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| The Discovery of Garnet from Yuyitalepenketi Granite Porphyry in Western Junggar and its Geological Significances |
| WANG Ran, ZHANG Sheng-long |
| Key Laboratory of Western China's Mineral Resources and Geological Engineering, Ministry of Education, Earth Science & Resources College of Chang'an University, Xi'an 710054, China |
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Abstract In order to probe the genesis of garnet from the garnet-bearing granite porphyry in the Yuyitalepenketi area, Xinjiang, a study on mineralogy and chemical compositions of the garnet has been carried out in this paper based on its field geological and petrographic features. Results show that the garnet occurs as phenocrysts of euhedral crystal distributed in the whole body rather than in the rim of the granite porphyry body. It is believed that those garnets are magmatic ones which contain large amounts of needle or columnar-like apatite inclusions. EPMA analytical results indicate that all garnets are rich in Fe, relatively rich in Ca, but poor in Mn and Mg, with calculated compositions of almandine(62.36~74.76%mol), grossular(10.90~15.56%mol), pyrope(6.78~16.43%mol), and spessartine(4.08~6.91%mol). These results suggested that the garnets crystallized early and are magmatic in origin rather than being xenocrysts or restite phases. Combining with previous researches on magmatic activities and structural development evolutions of the region, it is believed that formation of the granite in the region could be associated with the subduction-related magmatism.
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Received: 28 February 2015
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