KARAKTERISTIK ALTERASI DAN MINERALISASI DI DAERAH RORAHKADAL, KECAMATAN CIBALIUNG, KABUPATEN PANDEGLANG, PROVINSI BANTEN.
SARI
Daerah penelitian terletak pada cebakan emas Cibaliung, Kecamatan
Cibaliung, Kabupaten Pandeglang, Provinsi Banten. Daerah Rorahkadal secara
geologi terletak pada komplek batuan beku Honje dan disusun oleh batuan beku
vulkanik Miosen yang mengalami alterasi dan mineralisasi. Penelitian mencakup
studi alterasi dan mineralisasi dengan metode penelitian yang dilakukan yaitu
analisis petrografi, analisis mineragrafi dan analisis inklusi fluida.
Tipe alterasi yang terbentuk di daerah Rorahkadal ada dua yaitu tipe
propilitik dan tipe silisifikasi dengan kumpulan mineral-mineral ubahan yang ada
di daerah Rorahkadal yaitu silika, klorit, mineral lempung, epidot, kalsedon dan
oksida besi.
Pembentukan mineralisasi di daerah Rorahkadal yaitu pirit, kalkopirit dan
sfalerit. Mineral bijih tersebut hadir berupa urat sulfida (stockworks), tersebar
(disseminated) dalam masadasar batuan, serta hadir pada permukaan batuan.
Asosiasi mineral-mineral bijih tersebut dapat mengindikasikan adanya
pengkayaan Au di daerah Rorahkadal. Mineralisasi di daerah Rorahkadal
dipengaruhi oleh kekar yang secara regional berarah utara selatan.
Berdasarkan pengukuran inklusi fluida diketahui bahwa temperatur
homogenisasi (Th) berkisar antara antara 120~229 °C dengan rata-rata Th=191.5
°C, temperatur leleh (Tm) berkisar antara -0,18~-0,94 °C dengan rata-rata Tm= 0,65 °C dan salinitas fluida hidrotermal berkisar antara 0,32~1,67 wt% NaCl eq.
dengan rata-rata salinitas = 1,53 wt% NaCl equivalen.
Berdasarkan data tersebut dapat dikatakan bahwa pembentukan
mineralisasi di daerah Rorahkadal dipengaruhi oleh beberapa proses hidrotermal.
Gejala overprint di daerah Rorahkadal dibuktikan berdasarkan asosiasi mineral
ubahan, asosiasi mineral bijih, serta karakteristik inklusi fluidanya. Daerah
Rorahkadal berada pada lingkungan epitermal sulfidasi rendah pada kedalaman
190 meter serta berada di atas boiling level yang terletak pada horizon logam
mulia.
ii
ABSTRACT
Study area is located at Cibaliung gold deposit that administratively is a
part of District Cibaliung, Pandeglang Sub Province, Banten Province.
Geologically this area belongs to Honje igneous rocks complex in which
dominated by Miocene volcanic igneous rocks that already have been alterated
and mineralized. Objective of the research is studying alteration and
mineralization process by using some methods, such as Petrography analysis,
Mineragraphy analysis and Fluid Inclusion analysis.
The study area composed by prophylithic alteration and silicification
alteration. Associated alteration minerals such as silica, chlorite, clay minerals,
iron oxide, epidot and chalcedony.
Mineralization process at Rorahkadal, such as : sulphide group (pyrite,
chalcopyrite and sphalerite). The ore minerals was formed as stockworks,
disseminated minerals within groundmass of rock and coating minerals on the
surface of the rocks. The ore minerals associated can showing indicated that Au
and other precious metal enrichment in Rorahkadal Area. Mineralization at
Rorahkadal area controlled by activities of sheer that regionally trending NorthSouth.
Based on fluid inclusion measurement, the temperature homogenization is
in range 120~229 °C with Th average is191.5 °C, temperature melting (Tm) is in
range -0,18~-0,94 °C with Tm average is -0,65 °C and salinity of fluid
hydrothermal is in range 0,32~1,67 wt% NaCl equivalent, with average salinity is
about = 1,53 wt% NaCl equivalent.
