GEOCHEMISTRY AND ORGANIC PETROGRAPHY OF THE ANNA SHALE (PENNSYLVANIAN) AND THE OCCURENCE OF PYRITE “SUNS” IN SOUTHWESTERN ILLINOIS

• Main Author: Dyson, Jacob
• Format: Others
• Published: OpenSIUC 2019
• Subjects: bituminite; black shale; cyclothem; micrinite; pyrite sun; redox
• Online Access: https://opensiuc.lib.siu.edu/theses/2579; https://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=3593&context=theses

The Anna Shale (Pennsylvanian) is an organic-rich, marine black shale that commonly overlies the Herrin (No. 6) Coal of the Carbondale Formation, Illinois Basin. Disk-shaped iron sulfide concretions, called pyrite suns, which are commonly up to 10 cm or more across are found in the lowest few centimeters of the Anna Shale in coal mines near Sparta in southwestern Illinois. This area is the only known location where pyrite suns of this size have been found, suggesting that unusual geochemical and/or depositional conditions led to their formation. The primary objective of this study was to evaluate the geochemical conditions at the time of Anna Shale deposition in the area where the pyrite suns formed.