Magnetic anisotropy fabrics from the Cascadia accretionary prism
Magnetic anisotropy fabrics from the Cascadia accretionary prism
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卡斯卡迪亚吸积棱镜的磁各向异性织物
DOI：
10.2973/odp.proc.sr.146-1.217.1995
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Takaharu Sato
中科院分区：
文献类型：
--
作者：
B. Housen;Takaharu Sato
对从Cascadia吸积棱柱采集的495个样品的磁各向异性组构进行了测量，以表征矿物择优取向组构在变形过程中的发展。通过高场和低场磁化率的比较，确定了顺磁粘土矿物和亚铁磁性微量矿物(磁铁矿、云母、磁黄铁矿)对磁化率组构的相对贡献。888和891位具有磁化率各向异性(AMS)组构，主要受亚铁磁性矿物控制。889/890和892号站位具有不同程度受顺磁粘土和亚铁磁性矿物控制的AMS组构。岩石磁性实验表明，几乎所有的样品中都存在磁铁矿和磁性硫化物(绿泥石和/或磁黄铁矿)。尽管这些沉积物中存在复杂的磁性矿物学，但所有地点的AMS组构与观察到的结构吻合得很好。特别是，888号和891号站位似乎具有类似的磁性矿物学，以及相似的沉积环境、年龄和地层。以888站位为未变形参照物，891站位的AMS结果表明构造组构叠加较弱。
Magnetic anisotropy fabrics were measured in 495 specimens collected from the Cascadia accretionary prism to characterize the development of mineral preferred orientation fabrics during deformation. Comparison of high-field and low-field susceptibilities was used to determine the relative contributions of the paramagnetic clay minerals and the ferrimagnetic trace minerals (magnetite, greigite, pyrrhotite) to the magnetic susceptibility fabrics. Sites 888 and 891 have anisotropy of magnetic susceptibility (AMS) fabrics that are controlled primarily by the ferrimagnetic minerals. Sites 889/890 and 892 have AMS fabrics that are controlled, to varying degrees, by both paramagnetic clays and the ferrimagnetic minerals. Rock magnetic experiments indicate that both magnetite and magnetic sulfides (greigite and/or pyrrhotite) are present in nearly all the specimens. The AMS fabrics from all sites agree well with the observed structures in spite of the complex magnetic mineralogy in these sediments. In particular, Sites 888 and 891 appear to have comparable magnetic mineralogies, along with similar depositional environments, ages, and Hthologies. Using Site 888 as an undeformed reference, a weak tectonic fabric overprint is indicated by the Site 891 AMS results.