P-T histories of peridotite and amphibolite tectonic blocks in the Sanbagawa metamorphic belt, Japan
P-T histories of peridotite and amphibolite tectonic blocks in the Sanbagawa metamorphic belt, Japan
复制标题
日本三波川变质带橄榄岩和角闪岩构造块的 P-T 历史
DOI：
10.1144/gsl.sp.1989.043.01.51
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
A. Takasu
中科院分区：
文献类型：
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作者：
A. Takasu
位于日本西南部的三钵川变质带经历了白垩纪高压变质作用。该带的区域最高等级岩石（绿帘石-角闪岩相）出现在四国中部的Besshi地区，局部含有较高等级的粗粒变基性岩和超基性岩块，如Higashiakaishi橄榄岩、Iratsu绿帘石-角闪岩、Nikubuchi橄榄岩和Sebadani变辉长岩块（Kunugiza等人，1986年）（图1）。这些块体被认为是在三宝川带隆升初期形成的混杂岩带中的大型构造块体（最大7 × 3 km 2）（Takasu 1984，Kunugiza等，1986）。本文将揭示这些地块的不同成因和变质历史，并讨论与构造地块发展有关的构造。Sebadani（SB）变质辉长岩体的变质历史Sebadani（SB）变质辉长岩体位于钠长岩-黑云母带中，面积约0.3 × 0.2 km ~ 2，由石榴绿帘石角闪岩和残留榴辉岩组成。暗色角闪石富集层和浅色绿帘石富集层的条带记录了堆晶辉长岩中先前辉石和斜长石层的分层。Takasu（1984）认为SB块体中榴辉岩的平衡有两个阶段：一个是720-750°C和12-20 kbar的核-核对，另一个是610-630°C和10-17 kbar的边缘-边缘对。基性的Sanbagawa片岩，从SB块体到20米，在高压下经历了接触变质作用，产生了石榴石和绿辉石（最大Jd 36%），
The Sanbagawa (Sambagawa) metamorphic belt in south-west Japan suffered a high-pressure intermediate metamorphism of Cretaceous age. The regionally highest grade rocks (epidote-amphibolite facies) of the belt occur in the Besshi district in central Shikoku, and locally contain higher grade masses of coarse-grained metabasic and ultrabasic lithologies, such as the Higashiakaishi peridotite, Iratsu epidote-amphibolite, Nikubuchi peridotite and Sebadani metagabbro masses (Kunugiza et al. 1986) (Fig. 1). These masses have been regarded as large-scale tectonic blocks (maximum of 7 × 3 km2) in a mélange zone which formed at the initial stage of the uplifting of the Sanbagawa belt (Takasu 1984, Kunugiza et al. 1986). In this paper, quite a diverse origin and metamorphic history of these blocks will be revealed, and the tectonics associated with the development of the tectonic blocks will be discussed. Metamorphic history of the tectonic blocks Sebadani (SB) metagabbro mass The Sebadani (SB) metagabbro mass, 0.3 × 0.2 km2, is located in the albite-biotite zone, and consists of garnet-epidote amphibolites and relict eclogite which survived epidote amphibolization. The banding of melanocratic hornblende-rich and leucocratic epidote-rich layers records the layering of previous pyroxene and plagioclase layers of cumulate gabbro. Takasu (1984) recognized two stages of eclogite equilibrium in the SB mass; a core-core pair of 720–750°C and 12–20 kbar, and a rim-rim pair of 610–630°C and 10–17 kbar. The basic Sanbagawa schists, up to 20 m from the SB mass, underwent contact metamorphism at high pressure that produced garnet and omphacite (maximum Jd 36%) porphyroblasts from