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Journal : JGE (Jurnal Geofisika Eksplorasi)

EVOLUSI TUBUH GUNUNGAPI DAN IMPLIKASI STRUKTUR GEOLOGI DI GUNUNG PESAWARAN-BETUNG, LAMPUNG Happy Christin Natalia; Anjar Dwi Asterina Denhi
JGE (Jurnal Geofisika Eksplorasi) Vol 9, No 1 (2023)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v9i1.253

Abstract

Provinsi Lampung didominasi oleh produk vulkanik yang membentuk berbagai pola morfologi, baik itu morfologi dataran, perbukitan, hingga kaldera. Aktivitas vulkanik di Provinsi Lampung erat kaitannya dengan aktivitas tektonik yang berkembang sejak Miosen. Namun, belum ada penelitian terperinci terkait aktivitas vulkanisme tersebut. Tujuan penelitian ini adalah untuk menentukan evolusi tubuh gunungapi strato di Gunung Pesawaran dan Betung serta menentukan implikasi struktur yang mempengaruhi sebaran produk gunungapi. Penelitian ini menggabungkan data analisis morfologi areal dan linear berdasarkan Digital Elevation Model (DEM) untuk menentukan evolusi tubuh gunungapi. Data area dan linear daerah penelitian dianalisis menggunakan peta topografi, hillshade, data kemiringan lereng, dan kelurusan yang diolah menggunakan perangkat lunak ArcGIS 10.5. Berdasarkan analisis area dan analisis linear terdapat empat domain area dan dua pola kelurusan yang ditunjukkan oleh perbedaan tekstur, morfologi, and produk vulkanik. Daerah penelitian memiliki morfologi kaldera purba yang dikenal dengan Kaldera Gebang, bagian dari domain 1, di bagian timur daerah penelitian, dataran vulkanik di bagian utara dan merupakan bagian dari domain 2, dan tubuh gunungapi strato tipe C, yaitu Gunung Pesawaran (domain 3) dan Gunung Betung (domain 4) yang menempati bagian tengah daerah penelitian. Dua pola kelurusan menunjukkan arah baratlaut-tenggara dan baratdaya-timurlaut. Kedua pola kelurusan ini menunjukkan bahwa perkembangan patahan dan morfologi gunungapi daerah penelitian dipengaruhi oleh aktivitas tektonik dan vulkanisme sejak umur Miosen.
PENENTUAN FASIES, LINGKUNGAN PENGENDAPAN DAN IDENTIFIKASI SEBARAN BATUBARA DI FORMASI PALEMBANG, RIAU, SUMATRA Simatupang, Sandy Wesly; Widiatama, Angga Jati; Natalia, Happy Christin
JGE (Jurnal Geofisika Eksplorasi) Vol. 10 No. 3 (2024)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v10i3.432

Abstract

Cekungan Sumatra Tengah memiliki cadangan batubara melimpah yang dikelompokkan dalam Formasi Palembang. Formasi Palembang memiliki ekuivalensi dengan Formasi Muaraenim di Cekungan Sumatra Selatan. Penelitian pada Formasi Palembang masih relatif minim sehingga diperlukan pembahasa terkait fasies, asosiasi fasies, lingkungan pengendapan, dan juga geometri persebaran lapisan agar dapat digunakan sebagai rujukan kegiatan eksplorasi. Metode penelitian berupa analisis data petrofisika dan pemodelan bawah permukaan dari delapan data sumur pemboran. Dari interpretasi litologi yang dilakukan terdapat empat litologi dan tiga endapan pada daerah penelitian yang terdiri dari batubara, shaly coal, batupasir, batulempung, endapan konglomerat, endapan pasir, endapan lempung.  Litofasies pada daerah penelitian terdiri dari fasies endapan lempung, endapan pasir, endapan konglomerat, batulempung, batupasir, shaly coal, dan fasies batubara. Asosiasi fasies pada daerah penelitian terdiri dari channel, sandy bedform, overbank fines, dan swamps yang menginterpretasikan bahwa litologi yang ada pada daerah penelitian terendapkan pada daerah fluvial. Berdasarkan pemodelan bawah permukaan, litologi batubara pada daerah penelitian memiliki geometri melensa/membaji yang persebarannya dominan kearah timur. Batubara pada daerah penelitian diinterpretasikan terbentuk pada lingkungan pengendapan swamp.
THE STRATIGRAPHY AND GEOLOGICAL STRUCTURE IN KOTAAGUNG TIMUR DISTRICT, TANGGAMUS, LAMPUNG Natalia, Happy Christin; Wiguna, Lanang Rangga Setia
JGE (Jurnal Geofisika Eksplorasi) Vol. 11 No. 1 (2025)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v11i1.477

