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17.10.2024The Paleomagnetism laboratory helps to understand the tectonosedimentary evolution of the southern Pyrenean foreland basin during the Paleogene
The Paleomagnetism Laboratory of the CCiTUB and GEO3BCN-CSIC has collaborated on two new magnetostratigraphic studies that provide key information about the tectonic and sedimentary evolution of the south-Pyrenean foreland basin during the Paleogene, a period that spans approximately from 66 million to 23 million years ago.
The first study, published in The Depositional Record, focuses on the eastern area of this basin, in the Cadí plate, specifically in the Ripoll syncline. Using a magnetostratigraphic profile composed of 6.5 km of power (sediment thickness), covering a time range from the Paleocene to the Middle Lutetian (between 64 and 42 million years ago), the researchers analyzed the sedimentary layers and how they record the tectonic evolution of the area.
The second study, published in Marine and Petroleum Geology, reviews the tectonic and sedimentary evolution of the Àger sub-basin, located in the central part of the South Pyrenean basin. To do this, the scientists analyzed five magnetostratigraphic profiles, which spans the Lower and Middle Paleogene. These profiles, together with fossil data (biostratigraphy) from marine and terrestrial organisms, made it possible to study how sediment accumulation zones (depocenters) evolved between the Paleocene and the lower Eocene (between 66 and 49 million years ago).
The results of both studies have made it possible to establish a new chronology for these basins and a solid correlation between them. All this information has been synthesized in a series of paleogeographic maps that show the evolution of the South Pyrenean basin between the Paleocene and the lower Eocene. In addition, the studies reveal that the sedimentary systems of Pyrenean origin in the different sub-basins evolved in synchrony during the lower Eocene.
Both works have been carried out within the framework of the doctoral thesis of Philemon Juvany, carried out at the Department of Earth and Ocean Dynamics, Faculty of Earth Sciences UB, with funding from the Marie Skłodowska-Curie Innovative Training Networks (H2020-MSCA-ITN-2019) projects Signal Propagation in Source to Sink for the Future of earth Resources and Energies (S2SFuture) and PID2019-106440GB-C21 (Ministry of Science, Innovation and Universities).
What is magnetostratigraphic dating?
The geomagnetic field has undergone a multitude of non-periodic magnetic polarity reversals throughout Earth's history. Magnetostratigraphy is based on the ability of rocks to acquire a remnant magnetization parallel to the direction of the Earth's magnetic field present when they form, which allows the establishment of a zonation of sedimentary series according to their magnetic polarity. Each portion of the sedimentary record of a given polarity is called a "magnetozone". Magnetostratigraphic dating refers to the identification of "magnetozones" in the sedimentary record, which can be correlated with geomagnetic chrons of equivalent age from the Geomagnetic Polarity Time Scale.