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Paleomagnetism of Basalts from the Mid-Atlantic Ridge and the Bouvet Triple Junctionстатья Исследовательская статья
- Авторы: Maksimochkin V.I., Tselebrovskiy A.N.
- Сборник: Recent Advances in Rock Magnetism, Environmental Magnetism and Paleomagnetism (Eds. D. Nurgaliev, A.Kosterov, V. Shcherbakov, S. Spassov)
- Год издания: 2018
- Место издания: Springer
- Первая страница: 83
- Последняя страница: 96
- DOI: 10.1007/978-3-319-90437-5_7
- Аннотация: The magnetic properties of 18 basalt samples dredged from the south of the Mid-Atlantic Ridge (MAR), the region with Lat = (54.0°–55.0°) S, Long = (0.0°–2.0°) W and from the Bouvet Triple Junction (BTJ) with Lat = (53.5°–54.5°) S, Long = (3.0°–5.0°) E was investigated. The basalts age was determined from spreading rate, distribution of anomalous geomagnetic field (Bulychev et al. in Seafloor chronology in the region of the Bouvet lithospheric plate triple junction. Pleiades Publishing, 2000) at the sampling region and magnetochronological scale (Gradstein et al. in The Geologic Time Scale, 2012). Their ages fluctuate from 0.1 to 5.2 Ma, i.e. covered the Brunhes (9 samples), Matuyama (5 samples), Gauss (3 samples) and Gilbert (1 sample) Chrones. The growth of Curie temperatures from 90 up to 480 °C with the increase of basalts ages, and the decrease in natural remanent magnetization (NRM) due to low-temperature oxidation of titanomagnetite (TM) were observed. The average values of basalts NRM of the Brunhes, Matuyama, and Gauss Chrones was calculated. For MAR basalts NRMmid = 18.7, 11.0 and 2.8 A/m, respectively, and for the basalts of the BTJ—NRMmid = 18.5, 9.2, 3.2 A/m, respectively. There has been a tendency for Vr parameter—NRM normalized to the residual saturation magnetization (Mrs), to decrease, as the basalts age approaches the Brunhes-Matuyama boundary. The paleointensity of the geomagnetic field (Hpl), determined from no more than 3.5 Ma basalts NRM by the Thellier-Coe procedure, ranged from 16 to 42.5 A/m. For the most of the samples, a satisfactory correlation between Vr and the Hpl was found. The virtual axial dipole moment (VADM) values we calculated were fairly close to the averaged values of the VADM from the World Paleomagnetic Bank (WPB) of the Borok Observatory (http://www.brk.adm.yar.ru/palmag/index.html). The obtained results testify to the fact that NRM and Vr variations of basalts of the south of the MAR and the BTJ from the Brunhes and Matuyama Chrones can be caused not only by the formation conditions, but also by variations of the geomagnetic field. The definition of Hpl can be used to clarify the age of basalts and the geodynamic features of the spreading in the areas of mid-oceanic ridges.
- Добавил в систему: Целебровский Алексей Николаевич