Freshwater discharge controlled deposition of Cenomanian-Turonian black shales on the NW European epicontinental shelf (Wunstorf, northern Germany)

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doi: 10.5194/cp-11-495-2015
Author(s): van Helmond, N. A. G. M.; Sluijs, A.; Sinninghe Damste, J. S.; Reichart, G. J.; Voigt, S.; Erbacher, J.; Pross, J.; Brinkhuis, H.
Author Affiliation(s): Primary:
Utrecht University, Laboratory of Palaeobotany and Palynology, Utrecht, Netherlands
Other:
Goethe University Frankfurt, Germany
Bundesanstalt für Geowissenschaften und Rohstoffe, Germany
University of Heidelberg, Germany
Volume Title: Climate of the Past
Source: Climate of the Past, 11(3), p.495-508. Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1814-9324
Note: In English. 87 refs.; illus., incl. strat. cols., 1 table, sketch map
Summary: Global warming, changes in the hydrological cycle and enhanced marine primary productivity all have been invoked as having contributed to the occurrence of widespread ocean anoxia during the Cenomanian-Turonian oceanic anoxic event (OAE2; ∼94 Ma), but disentangling these factors on a regional scale has remained problematic. In an attempt to separate these forcing factors, we generated palynological and organic geochemical records using a core spanning the OAE2 from Wunstorf, Lower Saxony Basin (LSB; northern Germany), which exhibits cyclic black shale-marl alternations related to the orbital precession cycle. Despite the widely varying depositional conditions complicating the interpretation of the obtained records, TEX86H indicates that sea-surface temperature (SST) evolution in the LSB during OAE2 resembles that of previously studied sites throughout the proto-North Atlantic. Cooling during the so-called Plenus Cold Event interrupted black shale deposition during the early stages of OAE2. However, TEX86 does not vary significantly across black shale-marl alternations, suggesting that temperature variations did not force the formation of the cyclic black shale horizons. Relative (i.e., with respect to marine palynomorphs) and absolute abundances of pollen and spores are elevated during phases of black shale deposition, indicative of enhanced precipitation and run-off. High abundances of cysts from inferred heterotrophic and euryhaline dinoflagellates supports high run-off, which likely introduced additional nutrients to the epicontinental shelf resulting in elevated marine primary productivity. We conclude that orbitally forced enhanced precipitation and run-off, in tandem with elevated marine primary productivity, were critical in cyclic black shale formation on the northern European epicontinental shelf and potentially for other OAE2 sections in the proto-Atlantic and Western Interior Seaway at similar latitudes as well.
Year of Publication: 2015
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; 12 Stratigraphy, Historical Geology and Paleoecology; Assemblages; Atlantic Ocean; Atmospheric precipitation; Biochronology; Biomarkers; Biostratigraphy; Biozones; Black shale; C-13/C-12; Cape Verde Basin; Carbon; Cenomanian; Central Europe; Chemical composition; Clastic rocks; Climate forcing; Cretaceous; Cyclostratigraphy; DSDP Site 367; Deep Sea Drilling Project; Demerara Rise; Deposition; Depositional environment; Dinoflagellata; Discharge; Distribution; Epicontinental seas; Equatorial Atlantic; Europe; First occurrence; Fresh water; Geochemical methods; Germany; Hydrologic cycle; Hydrology; Isotopes; Leg 207; Leg 210; Leg 41; Lower Saxony Basin; Marine environment; Mechanism; Mesozoic; Microfossils; Miospores; Newfoundland Basin; North Atlantic; Northwest Atlantic; Nutrients; OAE 2; ODP Site 1260; ODP Site 1276; Ocean Drilling Program; Oceanic anoxic events; Orbital forcing; Organic compounds; Oxidation; Paleoclimatology; Paleoecology; Palynomorphs; Plenus Cold Event; Pollen; Precession; Preservation; Productivity; Reconstruction; Relative age; Runoff; Sea-surface temperature; Sedimentary rocks; Shelf environment; Spores; Stable isotopes; Thermal maturity; Total organic carbon; Turonian; Upper Cretaceous; West Atlantic; Wunstorf Germany
Coordinates: N452400 N452400 W0444700 W0444700
N091600 N091600 W0543300 W0543300
N122913 N122913 W0200250 W0200250
Record ID: 2015071087
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Copernicus Gesellschaft, Katlenburg-Lindau, Germany