科研之友
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摘要
Western Kunlun Ashikule volcano cluster (AVC) is located in the northwestern edge of Qinghai-Tibet Plateau. Because of the severe natural environment, few researches have been done. Daheishan volcano has the widest lava area, and is the largest volcano in this area. The petrographic texture, phenocryst type and chemical composition of the volcanic rocks in Daheishan volcano were analyzed in detail, and their implication in magmatic process was discussed. The whole rock composition of Daheishan volcano has a large range, from basaltic trachyandensite, trachyandensite to trachyte, and the Harker diagrams show some linear relationships, which indicate the existence of magmatic evolution relationship between the three types of magma. Phenocrysts in Daheishan volcanic rocks are mainly pyroxene and plagioclase, most of which have characteristics of corrosion, reverse zoning and reaction boundary structure, indicating magma mixing. The results estimated by using thermobarometers show that the equilibrium temperatures of basaltic trachyandensite and trachyandensite are 1124 similar to 1176 degrees C, and the equilibrium pressures are 0. 55 similar to 0. 81GPa, corresponding to the depth of about 16. 5 similar to 24. 3km. The equilibrium temperatures and pressures are 1059 similar to 1071 degrees C and 0. 39 similar to 0. 39GPa for trachyte, corresponding to the depth of 11. 8 similar to 17. 7km. Research shows that the primary magma under Daheishan volcano experienced an evolution from basaltic trachyandensite, trachyandensite to trachyte, and three types of magma characterized by layering may exist in the magma chamber at the same time, occurring magma mixing, and even mixing with the surrounding acidic magma.
- 出版日期2017-1
- 单位中国地震局
