RECOGNIZING THE CROSSWISE EXTENSIONAL TECTONICS OPEN WAYS FOR EXPLORATION OF NEW SUBSTANTIAL, HIGH GRADE CHROMITE ORES IN BULQIZA ULTRAMAFIC MASSIF, ALBANIA

Bulqiza Ultramafic massif that covers an area of c. 350 sq km, hosting the principal mined ores (Bulqiza-Batra, Thekna etc. with more than 22.6 Mt @ 40% Cr₂ O³) belongs to the Eastern Ophiolite Belt (EOB) of Albanian Ophiolites.

Exploration works performed during 2009-2011 at Bulqiza-Batra deposits, 6 km southeast, at Thekna deposit and 13 km northwest at Qafe Burreli area, indicated a substantial extension of the chromite mineralization potential (Hoxha, 2012).

In the structural point of view Bulqiza-Batra chromite deposit is widely accepted to be hosted by an overturned antiform, with easterly vergence, 4.5 km long, 1.2 km to 1.5 km wide and 0.5 to 1.7 km down dip with an axial orientation strike 330⁰.

According to many authors (Happel et al. and quoted references), at northern part, Bulqiza deposit is restricted by an abrupt flexural fold that changes the angle of deep fom from 40⁰ to 90⁰ within an horizontal distance of 400m. Fold axis of this flexure is crosswise with 5 km long, proven Bulqiza-Batra strike of 330⁰.

All drilling programs northwest or northeast, to prove continuity of Bulqiza deposit, have failed.

By analyzing Bulqiza-Bater mining data, can be distincted that hing line of the intact mined Bulqiza-Batra cusp /anticlinorium is break apart by a combined strike-slip-and-normal fault. The westward displacement of the Bulqiza block against Batra block, is about 170 m, whereas its vertical lowering about 100 m.

Recognizing the presence of these vertical displacements, can be concluded that, the northwest continuation of Bulqiza chromite anticlinorium/cusp, should be connected with several step faults, responsible for Bulqize valley forming.

This would open the possibility for finding in depth, new high chromite grade ores between Bulqiza and Qafe Burreli, approximately 3 times higher than those found in Bulqize-Batra area.

Principal references

Happel, U., Hausberg, J., Kisters, A. & Meyer, F.M.1998: The application of digital 3-D ore body modeling to the structural analysis of the Bulqiza-Batra chromite mine, central Albania. Erzmetall, 51: 685-692.

Hoxha, L. 2012: Polyphase tectonics as tool for exploration of chromite ores hosted by ultramafic rocks of Bulqiza Ultramafic Massif, Albania.

Geological Society of America Abstracts with Programs, Vol 44, No. 2, p.103