Petrogenesis of Plio-Pleistocene volcanic rocks from the chagai arc ...
Petrogenesis of Plio-Pleistocene volcanic rocks from the chagai arc ...
Petrogenesis of Plio-Pleistocene volcanic rocks from the chagai arc ...
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ABCDEFGHFig. 4. (A) a view <strong>of</strong> <strong>the</strong> nor<strong>the</strong>rn part <strong>of</strong> <strong>the</strong> Miri crater <strong>of</strong> <strong>the</strong> Koh-e-Sultan volcano, (B) andesitic lavaflows intercalated with <strong>volcanic</strong>lastic <strong>rocks</strong> on <strong>the</strong> sou<strong>the</strong>rn flank <strong>of</strong> <strong>the</strong> same volcano, (C)photomicrograph (KS-4) displaying large prismatic and polygonal phenocrysts and fragments <strong>of</strong>hornblende within a cryptocrystalline to glassy groundmass. (D) photomicrograph (KS-21)exhibiting cumulophyric texture developed by <strong>the</strong> clustering <strong>of</strong> <strong>the</strong> hypers<strong>the</strong>ne phenocrysts, (E)photomicrograph (KS-5) displaying cumulophyric texture formed by clustering <strong>of</strong> lamprobolitephenocrysts in a microcrystalline to glassy groundmass (in plane polarized light), (F) <strong>the</strong> samephotomicrograph in crossed polarized light. (G) photomicrograph (KS-20) displaying phenocryst<strong>of</strong> hornblende with well developed 124°-56° cleavage and small anhedral inclusions <strong>of</strong> quartz (incentre). Note strong zoning in some plagioclase crystals. Hornblede in top right containsmagnetite inclusions, (H) photomicrograph <strong>of</strong> dacite (KS-9) exhibiting twining and oscillatoryzoning in a phenocryst <strong>of</strong> plagioclase.7