The calcareous nannofossil crisis in Northern Spain (Asturias province) linked to the Early Toarcian warming-driven mass extinction

Palaeoclimatic oscillations in the Pliensbachian (Early Jurassic) of the Asturian Basin (Northern Spain)

“…A new warming period is recorded in the EarlyLate Pliensbachian transition, and the Late Pliensbachian is represented by an important cooling interval. Finally the Early Toarcian coincides with a severe (super)warming interval, linked to the important Early Toarcian mass extinction (Gómez and Arias, 2010;García Joral et al, 2011;Gómez and Goy, 2011;Fraguas et al, 2012;Clémence, 2014;Clé-mence et al, 2015;Baeza-Carratalá et al, 2015). The average palaeotemperature of the latest Sinemurian, Pliensbachian (palaeolatitude of 32 • N) and Early Toarcian (palaeolatitude of 40 • N), calculated from the δ 18 O values obtained from belemnite calcite in the present study, is 15.6 • C. As mentioned above, some belemnites could swim through the water column, and the palaeotemperatures calculated do not necessarily correspond only with the temperatures of the bottom or surface waters, but also the average temperature.…”

“…This is why many authors point to this period as one of the main candidates for the development of polar ice caps in the Mesozoic (Price, 1999;Guex et al, 2001;Dera et al, 2011;Suan et al, 2011;Gómez and Goy, 2011;Fraguas et al, 2012). This idea is based on the presence, in the Upper Pliensbachian deposits of different parts of the World, of (1) glendonites; (2) exotic pebble to boulder-size clasts; (3) the presence in some localities of a hiatus in the Late Pliensbachian-earliest Toarcian; (4) the results obtained in the General Circulation Models, and (5) the Late Pliensbachian palaeotemperatures calculated and the assumed pole-to-equator temperature gradient.…”

“…Berner, 2006a, b;Retallack, 2009;Steinthorsdottir and Vajda, 2015), causing this intense and rapid warming. Comparison of the evolution of palaeotemperature with the evolution of the number of taxa reveals that progressive warming first coincides with a progressive loss of taxa by several groups (Gómez and Arias, 2010;Gómez and Goy, 2011;García Joral et al, 2011;Fraguas et al, 2012;Baeza-Carratalá et al, 2015) marking the prominent Early Toarcian extinction interval. Seawater palaeotemperature rapidly increased around the Tenuicostatum-Serpentinum zonal boundary, where average values of approximately 21 • C were reached, with peak temperatures of 24 • C (Fig.…”

“…The close correlation between the severe Late Pliensbachian Cooling and the Early Toarcian Warming events, and the major Early Toarcian mass extinction indi- cates that warming was one of the main causes of this faunal turnover (Kemp et al, 2005;Gómez et al, 2008;Gómez and Arias, 2010;García Joral et al, 2011;Gómez and Goy, 2011;Fraguas et al, 2012;Clémence, 2014;Clémence et al, 2015;Baeza-Carratalá et al, 2015).…”

“…Especially relevant are the latest Pliensbachian−Early Toarcian climate changes, which have been documented in many sections from Western Europe (i. e. Saelen et al, 1996;McArthur et al, 2000;Röhl et al, 2001;Schmidt-Röhl et al, 2002;Bailey et al, 2003;Jenkyns, 2003;Rosales et al, 2004;Gómez et al, 2008;Metodiev and Koleva-Rekalova, 2008;Suan et al, 2008Suan et al, , 2010Dera et al, 2009Dera et al, , 2010Dera et al, , 2011Gómez and Arias, 2010;García Joral et al, 2011;Gómez and Goy, 2011;Fraguas et al, 2012), as well as in Northern Siberia and in the Artic Region (Zakharov et al, 2006;Nikitenko, 2008;Suan et al, 2011). The close correlation between the severe Late Pliensbachian Cooling and the Early Toarcian Warming events, and the major Early Toarcian mass extinction indi- cates that warming was one of the main causes of this faunal turnover (Kemp et al, 2005;Gómez et al, 2008;Gómez and Arias, 2010;García Joral et al, 2011;Gómez and Goy, 2011;Fraguas et al, 2012;Clémence, 2014;Clémence et al, 2015;Baeza-Carratalá et al, 2015).…”