山陰・北陸グリンタフ地域における新第三紀中新世粗粒玄武岩の岩石化学的地域性

The San'in-Hokuriku region is situated in inner belt of the Southwest Japan composed of the so-called "green-tuff", an important geologic unit of Japan. In this region, the violent volcanic products of this age are found as lavas, dikes, tuffs, tuff breccias and volcanic conglomerates from basic to acidic volcanic rocks. Their field appearance is generally greenish in color by special diagenesis and hydrothermal alterations. Therefore, they are generally refered to as green-tuff, although they are actually volcanic products composed of rhyolite, andesite, dacite, basalt and their pyroclastic sediments.
At this age, it must call a attention to this fact that dolerite intrusions found in there and here in this region. Furthermore, these dolerites are systematic variations in alkali-silica relation of the rocks. There is a fact that these rock type of the dolerites in this region shows the intimate relation to the Pre-Miocene basement rocks.
On the basis of the results of the petrological studies, the writer wants to describe an outline of the dolerites distributed in this region.