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CRC 806 – Our Way to Europe: palaeomagnetic dating and environmental magnetism of sedimentary records (project F6)

Project F6 was newly established for the second phase of the CRC 806 (2013 - 2017). This project primarily aims at conducting palaeomagnetic dating in order to enhance age control on sedimentary records investigated within the framework of the CRC 806 (from both the past and the new CRC phase). Background for palaeomagnetic dating is that the Earth’s magnetic field varies in a range of time scales: from decades to millions of years. Distinctive global and local changes in inclination, declination, and intensity, which have been accurately determined in time, can be used to correlate sedimentary horizons to this pre-defined time scale. This will corroborate dating by other methods, such as luminescence dating and radiocarbon dating, carried out by CRC projects F2 and F5, respectively, and allow age models to be further refined. Three types of geomagnetic behaviour related to different time scales can be used practically within the framework of the CRC: (i) globally defined geomagnetic field excursions that have occurred over the last 120 ka, (ii) broad regional and global trends in directions and relative palaeointensity during the past 250 ka, and (iii) smaller-scale regional changes in palaeosecular variation (PSV) over the last 10 ka and potentially beyond. In addition to the palaeomagnetic dating, measurements of rockmagnetic palaeoclimate proxies, such as magnetic susceptibility, S-ratio, and other grain size and compositional indicators, are conducted on selected records to complement other proxies in reconstructing environmental and climatic histories.

vergrößern:
Sketch illustrating the scientific objectives of CRC 806 project F6

Palaeomagnetic measurements will be made using a cryogenic magnetometer (2G Enterprises) at the University of Cologne that will be upgraded with: (a) a long core sample holder, (b) in-line three-axis alternating field (AF) demagnetization coils, and (c) a direct current field coil system to impart an anhysteretic remanent magnetization (ARM) allowing determination of relative palaeointensity. This upgrade will greatly enhance analytical efficiency. Employing magnetic methods will improve both temporal constraints on sedimentary sequences studied as part of CRC 806 and our understanding of how the sedimentary environment responds to environmental and climatic changes.