A peritidal evaporite environment in the Neoproterozoic of South Gabon (Schisto-Calcaire Subgroup, Nyanga Basin)

Stable isotopes of oxygen and carbon compositions in the Neoproterozoic of South Gabon (Schisto-Calcaire Subgroup, Nyanga Basin): Are cap carbonates and lithoherms recording a particular destabilization event after the Marinoan glaciation?

“…Although the timing of the series is poorly constrained, the Nsc3 carbonates C-isotopic values of +2‰ and +3‰ approximate depositional conditions (sensu Jacobsen and Kaufman, 1999) and do not appear to have been altered by post-depositional diagenetic processes (Préat et al, 2010). The Nsc3 d 18 O values range between À5.1‰ and À1.3‰ slightly heavier than those of the Neoproterozoic ocean (Jacobsen and Kaufman, 1999;Halverson et al, 2005).…”

“…First results from this study are reported in Prian et al (2009a,b) and Thiéblemont et al (2009). Isotopic results from the upper part of the Schisto-Calcaire Subgroup are reported in Préat et al (2010).…”

“…The former contains oolites and dolomites with a variable degree of silicification. Finally, the 75-100 m-thick Nsc3 Formation, consists of well-bedded grey or cream-coloured cherty stromatolitic limestones and oolitic dolomites (Préat et al, 2010).…”

“…This dolomitic formation (75-100 m thick) consists of flat microbial laminae and low domal stromatolitic columns in subtidal and intertidal lagoons (see Préat et al (2010) for a detailed analysis of this formation). The top of laminites contains mud-cracks, fenestrae and relicts of sulphates indicating episodic desiccation and evaporation in a muddy peritidal evaporite environment.…”

Diagenetic significance of carbon, oxygen and strontium isotopic compositions in the Aptian-Albian Mural Formation in Cerro Pimas area, northern Sonora, Mexico.

“…Very little information on the mid-Cretaceous events is available from Mexico (Scholle and Arthur, 1980;Bralower et al, 1999). The isotopic study on mid-Cretaceous shallow marine carbonates have shown evidence for global-scale tectonics (Gröcke et al, 2005;Maheshwari et al, 2005;Amodio et al, 2008), paleooceanographic processes (Kumar et al, 2002;Madhavaraju et al, 2004;Armstrong et al, 2009Armstrong et al, , 2011, climatic and biotic changes (Deshpande et al, 2003;Das Gupta et al, 2007;Mishra et al, 2010;Préat et al, 2010;Tewari et al, 2010).…”