Applicability of Muscovite/Biotite Ti geothermometers: A Case Study of Ziyuan Ductile Shear Zone in Northeast Guangxi

doi:10.19657/j.geoscience.1000-8527.2024.140

Abstract

Abstract:

Different stress regimes and strain rates in nature can influence the transition temperature of rocks from brittleness to ductility, estimating the deformation and metamorphism temperatures of mylonite in ductile shear zones is crucial for interpreting thermochronological results. To assess the applicability of geothermometers(biotite/muscovite Ti geothermometers) in ductile shear zones, our study employed mineral dynamic recrystallization of mylonite and plastic deformation features, such as EBSD quartz <c>-axis fabrics, to estimate the deformation and metamorphism temperatures of Ziyuan ductile shear zones in Northeastern Guangxi, ranging from 400 to 550 ℃. Through the utilization of electron probe analysis techniques, chemical composition analyses were conducted on newly formed fine-grained biotite and muscovite resulting from dynamic recrystallization during ductile shearing. By employing biotite/muscovite Ti thermometers, the metamorphic deformation temperature of mylonite in the Ziyuan ductile shear zone were estimated to be between 409-528 ℃ and 458-605 ℃, respectively. Through comparative analysis, the temperatures obtained using geothermometers were essentially consistent within the allowable error range with those estimated using plastic deformation features, providing a basis for the application of biotite/muscovite Ti thermometers in extensional ductile shear zones.

Key words: Northeast Guangxi, ductile shear zone, mylonite, geothermometer, metamorphic-deformation temperature

CLC Number:

P588.3

LIU Kun, LI Saisai, XIN Liangwei, SHI Chunyan, GENG Jieli. Applicability of Muscovite/Biotite Ti geothermometers: A Case Study of Ziyuan Ductile Shear Zone in Northeast Guangxi[J]. Geoscience, 2025, 39(03): 774-786.

Figures/Tables 12

References 66

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样品号	采样位置	基质矿物组合	残斑矿物组合	长石变形特征	石英变形特征	估算温度(℃)
Z21002	N26°09'50.83″, E110°43'19.02″	Qtz+Ms +Bt+Kfs	Qtz+Ms+Bt+Kfs	显微破裂+塑性拉长	亚颗粒旋转+ 颗粒边界迁移	400~550
Z21004	N26°09'28.79″, E110°43'55.64″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	颗粒边界迁移	400~550
Z21010	N21°57'29.72″, E110°01'55.52″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	颗粒边界迁移	400~550
Z21012	N21°58'10.61″, E110°02'50.87″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	颗粒边界迁移	400~550
Z21032	N21°52'24.05″, E109°53'02.01″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	颗粒边界迁移	400~550
Z21041	N21°51'54.71″, E109°50'30.60″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	亚颗粒旋转+ 颗粒边界迁移	400~550

样品号	采样位置	基质矿物组合	残斑矿物组合	长石变形特征	石英变形特征	估算温度(℃)
Z21002	N26°09'50.83″, E110°43'19.02″	Qtz+Ms +Bt+Kfs	Qtz+Ms+Bt+Kfs	显微破裂+塑性拉长	亚颗粒旋转+ 颗粒边界迁移	400~550
Z21004	N26°09'28.79″, E110°43'55.64″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	颗粒边界迁移	400~550
Z21010	N21°57'29.72″, E110°01'55.52″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	颗粒边界迁移	400~550
Z21012	N21°58'10.61″, E110°02'50.87″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	颗粒边界迁移	400~550
Z21032	N21°52'24.05″, E109°53'02.01″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	颗粒边界迁移	400~550
Z21041	N21°51'54.71″, E109°50'30.60″	Qtz+Ms+Bt+Pl	Qtz+Ms+Bt+Pl	显微破裂+塑性拉长	亚颗粒旋转+ 颗粒边界迁移	400~550

