Chengchao
Hubei, Edong ore cluster (Middle-Lower Yangtze River metallogenic belt), China
SkarnsFe
- Type
- Iron (magnetite) skarn
Largest high-grade magnetite skarn of the Middle-Lower Yangtze River belt: 280 Mt at 45 % Fe, nearly half above 53 % Fe, at the contact between granitoids (129 ± 2 Ma), a diorite (133 ± 1 Ma, zircon U-Pb in this study) and Triassic strata. Five stages: Na-K alteration, prograde skarn (garnet, pyroxene), retrograde skarn (magnetite, phlogopite, amphibole), sulphate-sulphide (anhydrite, pyrite), carbonate. Prograde fluids above 750 °C and over 50 wt% NaCl eq., iron-rich (daughter magnetite and pyrite in garnet and pyroxene); magmatic water dominant in the prograde stage, increasing meteoric water afterwards; repeated incursions of Fe-rich fluids linked to the intrusions according to Li et al. (2019). Coordinates not given.
δ18O in ‰ (per mil) Values of the same system
Standard : V-SMOW
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 5.15 ± 0.95 ‰ | 4.3 / 6.2 ‰ | 4 | prograde skarn garnet (Grt1 to Grt3 generations) Mean and standard deviation recalculated from 4 analyses, calculated fluid +7.3 to +8.9 ‰ (591 to 800 °C); Grt3 (CC354) temperature printed '52 °C', probably 552 °C. | Li et al. (2019), Mineralogy, Fluid Inclusion, and Stable Isotope Studies of the Chengcha… |
| 7.7 ‰ | 1 | prograde skarn pyroxene (CC30) Single analysis; calculated fluid +9.8 ‰ at 653 °C. | Li et al. (2019), Mineralogy, Fluid Inclusion, and Stable Isotope Studies of the Chengcha… | |
| 2.72 ± 1.37 ‰ | 0.9 / 4.8 ‰ | 11 | retrograde skarn magnetite (exoskarn) Mean and standard deviation recalculated from 11 analyses, calculated fluid +7.6 to +11.5 ‰ (550 °C) or +8.2 to +12.1 ‰ (450 °C), heavier than magmatic water through wall-rock interaction. | Li et al. (2019), Mineralogy, Fluid Inclusion, and Stable Isotope Studies of the Chengcha… |
| 9.74 ± 2.5 ‰ | 6 / 12.7 ‰ | 8 | sulphate-sulphide stage anhydrite Mean and standard deviation recalculated from 8 analyses, calculated fluid -1.5 to +6.5 ‰ (250 to 337 °C), mixing with meteoric waters. | Li et al. (2019), Mineralogy, Fluid Inclusion, and Stable Isotope Studies of the Chengcha… |
δD in ‰ (per mil) Values of the same system
Standard : V-SMOW
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −76.25 ± 20.43 ‰ | −96 / −52 ‰ | 4 | prograde skarn garnet (Grt1 to Grt3 generations) Mean and standard deviation recalculated from 4 analyses, δD decreasing from Grt1 to Grt3, magma degassing according to the authors. | Li et al. (2019), Mineralogy, Fluid Inclusion, and Stable Isotope Studies of the Chengcha… |
| −108 ‰ | 1 | prograde skarn pyroxene (CC30) Single analysis. | Li et al. (2019), Mineralogy, Fluid Inclusion, and Stable Isotope Studies of the Chengcha… | |
| −143.55 ± 12.37 ‰ | −158 / −121 ‰ | 11 | retrograde skarn magnetite (exoskarn) Mean and standard deviation recalculated from 11 analyses, very low values ascribed to magma degassing. | Li et al. (2019), Mineralogy, Fluid Inclusion, and Stable Isotope Studies of the Chengcha… |
| −81.88 ± 15.27 ‰ | −114 / −66 ‰ | 8 | sulphate-sulphide stage anhydrite Mean and standard deviation recalculated from 8 analyses. | Li et al. (2019), Mineralogy, Fluid Inclusion, and Stable Isotope Studies of the Chengcha… |
Deposits of the same type
- Hongshan-Hongniu China
- Azegour Morocco
- Santa Lucia (Buggerru) Italy
- Su Zurfuru Italy
- Rosas Italy
- Scalittas Italy
- Sarrabus Italy
- Dannemora Sweden
Cite this page
IsoFind Atlas (2026). Chengchao, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/chengchao/ (accessed 2026-10-15).
@misc{isofind2026chengchaoisotopesignatures,
title = {Chengchao, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/chengchao/},
note = {Accessed 2026-10-15}
}Updated : 2026-10-15