Structural Geology of the Relationship Between two Geologic Terrains

人们认为，这两个地质地体之间存在一条构造线或一条大断层。在日本九州，“野冈构造线”也被认为是将岛本带一分为二的断层。北部为白垩纪Morotsuka带，南部为古近纪天皇和Hyuga带，“Nobeoka构造线”被认为穿越天皇地区。为此，我们进行了详细的地质调查。我们在Morotsuka和Imkado群之间的边界上发现了一些露头。但没有观察到剪切构造，即断层泥或断层角砾岩。此外，这两个组具有一致的结构，并影响相同的折叠。两个群的岩性也相同，如海图纹片岩。因此，该地区不存在“野冈构造线”。

It has been considered that a tectonic line or a large fault is situated between the two geologic terrains. "Nobeoka Tectonic Line" is also regarded as such a fault dividing the Shimanto belt into to parts in Kyushu, Japan. Northern part is the Cretaceous Morotsuka belt and southern is the Paleogene Mikado and Hyuga belts."Nobeoka Tectonic Line" is believed that it passes through Mikado area. So we carried out the detail geologic survey. We find some outcrops of the very boundary between the Morotsuka and the Mikado groups. But no shear structure, i. e. fault gouge or fault breccia is observed. Moreover these two groups have concordant structures and affected the same folding. The same lithology such as chart-laminite is also found in the both groups. Therefore "Nobeoka Tectonic Line" does not exist in this area.