ANUGRAH, FEBRY (2016) IDENTIFIKASI STRUKTUR GEOLOGI BAWAH PERMUKAAN BERDASARKAN METODE MAGNETOTELURIK PADA DAERAH PULAU BIAK, KABUPATEN BIAK NUMFOR, PROVINSI PAPUA IDENTIFICATION OF SUBSURFACE GEOLOGICAL STRUCTURES BASED ON MAGNETOTELLURIC METHOD AT BIAK ISLAND, BIAK NUMFOR REGENCY, PAPUA PROVINCE. Other thesis, UPN ''VETERAN'' YOGYAKARTA.
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Abstract
Struktur Geologi merupakan salah satu faktor pengaruh karakteristik suatu daerah yang dapat dihasilkan dari proses tektonik dan vulkanik. Keberadaan struktur dapat dilihat dengan foto udara dan pemetaan topografi. Pulau Biak merupakan Pulau yang terbentuk dari aktivitas Lempeng Samudera Pasifik dan lempeng Benua Australia sehingga membentuk struktur geologi kompleks, Namun, pada bagian timur Pulau Biak didominasi oleh Gamping Terumbu dengan topografi relatif datar sehingga sangat sulit untuk mengetahui keberadaan struktur geologi. Untuk mengetahui keberadaan struktur tersebut dibutuhkan studi geofisika dengan menggunakan metode magnetotelurik yang dapat merepresentasikan struktur geologi bawah permukaan. Penelitian dilakukan pada tanggal 26 Juni sampai 26 Juli 2013 dengan cara pengukuran Single Sounding sebanyak 15 titik pengukuran AMT dan MT, untuk menghasilkan frekuensi 10-4 Hz hingga 104 Hz. Pada data MT dilakukan peningkatan kualitas data berdasarkan analisis Time Series untuk mereduksi Noise, tahapan ini mempengaruhi kualitas data yang mengacu pada peningkatan nilai koherensi. Pemodelan 1D dan 2D dilalukan melalui perangkat lunak WinGlink menggunakan inversi OCCAM dengan iterasi 30 dan RMS Error kurang dari 5%. Selanjutnya, didapatkan penampang dengan kedalaman mencapai 10 Km dan panjang penampang 35 km, kemudian dilakukan interpretasi struktur geologi bawah permukaan berdasarkan variasi nilai tahanan jenis. Interpretasi dilakukan secara kualitatif dan kuantitatif dengan mengacu pada informasi geologi dan data variasi nilai tahanan jenis. Dari hasil penampang 1D digunakan sebagai pengontrol kedalaman dan penampang 2D digunakan untuk interpretasi keberadaan struktur geologi pada daerah penelitian. Pada Penampang 2D diintrepretasikan terdapat cekungan sedimen berupa busur depan dengan umur tersier, sesar normal terbentuk pada Oligosen Akhir hingga Miosen Tengah, dan diidentifikasikan terdapatnya Intrusi Basalt. Kata kunci : Geofisika, Magnetotelurik, Audio Magnetotelurik, Analisis Time Series, Tahanan Jenis, Struktur Geologi, Cekungan Sedimen. Geological structure is one factor influences the characteristics of an area which is generated by tectonic and volcanic processes. The existence of the structure can be seen by Aerial Photographs and Topographic Mapping. Biak Island is formed by the activity of the Pacific Plate and the Australian Plate generating the Complex Geological Structure. The eastern part of the island is dominated by carbonate reef with relatively flat Topography. Therefore, it is difficult to know the existance of Geological Structures. To know the existence of such structures needed geophysical studies using Magnetotelluric method that can represent the subsurface geological structure. The study was conducted from June 26th to July 26th, 2013 in singles Sounding measurements with 15 AMT and MT measuring points, to generate frequency of 10-4Hz to 104 Hz . The MT data were improved by the analysis of time series to reduce noise. This stage affects the quality of the data that lead to increase the coherence value. This value is represented by a better pattern of pseudo resistivity graph and phase versus frequency. The 1D and 2D modeling was conducted in WinGlink software using Occam inversion with 30 iterations and RMS error of less than 5%. After the modelling process, the cross sections obtained with a depth of 10 km and 35 km long cross-section, then carried interpretation of subsurface geological structures based on variations in resistivity values. Interpretation was performed qualitatively and quantitatively with reference to the geological information and data variations in resistivity value. From the results, the 1D cross sections were used as depth control and the 2D cross sections were used for the geological structure interpretation in the research area. In the 2D cross-section are interpreted a fore arc sedimentary basins in tertiary age, normal faults formed in the Late Oligocene to Middle Miocene, and identified the presence of Basalt intrusions. Keywords: Geophysics, Magnetotelluric, Audio Magnetotelluric, Time Series Analysis, Resistivity, Geological Structures, Sedimentary Basin.
| Item Type: | Thesis (Other) |
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| Subjects: | Q Science > QE Geology |
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Geography |
| Depositing User: | Erny Azyanti |
| Date Deposited: | 09 Nov 2016 03:55 |
| Last Modified: | 09 Nov 2016 03:55 |
| URI: | http://eprints.upnyk.ac.id/id/eprint/8593 |
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