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Application of Magnetotellurics and Transient electromagnetic in Kibiro Geothermal Prospect-Western Uganda. Nur, Andi Agus; Mutebi, Denis; Taufan, Yoqi Ali; ilmi, Irpan
Journal of Geological Sciences and Applied Geology Vol 3, No 1 (2019): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v3i1.19866

Abstract

ABSTRACTGeophysics is an extremely important tool in geothermal exploration. Magnetotellurics (MT) and Transient electromagnetic (TEM) techniques are some of the widely used geophysical exploration techniques in Kibiro Geothermal prospect in Western Uganda. Between 2004 and 2016, a total of 157 TEM and 64 MT stations were acquired using DGSM Geonics Protem 57, Phoenix, and Zonge GDP32-12 systems. A central loop system receiver for TEM survey was used and frequency range for MT survey was between 0.5 and >200 Hz. The MT and TEM surveys imaged low resistivity clay-rich lake beds that cap a higher resistivity and potentially permeable clastic reservoir below 150 m depth. The unusually very low resistivity zone on top of the clay rich sediments inferred a hydrothermally altered sedimentary clay zone; and therefore a hot permeable aquifer exists below 150km depth. MT data imply that the North Tooro-Bunyoro (NTB) Fault dips steeply beneath sediments to the northwest.Key words: Geophysics, Magnetotellurics, Electromagnetics, resistivity, Clay.
MANGANESE PROSPECT IDENTIFICATION USING MAGNETIC AND INDUCED POLARIZATION METHODS Taufan, Yoqi Ali; ilmi, irpan; Denis, Mutebi; Nur, Andi Agus; Syafri, Ildrem
Bulletin of Scientific Contribution Vol 16, No 3 (2018): Bulletin of Scientific Contribution GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (578.175 KB) | DOI: 10.24198/bsc.v16i3.19706

Abstract

Surveys have been carried out using Magnetic and Induced Polarization methods over area dominated by Bobonaro complex formation. This survey was conducted with the purpose to identify a mineral source using data of magnetic, conductivity and resistivity of rock. Data acquisition applied 5 m dipole space with 50 m maximal depth coverage.The interpretation was conducted by analyzing 2D and 3D sections of resistivity inversion, subsurface Induced Polarization, and geomagnetic anomaly. The interpretation result of chargeability anomaly indicates that mineral source occurred as a mineral of manganese with thin layer spreading in complex structural sediment.  As is shown from IP anomaly supported by magnetic data obtained, the anomaly has a spread of 3 m to 10 m depth from the surface. The trend of anomaly has a continuity at other locations where is predicted as the manganese mineralization source.
IDENTIFIKASI PROSPEK ANDESIT MENGGUNAKAN METODE GEOLISTRIK DI KECAMATAN CILAKU, KABUPATEN CIANJUR, JAWA BARAT ilmi, irpan; Taufan, Yoqi Ali; Denis, Mutebi; Nur, Andi Agus; Syafri, Ildrem
Bulletin of Scientific Contribution Vol 16, No 3 (2018): Bulletin of Scientific Contribution GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (569.827 KB) | DOI: 10.24198/bsc.v16i3.19927

Abstract

Survei geolistrik ini dilakukan untuk mengetahui sebaran batuan andesit dan perlapisan pasir yang terdapat dibawah permukaan (di dalam bumi). Batuan tersebut memiliki nilai tahanan jenis kelistrikan (resistivitas) yang berbeda antara material-material lainnya dengan memanfaatkan sifat kelistrikan batuan untuk memetakan kondisi geologi di bawah permukaan. Kegiatan survei 2D geolistrik dilakukan selama 4 hari, yaitu dari 14-17 November 2017, di Kecamatan Cilaku, Kabupaten Cianjur, Jawa Barat. Pengukuran geolistrik ini dilakukan dengan menggunakan metoda resistivity konfigurasi Wenner dua dimensi, seta penyelidikan dilakukan sebanyak 21 lintasan pengukuran berarah Utara – Selatan, titik elektroda 0 berawal di utara dan titik elektroda 48 di selatan. Dari hasil pengukuran dan pengolahan data lapangan dapat dibuat model 2D penampang geolistrik untuk setiap lintasan, peta anomali lateran kedalam, dan 3D gabungan dari seluruh lintasan. Anomali sebaran di daerah penyelidikan dapat di bagi dalam beberapa kelompok anomali yaitu : 1. Anomali rendah, dengan kisaran nilai resistivitas 0 Ωm - 30 Ωm yang -menyebar pada kedalaman 0 – 10 m. Anomali ini di tandai dengan warna biru, di duga lapisan zona akuifer pasir terisi air. 2. Anomali sedang, dengan kisaran nilai resistivitas 30 Ωm - 90 Ωm. Anomali yang diduga lapisan pasir, lempung dan anomali ini juga dapat berupa pasir lempungan dengan banyak konkresi yang bersifat gampingan. Pada kedalaman 40-50 m lapisan ini terdapat menyebar di utara daerah penyelidikan. 3. Anomali tinggi dan sangat tinggi, dengan kisaran anomali lebih dari 100 Ωm. Anomali ini terdapat di tenggara daerah penyelidikan. Anomali ini ditandakan warna merah yang merupakan daerah paling menarik untuk untuk dijadikan prospek.Kata kunci : Geolistrik, Andesit, Cilaku, Resistivitas, Model 2D