* Astronomy

Jurassic 'burn-down' events explain patterns of organic matter richness in Kimmeridge Clay Formation

The sediments of the Kimmeridge Clay Formation were deposited during the Late Jurassic between around 160 and 145 million years ago, the age of the reptiles. They are the main oil source rock in the North Sea. However, within this unit beds rich in organic matter are interspersed with organic-poor sediments. New evidence demonstrates that organic-poor sediments were probably caused by post-depositional loss of organic matter during so-called 'burn-down' events.
The Kimmeridge Clay Formation is named after the English village of Kimmeridge on Dorset's 'Jurassic Coast,' a favourite haunt of fossil hunters. The sediments comprising the formation, which is particularly well exposed here, were probably deposited in shallow marine environment with an average water depth of 50-100 metres.

'We were particularly interested in the transition between organic-rich and organic-poor sediments' - Dr Ian Harding of the University of Southampton's School of Ocean and Earth Science at the National Oceanography Centre, Southampton (NOCS), and a member of the team that investigated the underlying processes.

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