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深海钻探计划(DSDP)的钻探结果表明,晚第三纪期间本州东北部的襟裳陆架在439号孔位处下沉了近3000米。这些钻探资料结合地震反射资料表明曾发生过广泛的沉降,局部沉降幅度达到6000米。我们认为这种沉降是由25百万年至30百万年前在襟裳边缘中生代岩石圈开始初次俯冲所造成的。弧前区下面的地幔的短暂变冷引起了收缩和沉降。笔者为估算这种沉降的速率提出一个简单的模式。
Drilling results from the Deepwater Drilling Program (DSDP) showed that the lapel shelf on northeastern Honshu Island in the late Tertiary sank nearly 3,000 meters at Hole 439. The combination of these drilling data with seismic reflection data shows that extensive subsidence has occurred and the subsidence amplitude has reached 6,000 meters. We think this subsidence was caused by the first subduction of the Mesozoic lithosphere between 25 and 30 million years ago on the edge of the plait. Short cooling of the mantle below the pre-arctic zone caused contraction and settlement. The author proposes a simple model for estimating the rate of this settlement.