Abstract

Kotaagung Timur region, Tanggamus Regency, Lampung, is the focus area of this research. In general, the area has a unique and complex geological setting such as the variety of volcanic rocks, granite, and the Sumatran Fault System that through this area. Geological research aims to obtain geology dynamics about stratigraphy and geology structure in the research area. Two analyses have been done to achieve these goals, i.e., field observation, petrography analysis, and structural geology analysis. The stratigraphy units of the study area are composed of volcanic rocks, plutonic rocks, and surface deposits and can be divided into eleven lithostratigraphic units. The stratigraphy of the research area can be grouped into 5 groups, i.e., the Mount Gisting volcanic group, the granitoid pluton group, the Cawang Haro Mountains volcanic group, the Mount Tanggamus volcanic group, and the alluvial deposit. Geological structures are well developed, and the research area is cut by ten faults, such as dextral strike-slip faults, sinistral strike-slip faults, and reverse faults. Based on these things, the geological history of the study area started in the Late Oligocene with three episodes of volcanism. The first episode was Mount Gisting’s volcanism during the Late Oligocene-Early Miocene, followed by the granitoid intrusion. The volcanic products of the Cawang Haro Mountains in the Middle Miocene mark the second episode. The last volcanic episode occurred in the Holocene, it came from Mount Tanggamus’s volcanism. The development of the structural geology happened before the previous volcanism episode.
IDENTIFICATION OF AQUIFER LAYERS USING THE ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT) METHOD IN GUNUNG KASIH AREA Alviyanda, Alviyanda; Farduwin, Alhada; Nugraha, Purwaditya; Widiatama, Angga Jati; Natalia, Happy Christin; Ogara, Evan Rosyadi; Piqri, Hafidz
JGE (Jurnal Geofisika Eksplorasi) Vol. 11 No. 3 (2025)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v11i3.491

Abstract

The varied physiographic conditions of Lampung, from the west to the center and east, are the main factors in determining the geological field campus as a suitable learning environment. Gunung Kasih is one of the areas located on the Bukit Barisan Range, which has unique geological conditions with exposed basement rocks on the surface, making it a key factor in determining the geological field campus. However, the presence of crystalline basement rocks in Gunung Kasih prevents water from penetrating below the surface, thereby affecting the availability of groundwater for the local community. This study aims to identify aquifer layers around the Gunung Kasih area, using the Electrical Resistivity Tomography (ERT) method. Stratigraphically, based on field observations of rocks, the study area has lithology consisting of schist, marble, and sandstone in the western part, with a landscape characterised by structural hills. On the eastern side, volcanic deposits such as tuff and andesitic lava were found, with a denudational plain landscape. The geophysical survey was conducted using Wenner-Schlumberger configuration, with four survey lines oriented relatively west to east and north to south. Low resistivity anomalies are indicated by layers with resistivity values of 0–20.7 Ωm, while moderate-to-high anomalies have resistivity values of 29.9–89.9 Ωm. Very high resistivity anomalies are indicated by layers with resistivity values of 61.9–128 Ωm. In comparison with observations of rock outcrops and rock resistivity values, the aquifer layer is interpreted as being indicated by low resistivity anomalies in the relatively eastern part of the study area, which is near the surface to a depth of 15 metres and 25 metres. This layer is interpreted as tuffaceousrock comparable to the Hulusimpang Formation. The aquifer layer in the study area is interpreted as a shallow unconfined aquifer.