EXPERIMENTAL STUDIES ON SYENITIC ROCKS IN THE YAMATO MOUNTAINS, EAST ANTARCTICA
The stability of amphibole was studied in the presence of syenite composition liquid. The melting relationships of three hornblende clinopyroxene quartz syenites and a hornblende two-pyroxene syenite from the Yamato Mountains were determined in the temperature range of 650-900℃, under a water pressu...
| Main Authors: | , , , |
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| Format: | Report |
| Language: | English |
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Department of Geoscience, Joetsu University of Education
1993
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| Online Access: | https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2720 http://id.nii.ac.jp/1291/00002720/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2720&item_no=1&attribute_id=18&file_no=1 |
| Summary: | The stability of amphibole was studied in the presence of syenite composition liquid. The melting relationships of three hornblende clinopyroxene quartz syenites and a hornblende two-pyroxene syenite from the Yamato Mountains were determined in the temperature range of 650-900℃, under a water pressure of 0.05-0.3GPa and oxygen fugacities of the FMQ buffer. Experimental results of hornblende clinopyroxene quartz syenites (Y406 and Y904) and one hornblende two-pyroxene syenite (Y557) at 0.1 GPa show that melting begins between 720℃ and 770℃, and amphiboles disappear between 810℃ and 895℃. With the increasing temperature at 0.1GPa, quartz disappears first, then plagioclase and amphibole in that order. The water saturated solidus temperature of a normative quartz-free hornblende clinopyroxene mela-syenite (Y405) is about 780℃ at 0.1GPa. K-feldspar in this sample disappears at lower temperature than amphibole. In two syenites (Y557 and Y904), solidus and the stability limit line of amphibole intersect at a lower pressure than 0.3GPa. Moreover, all rocks investigated are at least 40% melted at temperatures ∿50℃ above the solidus. The present results suggest that amphibole in these syenites could crystallize at pressures lower than 0.3GPa (∿10km in depth), indicating their emplacements at a relatively shallow crustal level. |
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