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25.04.2024The paleomagnetism laboratory of the CCiTUB participates in a study of magnetostatigraphic dating
PhD. Bet Beamud, head of the Paleomagnetism laboratory of the CCiTUB and the GEO3BCN-CSIC, has participated in a study in which magnetostratigraphic dating has been used to determine the ages of a profile of approximately 2.5 km of power in the deformed antecountry basin of the Zagros (Iran). The age of sediments and the deformation of foreland basins are key information for reconstructing the tectonic history of orogenic belts, such as that of the Zagros. The thermal demagnetization, the measurement of the remnant magnetization and the interpretation of the results of about 200 samples have been carried out in the Paleomagnetism laboratory of the CCiTUB.
The study, led by the Iranian Mining Engineering Organization (Tehran, Iran) in collaboration with researchers from Geosciences Barcelona (GEO3BCN, CSIC), has been published in the journal 'Marine and Petroleum Geology' under the title "Age of folding in NW Lurestan arc across the Khanaqin fault by magnetostratigraphy on Aghajari growth strata, Zagros folded belt".
The study area is located on the southern flank of the NW-SE trend Emam Hassan anticlinal, located on the N-S tendency Khanaqin base fault. The ages obtained indicate that the onset of folding took place around 10 Mya and persisted until approximately 6.5 Mya. Additionally, although not the central goal of this study, the results, combined with the understanding of regional structure, illustrate the potential in-depth three-dimensional structure of the Khanaqin Seismogenic Fault, the source of the 2017 Mw 7.3 Sarpol-e Zahāb earthquake.
The fundamentals of magnetostratigraphic dating
The geomagnetic field has undergone many nonperiodic magnetic polarity inversions throughout Earth's history. Magnetostratigraphy is based on the ability of rocks to acquire a magnetization remaining parallel to the direction of the Earth's magnetic field present when they are formed, which allows establishing a zonation of the 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 in the sedimentary record of "magnetozones", which can be correlated with geomagnetic chronicles of equivalent age of the Geomagnetic Polarity Time Scale.
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