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

在奥陶纪末期至志留纪早期，日本东北部的南北上构造带和Hayachine构造带存在与俯冲有关的花岗岩-辉长岩活动，它们是南北上古陆的遗迹。南北上古陆和黑河地块在古生代至中生代的大地构造史和古生物地理上有着密切的联系，被认为是在一个相近的构造环境中起源和发展的。日达-盖恩带在中上古生界的岩相，特别是中生代大地构造史上，与南北上古生界不同。在珊瑚动物群和似菊石动物群的基础上，南北上早石炭世位于潘塔拉萨和特提斯大洋之间的门户地带，二叠纪至三叠纪位于中国南部附近，均处于低纬度。岛曼托带增生杂岩中就地玄武岩的常量和微量元素分析表明，这些绿色岩石是在古沟-沟-脊三联结处及其附近的俯冲带中的火成岩活动形成的。随着形成板状窗口并中断火山弧型火成岩活动的三重结合部的迁移，弧前岩石被抬升到地表，形成了一条高山。北上地块中的大岛造山作用发生在早白垩世，是这种造山作用的一种。

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.