Decarbonization related to continental arc magmatism as a possible mechanism for Cretaceous warming

Elevated concentrations of CO₂ have been proposed as the reason that the Cretaceous climate was 6-14°C warmer than the present, however the source of Cretaceous CO₂ is unknown [Barron, 1983]. This study examines the possibility of continental arc magmatism as a mechanism for CO2 release, specifically as a volatile produced during crustal assimilation and contact metamorphism of carbonates around plutons. Bedrock maps of the North American Cordillera (a region of active continental arc magmatism during the Cretaceous), the relative locations of the carbonates, the Cretaceous plutons, and the calculated "decarbonation zones"around the plutons. These measurements were then input in a thermal and petrologoical model in order to estimate the quantity of CO₂ released by continental arc magmatism. Testing a number of cases with varying parameters, the model found the arc-magmatism-induced temperature difference between the present and Cretaceous global climates to have a lower limit of [Delta]T < 1°C and an upper limit of 5.1 < [Delta]T < 12.3°C. Decarbonation from continental arc magmatism is shown to be a possible mechanism of paleoclimatic warming, and more work is required to either confirm or refute the hypothesis.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2012

Author dc:creator

• Brunner, Anna Elizabeth

Advisor dc:contributor.advisor

• Oliver Jagoutz.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/114357

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/114357