Role of tectonic erosion in formation of accretionary prism - examples from the Southern Chichibu Belt and the Shimanto Belt

为了阐明地形高点俯冲的地质后果以及可能与构造侵蚀密切相关的增生棱柱体中年代缺失的含义，进行了以下工作：芦潮带Kuzuu杂岩的石灰石卵石年龄，秩父带南部Yukagi组的绿岩岩相学，四国西部四万东带北方与南方界线的地质和放射虫年龄，以及四国西部四万东带南部火山岩的产状和岩相学。主要结果如下：1.在Kuzuu杂岩的灰岩砾岩中发现了早Toarcian菊石，并对其意义进行了讨论; 2. Yukagi组玄武质岩石学和放射虫年龄表明九州会聚边缘晚侏罗世-早白垩世期间发生了海山碰撞; 3.四国西部四万十超群，其特征为：（1）在Kuzuu杂岩中发现了早Toarcian菊石;（2）在Kuzuu杂岩中发现了早Toarcian菊石;（3）在Kuzuu杂岩中发现了早Toarcian菊石;（4）在Kuzuu杂岩中发现了早Toarcian菊石;（5）在Kuzuu杂岩中发现了早Toarcian菊石;（6）在Kuzuu杂岩中发现了早Toarcian菊石;（7）在Kuzuu杂岩中发现了早Toarcian菊石;（7）在Kuzuuu杂岩中发现了早Toarcian菊石;（根据岩相和沉积时代可划分为12个构造地层单位，时代从Santonian到渐新世晚期-中新世早期。含砾页岩与大碎石砂岩和斜坡破坏成因的页岩开始在晚坎帕尼亚期之后增加。4.四国西部羽田半岛东海岸四万户群内，零星分布着火山角砾岩、火山砾岩、火山砂岩、火山泥岩等火山碎屑岩，其规模较小。大多数火山岩的地球化学亲和力的板内碱性玄武岩的海山起源的一些判别图上使用一些抗蚀变元素。这些数据表明，在四国西部会聚边缘的晚渐新世-早中新世期间，

The followings have been performed to clarify geologic consequences of subduction of topographic high and implication of chronological absence in accretionary prism which may have close association with tectonic erosion : age of limestone pebble from the Kuzuu Complex of the Ashio Belt, petrography of greenstones from the Yukagi Formation in the Southern Chichibu Belt, geology and radiolarian ages of the boundary area of the Northern and Southern Shimanto belts in western Shikoku, and occurrence and petrography of volcaniclastic rocks from the southern Shimanto Belt of western Shikoku. The main results are as follows.1.Early Toarcian ammonite was found from limestone conglomerate in the Kuzuu Complex, and its implication was discussed.2.Petrography of basaltic rocks and radiolarian age of the Yukagi Formation are indicative of a collision of seamount during the late Jurassic-Early Cretaceous at the convergent margin of Kyushu.3.The Shimanto Supergroup, western Shikoku, can be divided into twelve tectonostratigraphic units on the basis of lithofacies and depositional ages, and ranges in age from the Santonian to the late Oligocene-Early Miocene. Pebbly shales with large rubbles of sandstone and shale of slope-failure origin begin to increace after the Late Campanian. The sandstones from the Upper Paleocene were mainly derived from the Sanbagawa Metamorphic Belt.4.Volcaniclastic rocks such as volcanic breccia, volcanic conglomerate, volcanic sandstone and mudstone with volcanic rock gravels are found in small bodies sporadically scattered in the Shimanto Supergroup in east coast area of the Hata Peninsura, western Shikoku. Most volcanic rocks have a geochemical affinity of within-plate alkaline basalts of seamount origin on some discrimination diagrams using some alteration-resistant elements. The data are suggestive of a collision of seamount during the Late Oligocene-Early Miocene at the convergent margin of western Shikoku