北上山地中・古生層の層序と構造

概要

論文の詳細を見る
The Kitakami Mountains lies in the Pacific side of northeast Japan. It is divided into three tectonic units, the South Kitakami Belt, the Hayachine-Miyamori Belt and the North Kitakami Belt. The Southern Kitakami Mountains includes the former two belts, and the Northern Kitakami Mountains corresponds to the third one. The South Kitakami Belt occupies the most area of the Southern Kitakami Mountains, and is composed of Siluro-Devonian turbidites and olistostromes accumulated in a deep-sea basin, Carboniferous to early Cretaceous fossiliferous shallow-sea or deltaic sediments, and a large quantity of igneous rocks of four stages, namely, (1) late Devonian to early Carboniferous, (2) late Carboniferous to early Permian, (3) late Permian to early Triassic and (4) early Cretaceous. The Hayachine-Miyamori Belt, which borders the Southern Kitakami Mountains in the north and separate it from the Northern Kitakami Mountains, is characterized by pre-Silurian (Ordovician?) ophiolites. The basement rocks of the Southern Kitakami Mountains are represented by the ophiolitic rocks exposed in the Hayachine-Miyamori Belt. They occur also in the South Kitakami Belt as xenoliths in igneous rocks. The North Kitakami Belt consists of thick sequence of Triassic to earliest Cretaceous, mostly Jurassic deep-sea sediments containing poorly preserved radiolarian remains, unconformably overlaying late Early Cretaceous to Palaeogene fossiliferous shallow-sea or lacustrine sediments, and various volcanic and plutonic rocks of early Cretaceous to Palaeogene. The arcuate form, convex to N, of a serpentine belt, i. e., the Hayachine-Miyamori Belt, suggests that the Southern Kitakami Mountains is a large scale nappe, thrust over the Northern Kitakami Mountains. It is considered possible that the nappe newly named as the South Kitakami Nappe moved more than 50km from SW to NE and emplaced in Valanginian, just before the early Cretaceous (Hauterivian to Barremian) igneous activity.
地学団体研究会の論文
1988-07-25

北上山地中・古生層の層序と構造

スポンサーリンク

概要

著者

関連論文

スポンサーリンク