The Aptian, Albian and Cenomanian of Roter Sattel, Romandes Prealps, Switzerland: a high-resolution record of oceanographic changes

Abstract

The Aptian-Lower Turonian hemipelagic sediments of Roter Sattel in the Swiss Prealps are well dated by planktonic foraminifera. Stacking pattern of the limestone-marl alternations and facies evolution allow the identification of sequence boundaries, transgressive surfaces, and maximum-flooding events or condensed sections on at least two hierarchical levels.Calibrated by a precise biostratigraphic framework, the major sequence boundaries can be correlated with those recognized elsewhere in European basins. Organic-rich black shales are generally confined to transgressive and/or condensed intervals and correspond to the oceanic anoxic events (OAE) 1a-d and 2. OAE 1a and OAE 2 show well-marked positive shifts in 13 C. High-resolution analysis of the Roter Sattel section shows that eustatic sea-level changes and fluctuations in the global carbon cycle are clearly recognizable. However, these were overprinted by regional changes of climate and availability of terrigenous source areas controlling nutrient input and hence organic productivity, and by regional and local tectonics shaping basin morphology and modifying the paths of oceanic currents. This led to facies changes, strongly varying sedimentation rates, and non-deposition or erosion during the Aptian Planomalina cheniourensis Zone. Despite this distortion of the sedimentary record, the Roter Sattel section may serve as a corner-stone for the study of basin-wide or global oceanographic, climatic, and evolutionary changes when correlated with sections in other palaeogeographical domains.2001 Academic Press

Origin of rhythmic Albian black shales (Piobbico core, central Italy): Calcareous nannofossil quantitative and statistical analyses and paleoceanographic reconstructions

“…[18] The carbon isotope profile shows, with some departures, a drift from close to 3% at the base of the section to <2.5% close to the top, followed by an abrupt step up to higher values followed by a renewed downward trend. Such values are typical for those recorded in mid-Cretaceous pelagic carbonates and marlstones from elsewhere in Italy, Mexico, Switzerland and France [e.g., Bellanca et al, 1996;Bralower et al, 1999;Strasser et al, 2001;Herrle et al, 2003bHerrle et al, , 2004 and shallow-water guyot carbonates from the mid-Pacific Mountains [Jenkyns, 1995;Jenkyns and Wilson, 1999], which suggests that they are broadly representative of seawater compositions. Carbon isotope ratios of carbonate sediments, which have undergone simple lithification without the introduction of externally derived fluids, are known to behave in a conservative manner [Scholle and Arthur, 1980;Marshall, 1992].…”

The Albian–Cenomanian transition and Oceanic Anoxic Event 1d – an example from the Boreal Realm

“…Strasser et al . () described the ACBI also from the Swiss Prealps and Robinson et al . () from the Calera Limestone in central California.…”

Mid-Cretaceous oceanic anoxic events in the Pacific Ocean revealed by carbon-isotope stratigraphy of the Calera Limestone, California, USA

“…8) from North Atlantic and Tethyan Ocean sections (Erbacher and Thurow, 1997;Stoll and Schrag, 2000;Strasser et al, 2001;Wilson and Norris, 2001) on the basis of similarity in the carbon-isotope trends and foraminiferal biostratigraphy. It is clear that even amongst the Tethyan sections, there are slight differences in the relative positions of some biotic, lithological, and isotopic events, most likely a result of subtle differences in the biostratigraphic schemes used by different authors and variable sampling density.…”

“…The late Albian-early Cenomanian is characterized in the Atlantic and Tethyan records by a positive carbon-isotope excursion spanning an interval of organic-carbon-rich deposition that defi nes OAE1d, the so-called Breistroffer event (e.g., Erbacher and Thurow, 1997;Strasser et al, 2001;Wilson and Norris, 2001). Petrizzo et al (2008) discussed the problems with the diachroneity of black-shale deposition in the late Albian and the implications for the defi nition of OAE1d.…”