Based on the data said above that mineralization in Rorahkadal area is
influenced by more than one hydrothermal processes. Overprint indication at
Rorahkadal area is proven by association of alteration minerals, association of
ore minerals and characteristic of fluid inclusions. Furthermore, we can say that
Rorahkadal area is in stage at low sulphidation epithermal environment at depth
190 m and above boiling level on precious metal horizon.
iii
Daerah penelitian terletak pada cebakan emas Cibaliung, Kecamatan
Cibaliung, Kabupaten Pandeglang, Provinsi Banten. Daerah Rorahkadal secara
geologi terletak pada komplek batuan beku Honje dan disusun oleh batuan beku
vulkanik Miosen yang mengalami alterasi dan mineralisasi. Penelitian mencakup
studi alterasi dan mineralisasi dengan metode penelitian yang dilakukan yaitu
analisis petrografi, analisis mineragrafi dan analisis inklusi fluida.
Tipe alterasi yang terbentuk di daerah Rorahkadal ada dua yaitu tipe
propilitik dan tipe silisifikasi dengan kumpulan mineral-mineral ubahan yang ada
di daerah Rorahkadal yaitu silika, klorit, mineral lempung, epidot, kalsedon dan
oksida besi.
Pembentukan mineralisasi di daerah Rorahkadal yaitu pirit, kalkopirit dan
sfalerit. Mineral bijih tersebut hadir berupa urat sulfida (stockworks), tersebar
(disseminated) dalam masadasar batuan, serta hadir pada permukaan batuan.
Asosiasi mineral-mineral bijih tersebut dapat mengindikasikan adanya
pengkayaan Au di daerah Rorahkadal. Mineralisasi di daerah Rorahkadal
dipengaruhi oleh kekar yang secara regional berarah utara selatan.
Berdasarkan pengukuran inklusi fluida diketahui bahwa temperatur
homogenisasi (Th) berkisar antara antara 120~229 °C dengan rata-rata Th=191.5
°C, temperatur leleh (Tm) berkisar antara -0,18~-0,94 °C dengan rata-rata Tm= 0,65 °C dan salinitas fluida hidrotermal berkisar antara 0,32~1,67 wt% NaCl eq.
dengan rata-rata salinitas = 1,53 wt% NaCl equivalen.
Berdasarkan data tersebut dapat dikatakan bahwa pembentukan
mineralisasi di daerah Rorahkadal dipengaruhi oleh beberapa proses hidrotermal.
Gejala overprint di daerah Rorahkadal dibuktikan berdasarkan asosiasi mineral
ubahan, asosiasi mineral bijih, serta karakteristik inklusi fluidanya. Daerah
Rorahkadal berada pada lingkungan epitermal sulfidasi rendah pada kedalaman
190 meter serta berada di atas boiling level yang terletak pada horizon logam
mulia.
ii
ABSTRACT
Study area is located at Cibaliung gold deposit that administratively is a
part of District Cibaliung, Pandeglang Sub Province, Banten Province.
Geologically this area belongs to Honje igneous rocks complex in which
dominated by Miocene volcanic igneous rocks that already have been alterated
and mineralized. Objective of the research is studying alteration and
mineralization process by using some methods, such as Petrography analysis,
Mineragraphy analysis and Fluid Inclusion analysis.
The study area composed by prophylithic alteration and silicification
alteration. Associated alteration minerals such as silica, chlorite, clay minerals,
iron oxide, epidot and chalcedony.
Mineralization process at Rorahkadal, such as : sulphide group (pyrite,
chalcopyrite and sphalerite). The ore minerals was formed as stockworks,
disseminated minerals within groundmass of rock and coating minerals on the
surface of the rocks. The ore minerals associated can showing indicated that Au
and other precious metal enrichment in Rorahkadal Area. Mineralization at
Rorahkadal area controlled by activities of sheer that regionally trending NorthSouth.
Based on fluid inclusion measurement, the temperature homogenization is
in range 120~229 °C with Th average is191.5 °C, temperature melting (Tm) is in
range -0,18~-0,94 °C with Tm average is -0,65 °C and salinity of fluid
hydrothermal is in range 0,32~1,67 wt% NaCl equivalent, with average salinity is
about = 1,53 wt% NaCl equivalent.
Based on the data said above that mineralization in Rorahkadal area is
influenced by more than one hydrothermal processes. Overprint indication at
Rorahkadal area is proven by association of alteration minerals, association of
ore minerals and characteristic of fluid inclusions. Furthermore, we can say that
Rorahkadal area is in stage at low sulphidation epithermal environment at depth
190 m and above boiling level on precious metal horizon.
iii