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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Magnetic reorientation induced by pressure solution: A potential mechanism for orogenic-scale remagnetizations
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Magnetic reorientation induced by pressure solution: A potential mechanism for orogenic-scale remagnetizations

机译：压力溶液引起的磁重取向：造山带规模磁化的潜在机制

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摘要

New paleomagnetic analyses of Triassic, Cretaceous and Eocene strata in the south-central Pyrenees show evidence for a widespread remagnetization, located along the southern border of the Axial Zone, the Internal Sierras, and the northern part of the Jaca-Pamplona basin. This remagnetization, always reversed in polarity, was acquired after an extensive period of Late Eocene-Early Oligocene folding and tilting in the area, and affects limestones, sandstones, marls and red beds. In addition, a characteristic prefolding component was identified in 30% of Upper Cretaceous and Triassic red beds. These results, together with a revaluation of previously published paleomagnetic data from the central Pyrenees, indicate that the spatial distribution of the postfolding remagnetization coincides with that of a domain of pressure solution cleavage. A relationship between the intensity of the remagnetization and the characteristic (prefolding component) with respect to the density of cleavage surfaces, leads us to propose a mechanism for the remagnetization related to the development of pressure solution cleavage that is framed within the tectonic evolution of the central Pyrenees. Partial dissolution of rock under tectonic compression leads to the liberation and subsequent accumulation of insoluble minerals in cleavage planes. Magnetic grains are part of the relatively insoluble residue, and they reorient in the presence of the ambient field after they are freed during dissolution of the rock matrix. Chemical reequilibrium (dissolution and/or neoformation of magnetic carriers) during this process cannot be excluded. The remagnetization mechanism we propose can help to explain widespread remagnetizations in low to moderately deformed rocks without the need of large-scale migration of orogenic fluids. (C) 2007 Elsevier B.V. All rights reserved.
机译：在比利牛斯山中南部的三叠纪，白垩纪和始新世地层进行了新的古磁学分析，显示了沿轴带的南部边界，内部山脉和哈卡-潘普洛纳盆地北部的广泛磁化作用的证据。这种磁化总是极性反转，是在该地区晚始新世-早渐新世的广泛折叠和倾斜之后获得的，并影响了石灰石，砂岩，泥灰岩和红层。此外，在上白垩纪和三叠纪红层中有30％可以识别出特征性的折叠前成分。这些结果，再加上对比利牛斯山中部以前发表的古磁数据的重新评估，表明折叠后磁化的空间分布与压力溶液裂解域的空间分布相吻合。磁化强度与特性（预折叠分量）相对于劈裂面密度之间的关系，使我们提出了一种与高压溶液劈裂发展有关的磁化机理，这种机理被构造在构造的演化过程中。比利牛斯山脉中部。在构造压缩作用下岩石的部分溶解导致解理平面中不溶性矿物的释放和随后的堆积。磁性颗粒是相对不溶残留物的一部分，在岩石基质溶解过程中被释放后，它们会在环境磁场的存在下重新定向。不能排除此过程中的化学再平衡（磁性载体的溶解和/或新形成）。我们提出的磁化机制可以帮助解释低至中度变形岩石中的广泛磁化现象，而无需大规模造山流体的迁移。 （C）2007 Elsevier B.V.保留所有权利。

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