Widodo, Bagus Rizki (2020) Pemodelan 2D Struktur Geologi Bawah Permukaan Karst Pacitan Bagian Barat Berdasarkan Data Gayaberat. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Pacitan terletak pada zona peralihan antara subduksi zaman Kapur dengan subduksi zaman Tersier dengan wilayahnya terdiri dari kawasan vulkanik dan karst. Satuan karst menyebar di sepanjang pantai selatan, disusun oleh batugamping setempat bersifat tufan. Batugamping dibeberapa tempat mempunyai ketebalan yang beragam antara 100-500 m, namun belum diketahui ketebalan batugamping pada daerah penelitian. Terdapat juga struktur yang berkembang di daerah Pacitan dan sekitarnya seperti lipatan, sesar, dan kekar. Penelitian dilakukan dengan menggunakan metode gayaberat dengan tujuan untuk melakukan identifikasi struktur geologi bawah permukaan daerah penelitian berdasarkan analisis SVD (Second Vertical Derivative) dan Pemodelan 2D. Data gayaberat yang digunakan adalah 55 titik pengukuran yang didapatkan dari hasil akuisisi di lapangan dan 108 titik pengukuran yang didapatkan dari citra satelit TOPEX. Hasil penelitian menunjukan bahwa daerah penelitian memiliki nilai anomali Bouger antara 86 mgal sampai 130 mgal. Hasil analisis SVD pada lintasan barat-timur (A-A’) diidentifikasi terdapat sesar mendatar dengan nilai |SVDmin| = |SVDmaks| pada koordinat X= 504.5 - 506. Pada lintasan selatan-utara (B-B’) diidentifikasi terdapat sesar mendatar dengan nilai |SVDmin| = |SVDmaks| pada koordinat Y= 9093 – 9095 dan sesar normal dengan nilai |SVDmin| < |SVDmaks| pada koordinat Y= 9100 - 9101.5. Batuan karbonat di bagian barat mempunyai ketebalan 1000 m dan bagian timur mempunyai ketebalan 150 m. Batuan karbonat di bagian selatan mempunyai ketebalan 1000 m dan di bagian utara mempunyai ketebalan 250 m. Batuan karbonat di bagian barat-selatan daerah penelitian lebih tebal dibandingkan dengan batuan karbonat dibagian timur-utara. Tebal lapisan tersebut dipengaruhi oleh letak batuan dasar dan mempengaruhi proses karstifikasi pada daerah penelitian.
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Pacitan is located in a transitional zone between the Cretaceous subduction and the Tertiary subduction with its territory consisting of volcanic and karst regions. Karst units spread along the south coast, composed by local tuff-shaped limestone. Limestone in several places has a thickness that varies between 100-500 m, but not yet known the thickness of limestone in the study area. There are also structures that develop in the Pacitan and surrounding areas such as folds, faults, and joints. The study was conducted using gravity method with the aim to identify the subsurface geological structure of the study area based on SVD (Second Vertical Derivative) analysis and 2D Modeling. Gravity data used are 55 measurement points obtained from acquisitions in the field and 108 measurement points obtained from TOPEX satellite imagery. The results showed that the study area had a Bouger anomaly value between 86 mgal to 130 mgal. The results of SVD analysis on the west-east path (A-A’) identified a strike-slip fault with the value |SVDmin| = |SVDmaks| at coordinates X = 504.5 - 506. On the south-north path (B-B’) there is identified a strike-slip fault with the value |SVDmin| = |SVDmaks| at coordinates Y= 9093 - 9095 and normal fault with the value |SVDmin| < |SVDmaks| at coordinates Y= 9100 - 9101.5. Carbonate rock in the west has a thickness of 1000 m and the east has a thickness of 150 m. Carbonate rocks in the south have a thickness of 1000 m and in the north have a thickness of 250 m. Carbonate rocks in the west-south part of the study area are thicker than carbonate rocks in the east-north section. The thickness of the layer be affected by the location of bedrock and affects the karstification process in the study area.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Uncontrolled Keywords: | Bouger Anomaly, Second Vertical Derivative, 2D Modeling, Anomali Bouger, Second Vertical Derivative, Pemodelan 2D |
| Subjects: | T Technology > T Technology (General) |
| Divisions: | Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis |
| Depositing User: | Bagus Rizki Widodo |
| Date Deposited: | 13 Aug 2020 12:41 |
| Last Modified: | 17 May 2023 01:45 |
| URI: | http://repository.its.ac.id/id/eprint/78046 |
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