The Magnetite-series and Ilmenite-series Granitic Rocks
The Magnetite-series and Ilmenite-series Granitic Rocks
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DOI：
10.11456/shigenchishitsu1951.27.293
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发表时间：
1977-10
期刊：
影响因子：
--
通讯作者：
S. Ishihara
中科院分区：
文献类型：
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作者：
S. Ishihara
对常见花岗质岩石中的不透明矿物进行了显微研究。花岗岩类可分为（i）含磁铁矿的磁铁矿系列和（ii）无磁铁矿的钛铁矿系列。每个系列都有以下特征性的副矿物组合：磁铁矿系列：磁铁矿（0.1-2体积%），钛铁矿、赤铁矿、黄铁矿、紫帘石、绿帘石、高铁/亚铁（和高Mg/Fe）黑云母;钛铁矿系列：钛铁矿（小于0.1体积%），磁黄铁矿、石墨、白云母、低铁/亚铁（和低Mg/Fe）黑云母。矿物组合表明，在岩浆凝固过程中，磁铁矿系列花岗岩类的氧逸度高于钛铁矿系列花岗岩类。分离这两个系列的边界可能在Ni-NiO缓冲区附近。磁铁矿系列花岗岩类形成于深部（上地幔和下地壳），不与含碳物质发生相互作用;钛铁矿系列花岗岩类形成于中、下陆壳，在其岩浆演化史的不同阶段与含碳变质岩和沉积岩混生。前者携带斑岩型铜钼矿床，后者伴生云英岩型锡黑钨矿矿床。东亚中生代造山带缺乏斑岩型铜矿，与该区磁铁矿系列花岗岩类普遍缺乏有关。
Opaque minerals of common granitic rocks were studied microscopically. The granitoids were divided into (i) a magnetite-bearing magnetite-series and (ii) a magnetite-free ilmenite-series. Each series has the following characteristic assemblages of accessary minerals: Magnetite-series: Magnetite (0.1-2 vol.%), ilmenite, hematite, pyrite, sphene, epidote, high ferric/ferrous (and high Mg/Fe) biotite; Ilmenite-series: Ilmenite (less than 0.1 vol.%), pyrrhotite, graphite, muscovite, low ferric/ferrous (and low Mg/Fe) biotite. The mineral assemblages imply a higher oxygen fugacity in the magnetite-series granitoids than in the ilmeniteseries granitoids during solidification of the granitic magmas. The boundary separating the two series is probably near the Ni-NiO buffer. The magnetite-series granitoids are considered to have been generated in a deep level (upper mantle and lowest crust) and not to have interacted with C-bearing materials; whereas the ilmenite-series granitoids were generated in the middle to lower continental crust and mixed with C-bearing metamorphic and sedimentary rocks at various stages in their igneous history. The former carries porphyry copper-molybdenum deposits and the latter accompanies greisen-type tin-wolframite deposits. Lack of porphyry copper deposits in the Mesozoic orogeny belts in East Asia is related to a general paucity of the magnetite-series granitoids in this terrane.