Geologi dan Indikasi Mineralisasi Magmatik-Hidrotermal di Daerah Naflow, Mangoli Timur, Kepulauan Sula, Maluku Utara
Ahmad Hafizh Dhiya'ul Haq, Dr.rer.nat. Ir. Arifudin Idrus, S.T., M.T., IPU. ; Dr.rer.nat. Ernowo, S.T., M.T.
2024 | Skripsi | TEKNIK GEOLOGI
Penelitian dilakukan di desa Naflow, Kecamatan Mangoli Timur, Kabupaten
Kepulauan Sula, Maluku Utara. Area penelitian termasuk ke dalam bagian
mikrokontinen banggai-sula yang berasal dari pecahan benua australia. Proses
tektonisme yang kompleks berpotensi menghasilkan endapan bijih ekonomis di
area penelitian. Belum ada penelitian yang dilakukan sebelumnya di area
penelitian mengenai kehadiran mineralisasi bijih. Tujuan dari penelitian ini untuk
memahami kondisi tatanan geologi serta karakteristik alterasi dan mineralisasi
untuk mengetahui potensi kehadiran alterasi magmatik-hidrotermal. Metode
penelitian terdiri dari studi pendahuluan, pengambilan data dan sampel, analisis
laboratorium, integrasi dan interpretasi data, dan penyusunan laporan. Analisis
laboratorium yang dilakukan berupa petrografi, mineragrafi, dan Inductively
Coupled Plasma Mass Spectrometry (ICP-MS). Litologi penyusun daerah
penelitian dibagi menjadi enam satuan geologi dari tua ke muda meliputi satuan
metamorf, satuan granit amfibol, satuan gabro, satuan diabas, satuan granit biotit,
dan satuan endapan pasir-kerakal. Alterasi hidrotermal ditemukan pada batuan
mafik gabro dan diabas dengan intensitas rendah-sedang berupa asosiasi klorit +
kuarsa + serisit, epidot + klorit + serisit, epidot + klorit + aktinolit, dan serisit +
epidot + klorit. Kehadiran mineralisasi di daerah penelitian terdapat pada batuan
gabro, diabas, dan granit secara diseminasi. Mineral bijih yang ditemukan berupa
pirit, magnetit, sfalerit, kalkopirit, dan hematit. Data geokimia batuan
menunjukkan bahwa granit biotit berasosiasi dengan zona subduksi pada volcanic
arc hingga post-collision dengan tipe granit S peralumina dan memiliki seri
magma kalk-alkalin. Pada batuan granit biotit tidak dijumpai adanya pengkayaan
unsur ekonomis tertentu. Data geokimia batuan gabro menunjukkan magma
berasosiasi dengan proses subduksi dan terbentuk pada setting volcanic arc yang
berkomposisi kalk-alkalin. Kehadiran struktur geologi berupa NE-SW menjadi
pengontrol alterasi dan mineralisasi di area penelitian dengan jenis struktur berupa
sesar turun mengiri. Tahapan mineralisasi pada area penelitian dibagi menjadi
tahap magmatik (magnetit), tahap hidrotermal (pirit, kalkopirit, dan sfalerit), dan
supergen (hematit). Mineralisasi ini berasosiasi dengan fluida magmatikhidrotermal dengan pengkayaan kadar Fe-Cr-Ti
This research was held in Naflow village, East Mangoli District, Sula Islands
Regency, North Maluku. This area is part of the Banggai-Sula microcontinent,
originating from fragments of the Australian continent. The complex tectonism
process has the potential to produce economic ore deposits in the research area.
No previous research has been conducted in the area regarding the presence of ore
mineralization. The aim of this research is to understand the geological setting
conditions and the characteristics of alteration and mineralization to determine the
potential presence of magmatic-hydrothermal alteration. The research method The
research method consists of a preliminary study, data and sample collection,
laboratory analysis, data integration and interpretation, and report preparation.
Laboratory analyses included petrography, mineralography, and Inductively
Coupled Plasma Mass Spectrometry (ICP-MS). The lithology of the research area
is divided into six geological units from oldest to youngest: metamorphic unit,
granite amphibole unit, gabbro unit, diabase unit, granite biotite unit, and sandgravel deposit unit. Hydrothermal alteration was found in the mafic rocks of
gabbro and diabase-basalt with low to medium intensity, represented by
associations of chlorite + quartz + sericite, epidote + chlorite + sericite, epidote +
chlorite + actinolite, and sericite + epidote + chlorite. Mineralization in the
research area was found in gabbro, diabase-basalt, and granite rocks in a
disseminated form. Ore minerals discovered include pyrite, magnetite, sphalerite,
chalcopyrite, and hematite. Geochemical data of the rocks indicate that granite
intrusion is associated with a subduction zone in a volcanic arc to post-collision
setting with S-type peraluminous granite and a calc-alkaline magma series. No
enrichment of specific economic elements was found in the granite intrusion
rocks. Geochemical data of gabbro rocks suggest magma associated with
subduction processes formed in a calc-alkaline volcanic arc setting. The presence
of NE-SW geological structures controls alteration and mineralization in the
research area with structures such as left-lateral normal faults. The stages of
mineralization in the research area are divided into magmatic (magnetite),
hydrothermal (pyrite, chalcopyrite, and sphalerite), and supergene (hematite)
stages. This mineralization is associated with magmatic-hydrothermal fluids
enriched in Fe-Cr-Ti.
Kata Kunci : Mangoli, mikrokontinen Banggai-Sula, magmatik-hidrotermal, geokimia batuan