Igarapé Bahia
Pará, Carajás Northern Copper Belt (Amazonian Craton), Brazil
IOCGCu-Au
- Type
- IOCG (Cu-Au) with carbonate alteration
Neoarchean IOCG deposit of the Carajás Province (see also the Carajás entry); main mineralization around 2.55 Ga within Fe-K then chlorite alteration halos. Strongly altered and mylonitized volcano-sedimentary sequences of the Itacaiúnas Supergroup; tourmaline-bearing carbonate envelope dated at 2575 ± 12 Ma (U-Pb on monazite), late chloritization. Melo et al. (2021): tourmaline cores from +11.0 to +14.6 ‰, rims from +3.4 to +9.8 ‰.
δ11B in ‰ (per mil) Values of the same system
Standard : NIST SRM 951
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 12.8 ± 1.3 ‰ | 11 / 14.6 ‰ | 10 | tourmaline cores of the carbonate envelope, sample FD173 Mean and standard deviation recalculated from 10 analyses, +11.0 to +14.6 (FD173-4 g1 +11.0; FD173-7 g2 +14.6; FD173-8 g2 +12.8; FD173-9 g2 +13.8; FD173-11 g3 +11.6; FD173-12 g3 +12.3; FD173-14 g4 +14.5; FD173-15 g4 +13.6; FD173-17 g5 +11.4; FD173-20 g5 +12.5). Grain number noted g. Split between cores and rims inferred from the ranges of the text, which do not overlap: Supplementary Table 2 only distinguishes grains. | Melo et al. (2021), Magmatic-hydrothermal fluids leaching older seafloor exhalative rocks… |
| 6.8 ± 2.5 ‰ | 3.4 / 9.8 ‰ | 10 | tourmaline rims of the carbonate envelope, sample FD173 Mean and standard deviation recalculated from 10 analyses, +3.4 to +9.8 (FD173-1 g1 +8.9; FD173-2 g1 +8.7; FD173-3 g1 +5.7; FD173-5 g1 +4.5; FD173-6 g2 +3.5; FD173-10 g2 +9.7; FD173-13 g4 +5.7; FD173-16 g4 +3.4; FD173-18 g5 +9.8; FD173-19 g5 +8.1). Grain number noted g. Split between cores and rims inferred from the ranges of the text, which do not overlap: Supplementary Table 2 only distinguishes grains. | Melo et al. (2021), Magmatic-hydrothermal fluids leaching older seafloor exhalative rocks… |
| 18.9 ± 4.4 ‰ | 12.6 / 26.3 ‰ | 23 | disseminated tourmaline in the ore-breccia matrix, ACPS orebody Mean and standard deviation recalculated from 23 analyses, +12.6 to +26.3 (F382/228 A1A r +16.5; F382/228 A1A i +18.5; F382/228 A1A c +18.3; F382/228 A1A r +18.8; F382/228 A2A r +12.6; F382/228 A2A i +18.0; F382/228 A2A c +16.0; F382/228 A3A1 r +16.5; F382/228 A3A7 c +17.8; F382/228 4A/1 c +14.2; F382/228 4A/2 c +15.2; F382/228 4AB/1 c +13.9; F382/228 4AB/2 c +14.2; F382/236 A1A c +23.4; F382/236 A1A r +25.0; F382/236 A1A i +26.0; F382/236 A1B c +23.2; F382/236 A1B r +24.7; F382/236 A3A r +25.5; F382/236 A3A c +26.3; F382/253 A1 c +14.7; F382/253 A5 c +16.7; F382/253 A6 c +17.8). Text: 14 to 26 ‰; Table DR1 goes down to 12.6 ‰ (A2A rim, F382/228). Bluish-green and beige grains, boron inherited from marine evaporites according to the authors. | Xavier et al. (2008), Tourmaline B-isotopes fingerprint marine evaporites as the source o… |
| 7.2 ± 1.2 ‰ | 5.8 / 8.8 ‰ | 5 | disseminated ore-breccia tourmaline, sample F353/188 (high-grade ACPN orebody according to the text) Mean and standard deviation recalculated from 5 analyses, +5.8 to +8.8 (F353/188 1 c +8.8; F353/188 2 c +5.8; F353/188 3 c +7.0; F353/188 4 c +8.1; F353/188 5 c +6.3). Table DR1 assigns F353/188 to the ACPS orebody, but its values (5.8 to 8.8 ‰) are exactly those the text gives for the Fe-rich ACPN orebody; mixing with a lighter-boron fluid according to the authors. | Xavier et al. (2008), Tourmaline B-isotopes fingerprint marine evaporites as the source o… |
| 19.6 ± 1 ‰ | 18.1 / 20.6 ‰ | 7 | tourmaline from metachert fragments in the ore breccia, Furo Trinta orebody Mean and standard deviation recalculated from 7 analyses, +18.1 to +20.6 (F392/338.70 1 c +20.4; F392/338.70 3 c +18.1; F392/338.70 4 c +20.6; F392/338.70 5 c +18.6; F392/338.70 6 c +19.0; F392/338.70 7 c +20.1; F392/338.70 8 c +20.6). Text: 18.6 to 20.6 ‰ plus one analysis at 26.5 ‰; Table DR1 gives 18.1 to 20.6 ‰ and no value at 26.5 ‰. | Xavier et al. (2008), Tourmaline B-isotopes fingerprint marine evaporites as the source o… |
| 17.4 ± 1.1 ‰ | 16.2 / 18.3 ‰ | 3 | late discordant veinlet tourmaline (F382/223) Mean and standard deviation recalculated from 3 analyses, +16.2 to +18.3 (F382/223 A1 c +18.3; F382/223 A2 c +16.2; F382/223 A3 c +17.8). Text: 15.7 to 18.3 ‰; three analyses in Table DR1. | Xavier et al. (2008), Tourmaline B-isotopes fingerprint marine evaporites as the source o… |
Deposits of the same type
Cite this page
IsoFind Atlas (2026). Igarapé Bahia, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/igarape-bahia/ (accessed 2026-10-20).
@misc{isofind2026igarapebahiaisotopesignatures,
title = {Igarapé Bahia, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/igarape-bahia/},
note = {Accessed 2026-10-20}
}Updated : 2026-10-20