نقش تفريق ماگمايي و ذوب بخش پوسته در تكوين سنگهاي آتشفشاني اسيدي جنوب دانسفهان

The Role of Magmatic Differentiation and Crustal Partial Melting in the Genesis of Acidic Volcanic Rocks, South of Danesfahan

Geochemical characteristics and petrography of the acidic volcanic rocks from the South of Danesfahan indicate that these rocks are products of different petrogenetic processes. Magmatic differentiation through fractional crystallization has played the main role in the evolution of majority of acidic rocks. These rocks include the rhyolites with the following features: l)porphyritic texture, 2)negative anomaly of Eu, and 3)decreasing LILE and increasing REE contents with increasing silica. A few of acidic rocks from the study area show characteristics implying their generation through partial melting of the upper crustal rocks. These include the rhyolites with the following features: l)vitrophyric or perlitic texture, 2)lack of negative anomaly of Eu, and 3)the highest LILE/REE and LREE/HREE ratios amongst the acidic volcanic rocks.