ON THE RELATIVELY COMPOSITIONAL HOMOGENEITY OF ALBANIAN EASTERN OPHIOLITIC BELT
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Çina, Α.
Ophiolitic formation of Albanides, named as Mirdita zone, represents a compactsegment of oceanic lithosphere of Middle-Upper Jurassic. Based on petrographic,geochemical and metalogenical features two types of belts are distinguished: westernMORB and eastern SSZ types. In fact, structural and geological units as well as manyother elements have shed light on lack of a sharp separation between the two belts.Recent investigations have evidenced that different ultramafic massifs of westernophiolitic formation, represent an evident variation of their composition fromharzburgite to lherzolitic -types. This composition reflects a different grade of partialmelting of upper mantle. Peridotites show a high variability, from 0.3 - 3.8 wt.%Al2O3, varying from small to highly extreme depleted peridotite.On the contrary, Albanian eastern belt, it seems to be formed by a more homogeneoushartzburgitic mantle.Detailed petrologic and metallogenic investigations have evidenced that this beltchanges also from one massif to another, naturally at a smaller level, therefore it iseasier to be named relatively homogeneous. It is distinguished by a higher meltingdegree, chiefly of hartzburgitic-type, characterized by whole and thick ultramaficsection, as well as by metalogenic variety, mostly of metallurgic-type of chromitemineralization. It is supposed that rock-forming and mineraluzation processes havebeen developed not uniformly along the ophiolitic belt.
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