GEOLOGY AND MINERAL
DEPOSITS OF EAST-CENTRAL BALABAC
ISLAND, PALAWAN PROVINCE, PHILIPPINES
T. U. JOHN
The main results of an exploration
venture on Balabac Island, Philippines
are presented. The east-central portion
of Balabac is underlain by a volcanic-chert
associaticn intruded by ultramaflcs and
contains copper mineralization.
Isoclinal folding and thrusting have
been important. The remainder of the
island is mainly sandstone and mudstone.
It apparently contains no economic
Geophysical prospecting methods and the
proving of an orebody by diamond
drilling are described.
The Lorraine Orebody is a massive
hypothermal cupriferous pyrite deposit,
averaging over 4 percent copper. It is
of some interest in that hydrothermal
wallrock alteration is almost entirely
absent, with contracts between ore and
barren country rock generally
knife-edged. Some secondary enrichment
occurs. Controls of localization are
structural and lithologic, and the
presence of ultramafic intrusions
probably has genetic significance.
Some comparisons of the general geology
are made with mainland Palawan and North
Borneo, and the ore environment is
briefly compared with other areas.
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