Abstract

Late Sandbian–Early Katian marine carbonates from two sections in North America and one in south China were analyzed for paired δ 13C carb and δ 13C org, and revealed similar δ 13C carb but varying trends in δ 13C org stratigraphy while all sections recorded a well-known positive δ 13C carb shift. These δ 13C org records are the first through the Guttenberg δ 13C carb excursion (GICE) in China, Oklahoma, and West Virginia. In south China a positive excursion in δ 13C org is associated with the latter part of the positive δ 13C carb excursion and closely resembles trends from Iowa and Pennsylvania that have been interpreted to reflect a lowering of atmospheric pCO 2 levels. The δ 13C org trends from Oklahoma and West Virginia differ significantly from what is observed in China. This likely indicates that local changes in nutrient cycling and phytoplankton growth rates were the dominant control on 12C fractionation in Oklahoma and West Virginia, masking a possible global signal of lowered atmospheric pCO 2 levels observed in China.

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