论鲁东地体的形成机制及其归属

FORMATION MECHANISM OF LUDONG (EASTERN SHANDONG PROVINCE) TERRANE AND ITS ACTUAL SUBORDINATIVENESS

作者用地体说理论重新解释鲁东地区的胶东地块,认为是个外来地体——鲁东地体,不属于中朝地台范畴,应归属于扬子地台.作者指出鲁东地体与鲁西地块在基底变质程度、年代、地壳结构以及区域重磁特征等都有显著差异,在晚印支期鲁东地体才从古太平洋陆块分裂位移到郯庐断裂,与鲁西地块发生热拼贴.

For a long time in the opinion of China traditional geology, Jiaodong Block east of the Tanlu Rift, together with Luxi (Western Shandong Province) Block, geotectonically belongs to Sino-Korean Platform. But, to reinterpret the Jiaodong Block in Ludong area with the terrane theory after recent field geological investigations and studies of Ludong basement and especially after the geological surveys and tracking correlations of middle and upper Devonian profiles of Rimjin Group in the central part of Korea in April and May of last year, it should be an exotic terrane, and its Palaeozoic sedimentary environments are similar to those of lower Yangtze Platform. This can be proved according to the evident differences between Ludong and Luxi Blocks in basement metamorphic grades, ages, crustal struc-tures, and gravity and magnetic fields. In late Indo-Chinese Epoch, Ludong Terrane broke away from the anciertt Pacific Plate, moved to the Tanlu Rift and joined Luxi Block under high temperature?. In Qixia area of Ludong Terrane, there are still a series of remnant low-grade metamorphosed' sfrata, previously considered as Sinian System, but corresponding to Rimjin Group of Korea in the recent -regional stratigraphic correlations. And also Palaeozoic fossils in a far more southern facies have been found in the bottom gravels of early Jura-ssic Laiyang Formation in Huanghuadian of Jucheng County. In addition, the phyllonite nappe discovered in Zhubian of Junan County and the collisional complex rock belt in the Yangma Island have further shown the differences between Ludong and Luxi areas.