Terra (Silver Bear)
Northwest Territories, Great Bear Lake, Camsell River sector, Canada
Other hydrothermalAg (Ni, Co, Bi, U)
- Type
- Native silver and Ni-Co arsenide veins (five-element type)
Terra mine, also called Silver Bear, with a conformable sulfide zone interpreted as exhalative (lead model age 1767 Ma, Jory, 1964). Veins with native silver, Ni-Co arsenides, sulfarsenides, hematite, sulfosalts, native bismuth and sulfides, locally with pitchblende, in volcano-sedimentary roof pendants of the Great Bear batholithic complex (Wopmay orogen, about 1860-1875 Ma); uranium and silver production from 1930 to 1983. Changkakoti et al. (1986): steep, little radiogenic galena lead, highly radiogenic carbonates; multiple and poorly homogenised lead sources, mineralisation age proposed at about 1500 Ma; carbonate Sr from 0.709 to 0.720, above the initial Sr of the Echo Bay volcanics (0.702 ± 0.003). Indicative coordinates: mine position from its Mindat entry (65°36′15″ N, 118°06′55″ W).
206Pb/204Pb isotope ratio, no unit Values of the same system
Standard : NIST SRM 981
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 15.981 | 1 | vein galena Single analysis (AC/L1/SB). Composition of the ore fluid at deposition according to the authors. | Changkakoti et al. (1986), Pb and Sr isotope compositions of hydrothermal minerals from t… | |
| 20.141 ± 2.363 | 17.734 / 23.93 | 5 | vein carbonates (calcite and dolomite) Mean and standard deviation recalculated from 5 analyses, 17.734 to 23.930 (713(B)/SB, calcite 20.457; 711/SB, dolomite 19.860; 513/82(B)/SB, calcite 17.734; 2V/1L/SB, dolomite 23.930; 1/7V/3L/SB, calcite 18.723). Present-day ratios, not corrected for in situ decay of uranium in the carbonates. | Changkakoti et al. (1986), Pb and Sr isotope compositions of hydrothermal minerals from t… |
207Pb/204Pb isotope ratio, no unit Values of the same system
Standard : NIST SRM 981
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 15.405 | 1 | vein galena Single analysis (AC/L1/SB). Composition of the ore fluid at deposition according to the authors. | Changkakoti et al. (1986), Pb and Sr isotope compositions of hydrothermal minerals from t… | |
| 15.842 ± 0.251 | 15.607 / 16.254 | 5 | vein carbonates (calcite and dolomite) Mean and standard deviation recalculated from 5 analyses, 15.607 to 16.254 (713(B)/SB, calcite 15.855; 711/SB, dolomite 15.812; 513/82(B)/SB, calcite 15.607; 2V/1L/SB, dolomite 16.254; 1/7V/3L/SB, calcite 15.680). Present-day ratios, not corrected for in situ decay of uranium in the carbonates. | Changkakoti et al. (1986), Pb and Sr isotope compositions of hydrothermal minerals from t… |
208Pb/204Pb isotope ratio, no unit Values of the same system
Standard : NIST SRM 981
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 35.766 | 1 | vein galena Single analysis (AC/L1/SB). Composition of the ore fluid at deposition according to the authors. | Changkakoti et al. (1986), Pb and Sr isotope compositions of hydrothermal minerals from t… | |
| 39.607 ± 2.402 | 37.416 / 43.646 | 5 | vein carbonates (calcite and dolomite) Mean and standard deviation recalculated from 5 analyses, 37.416 to 43.646 (713(B)/SB, calcite 39.690; 711/SB, dolomite 38.858; 513/82(B)/SB, calcite 37.416; 2V/1L/SB, dolomite 43.646; 1/7V/3L/SB, calcite 38.423). Present-day ratios, not corrected for in situ decay of uranium in the carbonates. | Changkakoti et al. (1986), Pb and Sr isotope compositions of hydrothermal minerals from t… |
87Sr/86Sr isotope ratio, no unit Values of the same system
Standard : NIST SRM 987
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 0.71547 ± 0.0028 | 0.71369 / 0.71965 | 4 | vein carbonates (calcite and dolomite) Mean and standard deviation recalculated from 4 analyses, 0.71369 to 0.71965 (713(B)/SB, calcite 0.71965; 1/7V/3L/SB, calcite 0.71369; 711/SB, dolomite 0.71435; 513/82(B)/SB, calcite 0.71418). Rb (ppm), Sr (ppm), 87Rb/86Sr: 713(B)/SB 0.5785, 75.34, 0.0222; 1/7V/3L/SB 0.5645, 36.78, 0.0444; 711/SB 0.4320, 44.51, 0.0281; 513/82(B)/SB 0.4232, 39.59, 0.0309. Very low Rb/Sr: measured ratios approach those at deposition. | Changkakoti et al. (1986), Pb and Sr isotope compositions of hydrothermal minerals from t… |
Deposits of the same type
- Northrim Canada
- Norex Canada
- Smallwood Canada
- Contact Lake Canada
- McDermitt United States
- Turquoise Ridge (Getchell trend) United States
- Getchell United States
- Mike (Carlin Trend) United States
Cite this page
IsoFind Atlas (2026). Terra (Silver Bear), isotope signatures. https://www.isofind.tech/isotopes/en/deposits/terra-silver-bear/ (accessed 2026-10-22).
@misc{isofind2026terrasilverbearisotopesignatu,
title = {Terra (Silver Bear), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/terra-silver-bear/},
note = {Accessed 2026-10-22}
}Updated : 2026-10-22