TOARCIAN ANOXIC EVENT IN EUROPE - AN ORGANIC GEOCHEMICAL STUDY

Journal article

A total of 48 sediment samples, comprising both black shales and associated organic-poor interbeds, were examined from Toarcian organic-rich sections throughout Europe. Despite being contemporaneous deposits of a single oceanic anoxid event (OAE), the molecular organic geochemical characteristics, particularly the steroidal hydrocarbons, of the black shales are highly variable. This suggests different depositional environments in different regions. Although the sedimentary organic matter is dominantly of marine origin in all areas, environmental conditions apparently varied considerably, arguing against a simple oxygen-minimum layer model for the accumulation of organic-rich sediments. Furthermore, molecular evidence of hypersaline conditions at two sites suggests that salinity stratification may have been an important factor for black shale deposition in some areas. A more complex model for the widespread deposition of organic-rich sediments during the Toarcian OAE is presented.

Authors: Farrimond, P; Eglinton, G; Brassell, S; Jenkyns, H

• Publication status: Published
• Journal: MARINE AND PETROLEUM GEOLOGY
• Volume: 6
• Issue: 2
• Pages: 136-147
• Publication date: 1989-05-01
• DOI: 10.1016/0264-8172(89)90017-2
• ISSN: 0264-8172
• Language: English