Integrated chronology of the possible last-Interglacial marine terraces, southeast Shikoku Island, southwest Japan

日本西南部四国岛东南部可能的末间冰期海洋阶地的综合年代学

• 批准号: 18500789
• 负责人: UEKI Takeyuki
• 金额: $ 2.53万
• 依托单位: National Institute of Advanced Industrial Science and Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18500789/
• 关键词: Quaternary; Shikoku; marine terrace; chronology; paleomagnetism; bohore core; Pleistocene; 地質学

This study aims to construct a methodology to determine absolute age of Quatemary geomorphology and geology that lack a tephra bed. Integrated chronology including tephra correlation, paleomagnetic measurement, optically stimulated luminescence dating and various micro-fossil biostratigraphy were planed to apply the possible Last-Interglacial marine terraces distributed to the Tano Town, southeast Shikoku Island, southwest Japan. Fluvial sediments beneath the terraces buried a valley ; this stratigraphy suggests that the sediments were deposited during Oxygen Marine Isotope Stage 6 to 5e, and fine facies would contain a wide-spread tephra bed.This study focuses on following three strategy. Valley-fill sediments were continuously sampled by borehole coring. In addition to tephra correlation, paleomagnetic measurement and optically stimulated luminescence dating were applied to core samples. Physical property measurements, facies analysis, chemical analysis, micro-fossil biostratigraphy, molluscan assemblage were combined to core samples.Three coring were made for valley-fill sediments beneath the marine terraces. However, only one core contained valley-fill sediments and lacked a tephra bed. As a result, the ages of valley-fill sediments and overlying terraces were still unclear.Paleomagnetic measurements were performed for drilled valley-fill sediments. Samples held a stable remanent magnetization with downward inclination, without 50 cm horizon range with upward or shallowly downward inclination. This exceptional inclination may result from geomagnetic excursion.

这项研究旨在构建一种方法，以确定缺乏tephra床的绝对年龄和地质学的绝对年龄。计划的综合年代学包括tephra相关性，古磁测量，光学刺激的发光日期和各种微化石生物地层学，以应用分布在西南日本东南Shikoku Island的Tano Town的可能的近距离冰河海洋露台。露台下面的河流沉积物埋在山谷中；该地层图表明，沉积物是在6至5E期间沉积的，并且优质的相位将包含宽阔的tephra床。这项研究重点是以下三种策略。通过井眼芯连续采样山谷填充沉积物。除Tephra相关性外，还将古磁测量和光学刺激的发光日期应用于核心样品。物理性质测量，相分析，化学分析，微化石生物地层学，软体动物组合结合到核心样品中。在海洋露台下方制作了三芯，以用于山谷填充沉积物。但是，只有一个核心包含山谷填充的沉积物，缺乏tephra床。结果，山谷填充沉积物和上层梯田的年龄仍然不清楚。对钻孔谷填充的沉积物进行了磁磁测量。样品具有稳定的远程磁化，并具有向下倾斜度，没有50 cm的地平线范围，向上或向下倾斜。这种特殊的倾向可能是由地磁偏移引起的。