ISOTOPIC RECORDS OF BRACHIOPOD SHELLS FROM THE RUSSIAN PLATFORM - EVIDENCE FOR THE ONSET OF MID-CARBONIFEROUS GLACIATION

Abstract

We performed isotopic analyses of Carboniferous brachiopod shells from the Russian Platform to examine global and regional environmental change along the western and eastern margins of Laurussia during the formation of Pangea, and specifically to examine the isotopic evidence for the onset of mid-Carboniferous glaciation. Shell preservation was evaluated from shell microstructure, cathodoluminescence, trace element content and isotopic comparison with matrix material. Most interior nonluminescent (NL) prismatic shell appears to be chemically well preserved as indicated by low to undetectable Si, Al, Fe and Mn contents. With minor exception, NL shell δ¹³C and δ¹⁸O values are higher than those of corresponding cements and matrix.