Jhamarkotra
Rajasthan, Udaipur area, India
OtherP
- Type
- Marine sedimentary phosphorite (carbonate fluorapatite)
Phosphate rocks studied by Hill et al. (2024) to reconstruct redox conditions and diagenesis: U, Sr and rare earths carried by carbonate fluorapatite; samples taken at mines or from the Julius Kühn Institute archives. Palaeoproterozoic (about 1700 Ma) stromatolitic phosphorite of the Jhamarkotra Formation; varied mineralogy (fluorapatite above 90 %, or abundant dolomite, quartz or goethite); 87Sr/86Sr more radiogenic than contemporaneous seawater. Coordinates not given.
87Sr/86Sr isotope ratio, no unit Values of the same system
Standard : NIST SRM 987
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 0.714061 ± 0.002241 | 0.710946 / 0.717493 | 6 | phosphate rock (bulk) Mean and standard deviation recalculated from 6 analyses, samples IN-1, IN-2, IN-3, IN-4, IN-5, IN-6. | Hill et al. (2024), Reconstructing the depositional environment and diagenetic modificati… |
| 0.713082 ± 0.001573 | 0.710867 / 0.715613 | 6 | extracted carbonate fluorapatite (CFA) Mean and standard deviation recalculated from 6 analyses, samples IN-1, IN-2, IN-3, IN-4, IN-5, IN-6. | Hill et al. (2024), Reconstructing the depositional environment and diagenetic modificati… |
δ238U in ‰ (per mil) Values of the same system
Standard : NBL CRM 112-A
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −0.406 ± 0.045 ‰ | −0.453 / −0.363 ‰ | 3 | extracted carbonate fluorapatite (CFA) Mean and standard deviation recalculated from 3 analyses, samples IN-1, IN-3, IN-6; modern seawater at -0.38 ‰ for comparison. | Hill et al. (2024), Reconstructing the depositional environment and diagenetic modificati… |
δ234U in ‰ (per mil) Values of the same system
Standard : équilibre séculaire
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 12.43 ± 29.42 ‰ | −16.83 / 42.01 ‰ | 3 | extracted carbonate fluorapatite (CFA) Mean and standard deviation recalculated from 3 analyses, samples IN-1, IN-3, IN-6; a departure from 0 signals uranium mobility within the last two million years. | Hill et al. (2024), Reconstructing the depositional environment and diagenetic modificati… |
Deposits of the same type
- Central African Copperbelt (whole province) DR Congo and Zambia
- Witwatersrand basin South Africa
- Stelvio Italy
- Oris Italy
- Kupferschiefer, Lubin-Sieroszowice district Poland
- Timna Israël
- Datangpo-type manganese (Gaolou, Minle, Zhenxing) China
- Eyller Bruch bog iron ore Germany
Cite this page
IsoFind Atlas (2026). Jhamarkotra, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/jhamarkotra/ (accessed 2026-10-15).
@misc{isofind2026jhamarkotraisotopesignatures,
title = {Jhamarkotra, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/jhamarkotra/},
note = {Accessed 2026-10-15}
}Updated : 2026-10-15