Table 1

Zr isotopic data and Nb and Zr concentration data. ɛ 9xZr = {[(9xZr/90Zr)meas – (9xZr/90Zr)std]/(9xZr/90Zr)std} × 104, with (9xZr/90Zr)std = 0.333383 for 92Zr/90Zr, 0.217930 for91Zr/90Zr, and 0.054372 for96Zr/90Zr. The quoted analytical uncertainties for the Zr isotopic compositions and ɛZr values reflect the internal (2σmean) within-run precision. The errors of92Zr/ 90Zr refer to the least significant digits only. The ɛZr values do not include uncertainties for the standard. The 2σ long-term external reproducibilities, based on multiple measurements of the standard over a period of more than a year, are 0.3, 0.4, and 1.2 ɛunits for 92Zr/90Zr,91Zr/90Zr, and96Zr/90Zr, respectively (15).

SampleNb (ppm)Zr (ppm)93Nb/90Zr ±2σ mean92Zr/90Zr ±2σ meanɛ92Zr ±2σ meanɛ91Zr ±2σ meanɛ96Zr ±2σ mean
Estacado
Olivine + pyroxene0.473.60.253  ±  0.0200.333387  ±  120.13  ±  0.35−0.59  ±  0.66
Ilmenite83582.58  ±  0.360.333417  ±  131.01  ±  0.380.11  ±  0.381.73  ±  1.12
Whole rock0.516.40.154  ±  0.0080.333387  ±  070.11  ±  0.220.12  ±  0.260.27  ±  0.90
Chromite0.291.20.466  ±  0.0040.333388  ±  130.15  ±  0.390.75  ±  1.41
Troilite (fraction a)0.0570.830.132  ±  0.0180.333389  ±  360.17  ±  1.08−1.37  ±  1.00
Vaca Muerta
Ilmenite/troilite 56731.50  ±  0.090.333389  ±  60.19  ±  0.18−0.19  ±  0.170.67  ±  0.45
Whole rock3.9430.173  ±  0.0040.333384  ±  50.02  ±  0.16−0.14  ±  0.160.10  ±  0.36
Feldspar0.644.30.284  ±  0.0120.333383  ±  70.00  ±  0.20−0.19  ±  0.130.70  ±  0.45
Pyroxene2.5260.190  ±  0.0120.333382  ±  6−0.04  ±  0.18−0.09  ±  0.120.10  ±  0.42
Ilmenite2492082.31  ±  0.090.333400  ±  40.52  ±  0.11−0.05  ±  0.120.42  ±  0.26
Heavy minerals41184.41  ±  0.270.333406  ±  50.69  ±  0.15−0.07  ±  0.130.65  ±  0.47