Oceanic chlorine enrichment preceding end-Permian warming linked to volcanic degassing - Supplement Material
Description
The supplementary materials (S1–S3) include detailed experimental data and calibration information relevant to the study. S1 comprises data from 69 conodont samples collected from 20 horizons across the Permian–Triassic boundary (PTB) of the Jianzishan section, processed via diluted buffered acetic acid dissolution and sodium polytungstate heavy liquid separation, with hand-picked specimens having a Colour Alteration Index (CAI) ≤ 2. Using a CAMECA IMS 1280HR secondary ion mass spectrometer (SIMS) at the Beijing Research Institute of Uranium Geology, 144 paired in situ analyses of δ¹⁸O and chlorine (Cl) contents were conducted—Cs⁺ ions in Gaussian mode sputtered samples with a 10 μm beam diameter and 1.5 nA intensity, detecting ¹⁶O/¹⁸O and ³⁵Cl/³⁷Cl ions via Faraday cups (signals amplified by 10¹⁰ and 10¹¹ ohms resistors, respectively) over 20 collection cycles (4 seconds each). δ¹⁸O values were normalized to VSMOW with Durango apatite for correction, and sea-surface temperatures (SSTs) were estimated using Lécuyer et al.’s (2013) equation with a δ¹⁸Oseawater value of –1‰ VSMOW and a 1‰ downward correction for SIMS-TC-EA-IRMS offset; S1 presents raw/corrected δ¹⁸O values, calculated SSTs (with 2SE precision), relative Cl ion intensities, and corrected Cl contents (wt.%) stratified by sample horizon, formation, conodont zone, and taxon. S2 provides calibration data for Cl content analysis: apatite reference materials (Durango, MGMH128441, TUBAF37, TUBAF38) were analyzed in two sessions, with linear fitting between relative Cl ion intensities and true Cl contents generating calibration curves with R² > 0.99, alongside raw ion intensity data (IP, ³⁵Cl, ³⁷Cl) for reference materials. S3 includes electron probe microanalyzer (EPMA) data for 60 conodont specimens, measuring major elements (CaO, Cl, F, MgO, MnO, FeO, P₂O₅, etc.) to characterize apatite composition, complemented by derived molar ratios (Ca/5, F/1, Cl/1, OH⁻) and mole fractions of F, Cl, and OH⁻ in apatite.