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A facies model of contourites

等高线相模型

基本信息

批准号：
07640594
负责人：
ITO Makoto
金额：
$ 1.22万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640594/
关键词：
Contourite Turbidite Bottom current Kuroshio Current 堆積相鮮新統更新統房総半島

项目摘要

Lithofacies characteristics of bottom-current-influenced sandy deposits (sandy contourites) were studies based on detailed outcrop analyzes of late Cenozoic deep-sea successions in the Boso Peninsula and those from some other late Cenozoic sedimentary basins, such as the Kakegawa, Miyazaki, and Kumano Basins. Sandy contourites are characterized by traction structures, such as parallel lamination and ripple cross-lamination, together with minor inverse grading and wave ripple-lamination. In particular, ripple cross-lamination is commonly associated with mud drapes and flaser and lenticular bedding. These sedimentary structures, in general, do not show any regular vertical sequences, such as the Bouma sequence in turbidites.In general, sandy contourites are better sorted than associated turbidites and have sharp or gradational basal contacts with underlying turbidites or hemipelagites, and sharp upper contacts with overlying hemipelagites. Framework composition of sandy contourites, in contracts, is largely equivalent to that of associated turbidites. Paleocurrents of sandy contourites are variable in time and space and spatial and temporal variations intypes of turbidite-to-contourites continuums suggests varying intensity of deep-sea bottom currents in the late Cenozoic sedimentary basins.Variations in speed and direction of deep-water currents under the modern Kuroshio Current and its associated deep-sea environments have been documented off the Japanese Islands. Thus, analogous processes appear to have been responsible for the deposition of sandy contourites in the late Cenozoic sedimentary basins in Southwest Japan.

通过对房总半岛晚新生代深海层序和卡克川、宫崎、熊野等晚新生代沉积盆地的详细露头分析，研究了受底流影响的桑迪沉积（桑迪等深岩）的岩相特征。桑迪等深流岩以牵引构造为特征，如平行纹层和涟漪交错纹层，以及少量的反级配和波浪波纹纹层。特别是，涟漪交错纹层通常与泥披覆、压扁和透镜状层理有关。这些沉积构造一般不显示任何规则的垂向层序，如浊积岩中的Bouma层序。一般而言，桑迪等深流岩比相关浊积岩分选更好，与下伏浊积岩或半长岩有明显或渐变的基底接触，与上覆半长岩有明显的上部接触。在合同中，桑迪等深流岩的框架组成与伴生浊积岩的框架组成基本相同。桑迪等深流的古水流在时间和空间上是可变的，浊流-等深流连续体类型的时空变化表明晚新生代沉积盆地中深海底流强度的变化。因此，类似的过程似乎已负责桑迪等深流沉积在晚新生代沉积盆地在日本西南部。