Rachmawan, Dimas Putra (2025) Konversi Data Induksi Polarisasi Domain Waktu Ke Domain Frekuensi Dengan Pendekatan Debye Decomposition: Studi Kasus Eksplorasi Logam Emas Tipe Carlin Di Pit “GL” Daerah Ratatotok Selatan, Minahasa Tenggara, Sulawesi Utara. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Metode induced polarization (IP) time domain (TD) digunakan sebagai perpanjangan dari pengukuran resistivitas arus searah (DC). Pada time domain (TD), peluruhan tegangan transien diukur setelah penghentian injeksi arus. Untuk mengonversi kumpulan data tomografi IP time domain (TDIP) menjadi model tomografi resistivitas kompleks frequency domain (FD), diperlukan pendekatan yang sesuai untuk mengonversi transien TD IP beserta ketidakpastiannya ke dalam frequency domain (FD) dengan pendekatan Debye Decomposition (DD). Uji metode konversi diterapkan pada data lapangan berupa kumpulan data tomografi TDIP yang diukur di pit “GL”. Pit “GL” merupakan pit dengan tipe lingkungan pengendapan emas tipe carlin yang dicirikan oleh endapan emas (auriferous) pirit yang tersebar dan epigenetik yang biasanya terendapkan dalam batuan sedimen berkapur (calcareous sedimentary rocks). Emas hadir dalam bentuk inklusinya yang sangat kecil (submikron) atau sebagai larutan padat (solid solution) di dalam pirit yang kaya arsenik (As-rich pyrite). Dalam penelitian ini dilakukan identifikasi zona persebaran mineralisasi untuk mengetahui potensi endapan mineral emas dibawah permukaan. Berdasarkan hasil pengolahan data, diketahui bahwa nilai resistivitas pada pit “GL” berkisar antara 2,95 hingga 508 Ohm.m, dan nilai chargeabilitas berkisar antara 15 hingga 50 milidetik. Zona arsenian pyrite dicirikan dengan chargeabilitas sedang-tinggi (10-50 milidetik), resistivitas rendah-sedang (0,001-100 Ohm.m), fase tinggi (-60 hingga -45 miliradian), percent frequency effect tinggi (0-30 %), metal factor (0-6000), dan komponen imajiner konduktivitas bernilai rendah-tinggi (-2,5 hingga -1,5 log10(S/m)) namun nilainya menurun ketika terdapat dugaan zona ratatotok limestone. Sedangkan untuk zona ratatotok limestone dicirikan dengan nilai chargeabilitas sedang-tinggi (10-40 milidetik) sehingga hampir tidak bisa dibedakan dengan zona arsenian pyrite, resistivitas sedang-tinggi (50-4000 Ohm.m) nilai yang berada pada rentang yang sama dengan zona arsenian pyrite, fase rendah (-45 hingga -5 miliradian), percent frequency effect rendah (0 %), metal factor (0), dan komponen imajiner konduktivitas bernilai tinggi (-1,5 log10(S/m)) yang mengalami peningkatan ketika berada di sekitar zona arsenian pyrite.
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The time-domain induced polarization (TDIP) method is used as an extension of direct current (DC) resistivity measurements. In the time domain (TD), the transient voltage decay is measured after the cessation of current injection. To convert the TDIP tomographic dataset into a frequency-domain (FD) complex resistivity tomographic model, an appropriate approach is required to transform the TD IP transients and their uncertainties into the FD using the Debye decomposition (DD) method. The conversion method was tested on field data consisting of TDIP tomographic measurements taken at the "GL" pit. The "GL" pit represents a Carlin-type gold deposit environment, characterized by dispersed and epigenetic auriferous pyrite deposits typically hosted in calcareous sedimentary rocks. Gold is present as very fine submicron inclusions or as a solid solution within arsenic-rich pyrite (As-rich pyrite). This study aims to identify zones of mineralization distribution to assess the potential for subsurface gold deposits. Based on the data processing results, resistivity values at the “GL” pit range from 2.95 to 508 Ohm.m, and chargeability values range from 15 to 50 milliseconds. The arsenian pyrite zone is characterized by medium to high chargeability (10–50 milliseconds), low to medium resistivity (0.001–100 Ohm.m), high phase (-60 to -45 milliradians), high percent frequency effect (0–30%), metal factor (0–6000), and low to high imaginary conductivity component (-2.5 to -1.5 log10(S/m)), with its values decreasing in the presence of suspected Ratatotok limestone zones. Meanwhile, the Ratatotok limestone zone is characterized by medium to high chargeability (10–40 milliseconds), which makes it difficult to distinguish from the arsenian pyrite zone; medium to high resistivity (50–4000 Ohm.m), which also overlaps with the arsenian pyrite zone; low phase (-45 to -5 milliradians); low percent frequency effect (0%); metal factor (0); and a high imaginary conductivity component (-1.5 log10(S/m)), which tends to increase when located near the arsenian pyrite zone.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Induced polarization, Debye decomposition, Emas, Tipe Carlin, Resistivitas, Chargeabilitas, Fase, Komponen Imajiner Konduktivitas, Percent frequency effect, Metal factor |
| Subjects: | Q Science > QE Geology > QE601 Geology, Structural T Technology > T Technology (General) > T57.5 Data Processing T Technology > T Technology (General) > T57.6 Operations research--Mathematics. Goal programming |
| Divisions: | Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis |
| Depositing User: | Dimas Putra Rachmawan |
| Date Deposited: | 15 Jul 2025 02:26 |
| Last Modified: | 15 Jul 2025 02:26 |
| URI: | http://repository.its.ac.id/id/eprint/119748 |
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