PEMETAAN GEOLOGI PADA PENAMPANG 140 UNTUK MENGETAHUI SEBARAN LITOLOGI, ALTERASI, MINERALISASI, DAN DENSITAS VEIN BESERTA HUBUNGANNYA DENGAN KEBERADAAN ZONA HIGH GRADE ORE PADA ENDAPAN PORFIRI BATU HIJAU PT. NEWMONT NUSA TENGGARA TENGGARA

Abstract

Mineral mining industry is much needed at the present time given the
metal commodities is increasing from year to year. With increasing demands this,
and the search for an evidentiary contained mineral reserves requires several
steps in exploration activities in the early stages and update data. Batu Hijau is a
porphyry copper-gold deposition (Cu-Au) with its formation is controlled by the
distribution of lithology, alteration processes, and vein density.
The purpose of this study was to determine the distribution of lithology,
alteration, mineralization, and vein density and its relationship with the presence
of high grade ore that is focused on section 140.
The method used in this final study was conducted logging geology
consisting of 14 drill holes, highwall mapping at a distance of ± 200 m, located on
the Northwest wall and across the Southeast section 140, and blasthole polygon
mapping lies in the Northwest and Southeast the cross section 140.
Based on drill hole logging, highwall mapping and blasthole mapping,
lithology found growing at the study site consists of volcanic rock, equigranular
quartz diorite rocks, tonalite intermediates rocks, and young tonalite rocks.
Alteration consists of developing secondary biotite alteration (potassic
alteration), partial biotite alteration (potassic alteration), pale green mica
alteration (phyllic alteration), and chlorite-epidote alteration (propylitic
alteration). Mineralization developed in the study site consists of bornite mineral
composition largest copper 0.63% followed by 0.34% mineral chalcopyrite and
pyrite minerals as mineral broadcaster.In the analysis stage is divided into the
mineralized zone, the dominant of mineral bornite (Bn> Cp> py), the dominant of
mineral chalcopyrite (Cp> Bn> py) and the dominant of mineral pyrite (Py> Cp>
Bn). Vein density were found in the location of research classified as vein
density> 10%, vein density is 5% -10%, vein density is 3% -5%, and the density of
veins <3% with type vein vein consists of type A, type B vein, vein type C and
magnetite veins. The presence of high grade ore zone at section 140 contained in
the intermediate tonalite lithologies that are host rock mineralization along side
rocks in contact with intermediate tonalite rocks on stage secondary biotite and
pale green mica alteration, the dominant mineralization bornite and chalcopyrite,
with vein density > 5%. Thus prioritized production targets on the physical
conditions.