Estimation of accretionary complex growth by micropaleontological mapping

采用Matsuoka（1995）的侏罗纪-下白垩统放射虫分带框架及其数值年龄定标，对不同构造地层单元的大洋板块地层学（OPS）进行了精度为3-5倍的比较。以岩相为主要依据，提出了秩父复合地体的构造地层单元划分。北秩父地体的神吉田组和柏木组的OPSs与南秩父地体的富野组和三宝山组的OPSs相似。还认识到上述两个构造构造单元在OPS上的一些关键差异。这表明，北秩父地体和南秩父地体是由同一大洋板块沿一个横向遥远的俯冲带俯冲而形成的，它们是在后来以走滑运动为特征的构造事件中并置的。对比日本西南侏罗系增生杂岩的OPSs，认为主要走滑位错发生在黑川构造带，而不是中构造线。太平洋-日本放射虫分带方案也适用于藏南雅鲁藏布江缝合带、菲律宾北巴拉望地块和俄罗斯远东锡霍特阿林地区的吸积杂岩。对西太平洋ODP 801遗址上侏罗统段放射虫生物地层学的详细研究表明，独立于太平洋-日本和北美提出的两个分区方案具有良好的相关性。

The oceanic plate stratigraphy (OPS) of different tectonostratigraphic units is compared with 3-5 times accuracy by using a framewok of Jurassic-Lower Cretaceous radiolarian zonation and its numerical age callibration of Matsuoka (1995). A tectonostratigraphic unit division for the Chichibu composite terrane is poroposed on the basis mainly of lithofacies. The OPSs of the Kamiyoshida Unit and Kashiwagi Unit in the Northern Chichibu terrane are similar to those of the Togano and Sambosan Unit in the Southern Chichibu Terrane, respectively. Some critical differences in OPS of the above-mentioned pair of the tectonositratigraphic units are also recognized. This indicates that the Nothern Chichibu and Southern Chichibu terranes were formed by the subduction of the same oceanic plate along a single subduction zone at laterally distant places and they were juxtaposed in later tectonic events characterized by strike-slip movements. Comparison of OPSs among Jurassic accretionary complexes in Southwest Japan suggests that the main strike-slip dislocation took place along the Kurosegawa Tectonic Zone rather than the Median Tectonic Line.The Pacific-Japan radiolarian zonal scheme is also applicable to accretionary complexes of the Yarlung Zangbo Suture Zone in southern Tibet, of the North Palawan Block in the Philippines, and of Sikhote Alin in Russian Far East. Detailed radiolarian biostratigraphic research on Upper Jurassic interval at ODP Site 801 in the western Pacific reveals that two zonal schemes proposed independently from Pacific-Japan and North America are well correlated with each other.