样品	Z21002		Z21004			Z21010				Z21012				Z21032	Z21041
矿物	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms
SiO₂	44.66	45.78	45.36	46.58	45.89	46.71	47.59	45.95	45.33	46.22	46.01	46.58	46.53	47.21	46.08
TiO₂	0.99	0.88	0.99	1.25	1.14	0.99	0.52	0.84	1.40	0.80	0.88	0.86	1.06	1.03	0.87
Al₂O₃	33.90	33.21	31.78	33.79	34.73	26.53	29.08	33.88	32.57	34.16	34.07	34.52	34.82	33.04	33.93
FeO	2.08	2.09	2.59	2.85	2.11	2.29	2.45	2.21	2.36	2.12	2.18	2.28	1.98	2.84	2.40
MnO	0	0.06	0.04	0	0.03	0.02	0.06	0.03	0	0.01	0	0	0.03	0.07	0.05
MgO	0.87	0.93	1.21	1.20	0.95	1.08	1.2	1.11	1.22	1.31	1.22	1.19	1.21	1.21	0.85
CaO	0.01	0	0.02	0.10	0.02	0	0	0.01	0.05	0	0	0	0	0.35	0
Na₂O	0.35	0.29	0.30	0.35	0.47	0.35	0.30	0.33	0.31	0.51	0.35	0.32	0.44	0.35	0.36
K₂O	11.13	10.95	10.87	10.73	10.57	10.19	10.17	11.12	11.00	10.65	11.16	11.05	10.98	10.15	11.00
Total	94.35	94.47	93.24	97.05	95.91	88.64	91.36	95.68	94.34	95.81	95.98	97.09	97.15	96.40	95.54
Si	3.05	3.11	3.13	3.08	3.05	3.38	3.31	3.08	3.09	3.08	3.07	3.08	3.06	3.13	3.09
Al^IV	0.95	0.89	0.87	0.92	0.95	0.62	0.69	0.92	0.91	0.92	0.93	0.92	0.94	0.87	0.91
Al^VI	1.77	1.76	1.71	1.72	1.78	1.64	1.70	1.76	1.70	1.76	1.76	1.76	1.76	1.72	1.77
Ti	0.05	0.04	0.05	0.06	0.06	0.05	0.03	0.04	0.07	0.04	0.04	0.04	0.05	0.05	0.04
Fe	0.12	0.12	0.15	0.16	0.12	0.14	0.14	0.12	0.13	0.12	0.12	0.13	0.11	0.16	0.13
Mn	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
Mg	0.09	0.09	0.12	0.12	0.09	0.12	0.12	0.11	0.12	0.13	0.12	0.12	0.12	0.12	0.09
Ca	0	0	0	0.01	0	0	0	0	0	0	0	0	0	0.02	0
Na	0.05	0.04	0.04	0.04	0.06	0.05	0.04	0.04	0.04	0.07	0.05	0.04	0.06	0.04	0.05
K	0.97	0.95	0.96	0.91	0.90	0.94	0.90	0.95	0.96	0.91	0.95	0.93	0.92	0.86	0.94
Mg/(Mg+Fe)	0.43	0.44	0.45	0.43	0.44	0.46	0.47	0.47	0.48	0.52	0.50	0.48	0.52	0.43	0.39
P96(GPa)	0.08	0.25	0.33	0.23	0.13	1.02	0.74	0.17	0.28	0.16	0.15	0.16	0.16	0.34	0.17
WMT15	451	454	477	494	477	502	409	445	528	445	454	447	480	475	437

样品	Z21002		Z21004			Z21010				Z21012				Z21032	Z21041
矿物	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms	Ms
SiO₂	44.66	45.78	45.36	46.58	45.89	46.71	47.59	45.95	45.33	46.22	46.01	46.58	46.53	47.21	46.08
TiO₂	0.99	0.88	0.99	1.25	1.14	0.99	0.52	0.84	1.40	0.80	0.88	0.86	1.06	1.03	0.87
Al₂O₃	33.90	33.21	31.78	33.79	34.73	26.53	29.08	33.88	32.57	34.16	34.07	34.52	34.82	33.04	33.93
FeO	2.08	2.09	2.59	2.85	2.11	2.29	2.45	2.21	2.36	2.12	2.18	2.28	1.98	2.84	2.40
MnO	0	0.06	0.04	0	0.03	0.02	0.06	0.03	0	0.01	0	0	0.03	0.07	0.05
MgO	0.87	0.93	1.21	1.20	0.95	1.08	1.2	1.11	1.22	1.31	1.22	1.19	1.21	1.21	0.85
CaO	0.01	0	0.02	0.10	0.02	0	0	0.01	0.05	0	0	0	0	0.35	0
Na₂O	0.35	0.29	0.30	0.35	0.47	0.35	0.30	0.33	0.31	0.51	0.35	0.32	0.44	0.35	0.36
K₂O	11.13	10.95	10.87	10.73	10.57	10.19	10.17	11.12	11.00	10.65	11.16	11.05	10.98	10.15	11.00
Total	94.35	94.47	93.24	97.05	95.91	88.64	91.36	95.68	94.34	95.81	95.98	97.09	97.15	96.40	95.54
Si	3.05	3.11	3.13	3.08	3.05	3.38	3.31	3.08	3.09	3.08	3.07	3.08	3.06	3.13	3.09
Al^IV	0.95	0.89	0.87	0.92	0.95	0.62	0.69	0.92	0.91	0.92	0.93	0.92	0.94	0.87	0.91
Al^VI	1.77	1.76	1.71	1.72	1.78	1.64	1.70	1.76	1.70	1.76	1.76	1.76	1.76	1.72	1.77
Ti	0.05	0.04	0.05	0.06	0.06	0.05	0.03	0.04	0.07	0.04	0.04	0.04	0.05	0.05	0.04
Fe	0.12	0.12	0.15	0.16	0.12	0.14	0.14	0.12	0.13	0.12	0.12	0.13	0.11	0.16	0.13
Mn	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
Mg	0.09	0.09	0.12	0.12	0.09	0.12	0.12	0.11	0.12	0.13	0.12	0.12	0.12	0.12	0.09
Ca	0	0	0	0.01	0	0	0	0	0	0	0	0	0	0.02	0
Na	0.05	0.04	0.04	0.04	0.06	0.05	0.04	0.04	0.04	0.07	0.05	0.04	0.06	0.04	0.05
K	0.97	0.95	0.96	0.91	0.90	0.94	0.90	0.95	0.96	0.91	0.95	0.93	0.92	0.86	0.94
Mg/(Mg+Fe)	0.43	0.44	0.45	0.43	0.44	0.46	0.47	0.47	0.48	0.52	0.50	0.48	0.52	0.43	0.39
P96(GPa)	0.08	0.25	0.33	0.23	0.13	1.02	0.74	0.17	0.28	0.16	0.15	0.16	0.16	0.34	0.17
WMT15	451	454	477	494	477	502	409	445	528	445	454	447	480	475	437

