On the gabbroic rocks of the Ikomayama Mountains in the Kinki District
Bibliographic Information
- Other Title
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- 生駒山はんれい岩体について
- イコマヤマ ハンレイ ガンタイ ニ ツイテ
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Abstract
The gabbroic rocks and granites are exposed in the Ikoma Mountains on the eastern border of the Osaka Basin. The gabbroic rocks are divided into the following five rock-types; 1) fine-grained pyroxene-hornblende gabbronorite, 2) olivine-pyroxene-hornblenda gabbronorite, 3) hornblende gabbro, 4) plagioclase-por-phyritic hornblende gabbro, 5) leucocratic hornblende gabbro. Among them, hornblende gabbro is the main type. Fine-grained pyroxene-hornblende gabbronorite is included in hornblende gabbro. Olivine-pyroxene-hornblende gabbronorite and hornblende gabbro are intruded by plagioclase-porphyritic hornblende gabbro and leucocratic hornblende gabbro. These gabbroic rocks are intruded by granitic rocks. The granitic rocks are classified into tonalite, K-feldspar-porphyritic biotite granite, weakly schistose coarse-grained biotite granite, massive medium-grained granodiorite and fine-grained granite. Weakly schistose coarse-grained biotite granite and K-feldspar-porphyritic biotite granite are the main types of the granites. The intrusive succession of the granites is assumed that tonalite is oldest and fine-grained granite is youngest (Fig. 3). The major elements of the gabbroic rocks vary systematically with the SiO_2 content. The study of ^<87>Sr/^<86>Sr ratios suggests that the gabbroic rocks are the products of magmatic differention from the tholeiitic magma. Plagioclase has high anorthite contents (An 85-95), but forsterite contents of olivine are rather low ranging from 0.6 to 0.7. These facts suggest the crystallization under the high water vapor pressure.
Journal
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- Earth Science (Chikyu Kagaku)
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Earth Science (Chikyu Kagaku) 40 (2), 102-114b, 1986
The Association for the Geological Collaboration in Japan
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Details 詳細情報について
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- CRID
- 1390282679241885952
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- NII Article ID
- 110007091965
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- NII Book ID
- AN00141269
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- ISSN
- 21897212
- 03666611
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- NDL BIB ID
- 3077407
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- Text Lang
- ja
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- Data Source
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- JaLC
- NDL
- CiNii Articles
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- Abstract License Flag
- Disallowed