Tapera Grande

São Paulo State, Serra do Itaberaba Group (central Ribeira Belt), about 50 km NE of São Paulo, Brazil

Orogenic goldAu

Type: Gold in stratiform tourmalinites and quartz-tourmaline veins

Morro da Pedra Preta volcano-sedimentary Formation (Serra do Itaberaba Group, Mesoproterozoic, submarine back-arc basin), metamorphosed under amphibolite facies (peak at 640 °C and 750 MPa). Gold prospect: metabasites, metavolcaniclastic rocks, graphitic and sulphide-rich metapelites, banded iron formation, tourmalinite-bearing metachert. Garda et al. (2009): tourmalinites from -14.4 to -7.5 ‰ and vein tourmaline from -17.8 to -11.2 ‰, too light for a marine exhalative origin even with low-temperature fractionation; crustal boron mobilized during regional metamorphism, gold deposited by immiscibility of aqueous-carbonic fluids. Coordinates not published; Quartzito about 10 km away.

δ11B in ‰ (per mil) Values of the same system

Standard : NIST SRM 951

Value	Range	n	Mineral or matrix	Source
−11.56 ± 1.82 ‰	−14.38 / −7.51 ‰	34	tourmaline of stratiform tourmalinites (metachert) Mean and standard deviation recalculated from 34 analyses, -14.38 to -7.51 (F1107 -9.08; F1107 -11.32; F1107 -10.22; F1107 -9.38; F1107 -9.56; F1107 -8.72; F1107 -10.45; F1107 -10.89; T12 -11.14; T12 -10.03; T12 -9.96; T12 -10.92; T12 -11.62; T12 -11.29; T12 -11.74; T12 -14.08; T12 -7.51; T12 -13.93; T12 -14.38; T12 -13.52; T12 -14.23; LF-10 -11.82; LF-10 -10.45; LF-10 -12.19; LF-10 -9.53; LF-10 -11.01; LJ10A -13.81; LJ10A -12.70; LJ10A -12.89; LJ10A -13.33; LJ10A -14.30; LJ10A -13.19; LJ10A -12.85; LJ10A -10.96). Less than 5 ‰ spread per sample except T12, whose xy (near -14 ‰) and t (near -11 ‰) grains form two populations.	Garda et al. (2009), Boron isotope composition of tourmalinite and vein tourmalines assoc…
−12.86 ± 1.8 ‰	−17.83 / −11.15 ‰	12	quartz vein tourmaline (sample SRT5-157) Mean and standard deviation recalculated from 12 analyses, -17.83 to -11.15 (t1 -11.78; t2 -11.97; t3 -14.50; t4 -12.87; t5 -11.49; t6 -11.15; t7 -11.86; t8 -12.83; t9 -12.24; t10 -13.21; t11 -17.83; t12 -12.54). Primary aqueous-carbonic fluid inclusions in vein quartz homogenized at 180 to 265 °C (Beljavskis, 2003).	Garda et al. (2009), Boron isotope composition of tourmalinite and vein tourmalines assoc…

Deposits of the same type

Cite this page

IsoFind Atlas (2026). Tapera Grande, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/tapera-grande/ (accessed 2026-10-19).

@misc{isofind2026taperagrandeisotopesignatures,
  title = {Tapera Grande, isotope signatures},
  author = {{IsoFind Atlas}},
  year = {2026},
  url = {https://www.isofind.tech/isotopes/en/deposits/tapera-grande/},
  note = {Accessed 2026-10-19}
}

Updated : 2026-10-19