Submarine canyon formations and tectonics and climate changes in late Pliocene on forearc shelfin northern Japan

日本北部弧前陆架上新世晚期海底峡谷的形成、构造和气候变化

基本信息

批准号：
18540451
负责人：
HOYANAGI Koichi
金额：
$ 2.43万
依托单位：
Shinshu 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

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18540451/
关键词：
Pliocene Dainenii Formation shelf organic matter climate change submarine canyon stable carbon isotope diatom fossil 大年寺層金津層環境変動テクトニクス陸棚の堆積作用

项目摘要

Pliocene Dainenji Formation is distributed in the Pacific side of the Fukushima Prefecture. The Dainenji Formation is deposited on shelf environment and consists mainly of sandy siltstone and sandstone. It includes a number of volcanic ash layers, which serve as good key beds useful for precise correlation. Its depositional age is from 4.18 to 2 Ma. We carried out facies and geochemical analyses, such as total organic carbon (TOC), total sulfur (TS), and stable carbon isotope ratio of organic matter (δ^(13)C_org). The results are as follows: (1) Abundant land-derived organic matter was transported to the shelf and was preserved in the sediment in warm period (3.75-305 Ma). (2) productivity of marine organisms increased in the early cooling period (3.5-3.35 Ma),. (3) The considerable variations in TS, TOC andδ^(13)Corg are seen in cooling stage after 3 Ma, which succeeded to the Quaternary ice age. These considerable variations are shown inδ^(18)O curve of the same age.Mappable units of submarine canyon-fill sediment are recognized in this area. A valley has a maximum depth of 100 m and is considered to be formed by submarine landslide, which took place after 2.7 Ma. Submarine canyon-fill sediments are composed of siltstone interbedded with thin sandstone layers, thick sandstone beds and slump deposits. Formation and filling of the submarine canyon might be controlled by climate cooling of latest Pliocene age.

上新世二尼吉的形成分布在福岛县的太平洋一侧。 Dainenji地层沉积在货架环境上，主要由砂岩和砂岩组成。它包括许多火山灰层，它们是对精确相关性有用的好钥匙床。它的沉积年龄为4.18至2 mA。我们进行了面部和地球化学分析，例如总有机碳（TOC），总硫（TS）和有机物的稳定碳同位素比（δ^（13）C_org）。结果如下：（1）大量的土地衍生有机物被运输到架子上，并在温暖的时期（3.75-305 mA）保存在沉积物中。（2）海洋生物的生产力在冷却早期（3.5-3.35 MA）中提高。（3）在3 Ma后，在冷却阶段看到TS，TOC和δ^（13）CORG的考虑变化，该阶段成功地到达第四纪冰河时代。这些考虑因素以相同年龄的曲线显示。山谷的最大深度为100 m，被认为是由海底滑坡形成的，该海底滑坡发生在2.7 mA之后。海底峡谷填充沉积物由用薄砂岩层，厚厚的砂岩床和倒塌的沉积物组成。海底峡谷的形成和填充可以通过最新的上新世时代的气候冷却来控制。