Dyking Mechanism and Melt transfer, Misho granitoid Pluton (NW of Iran)

Abstract

Misho granitoid pluton is exposed at the North Western part of the Misho Mountains and at the South Western part of the Marand compresional depression. The minerals in the rocks of this pluton include unhedral to sub – hedral quartz, K – feldspar both as microcline with tartan twinning and  sub - hedral to unhedral orthoclase, two generations of biotite and zircon, subhedral to euhedral plagioclase (oligoclase - albite), magmatic epidote, titanite and apatite. One generation of zircon and biotite show restitic characteristics. The samples show distinct textures indicating the effect of pressure during crystallization (such as myrmekitic textures, slight alignment of mica, fragments of microcline in orthoclase). The samples exhibit syn-collisional, displaced and S-type geochemical features and the pluton is exposed in an area which is tectonically very faulted. The relative age of the pluton is Paleozoic. The source material for this pluton was a mixture of Meta – greywacke and metapelite. Field relations, mineralogy, geochemistry, existence of mica – rich enclaves and horse – shoe shape of the pluton all suggest a rapid ascent due to dyking and fracture distribution as the main mechanism for melt transport and formation of two generation of zircon and biotite. Therefore diapirism had negligible rule in emplacement and characteristics of misho granitoid.   

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مراجع

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