Magofond 4 campaign – southern flank, Rijser-Larsen Sea, Antarctic Plate
The Magofond 4 campaign focuses on the Earth's magnetic field over a particular period of almost 40 million years, during which the field did not reverse.
This period, known as the Cretaceous Superchron or CNS, extends from 83 to 120 million years ago. Significant variations in field strength are observed, which we are seeking to characterise, with the aim of gaining a better understanding of the field at this time and providing constraints for geodynamic models in the Earth’s core.
To do this, we use the recording of the field produced by the rocks of the oceanic crust as they cool at the axis of the ridges. By towing a magnetometer at low speed a few hundred metres above the seabed, we can observe a high-resolution signal. The few bottom magnetic profiles carried out during the first leg on the N/O Pourquoi pas? are being supplemented by surface magnetic profiles carried out during the first leg and in progress during the second leg on the N/O Marion Dufresne, to provide a substantial data set.
We are also trying to use the most remarkable variations observed to date the ocean floor and carry out palaeogeographic reconstructions for this period, hence the need to study the southern flank of the Rijser-Larsen Sea on the Antarctic plate.
