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.

上新世大念寺组分布于福岛县太平洋一侧，主要由砂质粉砂岩和砂岩组成，是进行精确对比的良好关键层。其沉积年龄为4.18~2Ma，进行了总有机碳（TOC）、总硫等地球化学分析。 (TS)、有机质稳定碳同位素比值(δ^(13)C_org) 结果如下： (1) 温暖期，丰富的陆源有机质被输送到陆架并保存在沉积物中。 (3.75-305 Ma)。 (2) 冷却初期(3.5-3.35 Ma) 海洋生物生产力增加。 (3) TS、TOC 和δ^(13)Corg 变化较大。 3Ma之后的冷却阶段，即第四纪冰河时代之后的阶段，这些相当大的变化在同龄的δ^(18)O曲线中表现出来。在该地区发现了海底峡谷填充沉积物的可制图单元。最大深度为100 m，被认为是由海底滑坡形成，发生于2.7 Ma之后。海底峡谷充填沉积物由粉砂岩夹薄砂岩层、厚砂岩组成。海底峡谷的形成和填充可能受上新世晚期气候变冷的控制。