论文部分内容阅读
引言日本群岛最大的岩基位于日本西南部内带。这一岩基(这里指内带岩基)的规模相当于美国加里福尼亚州内华达岩基。全岩 Rb-Sr 及矿物 K-Ar 法年龄表明,内带岩基形成于白垩纪—早第三纪,并且往北西方向年龄越来越年轻。岩基主要由花岗闪长岩和花岗岩组成,它们侵入于基底岩石和同期火山岩地层中,因此可认为它们属火山-深成杂岩。岩基的区域性变化已为众多的研究者所查明,这里应该特别提及石原舜三的不懈努力。在岩基化学成分方面所见到的最为突出的是全岩 Fe_2O_3/FeO 比值以及相应矿化的 Mo/W 比值的区域性变化,二者往北,即往边缘海旁侧递增。Fe_2O_3/FeO 比值的变化与磁铁矿含量相对应。南部花岗岩类的铁钛氧化物含量特别低,仅含钛铁矿,而磁铁矿含量往北部总的来
Introduction Japan’s largest rock archipelago is located in the southwestern part of Japan. The size of this rock base (here, the inner rock mass) is equivalent to that of the Nevada rock mass in California, USA. The age of the whole rock Rb-Sr and the mineral K-Ar method shows that the inner-hosted rock base was formed in the Cretaceous-Early Tertiary, and younger and younger in the NW direction. The rock foundation is mainly composed of granodiorite and granite. They invade basement rocks and contemporaneous volcanic formations, so they are considered volcanic-deep complex. The regional change of rock foundation has been identified by a large number of researchers. Special mention should be made here of the tireless efforts of Ishihara Ishihara. The most prominent features seen in the chemical composition of the rock base are the regional changes in the Fe 2 O 3 / FeO ratio of the whole rock and the corresponding mineralized Mo / W ratio, both increasing northward, ie towards the edge of the waterfront. The change of Fe 2 O 3 / FeO ratio corresponds to the content of magnetite. The southern granite class iron oxide content of iron is particularly low, containing only ilmenite, and magnetite content to the north of the total