Carbon-isotope stratigraphy of the Lower Ordovician succession in Northeast Greenland: Implications for correlations with St. George Group in western Newfoundland (Canada) and beyond

The Lower Ordovician sequence on the Ella O Island in Northeast (N-E) Greenland is a thick shallow marine platform carbonate sequence (similar to 1415 m thick) and constitutes the major part of the Kong Oscar Fjord Group. It consists, from bottom to top, of the Antiklinalbugt, Septemberso, and Cape Weber formations, which are believed to be respectively coeval with the Watts Bight, Boat Harbour, and Catoche formations of the St. George Group in western Newfoundland, Canada. Samples were collected from outcrops at high-resolution intervals and micritic materials were extracted by microdrilling after screening their petrographic and geochemical criteria to evaluate the degree of preservation. The delta C-13 and 6180 values of well preserved micrite microsamples range from -5.2 parts per thousand to 0.5 parts per thousand (VPDB) and from -10.3 parts per thousand to -6.5 parts per thousand (VPDB), respectively. The delta C-13(carb) profile of the sequence reveals few negative shifts, which vary between similar to 2 and 4.7 parts per thousand and are associated with unconformities/disconformities, thus reflecting the effect of significant sea-level changes. The delta C-13 shifts can be correlated with counterparts on the St. George Group and also on the global Lower Ordovician delta C-13 profiles around the early Tremadoc (similar to 2.3 parts per thousand) and late Tremadoc-early Arenig (similar to 4.7 parts per thousand). (C) 2010 Published by Elsevier B.V.