Environmental conditions during the Toarcian Oceanic Anoxic Event (T-OAE) in the westernmost Tethys: influence of the regional context on a global phenomenon

Abstract

A geochemical analysis has been conducted in the Fuente de la Vidriera section of the External Subbetic (Betic Cordillera, southern Spain) in order to interpret the incidence of the Toarcian Oceanic Anoxic Event (T-OAE) in the westernmost end of the Tethys. The obtained values of detrital, redox and palaeoproductivity proxies throughout the succession show minor fluctuations, but only punctual significant changes. Detrital input is nearly constant during the studied interval, except punctually in the lower part of serpentinum Zone, characterized by an increase in both fluvial and eolian detrital transport. Associated to this local higher fluvial and eolian activity, a comparatively higher concentration of organic matter is punctually registered, as revealed by the comparatively highest total organic carbon (TOC) value (0.99 wt.%). The remaining part of the section shows TOC values in the lower range of those registered in the Tethyan Toarcian sections (< 0.4 wt.%). The obtained ratios of redox-sensitive trace metals lead to the interpretation of oxic to dysoxic bottom-waters, with a singular sharp decrease in oxygenation corresponding to a short interval within the serpentinum Zone (sample FV-18) correlated to the T-OAE. The minor incidence of the T-OAE registered in this westernmost end of the Tethys, in which punctual dysoxic conditions are restricted only to a decimetre-scale interval reveals the importance of regional context and local oceanic-atmosphere dynamics on the local record of this phenomenon.•

Evolution of the last koninckinids (Athyridida, Koninckinidae), a precursor signal of the early Toarcian mass extinction event in the Western Tethys

“…These levels are barren of benthic infaunal assemblages and were interpreted as representative of slightly reductive conditions near the sediment-water interface during deposition and early diagenetic phases. These conditions are consistent with those documented in the westernmost Tethyan sea bottoms, where organic matter did not reach adequate values to be regarded as black shales (García Joral et al, 2011;Reolid et al, 2012;Rodríguez-Tovar and Reolid, 2013). Overlying these dark levels described by Tent-Manclús (2006), Baeza-Carratalá (2013) recorded Soaresirhynchia bouchardi, assigned to the lower-middle part of the Serpentinum Zone, widely regarded as an opportunistic taxon that colonized the Western…”

Petrophysical and geochemical signature of the Hangenberg Events: an integrated stratigraphy of the Devonian-Carboniferous boundary interval in the Northern Rhenish Massif (Avalonia, Germany)

“…Higher Mn values are typical of the oxidising front in sediment (Thomson et al 1995, Schnetger et al 2000, Maynard 2005, Roy 2006, Tribovillard et al 2006, Rodríguez-Tovar & Reolid 2013.…”

New deep-water brachiopod resilient assemblage from the South-Iberian Palaeomargin (Western Tethys) and its significance for the brachiopod adaptive strategies around the Early Toarcian Mass Extinction Event

“…The rocks comprising the CE section represent a pelagic marine setting with deep habitats below storm wave base in the South-Iberian palaeomargin, close to the Hispanic Corridor and the passage between the Western Tethys and the Proto-Atlantic seaway (Aberhan 2001, Bailey et al 2003, at a palaeolatitude of~20°N (Jiménez et al 1996, Rodríguez-Tovar & Reolid 2013. The Zegrí Formation exposed at CE section was deposited in a subsiding area with an expanded sedimentation and a greater cumulative thickness (Reolid et al 2014a).…”

“…1), which typify the first stages of the "escape and extinction" phase in the higher latitude Atlantic basins. In this sense, from a palaeogeographical point of view, the CE section would be located in a hemipelagic trough connected with the Hispanic Corridor (Sandoval et al 2012, Rodríguez-Tovar & Reolid 2013, Reolid et al 2014a, allowing both migration through the Atlantic seaway and surviving of long-lasting species up to their total extinction within the serpentinum Zone.…”

“…Gómez et al 2008;Hermoso et al 2009;Rodríguez-Tovar & Reolid 2013;Reolid et al 2014a, b). Recent analyses have documented the role of local and regional factors that overprint the typical pattern of the T-OAE (Braga et al 1981;McArthur et al 2008;Rodríguez-Tovar & Uchman 2010;Reolid et al 2013a, b;Rodríguez-Tovar & Reolid 2013).…”