Details

Autor(en) / Beteiligte

• Came, R E
• Eiler, J M

Titel

Global temperatures during the Paleozoic determined using the new Delta47 paleotemperature proxy

Ist Teil von

• Eos (Washington, D.C.), 2006-12, Vol.87 (52)

Erscheinungsjahr

2006

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Modeling studies have shown that atmospheric CO2 concentrations during much of the Paleozoic Era (570- 245 Ma before present) were several times modern levels (Berner, 1991, 1994; Caldeira and Kasting, 1992; Franccois and Walker, 1992). However, due to the inapplicability of traditional paleotemperature proxies for the distant geologic past, very little is known about the link between the high atmospheric CO2 concentrations and earth surface temperatures. While temperature estimates for the Paleozoic have been generated using modeled atmospheric CO2 as a forcing mechanism (Berner, 1994), temperature estimates based on the delta18O of carbonate shells suggest that atmospheric CO2 and earth surface temperatures were decoupled at certain times during the Paleozoic, specifically during the Silurian Period (438-408 Ma) (Veizer et al., 2000). However, post-depositional alteration of fossil carbonates and the inability to constrain the influence of seawater delta18O dramatically limit our ability to interpret the delta18O record. In this study, we present new evidence of ocean temperatures during the Paleozoic using the recently developed Delta47 paleotemperature proxy (Ghosh et al., 2006). Our results suggest that the overall Phanerozoic trend in delta18O may be primary in nature, although it is evident that post-depositional alteration can either raise or lower the delta18O of fossil carbonates. In addition, our results suggest that global temperatures during the Carboniferous (360-286 Ma before present) and the Silurian are consistent with the modeled atmospheric CO2 concentrations, supporting the hypothesis that atmospheric CO2 concentrations and earth surface temperatures are strongly coupled.