样品	Z21002		Z21004			Z21010				Z21012				Z21032	Z21041
矿物	Bt	Bt	Bt	Bt	Bt	Bt	Bt	Bt	Bt	Bt	Bt	Bt	Bt	Bt	Bt
SiO₂	33.04	34.63	35.17	34.02	34.10	36.03	34.39	34.71	35.60	36.53	36.38	36.78	37.08	35.98	34.40
TiO₂	2.10	1.90	1.97	2.32	2.33	2.28	1.80	2.30	2.44	1.60	1.43	1.83	1.76	1.97	1.99
Al₂O₃	17.86	18.24	17.28	17.49	17.74	17.01	16.73	17.18	17.20	17.67	17.65	17.54	17.58	17.38	17.86
FeO	23.97	23.23	22.57	23.22	23.09	22.18	22.00	21.91	22.61	16.34	16.36	16.40	16.08	23.41	22.80
MnO	0.34	0.45	0.34	0.48	0.39	0.36	0.36	0.39	0.41	0.20	0.18	0.34	0.23	0.35	0.41
MgO	5.85	5.80	7.04	6.43	6.74	7.18	7.22	7.52	7.18	12.35	12.54	12.29	12.53	5.95	6.77
CaO	0	0.02	0.02	0.01	0.12	0	0.01	0	0.02	0	0	0.02	0.02	0	0
Na₂O	0.09	0.03	0.06	0.08	0.10	0.14	0.05	0.06	0.09	0.09	0.03	0.03	0.05	0.09	0.07
K₂O	8.97	9.48	9.64	9.22	9.07	9.77	9.92	9.83	9.82	9.92	9.88	9.96	9.85	9.41	9.47
Total	92.83	94.42	94.95	93.54	94.14	95.38	92.73	94.37	96.04	95.22	94.99	95.63	95.75	95.55	93.77
Si	2.68	2.74	2.77	2.72	2.70	2.80	2.76	2.74	2.77	2.76	2.76	2.77	2.78	2.82	2.72
Al^IV	1.32	1.26	1.23	1.28	1.30	1.20	1.24	1.26	1.23	1.24	1.24	1.23	1.22	1.18	1.28
Al^VI	0.38	0.44	0.37	0.36	0.36	0.36	0.35	0.34	0.34	0.34	0.34	0.33	0.34	0.42	0.39
Ti	0.13	0.11	0.12	0.14	0.14	0.13	0.11	0.14	0.14	0.09	0.08	0.10	0.10	0.12	0.12
Fe	1.63	1.54	1.49	1.55	1.53	1.44	1.48	1.45	1.47	1.03	1.04	1.03	1.01	1.53	1.51
Mn	0.02	0.03	0.02	0.03	0.03	0.02	0.02	0.03	0.03	0.01	0.01	0.02	0.01	0.02	0.03
Mg	0.71	0.68	0.83	0.77	0.80	0.83	0.86	0.88	0.83	1.39	1.42	1.38	1.40	0.69	0.80
Ca	0	0	0	0	0.01	0	0	0	0	0	0	0	0	0	0
Na	0.01	0.01	0.01	0.01	0.02	0.02	0.01	0.01	0.01	0.01	0	0	0.01	0.01	0.01
K	0.93	0.96	0.97	0.94	0.92	0.97	1.02	0.99	0.97	0.96	0.96	0.96	0.94	0.94	0.96
X_Ti	0.05	0.04	0.04	0.05	0.05	0.05	0.04	0.05	0.05	0.03	0.03	0.04	0.03	0.04	0.04
X_Mg	0.25	0.25	0.29	0.27	0.28	0.30	0.31	0.32	0.30	0.49	0.49	0.49	0.49	0.25	0.28
X_Fe	0.57	0.55	0.53	0.55	0.54	0.52	0.53	0.52	0.53	0.36	0.36	0.36	0.35	0.55	0.54
Ps(GPa)	0.15	0.15	0.24	0.24	0.24	0.35	0.35	0.35	0.35	0.17	0.17	0.17	0.17	0.22	0.24
WBT15	605	599	562	599	593	579	543	570	587	472	458	487	483	597	572
Fe²⁺	1.51	1.44	1.39	1.45	1.43	1.35	1.38	1.36	1.38	0.99	0.99	0.99	0.97	1.43	1.41
Fe³⁺	0.11	0.10	0.09	0.10	0.10	0.09	0.09	0.09	0.09	0.05	0.05	0.05	0.04	0.10	0.10