Recent formations and Their Basal Topography in and around Tokyo Bay, Central Japan
Recent formations and Their Basal Topography in and around Tokyo Bay, Central Japan
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日本中部东京湾及周边地区的最新构造及其基底地形
DOI：
10.1016/0033-5894(77)90055-2
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发表时间：
1977
影响因子：
2.3
通讯作者：
I. Matsuda
中科院分区：
文献类型：
--
作者：
S. Kaizuka;Y. Naruse;I. Matsuda
本文概述了日本晚第四纪典型地区东京湾及其周围地区新近（全新世和更新世）地层的地下地质和埋藏地形。埋藏地形中的埋藏磨蚀平台分为上部（约100米）和下部（约100米）。0至-10米高）和更低（约-20至-40米）平台;上部和下部的埋藏河流阶地也被区分开来，并分别与Tc 1和Tc 2的陆上晚更新世阶地相关。一个埋藏的山谷系统被阐明，其中树干谷底达到-70米在东京和出现在一个平坦的表面在陆架边缘在东京湾的入口。这些地貌表面的近似日期。海平面与埋藏的谷底同时期的高度（约。20，000 - 15，000年BP）估计约为-135米。现代地层被中间的砂层和最低的埋藏谷底砾石分为上下两段。下段由复杂岩相的半咸水-海相沉积物组成，在有乐町（弗兰德里亚）海侵的早期阶段堆积在狭窄的淹没山谷中。中砂层为三角洲前积层，形成于约1000 ~ 2000年的轻微海退过程中。11，000和10，000年BP。上段主要由广泛分布的均质海相粘土和三角洲砂组成，在有乐町海侵晚期和随后的相对稳定的海平面阶段，在一个宽阔的海湾及其海湾中堆积。
This paper summarizes the subsurface geology of the recent (both Holocene and latest Pleistocene) formations and the buried topography beneath them in and around Tokyo Bay, the type area of the late Quaternary in Japan. Buried abrasion platforms in the buried topography are classified into upper (ca. 0 to −10 m high) and lower (ca. −20 to −40 m) platforms; upper and lower buried river terraces are also distinguished, and are correlated to the subaerial late Pleistocene terraces of Tc1 and Tc2, respectively. A buried valley system is elucidated, of which the trunk valley floor reaches −70 m in Tokyo and emerges into a flat surface at the shelf edge in the entrance to Tokyo Bay. Approximate dates for these geomorphic surfaces are given. The height of sea level contemporaneous with the buried valley floor (ca. 20,000–15,000 yr BP) is estimated at about −135 m. The recent formations are divided into two members, upper and lower, by a middle sand bed, in addition to the lowest buried valley floor gravel. The lower member, which is composed of brackish to marine deposits of complicated lithofacies, was accumulated in narrow drowned valleys during the early stage of the Yurakucho (Flandrian) transgression. The middle sand bed is the foreset bed of deltas, which was formed during a slight regression between ca. 11,000 and 10,000 yr BP. The upper member, which consists mainly of widespread homogeneous marine clay and deltaic sand, was accumulated in a wide bay and its embayments during the late stage of the Yurakucho transgression and the following stage of a relatively stable sea level.