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RESEARCH ON THE BASIS OF ACCRETIONARY PRISM FORMATION IN VIEW OF DEFORMATION AND DIAGENESIS OF PELAGIC SEDIMENTS

远洋沉积物变形与成岩作用下的增生棱柱形成基础研究

基本信息

批准号：
10304037
负责人：
OGAWA Yujiro
金额：
$ 18.75万
依托单位：
UNIVERSITY OF TSUKUBA
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10304037/
关键词：
pelagic sediments accretionary prism deformation diagenesis texture scanning electron microscope

项目摘要

These three year project on deep-sea sediments (pelagic sediments) has done the research on the process of sedimentation and accretion to the accretionary prism. We mainly focused the project on the mechanism and the role of the pelagic sediments when they are accreted. The main target is the textural change during accretion, particularly how the sediments work during the diagenesis and deformation ; for the original pelagic sediments on the open ocean suffer compaction due to vertical loading, while they get horizontal stress with higher temperature and pressure within the accretionary prisms. The sediments have their own depositional environments and age control, so that the biostratigraphic data by means of microfossils, and provenance determination are also important. In addition the chemical and mineralogical change of the minerals and bulk rocks are also related to the physical change. Many methods were used, but the SEM is above all the most important way to know the texture of … More the sediments. We obtained many results as follows ;The representative pelagic sediment minerals are clays, and they are locally different ; smectite is largely deposited in front of volcanic arcs ; siliceous microfossils are dominant within the pelagic sediments, and they are useful for determination of the ages ; smectite-bearing horizon is most important for the accretionary prism formation ; this zone becomes the decollement (the mechanical boundary) of the prism ; siliceous deposits in the open ocean have only very slow change of texture and chemical/mineralogncal diagenesis, while they vastly change into chert during incorporation into the accretionary prism ; this means the pelagic sediments have the most important role for the formation of the accretionary prism ; pelagic sediments are responsible for the large structures which are characterized by duplex structures ; reconstruction of the accretionary prism need radiolarian biostratigraphy and chromian spinel sandstone petrography. Less

这三年的深海沉积物（远洋沉积物）项目对增生棱柱体的沉积和增生过程进行了研究。我们主要集中在该项目的机制和作用的远洋沉积物时，他们的加积。主要目标是在加积过程中的结构变化，特别是沉积物在成岩和变形过程中的作用;因为原始远洋沉积物在开阔海洋上由于垂直载荷而受到压实，而它们在加积棱柱内受到水平应力，温度和压力较高。这些沉积物有其独特的沉积环境和时代控制，因此，通过微体化石获得的生物地层资料和物源确定也很重要。此外，矿物和岩石的化学和矿物学变化也与物理变化有关。使用了许多方法，但扫描电子显微镜首先是了解材料纹理的最重要方法 ...更多信息沉淀物。研究结果表明：本区中上层沉积物中的代表矿物为粘土，且具有局部差异性，蒙皂石主要沉积在火山弧前，硅质微体化石在中上层沉积物中占优势，对时代的确定有重要意义，含蒙皂石层位对增生棱柱体的形成有重要意义;这一地带成为滑脱带开阔洋中硅质沉积物的结构和化学/矿物成岩作用变化很慢，而它们在进入增生棱柱体的过程中大量转变为硅质岩;这表明，远洋沉积物对加积棱体的形成起着最重要的作用; 2远洋沉积物对以双重构造为特征的大型构造起着重要作用; 3加积棱体的重建需要进行放射虫生物地层学和铬尖晶石砂岩岩石学研究。少