant with the Weissert Event, characterized by a positive δ13C excursion of about 2‰in marine carbonates. However, it is unclear if the response of these two carbonate systems to the global perturbations is contemporaneous, or if they react differently. For this purpose, accumulation rates of pelagic carbonates produced by nannofossils and of platform-derived carbonates have been quantified in a hemipelagic environment (the Vocontian Basin, SE France) that has the potential to record the reaction of both shallow-water and p…
Conflicting coccolithophore and geochemical evidence for productivity levels in the Eastern Mediterranean sapropel S1
2011
Abstract The cyclic development of anoxic conditions in the eastern Mediterranean deep sea waters is one of the most fascinating research topics in paleoceanographic studies. In combination with bottom water stagnation, enhanced primary production is a common explanation for the deposition of organic-rich layers (sapropels). This is supported by extensive evidence from both geochemical and micropaleontological studies. The correspondence of recent sapropel layers with peaks of the lower photic zone coccolithophore species Florisphaera profunda has been interpreted as a proxy for the development of a deep chlorophyll maximum (DCM), due to the pycnocline/nutricline shallowing into the lower p…