Identifikasi Struktur Bawah Permukaan Kawasan Karst Pacitan Bagian Barat Menggunakan Pemodelan Gayaberat dan Analisis Densitas Kelurusan

Maulina, Dinda (2023) Identifikasi Struktur Bawah Permukaan Kawasan Karst Pacitan Bagian Barat Menggunakan Pemodelan Gayaberat dan Analisis Densitas Kelurusan. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kawasan karst Pacitan merupakan bagian dari sistem karst Gunungsewu yang ditandai dengan bukit-bukit batugamping. Sesar dan kekar cukup sulit dilacak pada daerah yang tersusun oleh batugamping. Kawasan karst Pacitan bagian barat menjadi fokusan dalam penelitian ini. Penelitian ini dilakukan untuk mengidentifikasi, memetakan arah struktur geologi, serta mengkorelasikan hasil pemodelan anomali gayaberat dan analisis densitas kelurusan. Metode gayaberat mampu menggambarkan keberadaan struktur geologi dan batas formasi karena adanya variasi lateral densitas. Analisis densitas kelurusan digunakan untuk menentukan pola dominan struktur geologi. Data yang digunakan berupa data pengukuran gayaberat dan DEM SRTM. Data gayaberat direduksi sehingga menghasilkan nilai Complete Bouguer Anomaly. Pemodelan inversi dilakukan terhadap anomali residual dengan metode inversi Singular Value Decomposition dan Occam. Ekstraksi kelurusan dilakukan menggunakan modul LINE terhadap peta shaded relief yang dihasilkan dari DEM SRTM, dimana kelurusan mengindikasikan keterdapatan struktur geologi. Hasil kelurusan diolah untuk mendapatkan peta sebaran densitas kelurusan. Berdasarkan hasil pemodelan gayaberat anomali rendah berasosiasi dengan formasi Wonosari, Oyo, dan Kalipucang pada barat-selatan daerah penelitian. Pada utara-tenggara daerah penelitian didominasi oleh anomali tinggi yang berasosiasi dengan formasi Nampol, Wuni, Jaten, Arjosari, dan batuan intrusi. Hasil pemodelan inversi untuk lintasan A-A’, B-B’, C-C’, dan D-D’ teridentifikasi adanya struktur geologi berupa sesar Buyutan, Pucunglangan, Punung, sesar geser dekstral, sesar geser sinistral, dan patahan naik serta batas formasi yang ditunjukkan oleh kontras densitas. Berdasarkan hasil analisis densitas kelurusan, arah dominan struktur berupa NE-SW. Struktur geologi yang teridentifikasi pada hasil pemodelan gayaberat berasosiasi dengan densitas kelurusan tinggi yang menyebar pada area utara, timur, hingga tenggara daerah penelitian.
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The Pacitan karst area is part of the Gunungsewu karst system, which is characterized by limestone hills. Faults and joints are difficult to trace in areas composed of limestone. The western part of the Pacitan karst area is the focus of this research. This research was conducted to identify and map the direction of the geological structures and correlate the results of gravity anomaly modeling and lineament density analysis. The gravity method can identify geological structures and formation boundaries due to the lateral variations of density. Lineament density analysis is used to determine the dominant direction of the geological structure. The data used are gravity measurement and DEM SRTM. The gravity data is reduced to obtain a Complete Bouguer Anomaly value. Inversion modeling was carried out on residual anomalies using Singular Value Decomposition and Occam inversion methods. Lineament extraction was carried out using the LINE module on the shaded relief maps generated from the DEM SRTM, where lineaments indicate the presence of geological structures. The lineaments are processed to obtain a lineament density distribution map. Based on the results of gravity modeling, low anomalies are associated with the Wonosari, Oyo, and Kalipucang formations in the west-south of the research area. In the north-southeast of the research area, high anomalies are associated with the formations of Nampol, Wuni, Jaten, Arjosari, and intrusive rocks. Inversion modeling results for profiles A-A', B-B', C-C', and D-D' identified formation boundaries and faults, namely Buyutan, Pucunglangan, Punung, dextral strike-slip faults, sinistral strike-slip faults, and thrust faults indicated by density contrast. Based on the results of the lineament density analysis, the dominant direction of the structure is NE-SW. The geological structures identified in the gravity anomaly modeling are associated with a high lineament density that spreads to the north, east, and southeast of the research area.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Densitas Kelurusan, Gayaberat, Karst Pacitan, Struktur Geologi, Lineament Density, Gravity, Pacitan Karst, Geological Structure
Subjects:	G Geography. Anthropology. Recreation > GB Physical geography > GB600 Karst conservation. Q Science > QC Physics > QC111 Density and specific gravity Q Science > QE Geology > QE601 Geology, Structural
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Dinda Maulina
Date Deposited:	29 Nov 2023 02:01
Last Modified:	29 Nov 2023 02:01
URI:	http://repository.its.ac.id/id/eprint/102712

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