Sedimentary evolution of the continental Early–Middle Triassic Cañizar Formation (Central Spain): Implications for life recovery after the Permian–Triassic crisis

Abstract

The Permian-Triassic transition (P-T) was marked by important geochemical perturbations and the largest known life crisis. Consequences of this event, as oxygen-depleted conditions and the unusual behavior of the carbon cycle, were prolonged during the Early Triassic interval delaying the recovery of life in both ter restrial and marine ecosystems. Studies on Lower Triassic sediments of continental origin, as in the case of Western Europe, are especially problematic due to the scarcity of fossils and absence of precise dating. The The Cafiizar Fm. has been subdivided into six members (A-F) separated by seven (1-7) major bounding surfaces (MBS). These surfaces are well recognized laterally over hundred of km and they represent 10 4 _10 5 My. MBS-5 is considered to be of late Spathian age and it is a clear indication of tectonic activity, represented by a mild unconformity. This event represents a change in the sedimentary characteristics (reactivation) of the unit and from here to the top of the unit are found the first signals of biotic recovery, represented by tetrapod footprints, plants, roots and bioturbation. All of these characteristics and the esti mated age represented by the MBS-5 event permit this surface to be related to the coeval Hardegsen un conformity of Central-Western Europe. These first signals of biotic recovery can thus be related to an increased oxygen supply due to the new created paleogeographical corridors in the context of this tectonic activity. These biotic signals occurred 5 My after the Permian-Triassic limit crisis; a similar delay as oc curred in other coeval and neigh boring basins.

The beginning of the Buntsandstein cycle (Early–Middle Triassic) in the Catalan Ranges, NE Spain: Sedimentary and palaeogeographic implications

“…Sandy fluvial systems (SB, CH and FF elements) evolved as unconfined systems in the Prades subbasin. The scarce presence of vegetation allowed extensive lateral development of the fluvial systems similar to examples described by López-Gómez et al (2012) in similar Triassic red beds of Central Europe, Lodeve Basin (SE France) and Iberian Basin (E Spain).…”

“…Magnetostratigraphic studies in this megasequence indicate a Spathian (late Olenekian) age for most of the Riera de San Jaume sequence, with an Aegian (early Anisian) age for its uppermost part, and Bithynian to Illyrian age for El Figarò s.s (Dinarès-Turell et al, 2005). However, we consider the lower part of the Buntsandstein sedimentary cycle could be of Smithian age when the general characteristics of the sedimentary succession are compared to those of similar successions of neighbour basins of Spain and SE France described by Péron et al (2005), López-Gómez et al (2012). Studies based on tetrapod bones and footprints (Calzada, 1987;Gaete et al, 1994;Fortuny et al, 2011) in the overlying El Figaró Lutites and Sandstones unit, allowed to establish lithostratigraphic correlations with units of the neighbouring Iberian basin (Arche et al, 2004;Galán-Abellán, 2011), corroborating this age.…”

“…In this area, the Permian and Triassic succession record is also marked by a hiatus and/or unconformity between both periods. Questions related to the precise age of the continental Triassic sediments, abrupt climate changes and pulses of life recovery are still unresolved Durand, 2006Durand, , 2008Bourquin et al, 2007;Cassinis et al, 2007Cassinis et al, , 2009Cassinis et al, , 2012López-Gómez et al, 2012). The palaeogeographical location and the sedimentary characteristics of the Catalan Basin during the Triassic may shed light on some of these questions.…”

“…A cooler episode characterized the beginning of the Spathian (Szurlies, 2007;Romano et al, 2013) when paleosoils and tetrapod footprints were developed in Central Pangea (Haubold, 1983;Fichter and Kunz, 2004). However, the middle Spathian also shows an arid to hyper-arid episode in Central-Western Europe interrupting the general cooling tendency (Röhling, 1991;Bourquin et al, 2006Bourquin et al, , 2009Ghinassi et al, 2009;López-Gómez et al, 2012). This arid episode is well recorded by the development of dune field deposits in the southern Catalan Basin which was coetaneous with other similar aeolian dune fields in Central-Western Pangea as described by Geluk (1998), Cassinis et al (2003), Bourquin et al (2007), Durand (2008, Linol et al (2009), McKie andWilliams (2009) and Soria et al (2011).…”

Environmental conditions of E Iberia’s Early Triassic: an Earth example for understanding the habitability of ancient Mars

“…For this purpose, we consider the variations in extreme conditions during this particular period on Earth, in order to better understand the palaeoenvironmental and habitability changes produced in Meridiani Martian regions. Although there are clear differences between both sites and periods such as age (247 Myr vs. 3.7 Gyr) (Hynek and Phillips, 2008;López-Gómez et al, 2012) or atmospheric composition (oxic vs. anoxic) (Berner, 2006;Lammer et al, 2013), nevertheless they present strikingly similar, sedimentary features, and mineralogical associations. Thus, this paper may provide a step forward in the understanding of the causes that led to a life recovery in the Triassic of the Earth and that could have prevented its appearance and/or development on early Mars.…”