Analisis Data Magnetotelurik dengan Pemodelan Resistivitas 2D Daerah Gondang, Bojonegoro

Priambodo, Galih (2021) Analisis Data Magnetotelurik dengan Pemodelan Resistivitas 2D Daerah Gondang, Bojonegoro. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

ABSTRAK
Penelitian terdahulu di Kecamatan Gondang, Kabupaten Bojonegoro, telah menemukan adanya reservoir lumpur bawah tanah yang menjadi sumber mud volcano di lokasi tersebut, yang berdekatan dengan intrusi batuan. Penelitian yang serupa mengenai identifikasi sumber mud volcano menunjukkan bahwa massa lumpur bawah dikarakterisasi oleh resistivitas rendah. Selain mud volcano, pada Kecamatan Gondang didapati manifestasi geothermal lain berupa mata air panas. Sementara itu, penelitian menggunakan metode magnetotelurik pada zona yang berdekatan dengan Kecamatan Gondang telah mengidentifikasi struktur sesar dalam. Penelitian ini akan mengidentifikasi distribusi dan karakteristik fitur geologi yang diduga ada pada daerah tersebut, serta mendeskripsikan hubungan antara fitur geologi tersebut berkaitan dengan geologi setempat berdasarkan persebaran resistivitas yang dimodelkan secara 2D dari data MT di daerah tersebut. Stasiun pengukuran data MT yang digunakan sebanyak 7 titik dan 1 trace profil akan dibuat searah utara-selatan. Di samping inversi data resistivitas semu, dilakukan juga forward modelling untuk menentukan jumlah, resistivitas, dan tebal lapisan di bawah tiap stasiun. Hasil menunjukkan 5 zona resistif (20-1250 m) dan 4 zona konduktif (≤10 m). Zona resistif terdiri dari 4 zona vertikal yang terletak di bagian tengah, 1 zona vertikal di bagian selatan lebih dalam dari 5 km, dan 1 zona horizontal memanjang di sepanjang bagian selatan dekat permukaan. Zona resistif vertikal diinterpretasikan sebagai intrusi andesit, dan zona horizontal sebagai breksi vulkanik. Zona konduktif ditafsirkan terdiri dari tufa dan napal dengan kemungkinan kandungan air asin. Setidaknya 3 sesar diperkirakan berada di sekitar dan di antara intrusi. 3 intrusi di bagian tengah diperkirakan memiliki sumber yang sama, dan keempat intrusi tersebut diduga terjadi bersamaan dengan intrusi Gunung Pandan, bersamaan dengan pembalikan Zona Kendeng pada Pliosen Akhir. Patahan yang tidak teridentifikasi di bagian selatan diperkirakan telah terputus oleh intrusi.
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The preceding studies in Gondang District, Bojonegoro Regecy, had identified the presence of an subterranean mud reservoir which serves as the source for mud volcano in the location, which is located near rock intrusions. Similar studies regarding the identification of mud volcano sources show that the subterranean mud mass is characterized by low resistivity. In addition to the mud volcano, in Gondang District, other geothermal manifestations are found in the form of hot springs. Meanwhile, research using the magnetotelluric method in the zone adjacent to Gondang District has identified deep fault structures. This study will identify the distribution and characteristics of geological features that are thought to exist in the area, as well as describe the relationship between these geological features with respect to local geology based on the distribution of resistivity modeled in 2D from MT data in the area. The MT data measurement station used is 7 points and 1 profile trace will be made in the direction of north-south. In addition to the inversion of apparent resistivity data, forward modeling is also carried out to determine the number, resistivity, and layer thickness under each station. The results show 5 resistive zones (20–1250 Ω∙m) and 4 conductive zones (≤10 Ω∙m). The former consist of 4 vertical zones located middle section, 1 vertical zone at south section deeper than 5 km, and 1 horizontal zone extending along south section near the surface. The vertical resistive zones are interpreted as andesite intrusions, and the horizontal one as volcanic breccia. The conductive zones are interpreted as consisting of tuff and marl with possible saline water content. At least 3 faults are predicted to be around and between the intrusions. 3 intrusions in the middle section are thought to have the same source, and all 4 intrusions are suspected to co-occurr with the Pandan Volcano intrusion, along with the Kendeng Zone reversal during Late Pliocene. Unidentified faults in the south section are thought to have been cut off by intrusions.

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	Gondang, Pemodelan 2D, Magnetotelurik, Resistivitas
Subjects:	Q Science > QE Geology > QE601 Geology, Structural
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geomatics Engineering > 29202-(S1) Undergraduate Thesis
Depositing User:	Galih Priambodo
Date Deposited:	24 Aug 2021 02:11
Last Modified:	24 Aug 2021 02:11
URI:	http://repository.its.ac.id/id/eprint/89970

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