A mechanism for brief glacial episodes in the Mesozoic greenhouse

Abstract

[1] The Mesozoic, perhaps the longest period of warmth during the Phanerozoic Earth history, has been repeatedly affected by short-lived cold interludes lasting about one million years. While the origin of these cold snaps has been classically attributed to a temporary atmospheric CO 2 drawdown, quantified mechanisms explaining these instabilities of the carbon cycle are still lacking. Based on a climate carbon cycle model, we show that the general demise of carbonate platforms accompanying these short-lived cold interludes is a powerful mechanism capable of generating a fast atmospheric CO 2 decrease and a moderate sea level drop associated with ice sheet buildup. The temporary nature of the carbonate production decline explains the relative short time of these cold events but makes it possible to account for ice sheet waxing and waning.

Depositional characteristics and constraints on the mid-Valanginian demise of a carbonate platform in the intra-Tethyan domain, Circum-Rhodope Belt, northern Greece

“…The coeval increase of humidity and possibly CO 2 excess in the atmosphere enhanced continental weathering rates and caused intensive siliciclastic flux and nutrient supply in marine surface waters of the Western Tethys triggering marine productivity Weissert and Erba, 2004;Kuhn et al, 2005;Duchamp-Alphonse et al, 2007;Gr eselle and Pittet, 2010;F€ ollmi, 2012). The Valanginian decline of the photozoan carbonate factory was therefore related to a drastic climate change (Gr eselle and Pittet, 2010;Donnadieu et al, 2011;Gr eselle et al, 2011;Bonin et al, 2012;F€ ollmi, 2012) as a shift to heterozoan neritic community prior to the demise of carbonate platforms was recorded in many Western Tethys areas (Funk et al, 1993;Weissert et al, 1998;F€ ollmi et al, 2006, 2007Gr eselle and Pittet, 2010;Bonin et al, 2012;F€ ollmi and Godet, 2013;Morales et al, 2013).…”

“…Meanwhile, significant changes in the reef communities occurred (Wood, 1999;Flügel and Kiessling, 2002;Leinfelder et al, 2002), coevally with some reduction of the total carbonate platform area as compared to the Late Jurassic (Kiessling et al, 2000(Kiessling et al, , 2003. Despite these general considerations little information is available on the development of individual tropical carbonate platforms during the earliest Cretaceous (Donnadieu et al, 2011).…”

Evolution of a Late Oxfordian: early Kimmeridgian carbonate platform, French Jura Mountains

“…The Late Jurassic generally is thought to have had an equable global climate and warm temperatures (Frakes et al 1992;Hallam et al 1993). Nevertheless, several recent studies indicate Late Jurassic climate variations in shallow platform carbonates with short-term sea surface temperature changes in the northwestern Tethys (Dromart et al 2003a, b;Carpentier et al 2006;Brigaud et al 2008;Donnadieu et al 2011;Dera et al 2011).…”

Stepwise basin evolution of the Middle Jurassic–Early Cretaceous rift phase in the Central Graben area of Denmark, Germany and The Netherlands

“…The Jurassic Period is generally considered as a greenhouse world, devoid of major glacial episodes (Donnadieu et al 2011). The start of the Jurassic might even be considered a super-hothouse, with extreme high atmospheric CO 2 levels as a result of volcanic outgassing associated with the Central Atlantic Magmatic Province (Korte & Hesselbo 2011).…”