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Anisotropy of magnetic susceptibility as an indicator for palaeocurrent analysis in folded turbidites (Outer Western Carpathians, Poland)
Sedimentology ( IF 2.6 ) Pub Date : 2020-06-10 , DOI: 10.1111/sed.12770
Aleksandra Stachowska 1 , Maciej Łoziński 2 , Michał Śmigielski 2 , Anna Wysocka 2 , Leszek Jankowski 3 , Piotr Ziółkowski 4
Affiliation  

The anisotropy of magnetic susceptibility is a well‐known geological proxy in revealing the directional tectonic and sedimentological features of rocks, although it can be ambiguous in situations where these two factors co‐occur. This paper demonstrates the usefulness of the anisotropy of magnetic susceptibility in determining palaeotransport directions in turbiditic rocks that underwent subsequent thrusting and folding. This study demonstrates that the magnetic lineation is largely unsuitable as a palaeocurrent direction proxy, and suggests that the imbrication of magnetic foliation is better in such cases. Moreover, the anisotropy of magnetic susceptibility results were analyzed in reference to a joint and fold study within the framework of the regional structural geology. Magnetic fabric investigations were conducted in the eastern part of the Outer Western Carpathians (south‐east Poland). During the study, a total of 191 oriented palaeomagnetic samples were collected from three outcrops (Nasiczne, Dwernik and Hoczew) in the Krosno Beds, Silesian Unit. For the purpose of sedimentological analysis, 121 m of turbidite successions were documented and 126 directional sedimentary structures were measured. The magnetic anisotropy of sandstones revealed typical sedimentary fabrics, often overprinted by variably intense tectonic deformation. Oblate susceptibility ellipsoids from Nasiczne showed tilt coherent with the palaeoflow direction, whereas the rocks from Dwernik and Hoczew contained triaxial magnetic fabric developed during compressional palaeostress. This paper suggests that medium‐grained and coarse‐grained sandstones, preferably with high mica content, are the most suitable for palaeotransport reconstructions among the studied lithologies.

中文翻译:

磁化率的各向异性作为折叠浊质中古流分析的指标(波兰西部喀尔巴阡山脉)

磁化率各向异性是揭示岩石定向构造和沉积学特征的众所周知的地质特征,尽管在这两个因素同时发生的情况下它可能是模棱两可的。本文证明了磁化率的各向异性在确定经历了随后的逆冲和褶皱作用的湍流岩石中古运输方向的确定方面的有用性。这项研究表明,磁力线在很大程度上不适合用作古流方向的替代物,并表明在这种情况下磁化作用的岩化效果更好。此外,磁化率结果的各向异性是在区域构造地质学框架内进行的联合和折叠研究的基础上进行分析的。在喀尔巴阡山脉西部地区(波兰东南部)的东部进行了磁性织物调查。在研究过程中,从西里西亚单元克罗斯诺河床的三个露头(Nasiczne,Dwernik和Hoczew)总共收集了191个定向古地磁样品。为了进行沉积学分析,记录了121 m的浊积岩演替,并测量了126个定向沉积结构。砂岩的磁各向异性显示出典型的沉积构造,常常被强烈的构造变形所覆盖。Nasiczne的扁率磁化椭球显示出与古流向一致的倾斜,而Dwernik和Hoczew的岩石含有在压缩古应力作用下发育的三轴磁性织物。
更新日期:2020-06-10
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