ABSTRACT

We performed petrographic, cathodoluminescence, electron-microprobe, and isotopic analyses of brachiopod shells from the Permian Kapp Starostin Formation in West Spitsbergen to reevaluate the >9‰ negative shift in d¹³C and d¹⁸O values reported in 1989 by M. Gruszczynski, S. Halas, A. Hoffman, and K. Malkowski. The d¹³C and d¹⁸O values within shells typically decrease with increasing luminescence, indicating diagenesis. Nonluminescent (NL) shell d¹³C and d¹⁸O values are 4.3‰ and 6.2‰ higher, respectively, than those of associated cements and matrix. For the same stratigraphic interval, d¹³C and d¹⁸O values of the NL shells are equal to, or substantially greater than, those reported by Gruszczynski et al. For the interval where those authors saw a 10‰ d¹³C shift, our mostly NL Spiriferella polaris shells only yield a 1.5‰ shift. Gruszczynski et al. reported a 9‰ d¹⁸O shift, whereas we observe almost none. Our results strongly suggest that the >9‰ isotopic shifts reported in Gruszczynski et al. are diagenetic artifacts. On the other hand, their Kazanian-Tatarian d¹³C maximum of 7.5‰ is substantiated by our data. This Late Permian ¹³C maximum represents the highest spiriferid brachiopod d¹³C values in the Phanerozoic and, within stratigraphic uncertainty, correlates with the whole-rock d¹³C maximum in East Greenland and northwestern Europe. The d¹³C shift may reflect changes in global storage of organic carbon indicated by coal-volume changes in the Late Permian.

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