Finding
We suggest that the history of δ 13 C in coal may reflect isotopic changes in atmospheric CO 2 caused by interactions of the short-term and long-term carbon cycles, in addition to factors in the photosynthetic process.
Paper
Global mapping of carbon isotope ratios in coal
Abstract
Abstract We present stable carbon isotope ratios ( δ 13 C) in 95 coals from 10 countries on a global δ 13 C map and trace the relationship between δ 13 C and coal production over geologic time. In addition, we compare δ 13 C trends in coal as determined from samples and as calculated independently from trends in the δ 13 C of atmospheric carbon dioxide (CO 2 ). We show that the δ 13 C values measured in coal display a wide range (− 27.4‰ to − 23.7‰). Furthermore, the δ 13 C values in Cenozoic coals are systematically lighter than those in Paleozoic coals. We made independent estimates of δ 13 C values in coal by tracing the derivation of carbon from atmospheric CO 2 , from its incorporation in plants to the resulting coals. The resulting δ 13 C histories in coal also show a trend toward lighter values. We suggest that the history of δ 13 C in coal may reflect isotopic changes in atmospheric CO 2 caused by interactions of the short-term and long-term carbon cycles, in addition to factors in the photosynthetic process.
Authors
N. Suto, H. Kawashima
Journal
Journal of Geochemical Exploration