Magmatic systems beneath Ashikule volcanic cluster (Western Kunlun, China): insights from compositional and textural fea
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ORIGINAL PAPER
Magmatic systems beneath Ashikule volcanic cluster (Western Kunlun, China): insights from compositional and textural features of lavas Hongmei Yu 1,2 & Jiandong Xu 1,2 & Bo Zhao 1,2 & Feixiang Wei 1,2 Received: 13 November 2019 / Accepted: 28 May 2020 # Saudi Society for Geosciences 2020
Abstract This study considered the petrology, chemical composition, texture, and magma temperature and pressure of the volcanic rocks in the Ashikule volcanic cluster (AVC), Western Kunlun, China, to investigate the magmatic systems prior to eruption. The whole rock geochemistry of AVC lavas revealed a wide compositional range that included phonotephrite, basaltic trachyandesite, trachyandesite, trachyte, and acid rhyolite but mainly trachyandesite. The K2O/Na2O ratios were greater than 1, falling into the shoshonite series in a K2O vs. SiO2 diagram. Oxide diagrams showed that intermediate and acidic volcanic rocks have similar magmatic evolutions, mainly related to the fractional crystallization of pyroxene, plagioclase, apatite, and ilmenite. Acidic magma was found as the product of magmatic crystallization in the final stage. Trace element contents indicated that the magma underwent mixing with crustal components in the process of crystallization before eruption. Xishan phonotephrite revealed a different evolutionary series compared with the intermediate and acidic volcanic rocks, highlighting the differences of their magmatic sources. The equilibrium temperature and pressure of phonotephrite were 1146–1316 °C and 0.38–1.70 GPa, respectively, which correspond to a depth of 14–62 km. The equivalent values for intermediate rocks were 1062–1215 °C and 0.22–1.18 GPa, respectively, corresponding to a depth of 8–43 km. Acidic rocks had lower magmatic temperatures (778–889 °C). Active tectonics led to multiple events of magma upwelling, and the magma in each event underwent its own evolution. There were many different components of magma beneath the study area contemporaneously, i.e., multiple magma capsules with different compositions. Keywords Magmatic systems . Petrology . Chemical composition . Texture . Temperature and pressure . Ashikule volcanic cluster
Introduction The India Plate began to collide with the Eurasian Plate about 45 ± 5 Ma ago, and its subsequent continuous northward
movement formed the Tibetan Plateau (Molnar and Tapponnier 1975; Molnar et al. 1993; Rowley 1996; Tapponnier et al. 2001). Following the collision, a series of potassic to ultrapotassic volcanic rocks became distributed
Responsible Editor: Domenico M. Doronzo Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12517-020-05506-4) contains supplementary material, which is available to authorized users. * Hongmei Yu [email protected]
Feixiang Wei [email protected]
Jiandong Xu [email protected]
1
National Observation and Research Station of Jilin Changbaishan Volcano, Antu 133613, China
Bo Zhao [email protected]
2
CEA Key Laboratory of Seismic and Volcanic Hazards, Institute of
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