Table 3 Sr isotopic ratios of silicate fractions of carbonate concretions.

From: 87Sr/86Sr age determination by rapidly formed spherical carbonate concretions

Sample

fraction

87Sr/86Srmeasured*,a

87Sr/86Srcorrected*,b

tusk-shell concretion

  111401

silicate

0.707611 +/− 0.000011

0.707598

  111403

silicate

0.707640 +/− 0.000013

0.707627

  111404

silicate

0.707683 +/− 0.000014

0.707670

  111405

silicate

0.707673 +/− 0.000014

0.707659

  111406

silicate

0.707695 +/− 0.000013

0.707681

  111409

silicate

0.707621 +/− 0.000013

0.707608

matrix

  111407

silicate

0.707601 +/− 0.000011

0.707588

  111408

silicate

0.707448 +/− 0.000011

0.707434

  111410

silicate

0.707426 +/− 0.000014

0.707413

  1. Sr isotopic ratios of the silicate fractions from the concretions and surrounding matrices are clearly different from the range of values given by the calcite/aragonite fractions.
  2. *,aThe errors are 2 SE level on single measurements.
  3. 87Sr/86Sr ratio is normalized to NIST Standard Reference Material (SRM) 987 value (=0.710248). *,bThe value of repeated analysis of NIST-SRM987 during this study was 0.710261 ± 0.000005 (2 SE, n = 14).
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