文章基本信息

标题：Magnetic minerals and magnetic properties of the Siwalik Group sediments of the Karnali river section in Nepal
本地全文：下载
作者：Pitambar Gautam ; Azumi Hosoi ; Kamal Raj Regmi 等
期刊名称：Earth, Planets and Space
电子版ISSN：1880-5981
出版年度：2014
卷号：52
期号：5
页码：337-345
DOI：10.1186/BF03351645
出版社：Springer Verlag
摘要：Sandstones and siltstones collected from the Siwalik molasse sequence (~ 16 to 5 Ma) of the Karnali river section have been studied for their magnetic properties. Behavior of the specimens during demagnetization (of the NRM and IRM) and magnetic susceptibility vs. temperature data suggest that goethite, maghemite/magnetite, and hematite are the main magnetic minerals in the section. Goethite, carrying a recent component, is the dominant magnetic mineral in the fine-grained lithologies from the lower part. Maghemite and magnetite, which also carry a secondary remanence, occur in the sandstones from the upper part. Hematite, mainly of detrital origin, is present in the whole sequence. The magnetic fabric is defined by mainly oblate AMS ellipsoids and a low degree of anisotropy (P′ < 1.20). The magnetic lineations (declinations: 75°–130° or 245°–310°; peak orientation: 290°/2.8°) are subparallel to the fold axes/bedding strikes/thrust fronts (WNW-ESE). The initial sedimentary-compactional fabric has been overprinted by a secondary tectonic fabric, which was probably induced by mild deformation active in the compressive tectonic setting.