Environmental conditions and microbial community structure during the Great Ordovician Biodiversification Event; a multi-disciplinary study from the Canning Basin, Western Australia

Abstract

The Great Ordovician Biodiversification Event (GOBE) is regarded as one of the most significant evolutionary events in the history of Phanerozoic life. The present study integrates palynological, petrographic, molecular and stable isotopic (δ 13

Lipid biomarker and stable isotopic profiles through Early-Middle Ordovician carbonates from Spitsbergen, Norway

“…The organic geochemical and stable isotopic characteristics of Early-Middle Ordovician carbonates from Spitsbergen exhibit some broad characteristics similar to those reported previously from Middle-Late Ordovician marine settings (e.g., Rohrssen et al, 2013;Spaak et al, 2017), albeit with some deviations likely due to local overprint effects, such as organic matter source inputs and local paleoenvironments. Ordovician marine sedimentary rocks and oils often contain low acyclic isoprenoids abundances, elevated hopane/sterane ratios, high 3βmethylhopanes, as found also for our sample set (e.g., Fowler & Douglas, 1984;Jacobsen et al, 1988;Summons & Jahnke, 1990;Rohrssen et al, 2013;Spaak et al, 2017).…”

“…In this scenario, biphytane could be derived from methanotrophic and/or methanogenic archaea (Kuypers et al, 2001) with the abundant 3β-methylhopanes largely sourced from microaerophilic methanotrophic bacteria. Previously, elevated 3β-methylhopanes have been reported from samples from the Late Ordovician of Laurentia and Baltica (Rohrssen et al, 2013) and more recently from the Middle Ordovician of Gondwana (Spaak et al, 2017).…”

“…δ 13 C org values-average -30.4‰-from the Oslobreen Group are similar to reports from other Early-Middle Ordovician localities (e.g., Buggisch et al, 2003;Azmy & Lavoie, 2009;Zhang et al, 2010;Edwards & Saltzman, 2016) and close to the average δ 13 C org of -29.4‰ for global bulk marine sedimentary organic matter for this time period (Hayes et al, 1999 and references therein). Some sections from South China (Zhang et al, 2010), Ireland (Jahren et al, 2013), and France (Alvaro et al, 2008) Strother et al, 1996;Tomescu et al, 2009;Rubinstein et al, 2010;Spaak et al, 2017) may be a possible explanation for these anomalously 13 C-enriched bulk isotopic values (Tomescu et al, 2009;Jahren et al, 2013). Such signature contributions are not evident in bulk δ 13 C org values from the Early-Middle Ordovician strata of Spitsbergen.…”

“…Hopanes methylated at the C-3 position are typically low in abundance relative to the regular hopane series in most Phanerozoic marine sedimentary rocks (usually within a tight range of 1-3% of C 30 αβ hopane; Peters et al, 2005;Cao et al, 2009;Rohrssen et al, 2013), but have been found to be moderately to highly elevated during certain periods in Earth history associated with low marine sulfate conditions; e.g., in the Paleoproterozoic (Brocks et al, 2005), the Mesoproterozoic (Blumenberg et al, 2012), the Middle Ordovician (Spaak et al, 2017), the Late Ordovician-Silurian (Summons & Jahnke, 1990;Rohrssen et al, 2013), and the Late Permian (Cao et al, 2009). Biological precursors of 3β-methylhopanoids include diverse groups of proteobacteria (Welander & Summons, 2012), although microaerophilic proteobacteria (typically Type I methanotrophic bacteria) are usually invoked as a major source (Farrimond et al, 2004).…”

“…Period have focused largely on intervals of the Middle Ordovician (Hatch et al, 1987;Foster et al, 1989Foster et al, , 1990Summons & Jahnke, 1990;Pancost et al, 1998Pancost et al, , 1999Ambrose et al, 2001;Edwards et al, 2013;Spaak et al, 2017), and the Late Ordovician (Rohrssen et al, 2013;Mustafa et al, 2015;Smolarek et al, 2017). Oil shales of the Middle Ordovician (Estonian kukersites; Mastalerz et al, 2003) and carbonate reservoirs containing oil source rocks from the United States (Guthrie & Pratt, 1995) and northwest China (Tarim Basin; e.g., Cai et al, 2009;Pang et al, 2013;Xiao et al, 2016) are of economic importance.…”