A new INGV study reconstructs 150.000 years of geomagnetic variations in East Africa
A team of researchers from Lancaster University (UK), theNational Institute of Geophysics and Volcanology (INGV) and the University of Ghent (Belgium) has reconstructed 150.000 years of variations in the Earth's magnetic field thanks to the analysis of sediments from the Chala Lake, located on the border between Kenya and Tanzania. These data provide valuable information on the history of our planet and represent an important reference point for other geological and climatic studies in Africa.
The Earth's magnetic field, in addition to protecting us from cosmic radiation, is a key element in understanding the Earth's internal structure and dynamics. Furthermore, its variation over time is used as a dating tool in various fields, from archaeology to volcanology. However, for some regions, such as central-eastern Africa, the available paleomagnetic data are limited and sometimes discordant.
"Thanks to this study, we have obtained a detailed picture of the variations of the magnetic field in an area crucial for the history of human evolution,” explains Anita Di Chiara, researcher at INGV. "East Africa is considered one of the areas from which hominids moved away to populate the rest of the world, perhaps precisely because of extreme climatic events.. "
Lake Chala, a crater lake located near Kilimanjaro, has been the subject of a drilling project under the international program ICDP DeepCHALLA. By analyzing the 129 meters of sediments extracted, the researchers were able to reconstruct the history of the Earth's magnetic field in the region. The dating was carried out with advanced geochronological methods, including radiocarbon and argon isotope ratios, allowing them to obtain a reliable age model.
The study identified six magnetic excursions, or periods in which the magnetic field underwent significant variations. Among these, the most recent are the Laschamp (42.000 years ago), the Mono Lake (24.000 years ago) and the Hilina Pali (about 19.000 years ago). The precision of the data obtained allowed to redefine the age of the Hilina Pali excursion between 19.000 and 21.000 years ago, improving the knowledge on the frequency and duration of magnetic field instabilities.
In addition to their importance for studies of the Earth's magnetic field, these data represent a fundamental resource for refining dating models of other African lakes, contributing to the correlation between climatic and environmental events at a global level.
"The results of this research not only improve our understanding of the evolution of the Earth's magnetic field, but also provide a methodological basis for future studies in other equatorial and Southern Hemisphere regions.” concludes Anita Di Chiara. “This is a significant step forward toward a more complete mapping of our planet's magnetic history.. "
The study, the result of an international collaboration, represents an important contribution to paleomagnetic research and opens new perspectives for the understanding of the Earth's geodynamics and its influence on the environment and life throughout geological history.
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