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Students from the School of Resources and Environment Have Published Their Research Achievements in the top international journal Geophysical Research Letters

On November 1, the top international journal Geophysical Research Letters published an online paper titled "Identification of Growth Strata: New Insights From Anisotropy Corrected Paleomagnetic Data", exploring how Earth's surface sediments reliably record past magnetic field information. The first author affiliation of the paper is Capital Normal University, and the first author is Sun Xinxin, a doctoral student from the School of Resources and Environment of our university. The paper is supported by the National Natural Science Foundation of China (42172254 and 42274095).

The magnetic field on the Earth was used for navigation in ancient China, and the nature of the earth magnetic field can help us understand the (ancient) geographical location of different regions during the Earth's historical period. The study uses a high-sensitivity superconducting magnetometer to determine the properties of the earth magnetic field during the formation of rocks in a certain region of a continent during geological periods, and study the changes of the position of continents and oceans on the earth surface in geological history, as well as the changes of the earth paleogeography and climate-environment in different geological periods. At present, there have been studies on the reliability grading evaluation of the magnetic properties recorded in rocks to determine whether rocks can reliably record the geomagnetic field information at the time of rock formation. Sedimentary rocks formed in different periods have also been widely used in this regard. However, whether the sediments can accurately record the direction of the geomagnetic field during the formation of some sedimentary basins has not been concerned. For example, the formation of structurally controlled basins and the tectonically active sediments may lead to anomalies of recorded geomagnetic inclinations.

In order to explore the influence of growth strata in the tectonically active basins on paleomagnetic inclination records and how to quickly identify growth strata, Sun Xinxin et al. conducted a study on the geomagnetic field properties and anisotropy of magnetic susceptibility (AMS) of the Miocene growth strata in the Gengma Basin on the southeastern edge of the Qinghai-Tibet Plateau and analyzed the correlation between the geomagnetic inclination and AMS data recorded by sediments during this period and the sampling location of the structure. It is found that the paleomagnetic inclination and AMS results at the growing end of the Gengma Basin edge (section A) are different from those at the stable sedimentary end of the basin (section D). The reason for the difference is that there is a growth angle in the growing strata, that is, the original bedding of the strata is not horizontal, which leads to incorrect correction of the paleomagnetic inclination and AMS data at the growing end of the basin edge.

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The study proposes a more concise method for paleomagnetic data and tectonic deposition, which eliminates the discreteness of magnetic inclination between the stable sedimentary end and the growing end of the basin. Its innovation lies in the use of AMS data to quickly identify the growth formation, quantify the growth angle of the growth formation, and correct the paleomagnetic inclination and AMS data of the growth formation. The study also provides a key new method for the correction of paleomagnetic data of tectonic basin sediments.

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The School of Resources and Environment of our university attaches great importance to the cultivation of graduate students, gives full play to the advantages of the discipline, and actively explores and reforms the cultivation of high-level and innovative talents, and has achieved good results. In the future, the School of Resources and Environment will continue to improve the training mode of high-level innovative talents, and contribute to the construction of "Double First-Class" of our university and the implementation of "Climbing Program".

Paper link: https://doi.org/10.1029/2023GL105625