• journal_title：Geology
• Contributor：Claudia I. Mora ; Steven G. Driese ; Paula G. Seager
• Publisher：Geological Society of America
• Date：1991-
• Format：text/html
• Language：en
• Identifier：10.1130/0091-7613(1991)019<1017:CDITPA>2.3.CO;2
• journal_abbrev：Geology
• issn：0091-7613
• volume：19
• issue：10
• firstpage：1017

Stable carbon-isotope compositions of pedogenic carbonate occurring in three clay-rich vertic paleosols within Paleozoic red-bed successions in central Pennsylvania provide a record of past pedogenic environments and can be used to estimate CO₂ pressure (P_CO2) of the Paleozoic atmosphere. The δ¹³C values of carbonate nodules from paleosols in the deltaic lower Bloomsburg Formation (Upper Silurian) reflect the contribution of carbon from marine groundwater or fossils, coupled with low biological activity. The δ¹³C values of carbonate rhizocretions from stratigraphically high paleosols in the Bloomsburg Formation, and in the alluvial Catskill (Upper Devonian) and Mauch Chunk (Upper Mississippian) Formations, suggest an extensive C₃ flora and significant contribution of atmospheric CO₂. Paleozoic atmospheric CO₂ levels inferred from δ¹³C of pedogenic carbonate are significantly higher than present levels.