/* DATA DESCRIPTION: Citation: Choi, Sarang; Park, Jung-Woo; Im, Sunghwan; Kim, Wonnyon; Choi, Sun Ki: Structural formula allocations and hydrothermal temperature estimates derived from vein-center chlorite compositions at the Onnuri Oceanic Core Complex [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.996124 (dataset in review), In: Choi, S et al.: Geochemical, Mineral Chemical, and Petrological Dataset of Serpentinites and Talc-Rich Metasomatites from the Onnuri Oceanic Core Complex, Central Indian Ridge [dataset bundled publication]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.996097 (dataset in review) Abstract: Mineral structural formula re-calculations (atoms per formula unit, apfu) based on 28 oxygen equivalents and derived late-stage hydrothermal crystallization temperatures were obtained from vein-filling chlorite cores within the proximal metasomatic zones of the Onnuri Oceanic Core Complex, Central Indian Ridge, during the 2019 and 2022 R/V ISABU dredge operations (RD1912, RD1913, RD2208). The aim was to place precise thermodynamic constraints on the late-stage cooling profile of focused V1 hydrothermal conduits, defining the thermal baseline prior to crystallization-driven fracturing. EPMA major element datasets of vein-center chlorites were processed through structural inversion frameworks. Crystallization temperatures were computed and cross-validated using two independent geothermometers: the empirical AlIV-in-chlorite model of Cathelineau (1988) and the semi-empirical low-to-medium temperature thermodynamic approach of Bourdelle et al. (2013). Keyword(s): Chlorite geothermometry; Hydrothermal conduit cooling; Thermal decay References: Cation site occupancy in chlorites and illites as a function of temperature (1988). Clay Minerals, 23(4), 471-485, https://doi.org/10.1180/claymin.1988.023.4.13 Bourdelle, Franck; Parra, Teddy; Chopin, Christian; Beyssac, Olivier (2013): A new chlorite geothermometer for diagenetic to low-grade metamorphic conditions. Contributions to Mineralogy and Petrology, 165(4), 723-735, https://doi.org/10.1007/s00410-012-0832-7 Coverage: LATITUDE: -11.420833 * LONGITUDE: 66.407000 MINIMUM DEPTH, sediment/rock: 0 m * MAXIMUM DEPTH, sediment/rock: 0 m Event(s): RD2208_DREG * LATITUDE: -11.420833 * LONGITUDE: 66.407000 * ELEVATION: -2160.0 m * METHOD/DEVICE: Dredge (DRG) * COMMENT: Geomorphology: Detachment fault surface. Lithology: Diabase, Serpentinite, Talc-rich metasomatite, Breccia Parameter(s): Event label (Event) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) DEPTH, sediment/rock [m] (Depth sed) * GEOCODE * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) Lithology/composition/facies (Lithology) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) Sample number (Sample no) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) Point number (Point no) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) Mineral phase (Mineral phase) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) Texture (Texture) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: Textural domain Silicon dioxide [%] (SiO2) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Titanium dioxide [%] (TiO2) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Aluminium oxide [%] (Al2O3) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Chromium(III) oxide [%] (Cr2O3) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Iron oxide, FeO [%] (FeO) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Manganese oxide [%] (MnO) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Magnesium oxide [%] (MgO) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Calcium oxide [%] (CaO) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Sodium oxide [%] (Na2O) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Potassium oxide [%] (K2O) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Total [%] (Total) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * COMMENT: wt. % Aluminium (IV) concentration in atoms per formula unit [apfu] (Al(IV)) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) Temperature, calculated [°C] (T cal) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * METHOD/DEVICE: Calculated, chlorite geothermometer (Cathelineau, 1988) (URI: https://doi.org/10.1180/claymin.1988.023.4.13) Temperature, calculated [°C] (T cal) * PI: Choi, Sarang (https://orcid.org/0000-0003-4942-8625, csr7824@gmail.com) * METHOD/DEVICE: Calculated, chlorite geothermometer (Bourdelle et al., 2013) (URI: https://doi.org/10.1007/s00410-012-0832-7) License: Creative Commons Attribution 4.0 International (CC-BY-4.0) (URI: https://creativecommons.org/licenses/by/4.0/) (License comes into effect after moratorium ends) Status: Curation Level: Enhanced curation (URI: https://wiki.pangaea.de/wiki/Curation_levels) Size: 228 data points */ Event Depth sed [m] Lithology Sample no Point no Mineral phase Texture (Textural domain) SiO2 [%] (wt. %) TiO2 [%] (wt. %) Al2O3 [%] (wt. %) Cr2O3 [%] (wt. %) FeO [%] (wt. %) MnO [%] (wt. %) MgO [%] (wt. %) CaO [%] (wt. %) Na2O [%] (wt. %) K2O [%] (wt. %) Total [%] (wt. %) Al(IV) [apfu] T cal [°C] (Calculated, chlorite geotherm...) T cal [°C] (Calculated, chlorite geotherm...) RD2208_DREG 0 Talc-rich metasomatite RD2208-12 RD2208-12-Chl1 Chlorite Vein 1 30.48 0.00 16.85 0.01 11.51 0.13 25.26 0.08 0.08 0.01 84.42 0.91 231 263 RD2208_DREG 0 Talc-rich metasomatite RD2208-12 RD2208-12-Chl2 Chlorite Vein 1 30.75 0.02 16.69 0.00 10.99 0.15 26.13 0.10 0.07 0.01 84.92 0.91 231 256 RD2208_DREG 0 Talc-rich metasomatite RD2208-12 RD2208-12-Chl3 Chlorite Vein 1 30.76 0.03 17.09 0.00 11.42 0.12 25.97 0.06 0.06 0.00 85.51 0.93 238 273 RD2208_DREG 0 Talc-rich metasomatite RD2208-12 RD2208-12-Chl5 Chlorite Vein 1 30.56 0.02 17.06 0.01 11.00 0.19 26.24 0.07 0.02 0.01 85.18 0.94 241 261 RD2208_DREG 0 Talc-rich metasomatite RD2208-12 RD2208-12-Chl6 Chlorite Vein 1 31.15 0.00 16.49 0.04 12.30 0.14 25.35 0.09 0.08 0.01 85.66 0.88 221 225 RD2208_DREG 0 Talc-rich metasomatite RD2208-04 RD2208-04-Chl(S2V)-1 Chlorite Vein 1 30.96 0.00 15.93 0.01 13.84 0.26 24.48 0.12 0.04 0.01 85.65 0.87 218 227 RD2208_DREG 0 Talc-rich metasomatite RD2208-04 RD2208-04-Chl(S2V)-2 Chlorite Vein 1 30.48 0.02 15.84 0.00 13.11 0.24 24.39 0.12 0.02 0.01 84.24 0.88 221 241 RD2208_DREG 0 Talc-rich metasomatite RD2208-04 RD2208-04-Chl(S2V)-3 Chlorite Vein 1 31.81 0.00 15.93 0.02 12.48 0.09 24.43 0.25 0.17 0.04 85.22 0.80 196 170 RD2208_DREG 0 Talc-rich metasomatite RD2208-04 RD2208-04-Chl(S2V)-4 Chlorite Vein 1 32.56 0.00 14.20 0.01 12.26 0.03 23.99 0.34 0.14 0.04 83.57 0.67 154 136 RD2208_DREG 0 Talc-rich metasomatite RD2208-04 RD2208-04-Chl(S2V)-5 Chlorite Vein 1 32.08 0.03 15.19 0.00 12.06 0.03 25.19 0.24 0.10 0.02 84.94 0.77 186 161 RD2208_DREG 0 Talc-rich metasomatite RD2208-04 RD2208-04-Chl(S2V)-6 Chlorite Vein 1 32.69 0.01 14.41 0.00 10.81 0.09 26.55 0.17 0.07 0.02 84.82 0.73 173 149 RD2208_DREG 0 Talc-rich metasomatite RD2208-04 RD2208-04-Chl(S2V)-7 Chlorite Vein 1 32.34 0.00 15.21 0.00 11.10 0.13 25.38 0.19 0.12 0.01 84.48 0.75 180 151