四国東部および紀伊半島西部の三波川帯の苦鉄質・超苦鉄質貫入岩について : (その1)四国東部の三成川帯の苦鉄質・超苦鉄質貫入岩について

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The Sambagawa zone of this region can be divided into the following three regions. a) Northern region with igneous activity b) Central region with no igneous activity c) Southern region with igneous activity The regions with igneous activity in the north and south are where basic volcanic ejecta were thickly deposited in the subsiding stage. The ultramafic rocks of the northern igneous activity region are mostly serpentinite which are composed almost entirely of serpentine minerals, but the greater parts of the ultramafic rocks of the southern region are cortlandite. The mafic rocks of the northern region are almost entirely alkali gabbro, but they are mostly composed of metamorphic minerals as follows. There are two types of the combination of metamorphic minerals. The first type is composed of omphacite, glaucophane, muscovite, green-biotite, albite, chlorite and clinozoisite. The second type is composed of glaucophane, barroisite, muscovite, albite, chlorite, clinozoisite and quartz. In the southern region, the original mineral composition of some mafic intrusive rocks is titanaugite, kaersutite, plagioclase and olivine. These are determined to be alkali gabbro by the chemical composition of the clinopyroxene and rocks. Most mafic intrusive rocks of this region can not be determined whether they are alkaline or non-alkaline. Some of them are associated with cortlandite. The alkaline intrusive rocks in the two regions are located in the southern district of each region. The central region is occupied by the Nonowaki formation which consists mainly of coarse clastic materials, and intrusive rocks, related to the Sambagawa metamorphism, are not present in the region. In the so-called "Mikabu Zone" of the southern region, the mafic intrusive rocks are tholeiitic rocks. The authors assumed that the petrological difference in intrusive rocks in places mentioned above may be due to the difference of chemical composition in the uppermost mantle or the lowest part of earth crust.
地学団体研究会の論文
1983-09-25

四国東部および紀伊半島西部の三波川帯の苦鉄質・超苦鉄質貫入岩について : (その1)四国東部の三成川帯の苦鉄質・超苦鉄質貫入岩について

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