CO (sub 2) as the driver of changes in Silurian climate?

Bradley D Cramer; Matthew R Saltzman

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Abstract

CO (sub 2) as the driver of changes in Silurian climate?

Bradley D Cramer and Matthew R Saltzman

Abstracts with programs - Geological Society of America, Vol.36(5), p.543

Geological Society of America, 2004 annual meeting

11/2004

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Abstract

A major early Silurian positive carbon isotope excursion began at or near the top of the Pterospathodus amorphognathoides conodont biozone (herein referred to as the Ireviken Excursion), and is recorded in sections in Europe, Australia and North America. We have documented the shift in carbonate carbon in three successions in the mid-continent of North America, also conducting paired carbon isotope analyses of carbonate and organic carbon on the section of the Wayne Formation in central Tennessee. The results indicate that a positive shift in delta (super 13) C (sub carb) of +3.9ppm coincided with a minimum in delta (super 13) C (sub org) of -30.1ppm. This data indicate that pCO (sub 2) was increasing during the onset of the Ireviken Excursion. Subsequently, the delta (super 13) C (sub carb) curve decreased to a stable baseline near +1ppm in the upper part of the Maddox, while the delta (super 13) C (sub org) curve increased back to baseline. The rate and timing of changes in the two isotopic records reveal a complex, counter-intuitive relationship suggesting that high organic carbon burial initially coincided with increasing pCO (sub 2) during the Early Silurian Ireviken Excursion. This is proposed to reflect warming in polar regions that switched the site of deep water formation to low latitudes. As a result, organic carbon burial increased in the anoxic deep oceans, which provided a negative feedback on rising pCO (sub 2) levels. The alteration of deep ocean circulation also lowered nutrient availability in shelf environments, which severely affected the biota and allowed a healthy carbonate factory to develop throughout the tropics.

Australasia

Australia

Carbon Dioxide

Europe

Marine Environment

North America

Stratigraphy

United States

biota

biozones

C-13/C-12

carbon

central Tennessee

Conodonta

isotope ratios

isotopes

microfossils

Middle Silurian

nutrients

organic carbon

paleoclimatology

paleoenvironment

Paleozoic

Pterospathodus amorphognathoides

shelf environment

Silurian

stable isotopes

Tennessee

tropical environment

Wayne Formation

Details

Title: Subtitle: CO (sub 2) as the driver of changes in Silurian climate?
Creators: Bradley D Cramer - Ohio State University, Department of Geological Sciences Columbus, OH USA United States
Matthew R Saltzman
Resource Type: Abstract
Publication Details: Abstracts with programs - Geological Society of America, Vol.36(5), p.543
Conference: Geological Society of America, 2004 annual meeting
Publisher: Geological Society of America (GSA)
ISSN: 0016-7592
Alternative title: Geological Society of America, 2004 annual meeting
Language: English
Date published: 11/2004
Academic Unit: Earth and Environmental Sciences; International Programs; Office Of The Provost
Record Identifier: 9984240806902771

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