4.1 Monitor Range, Nevada, USA
Detailed carbon isotope data have been published from the Monitor Range section, documenting the HICE and other minor excursions (Murphy et al., 1979; Finney et al., 1999; Jones et al., 2016). The new I/(Ca+Mg) ratios from this section show relatively low values throughout the Katian and Hirnantian (Fig. 2), with average values in the Dicellograptus ornatus graptolite biozone at ~1.5 μmol/mol, declining to 0 μmol/mol in the Paraorthograptus. pacificus toDiceratograptus murnis biozones, and remaining at 0 μmol/mol to the uppermost part of the section where values rise to an average of ~1.5 μmol/mol. δ34SCASdata from this section show an average of +36‰ throughout much of the lower Hanson Creek Formation, with a protracted fall beginning in the late Katian D. ornatus biozone and reaching minimum values of +26‰ in the early Hirnantian M. extradinarious biozone. Within the late Hirnantian M. persculptus biozone, δ34SCAS values increase to an average of +29‰ and continue to increase to +35‰ in the Silurian RhuddanianDistomodus kentuckyensis conodont biozone.