Citation:

PANGAEA.996097 (dataset in review)

Name: Structural formula allocations and hydrothermal temperature estimates derived from vein-center chlorite compositions at the Onnuri Oceanic Core Complex
License: https://creativecommons.org/licenses/by/4.0/
Keywords: Chlorite geothermometry; Hydrothermal conduit cooling; Thermal decay

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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):

#	Name	Short Name	Unit	Principal Investigator	Method/Device	Comment
1	Event label	Event		Choi, Sarang
2	DEPTH, sediment/rock	Depth sed	m	Choi, Sarang		Geocode
3	Lithology/composition/facies	Lithology		Choi, Sarang
4	Sample number	Sample no		Choi, Sarang
5	Point number	Point no		Choi, Sarang
6	Mineral phase	Mineral phase		Choi, Sarang
7	Texture	Texture		Choi, Sarang		Textural domain
8	Silicon dioxide	SiO2	%	Choi, Sarang		wt. %
9	Titanium dioxide	TiO2	%	Choi, Sarang		wt. %
10	Aluminium oxide	Al2O3	%	Choi, Sarang		wt. %
11	Chromium(III) oxide	Cr2O3	%	Choi, Sarang		wt. %
12	Iron oxide, FeO	FeO	%	Choi, Sarang		wt. %
13	Manganese oxide	MnO	%	Choi, Sarang		wt. %
14	Magnesium oxide	MgO	%	Choi, Sarang		wt. %
15	Calcium oxide	CaO	%	Choi, Sarang		wt. %
16	Sodium oxide	Na2O	%	Choi, Sarang		wt. %
17	Potassium oxide	K2O	%	Choi, Sarang		wt. %
18	Total	Total	%	Choi, Sarang		wt. %
19	Aluminium (IV) concentration in atoms per formula unit	Al(IV)	apfu	Choi, Sarang
20	Temperature, calculated	T cal	°C	Choi, Sarang	Calculated, chlorite geothermometer (Cathelineau, 1988)
21	Temperature, calculated	T cal	°C	Choi, Sarang	Calculated, chlorite geothermometer (Bourdelle et al., 2013)

License:

Creative Commons Attribution 4.0 International (CC-BY-4.0) (License comes into effect after moratorium ends)

Status:

Curation Level: Enhanced curation (CurationLevelC)

Size:

228 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 Event	3 Lithology	4 Sample no	5 Point no	6 Mineral phase	7 Texture (Textural domain)	8 SiO2 [%] (wt. %)	9 TiO2 [%] (wt. %)	10 Al2O3 [%] (wt. %)	11 Cr2O3 [%] (wt. %)	12 FeO [%] (wt. %)	13 MnO [%] (wt. %)	14 MgO [%] (wt. %)	15 CaO [%] (wt. %)	16 Na2O [%] (wt. %)	17 K2O [%] (wt. %)	18 Total [%] (wt. %)	19 Al(IV) [apfu]	20 T cal [°C] (Calculated, chlorite geotherm...)	21 T cal [°C] (Calculated, chlorite geotherm...)
RD2208_DREG	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	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	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	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	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	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	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	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	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	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	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	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