In the end of 2020, an approx. 650 m deep core was drilled at Prees in Shropshire, England, as part of the ICDP project JET (Integrated Understanding of the Early Jurassic Earth System and Timescale). The main objective of this project is to obtain and characterize a complete and continuous sedimentary archive of the 25 million years of the Early Jurassic. The Early Jurassic period (200-175 million years) was a period of extreme environmental changes: Rapid transitions from cold or ice ages to super-greenhouse events have been documented, including global changes in sea level and organic carbon distribution, as well as mass extinctions.
Knowledge of this part of the Earth's history is supposed to serve as an analogue for present and future environmental changes. The project will provide a "master record" for an integrated stratigraphy (bio-, cyclo-, chemo- and magnetostratigraphy) of this period. In addition, the project will allow the reconstruction of the local and global palaeoenvironment and the driving mechanisms and feedbacks responsible for environmental changes in the Early Jurassic.
The analysis of geophysical borehole measurements contributes to interpretations with respect to the lithological characterization of sediments and their boundaries, but also allows the description of sedimentary cycles related to orbital parameters, insolation and therefore to paleoclimatic history.
First results of these borehole measurements include a lithological classification which is based on cluster analysis of solely physical data. Furthermore, core-log integration has been carried out and a first attempt towards astrochronology and cyclostratigraphy has been made.