| Abstract |
Petrological studies by TOMITA and the writer of the Matsura basalts and other post-Miocene basaltic rocks in northern Kyushu arrived at the following conclusions: (1) These basaltic rocks which are r...emarked by high-alumina and low-lime character belong to the "abnormal basalts" (TOMITA 1958). (2) Their parent magma is regarded as of alkali olivine basalt, presenting various unusual evolutional tendencies. (3) As one of the reason for these peculiaties, contamination and/or other actions, say, the effects of water are conceivable. Of these basaltic roks, the so-called high-alumina basalts (KUNO 1960) from northern Kyushu in the post-Miocene are dealt with in this paper, especially on their occurrences, rock series, xenolithes and xenocrysts, chemical composition and average chemical composition. Petrochemical characters are shown in the normative or-ab-an, wo-en-fs, wo-fo-Q, Q-fo-fa and Mgo-(FeO+Fe_2O_3)-(Na_2O+K_2O) diagrams. In summary, the following can be said : the so-called high-alumina basalts of post-Miocene time from northern Kyushu may be of a special type of the "abnormal basalts"; in other words, it is not necessary to give especial petrological importance to KuNo's highalumina basalts.show more
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