Paleomagnetism and Geochronology of 2.68 Ga Dyke from Murmansk Craton, NE Fennoscandia: New Data for Earth’s Magnetic Field Regime in the Neoarchean

IF 0.9 4区地球科学 Q4 GEOCHEMISTRY & GEOPHYSICS

Izvestiya, Physics of the Solid Earth Pub Date : 2024-09-30 DOI:10.1134/S1069351324700538

R. V. Veselovskiy, A. V. Samsonov, A. V. Stepanova, Yu. O. Larionova, A. A. Arzamastsev, A. V. Travin, S. V. Egorova, K. G. Erofeeva, A. A. Kosterov, V. V. Shcherbakova, V. P. Shcherbakov, G. V. Zhidkov, V. S. Zakharov

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Abstract

We present new results of geochronological, rock magnetic, paleomagnetic and paleointensity studies of the olivine gabbro dyke located at the northern part of the Murmansk craton, NE Fennoscandia (the Kola Peninsula). According to its geochemistry, petrographic and geochronology features, the dyke belongs to the 2.68 Ga dyke swarm, as confirmed by Sm-Nd mineral isochron. We find a significant difference in the rock magnetic and paleomagnetic characteristics of the central and marginal parts of the dyke, which is independently supported by petrography and geochemistry. It is shown that the rocks of the central part of the dyke retained not only their primary mineral composition, but also the primary component of the natural remanent magnetization. We use its direction to determine the 2.68 Ga virtual geomagnetic pole for the Murmansk craton: Slat = 68.64292° N, Slong = 37.7945° E, N = 41 specimens, Plat = –73.5°, Plong = 138.9°, dp/dm = 3.2°/3.4°, paleolat = –65.9°. We also obtain reliable estimates (17 samples) of the Earth’s magnetic field intensity at ca. 2.68 Ga: VDM value is found to be 1.85 × 10²² A m² corresponding to the geomagnetic field several times weaker than the present-day field.

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来自芬诺斯坎迪亚东北部摩尔曼斯克克拉通的 2.68 Ga 堤的古地磁学和地质年代学：新元古代地球磁场机制的新数据

我们介绍了对位于芬诺斯康迪亚东北部摩尔曼斯克克拉通北部（科拉半岛）的橄榄石辉长岩堤进行地质年代、岩石磁性、古地磁和古强度研究的新结果。根据其地球化学、岩相学和地质年代学特征，该堤坝属于 2.68 Ga 堤坝群，Sm-Nd 矿物等时线证实了这一点。我们发现堤坝中心部分和边缘部分的岩石磁性和古地磁特征存在明显差异，岩石学和地球化学也独立地证实了这一点。结果表明，堤坝中央部分的岩石不仅保留了其主要矿物成分，还保留了天然剩磁的主要成分。我们利用其方向确定了摩尔曼斯克克拉通的 2.68 Ga 虚拟地磁极：Slat = 68.64292° N，Slong = 37.7945° E，N = 41 标本，Plat = -73.5°，Plong = 138.9°，dp/dm = 3.2°/3.4°，paleolat = -65.9°。我们还获得了约 2.68 Ga 时地球磁场强度的可靠估计值（17 个样本）：发现 VDM 值为 1.85 × 1022 A m2，对应的地磁场比现在的地磁场弱几倍。

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来源期刊

Izvestiya, Physics of the Solid Earth 地学-地球化学与地球物理

CiteScore

1.60

自引率

30.00%

发文量

审稿时长

6-12 weeks

期刊介绍： Izvestiya, Physics of the Solid Earth is an international peer reviewed journal that publishes results of original theoretical and experimental research in relevant areas of the physics of the Earth''s interior and applied geophysics. The journal welcomes manuscripts from all countries in the English or Russian language.