GEOLOGICAL CHARACTERISTICS AND PROSPECTING TARGETS OF THE QAGAN OBO Fe-Zn POLYMETALLIC DEPOSIT IN INNER MONGOLIA

The Qagan Obo Fe-Zn polymetallic deposit tectonically lies in the eastern part of the Early Paleozoic Qagan Obo-Aoyoute-Chaobuleng tectonomagmatic belt. The Middle Ordovician Duobaoshan Formation, serving as the main host, is closely related to the metallogenesis. The skarn zones with Fe-Zn and Mn layers commonly occur at the contact between Qagan Obo quartz diorite stock and the neritic facies sedimentary rocks of Duobaoshan Formation. The Fe-Zn orebodies are mainly hosted by the skarn in stratiform, banded or lenticular shapes. The Qagan Obo quartz diorite stock supplies not only the ore materials, but also the ore-forming fluid and dynamic. The regional NE-striking Qagan Obo-Dongwuqi deep fault controls the occurrences of rock bodies and polymetallic deposits. The secondary NE-and NW-trending fractures control the distribution Fe-Zn orebodies. The favorable areas for seeking Fe-Zn polymetallic deposits are the contact zones between the multi-staged acid-intermediate magmatic intrusions and the neritic facies sedimentary rocks of Middle Ordovician Duobaoshan Formation and the concentrated fissure belts in the wallrocks.