Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism

Abstract

One of the five largest mass extinctions of the past 600 million years occurred at the boundary of the Triassic and Jurassic periods, 201.6 million years ago. The loss of marine biodiversity at the time has been linked to extreme greenhouse warming, triggered by the release of carbon dioxide from flood basalt volcanism in the central Atlantic Ocean. In contrast, the biotic turnover in terrestrial ecosystems is not well understood, and cannot be readily reconciled with the effects of massive volcanism. Here we present pollen, spore and geochemical analyses across the Triassic/Jurassic boundary from three drill cores from Germany and Sweden. We show that gymnosperm forests in northwest Europe were transiently replaced by fern and fern-associated vegetation, a pioneer assemblage commonly found in disturbed ecosystems. The Triassic/Jurassic boundary is also marked by an enrichment of polycyclic aromatic hydrocarbons, which, in the absence of charcoal peaks, we interpret as an indication of incomplete combustion of organic matter by ascending flood basalt lava. We conclude that the terrestrial vegetation shift is so severe and wide ranging that it is unlikely to have been triggered by greenhouse warming alone. Instead, we suggest that the release of pollutants such as sulphur dioxide and toxic compounds such as the polycyclic aromatic hydrocarbons may have contributed to the extinction.

Climatic disaster at the Triassic-Jurassic boundary - a clay minerals and major elements record from the Polish Basin

“…Those lay ers par tic u larly rich in kaolinite with usu ally very high CIA val ues were de vel oped as a re sult of ex treme chem ical weath er ing of source ter rains in the af ter math of rapid green house warm ing and abun dant rain fall. The ex treme weath er ing of bed rock, and soil ero sion, was prob a bly ex ac erbated by acid rain and sub se quent de for es ta tion due to the CAMP-re lated emis sion of sul fur and car bon di ox ide (Schootbrugge et al, 2009). Dis tinct ep i sodic warm ing and contem po ra ne ous hu mid events are in di cated by the high abundance of kaolinite cou pled with dis ap pear ance of smectite, which sug gests hot and wet trop i cal con di tions with low sea sonal ity con trasts.…”

“…in Slovakia (Michalík et al, 2010), and from the top most Tri as sic Triletes beds in the German Ba sin (Schootbrugge et al, 2009). Re cently, dis tinct kaolinite en rich ment has also been doc u mented from the topmost Tri as sic Kössen For ma tion (Eiberg Ba sin) in Aus tria Zajzon et al, 2012).…”

“…A pro found cli mate de sta bi li sa tion that man i fested in a se ries of rapid, cat a strophic cli ma tic re ver sals, cou pled with emis sion of di verse toxic com pounds re lated to CAMP de vel opment, were most prob a bly the fun da men tal rea sons of the end-Tri as sic eco log i cal di sas ter and mass-ex tinc tion (cf. Schootbrugge et al, 2009;Pieñkowski et al, 2012Pieñkowski et al, , 2014.…”

“…Some au thors, though, have re cently chal lenged the causal link be tween end-Tri as sic meth ane re lease and ter res trial eco sys tem cri sis . In deed, the green house ef fect as a single cause of ter res trial ex tinc tions is chal lenged by many authors, who em pha size en vi ron men tal stress caused by emission of volcanogenic toxic com pounds, soil acid i fi ca tion and suc ces sive rapid cli ma tic re ver sals (Self et al, 2006;Ganino and Arndt, 2009;Schootbrugge et al, 2009;Racki, 2010;Pieñkowski et al, 2012Pieñkowski et al, , 2014Schaller et al, 2012). More over, it was found that at mo spheric CO 2 con cen tra tions had increased ear lier in the Rhaetian (Cleve land et al, 2008;.…”

A triász és a jura időszak határán lezajlott globális krízis és annak nyomai magyarországi rétegsorokban

“…Ennél meggyőzőbbek a számos tanulmány által szolgáltatott bizonyítékok a határ körüli gyors klímaváltozásra. Lehűlést a légkörbe kerülő SO 2 -ből képződő szulfátaeroszolok indít -hatnak el, amire geokémiai (VAN DE SCHOOTBRUGGE et al 2009) és paleobotanikai ada tok is utalnak (BACON et al 2013). Még nagyobb jelentősége van a gyors és nagymértékű CO 2 -növekedés vezérelte fel melegedésnek (MCELWAIN et al 1999, SCHALLER et al 2011.…”