作者们对日本西南五县地区白垩纪—古第三纪火山岩中Fe—Ti氧化矿物的产状及化学成分作了研究。本题所指地区的火山岩层可分为自下部层位至白垩纪的关门、周南、匹见、阿武群及古第三纪的田万川群两组。其中关门及田万川群的火山岩中磁铁矿极为发育,在玄武岩质安山岩中可见到铬尖晶石。而在匹见、阿武群火山岩中却几乎完全没有磁铁矿。周南群 The authors studied the origin and chemical composition of Fe-Ti oxide minerals in the Cretaceous-Paleogene volcanic rocks in five counties of southwestern Japan. Volcanic rocks in this area can be divided into two groups from the lower layer to the Cretaceous closed, Zhounan, match see, Awu group and Paleogene Tianwanchuan group. Among them, the magnetite in the volcanic rocks that close up and Tianwanchuanqun is extremely developed, and chrome spinel can be seen in basalt andesite. In the match, the alluvial rocks in Albuquerque have almost no magnetite. Zhou Nanqun