Geomorphological and Geological verification for documented paleo-seismic activity occurred in Nankai trough

南海海槽古地震活动记录的地貌和地质验证

基本信息

批准号：
18500779
负责人：
MAEMOKU Hideaki
金额：
$ 2.61万
依托单位：
Hiroshima University
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

项目摘要

The main puipose of the research project is to verify huge earthquakes which were identified through historical documents in geological or geomoiphological method. Sedimentologic analyses were conducted on Holocene limestones that occur along the mast from Muroto-misaki to Meoto-iwa, located ~13km north of the cape. The limestones are limited to less than 9.2 in in elevation. The limestones are up to 4.4 min mean diameter, up to 0.5 in in thickness, and consist mainly of ossilized sessile organisms, including annelids, corals, biyozoans, encrusting foraminifers, barnacles, nongeniculate coralline algae, and, to a lesser extent, molluscs and peyssonneliacean algae. Acicular and equant cements are minor components. Acicular cements are found in semiclosed spaces between coralline algal crusts and their substrates. The modal composition of limestones was determined by a point-cointing technique. Based on the biotic composition, the Holocene limestones can be classified into six types(Types I to VI) A comparison of the vertical distribution of these rock types with that of modem sessile organisms indicates that the top of Type I limestone, which is characterized by the occurrence of hennatypic corals, corresponds approximately to the mean low water springs when the limestones formed. A difference in the highest occurrence of Type I limestone between two sites may represent the variation in the total amount of uplift over the last 1000 to 1500 years, which resulted in an apparent northward decline of palemnean low water springs at a rate of ~10cm/km. Therefore, the Holocene limestones are a good paleobathymeter to reconstruct past seismic activities in this area. This study shows thatwann temperate carbonate deposits are as excellent recorders of geologic events, such as the timing and scale of repeated coseismic uplifts and elevation of sea levels, as those in the tropics.

该研究项目的主要素质是验证通过地质或地质学方法中历史文件识别的巨大地震。在沿披风以北约13公里处的Meoto-iwa沿桅杆上发生的全新世石灰岩进行沉积分析。石灰石在海拔中仅限于9.2。石灰岩的平均直径高达4.4分钟，厚度高达0.5，主要由渗透式的无柄有机体组成，包括annelids，珊瑚，生物生物，生物生物，包裹有孔，barnacles，barnacles，barnacles，barnacles，barnacles，nongenenenicalinicalinicalinicalinicalinicaline algae and sipser，以及较小的Molluscs和Peysnelean和Peysernean和PeyseNeAN。钩形水泥是较小的成分。在冠状藻壳及其底物之间的半狭缝空间中发现了卵形水泥。石灰石的模态组成是通过点尖端技术确定的。基于生物组成，全新世石灰岩可以分为六种类型（I型至VI），将这些岩石类型的垂直分布与调制解调器配音有机体的垂直分布进行比较，这表明I型石灰石的顶部表明，这是由Hennatypic Corals出现的特征在于Hennatypic Corals的特征，该型hennatypic corals大约对应于平均低水源时的含量。在过去1000至1500年中，两个地点之间I型石灰石的最高发生率的差异可能代表升高的总数差异，这导致帕利恩尼（Palnean）低水弹簧的北向北下降，速度约为10 cm/km。因此，全新世石灰岩是重建该地区过去地震活动的良好古细胞传理。这项研究表明，温带碳酸盐沉积物是地质事件的出色录音机，例如反复的coseisic升高和海平面的升高的时间和尺度，就像热带地区的时机一样。