پتانسیل شیمیایی آنورتیت عاملی برای تمرکزهای کرومیتی در مجموعه های الترامافیک ـ مافیک

ABSTRACT

In recent years various hypothesis concerning the origin of chromitite concentration have been presented among which two hypothesis are universally .

Most favourally accepted : These two hypothsis are : (۱) Magma mixing (۲) : Interaction of melt - solid mantle peridotite .

۱- مسیب سبزه ئى سازمان زمین شناسى و اکتشاف معدنى کشور پژوهشکده علوم زمین –صندوق پستى ۱۴۹۴-۱۳۱۸۵ تهران.

In none of these hypothesis the structural evolution of mixed magmas or invading magmas which result in the appearance of an immiscible chromite melt or solid chromite , has been treated .

Field, laboratory and Geochemical investigation have shown that if a magma rich in “ Anorthite structural complex ” is mixed with a magma rich in “ olivine structural complex ”.

“ Spinel structural complex ” is formed by following reaction :

     Anorthite + ۲ olivine ó Spinal + Orthopyroxene + Clinpyroxene

Immediately after Spinal structural complex is formed or of both magmas will inter into this complex and a chromite rich magma is formed .In the case of magma - solid peridotite interaction the same reaction happens between Anorthite  of melt and Olivine in solid peridotite. a

The deriving force of this reaction is the gradient  of chemical potential of anorthite between melt and solid because Anorthite of magma has a great tendency to react with solid Olivine in the host peridotite.

کلید واژه ها: الترامافیک آنورتیت اولیوین پترولوژی سایر موارد