GEOLOGICAL AND STRUCTURAL
SETTING OF THE
MUHONG ORE BODIES IN BASAY, NEGROS ORIENTAL
Romel P. Jacinto
William C. Holifena
ABSTRACT
The prophyry copper deposits of Muhong
lie near the southeastern end of a
mineralized belt in Southwestern Negros
that extends approximately 55 kilometers
along a northwesterly trend. Presently,
there are three known deposits: (1) the
Northwest, (2) Central and (3) Southeast
orebodies. Host rocks to mineralization
at Muhong are volcanic flows and
pyroclastics of intermediate to acidic
composition and quartz diorite stocks.
Copper mineralization consists mainly of
chalcopyrite occurring as dissemination:
and fracture fillings commonly
associated with quartz veining. Where
supergene enrichment has developed, most
of the primary chalcopyrite is altered
to digenite. Molybdenite is constantly
discernible within the ore zones
although usually much less erratic
concentrations confined mostly along
fractures and highly silicified
sections.
Hydrothermal alteration is well
represented by varying degrees of
chloritization, argillization,
silicification and mica development in
the vicinity of the orebodies. Major
structures that control the Muhong
orebodies are pair of steeply dipping
parallel first-order faults trending
northwest. Outside the zone bounded by
these faults, ore mineralization
terminates abruptly. The close
similarity in the mineralogy, alteration
and proximity of the deposits suggest
the strong possibility of their being
originally one continuous body.
Subsequent second-order faults trending
northeast and north-south caused lateral
as well as vertical displacements in the
ore mass imparting to it its present
configuration.
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