Enclaves in the scoria cone of the Qezeljeh-Kand (N-Qorveh): xenolith or cumulate?
Subject Areas :عباس آسیابانها 1 , سارا ویسی 2 , کیومرث شهبازی 3 , محسن نصرآبادی 4
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Abstract :
The Plio-Quaternary volcanic cones in N-Qorveh have been comprised of three volcanic facies includings: pumiceous pyroclastics, fall-out scoria deposits and lava flows. The scoria clasts form the main volume of the cones. Because of this, we call them as “scoria cones”. Two types of enclaves are found in the scoria ejecta that are felsic or crustal xenoliths and mafic enclaves. Based on the type and abundances of the minerals, the latter enclaves are subdivided into three types: mica-apatite-hornblende (MAH), mica-apatite-olivine (MAO), and hornblende-apatite-pyroxene (HAP). Because of the textural and compositional similarities between minerals of the mafic enclaves and lava flows and scoria clasts, it must be stated that the mafic enclaves had been the cumulates that brought up the surface by the Strombolian-type explosive eruptions. Moreover, because of high-Mg contents in the mafic minerals and also the co-existences of volatile-bearing and volatile-free minerals, it can be stated that the forming magma of the scoria cones had been produced by the partial melting of the upper mantle due to the mantle metasomatism.
