In autumn 2020, an approx. 850 m deep core will be 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 the 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 change: 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 and large-scale isotope anomalies.
Knowledge of this part of the Earth's history is still incomplete, but relevant, as it can serve as an analogue for present and future environmental changes. It is expected that the project will provide a "master record" for an integrated stratigraphy (bio-, cyclo-, chemo- and magnetostratigraphy) of this period, which will also be useful for Earth system modeling. 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.
Within the project, Section S5 is responsible for the interpretation of the geophysical borehole measurements and some additional measurements of physical properties on core samples in the laboratory. The interpretation focuses on the following topics, which are part of the overall objectives of the project:
- the lithological characterization of the sediments including the determination of lithological boundaries
- the determination of the paleoclimatic history of this area
- the description of sedimentary facies and sedimentary cycles
- the determination of the compaction
- an increased understanding of neotectonics and recent tectonics
- the integration and calibration of seismic reflection profiles and 3D geological models around the borehole
- the calibration of the depth assignment of core measurements to the "true" depths obtained from downhole measurements.