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Early Silurian positive δ 13 C excursions and their relationship to glaciations, sea‐level changes and extinction events
Author(s) -
Loydell David K.
Publication year - 2007
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.1090
Subject(s) - conodont , acritarch , paleontology , geology , extinction event , gondwana , palynology , extinction (optical mineralogy) , sea level , carbonate , excursion , biostratigraphy , oceanography , pollen , biological dispersal , chemistry , population , ecology , demography , structural basin , sociology , biology , organic chemistry , political science , law
Abstract Evidence is presented from the upper Aeronian, lower Sheinwoodian and middle Homerian demonstrating that positive δ 13 C excursions in the lower Silurian are the result of increased carbonate weathering and probably also enhanced burial of organic carbon coincident with sea‐level falls resulting from growth of ice sheets on the South American part of Gondwana. Graptolite extinctions are coincident with the δ 13 C excursions, whereas major conodont extinction events (Ireviken and Mulde) are not, but conversely, occur at times of high sea level. This suggests very different controls on graptolite and conodont global diversity patterns. Palynological studies suggest that netromorph acritarchs may have been opportunists that flourished during positive δ 13 C excursion intervals. Copyright © 2007 John Wiley & Sons, Ltd.