Université de Fribourg

Molybdenum isotopic composition of modern and Carboniferous carbonates

Voegelin, Andrea R. ; Nägler, Thomas F. ; Samankassou, Elias ; Villa, Igor M.

In: Chemical Geology, 2009, vol. 265, no. 3-4, p. 488-498

We investigate the redox-sensitive isotope system of molybdenum (Mo) in marine carbonates to evaluate their potential as archive of the Mo isotopic composition of coeval seawater. We present Mo isotope data (δ98/95Mo) of modern skeletal and non-skeletal carbonates as well as a variety of precipitates from the mid and late Carboniferous. The external reproducibility is...

Université de Neuchâtel

Cadmium anomalies in Jurassic carbonates (Bajocian, Oxfordian) in western and southern Europe

Rambeau, Claire ; Föllmi, Karl B. (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2006 ; 1858.

The trace metal cadmium (Cd) is a highly toxic element, with adverse effects both on human health as well as on ecosystem equilibriums. Its transfer into the environment occurs by the mediation of natural and anthropogenic processes. Important natural sources comprise volcanic emissions and the biogeochemical weathering of Cd-enriched rocks, such as phosphorites or organic-rich deposits. This...

Université de Neuchâtel

Microbe–mineral interactions: early carbonate precipitation in a hypersaline lake (Eleuthera Island, Bahamas)

Dupraz, Christophe ; Visscher, Pieter T. ; Baumgartner, K. L. ; Reid, R. P.

In: Sedimentology, 2004, vol. 51, p. 745-765

Microbialites (benthic microbial carbonate deposits) were discovered in a hypersaline alkaline lake on Eleuthera Island (Bahamas). From the edge towards the centre of the lake, four main zones of precipitation could be distinguished: (1) millimetre-sized clumps of Mg-calcite on a thin microbial mat; (2) thicker and continuous carbonate crusts with columnar morphologies; (3) isolated patches of...

Université de Fribourg

Quantification of high-frequency sea-level fluctuations in shallow-water carbonates: an example from the Berriasian–Valanginian (French Jura)

Hillgärtner, Heiko ; Strasser, André

In: Palaeogeography, Palaeoclimatology, Palaeoecology, 2003, vol. 200(1-4), p. 43

When quantifying sedimentary processes on shallow carbonate platforms, it is important to know the high-frequency accommodation changes through time. Accommodation changes in cyclic successions are often analysed by simply converting cycle thickness to Fischer plots. This approach is not satisfactory, because it does not account for differential compaction, possible erosion, sea-level fall below...