Pacing of the Toarcian Oceanic Anoxic Event (Early Jurassic) from astronomical correlation of marine sections

Base of the Toarcian Stage of the Lower Jurassic defined by the Global Boundary Stratotype Section and Point (GSSP) at the Peniche section (Portugal)

“…2b) comparable to the precessionrelated carbonate content fluctuations recorded in the Polymorphum Zone (two cyclicities at 23 and 33 cm; Suan et al, 2008b). Similar results were obtained by Huang and Hesselbo (2014) who applied spectral analysis to the high-resolution δ …”

“…Above this level, the trend is reversed and an abrupt large negative carbon-isotope excursion is observed in the Lusitanian Basin at the base of the Levisoni Zone, which is considered as a characteristic feature of the T-OAE (Duarte, 1998;Jenkyns et al, 2002;Duarte et al, 2004aOliveira et al, 2005;Hesselbo et al, 2007;Suan et al, 2008a;Pittet et al, 2014). According to cyclostratigraphy, the negative shift in δ 13 C values characterizing the T-OAE occurred ~860 kyr after the PLB/TOA (Suan et al, 2008b;Huang and Hesselbo, 2014). Oxygen-isotope values of bulk carbonates through the Upper Pliensbachian and Lower Toarcian interval fluctuate considerably.…”

Charcoal Evidence That Rising Atmospheric Oxygen Terminated Early Jurassic Ocean Anoxia

“…Because charcoal abundance is limited below this point, reworking of the older sediments appears an unlikely source for the abundant charcoal that appears in the final phases of the OAE. Published astronomically calibrated timescales for the Peniche section 23,24 , estimate a total duration of between B900 kyrs and B1.7 Myrs for the T-OAE, respectively. These timescales have previously been compared and correlated with Toarcian sediments exposed in Yorkshire, UK, which also illustrates a strong astronomical forcing within the d 13 C org record 25 .…”

“…24) prior to the initiation of the OAE. The sustained increase in charcoal abundances at 22.4 m at Peniche and 809 m at Mochras, occurs at an estimated B1 Myrs after the OAE onset (Fig.…”

The Strawberry Bank Lagerstätte reveals insights into Early Jurassic life

“…The T-OAE spanned the upper part of the underlying semicelatum Ammonite Subzone, and extended through the exaratum Ammonite Subzone, peaking at about one-third of the way through the latter (van de Schootbrugge et al 2005). The entire T-OAE isotopic excursion has been estimated as lasting 0.3-0.5 myr (Boulila et al 2014) or 0.6 ± 0.1 myr (Huang & Hesselbo 2014), with the two major anoxic episodes, termed T-OAE1 and T-OAE2, falling on either side of the 183 Ma age estimate (Ikeda & Hori 2014;Sell et al 2014). The substantial carbon isotopic anomaly has been explained by input of large volumes of isotopically light carbon from the Karoo-Ferrar basaltic province (Suan et al 2010;Burgess et al 2015).…”