Data from: An expanded Smithian-Spathian (Early Triassic) boundary from a reefal build-up record in Oman: Implications for conodont taxonomy, high-resolution biochronology and the carbon isotope record

Sedimentological analysis (S1) The rock samples for the sedimentological analysis were recovered during two individual fieldtrips in 2015 and 2017. The sedimentological analysis was achieved via a qualitative description of the of the lithology by observations in the field and via further analysis of the samples wich were sent to the University of Zurich. The figures for the microstructures were obtained by cutting the rocks into thin sections at the University of Lausanne. Conodont samples for Unitary Association Method (S2 and S3) A total of 60 samples was collected for conodonts, 26 from Wadi Musjah and 34 from Jebel Aweri. The spacing between the samples varies between 10–40 cm in the Wadi Musjah section and 0.5–3 m in the Jebel Aweri section. From Wadi Musjah, samples of 1–3 kg of carbonate rock material were dissolved with a 10 % buffered acetic acid solution following the procedure of Jeppsson et al. (1999). In Jebel Aweri, the same procedure was applied to 10–15 kg samples. The residues were treated by heavy liquid separation using sodium polytungstate (Jeppsson & Anehus 1999), then sieved with a 0.075-mm mesh. The heavy fraction was handpicked under a binocular microscope and selected conodont elements were coated with carbon and illustrated using Scanning Electron Microscopy (SEM) (JEOL JSM-6010). Uncoated elements were illustrated with a Keyence VHX 6000 digital microscope. Five sections from Oman (Wadi Musjah (this study), Jebel Aweri (this study), Jebel Safra (Orchard 1995), Radio Tower (Chen et al. 2019) and Wadi Bani Khalid (Chen et al. 2019)) were included in the analysis. Taxonomic revisions were made to ensure the consistency of the data set using all published material. Carbon isotope data (S4) We analyzed the micritic matrix of 50 carbonate rock samples from Wadi Musjah and 61 samples from Jebel Aweri for bulk carbonate carbon isotopes (δ13Ccarb). The samples were carefully cleaned and cut into slabs in order to recover unaltered micrite. The most homogenous part was drilled on a sawed surface with a diamond-tipped drill to produce a fine powder. All samples were processed at the Institute of Mineralogy and Geochemistry of Lausanne University and measured with a GasBench II connected to a Finnigan MAT DeltaPlus XL mass spectrometer with a He-carrier gas system (Spötl and Vennemann, 2003). Reproducibility (n=3 per run) of replicate analysis was better than 0.1 ‰ for standards and 0.15 ‰ for sediment samples. All reported carbonate carbon isotope results are in the standard δ notation (‰ deviation versus VPDB). Conodont biochronozones across the Smithian-Spathian boundary (S5) Conodont biochronozones from Oman and South China calibrated against U-Pb ages. Intercalibrated with ammonoid biochronozones from Oman and China and the δ13Ccarb records from Jebel Aweri, Wadi Musjah, Qiakong, Laren, Shanggang and Lilong. Timing of Early Triassic after Bayesian age-depth model by Widmann (2019, thesis), Ammonoid zones after Brayard & Bucher (2008) and Brühwiler et al. (2009, 2010, 2012). South China conodont biochronozones after Leu et al. (subm.).