“…The maturity of the Lower Palaeozoic shales is typically assessed by EqVRo that is calculated from solid bitumen reflectance or zooclast reflectance. Equivalent empirical equations have been proposed in a diversity of studies (Bertrand, 1990(Bertrand, , 1993Bertrand & Malo, 2001; Bertrand & Malo, 2012;Cole, 1994;Colţoi et al, 2016;Jacob, 1989;Landis & Castaño, 1995;Petersen et al, 2013;Schoenherr et al, 2007) and empirical correlations have been thoroughly reviewed by Hackley and Cardott (2016), Mastalerz et al (2018), Hackley and Lewan (2018), Wang et al (2019Wang et al ( , 2020 and Schmidt et al (2019).…”