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ORIGIN OF THE SOUTH KITAKAMI PALEOLAND AND SUCHLIKE ALLOCTHONOUS CONTINENTAL BLOCKS IN THE JAPANESE ISLANDS

日本列岛南北上古兰及此类异地大陆块的起源

基本信息

批准号：
09640537
负责人：
EHIRO Masayuki
金额：
$ 1.92万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

There were subduction-related granitic-gabbroic igneous activities in the South Kitakami and Hayachine Tectonic Belts of Northeast Japan, which are remnants of the South Kitakami Paleoland, during the latest Ordovician to earliest Silurian age. The South Kitakami Paleoland and Kurosegawa Landmass are closely related in their geotectonic history and paleobiogeography during the Paleozoic to Mesozoic, and are considered to be originated and developed in a closely located region with same tectonic settings. The Hida-Gaien Belt differs from the South Kitakami in lithofacies of the Middle-Upper Paleozoic and, particularly, in Mesozoic geotectonic history. Based on the coral fauna and ammonoid ones, the South Kitakami situated in a gateway between the Panthalassa and Tethys Oceans at early Carboniferous, and near South China during the Permian to Triassic, both at a low latitude.The major and trace elements analyses on the in situ basalts in the accretionary complex of the Shimanto Belt suggest that these green rocks were formed by igneous activity in a subduction zone at and close to the ancient trench-trench-ridge triple junction. Following the migration of the triple junction, which forms of a slab window and interrupts volcanic arc-type igneous activity, forearc rocks were uplifted to the surface, forming a high mountain range. The Oshima Orogeny in the Kitakami Massif, which took place at the early Cretaceous, is one of this type orogenies.

日本东北部的南北上构造带和早前构造带是南北上古陆的残余，在奥陶纪末至志留纪初存在与俯冲有关的花岗辉长岩岩浆活动。南北上古陆和黑濑川陆块在古生代至中生代的大地构造历史和古生物地理上有着密切的联系，被认为是在同一构造背景下形成和发展的。飞田-外苑带与北上南部在中-上古生界岩相，特别是中生代大地构造史上存在差异。根据珊瑚动物群和菊石动物群，早石炭世南北上位于泛地中海和特提斯洋之间的门户，二叠纪-三叠纪位于华南附近，对四万十带增生杂岩中的原地玄武岩进行的主量元素和微量元素分析表明，这些绿色岩石是由俯冲带中的岩浆活动形成的。古海沟-海沟-山脊三重连接随着三联点的迁移，它形成了一个板状窗口，并中断了火山弧型火成岩活动，弧前岩石被抬升到地表，形成了一个高山脉。发生在早白垩世的北上地块的大岛造山运动就是这类造山运动的一种。