Ghodrat TORABI

Subduction-related Eocene shoshonites from the Cenozoic Urumieh-Dokhtar magmatic arc (Qaleh-Khargooshi area, western Yazd Province, Iran)

Urumieh-Dokhtar magmatik yayının (UDMA) orta kesimlerindeki Eosen volkanizmasının beşinci evresi trakibazaltan trakidasite kadar değişen şoşonitik karakterli lavları içermektedir. Qaleh-Khargooshi bölgesinin şoşonitlerinde lösit analsime, analsim albite, sanidin albit ve anortoklasa ve klinopiroksen de albite değişir. Bu reaksiyonlar ile arazi, petrogragik ve jeokimyasal özellikler birlikte farklı kaya birimlerini oluşturmak üzere değişime uğrayan orijinal absarokitik magmanın verilerini oluşturmaktadır. Bu şoşonitlerin kaynak magması metasomatize zenginleşmiş manto kaynağının düşük dereceli kısmi ergimeye uğraması sonucu oluşmuştur. Kıta kabuğu boyunca yükselen şoşonitik magmada kabuk kirlenmesi, kimyasal değişimler ve mineral dönüşümleri de gerçekleşmiştir. Şoşonitik kayaçların jeokimyası kıtasal yay veya çarpışan kıta kenarlarındaki potasik volkanik kayaçlarla benzerlik sunmaktadır.

Senozoyik Urumieh-Dokhtar magmatik yayı’ndan Dalma-batma ilişkili Eosen Şoşonitleri (Qaleh-Khargooshi bölgesi, Batı Yazd Eyaleti, İran)

The fifth phase of Eocene volcanism in the central part of the Urumieh-Dokhtar magmatic arc (UDMA), comprises lavas with shoshonitic characteristics, ranging from trachybasalt to trachydacite. In shoshonites of the Qaleh- Khargooshi area, leucite changes to analcime, analcime to albite, sanidine to albite and anorthoclase, and clinopyroxene to albite. These reactions, together with other field, petrographic and geochemical features, are evidence of an original absarokitic magma which was changing to generate the different rock units. The parental magma of these shoshonites was produced by a low degree of partial melting from a metasomatized enriched mantle source. During the ascent of shoshonitic magma through the continental crust, crustal contamination, chemical changes and mineralogical transformations took place. The geochemistry of these shoshonitic rocks is similar to potassic volcanic rocks of continental arcs or convergent margins.

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