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Pendugaan Mineral Kromit Menggunakan Metode Induced Polarization (Ip) di Daerah Kabaena Utara, Bombana Sulawesi Tenggara Budy Santoso; Subagio Subagio
Jurnal Geologi dan Sumberdaya Mineral Vol. 17 No. 3 (2016): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v17i3.17

Abstract

Mineral kromit di daerah Kabaena Utara terdapat pada batuan ultramafik (batuan peridotit) dan endapan aluvial. Untuk mengetahui penyebaran mineral kromit di daerah penelitian maka dilakukan pengukuran Induced Polarization. Induced Polarization merupakan salah satu metode geofisika yang dapat digunakan untuk pendugaan mineral kromit berdasarkan parameter fisis chargeabilitas dan resistivitas batuan. Teknik pengukuran Induced Polarization dilakukan dengan metode Sounding Profilling 2D, dengan metode ini penyebaran mineral kromit secara lateral dan vertikal dapat diketahui. Konfigurasi elektroda yang digunakan dalam akuisisi data IP yaitu Konfigurasi Dipole-Dipole dengan menggunakan alat Res & IP Meter Supersting-R8. Pengolahan data menggunakan program inversi Res2Dinv. Endapan kromit di daerah penelitian terdiri dari endapan primer dan endapan sekunder. Berdasarkan hasil pengukuran Induced Polarization, endapan kromit primer yang terdapat pada batuan ultramafik (batuan peridotit) mempunyai nilai chargeabilitas (221 – 320) msec dan resistivitas (900 – 6000) Ohm.m, sedangkan endapan kromit sekunder yang terdapat pada lapisan pasir yang mengandung gravel dan fragmen batuan peridotit mempunyai nilai chargeabilitas (203 – 270)  msec dan resistivitas (296 – 400) Ohm.m. 
ANOMALI GAYABERAT DAN POTENSI BENCANA GEOLOGI DI KAWASAN JAWA BARAT BAGIAN TENGAH Subagio Subagio
Jurnal Geologi dan Sumberdaya Mineral Vol. 23 No. 2 (2013): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v23i2.90

Abstract

In the Central part of West Java, anomaly Bouguer values vary from 5 to 125 mGals, forming high and low anomalies. The lowest anomaly located around Tagogapu, Padalarang area showing a sediment basin; while the highest anomaly is located around Pelabuhanratu, that are controlled by the existence of ultramafic rocks. In the survey area the rocks are divided into three groups, involving Tertiary sedimentary rocks with density 2,4 gr/cm3; Quaternary volcanic rocks with density 2,2 gr/cm3; and andesite with density 2,8 gr/cm3. Based on the modellings, faults in this area consist of thrust, normal and strike slip faults, partly are active faults. In Puncak area and its surroundings are a graben zone, that filled by low density rocks consisting of Quaternary volcanic rocks, is controlled by sub-surface active faults. Therefore the areas potentialy undergo landslides.Key words: gravity anomaly, active faults,Puncak, graben zone, landslide
INTERPRETASI POLA ANOMALI GAYA BERAT REGIONAL KAITANNYA TERHADAP POTENSI SUMBER DAYA GEOLOGI DI LENGAN SELATAN SULAWESI Subagio Subagio; Bambang S. widijono
Jurnal Geologi dan Sumberdaya Mineral Vol. 22 No. 1 (2012): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v22i1.106

Abstract

The research area is part of Western Sulawesi Geological Terrain, arranged by pre-Tertiary to Quarternary rocks. The pre Tertiary rocks exposed in Latimojong Mountain located at northeastern research area and Maros Mountain near Bantimala district at southwestern area. The pre Tertiary rocks consist of metamorphic, and ultrabasic rocks overlain by flysch sediments. These flysch sediments overlain by Paleogen terrestrial sediments and carbonate rocks. The Oligosen - Early Miosen rocks exposed at Bone Mountains. These rocks consist of clastic and volcanic clastic sediments. The carbonate rocks have also been faund in that area. The Middle Miosen - Pliosen clastic sediments exposed along the valley in Graben Wallanae. The Quarternary sediments is distributed in Wallanae River. Regional gravity anomalies indicate the main lineaments geological structure that developed in the study area. The lineaments are north-south, northwest-southeast, and north northwest-south southeast directions. Wallanae fault is indicated by north-south direction indicating parallel contours anomaly that separate high anomaly in the west and low anomaly in the east of Wallanae Fault. The high anomaly pattern indicates the occurrance of ultramafic basement rock with having a mass density 2.9 gr/cc, while low anomaly indicates the occurrence of metamorphic basement rock with having mass density 2,8 gr/cc. The undulation of residual anomaly reflects the straightness of shallow geological structures. The geological resources of the region area are hydrocarbon, coal, and metallic minerals. This hydrocarbon probably present in the low anomaly, coal in the marginal basinal anomaly, while metallic mineral is found at high anomaly area.Key words : Lineament, anomalies, basement rocks, geological resources, Sulawesi
INDIKASI FENOMENA STRUKTUR GEOLOGI BAWAH PERMUKAAN DAERAH RENCANA TAPAK PEMBANGKIT LISTRIK TENAGA NUKLIR GUNUNG API GENUK DAN SEKITARNYA, JEPARA, JAWA TENGAH Saultan Panjaitan; Subagio Subagio
Jurnal Geologi dan Sumberdaya Mineral Vol. 19 No. 1 (2009): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v19i1.193

Abstract

Generally, gravity anomaly pattern in research area is devided into two groups, high anomaly with the value ranges from 37 mgal to 43 mgal, and low anomaly, varies from 10 mgal to 37 mgal. The high anomaly group might be caused by the existing volcanic Quartenary rocks, and the low anomaly group indicates a sedimentary basin. Based on the result of 3 quantitative analysis, the high anomaly group reflects the existing volcanic Quartenary rocks with density 2.8 gr/cm relatively higher than surrounding. Analysis also shows in the site plan of Ujung Lemahabang the predicted faults are not encountered. The area in radius 5 km from research area, predicted the capable fault not exist in radius 25 km, found two faults ofshore and three faults in western part of investigation area. Keywords : Lemahabang, gravity anomaly, sedimentary basin arc fault
STRUKTUR GEOLOGI BAWAH PERMUKAAN LINTASAN PANGALENGAN-SUBANG, IMPLIKASINYA TERHADAP KESTABILAN LAHAN Subagio Subagio; Bambang Suci Widijono
Jurnal Geologi dan Sumberdaya Mineral Vol. 19 No. 6 (2009): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v19i6.222

Abstract

The high anomaly pattern of West Java extending from Banten Province to the boundary of West - Central Java area, changes to low anomaly pattern in Bandung to Pamanukan. This phenomenon formed anomaly alignment with high gradient in the boundary part of both anomaly patterns. The profile pattern of Bouguer anomaly along Pangalengan­Subang and Gudangkahuripan-Parongpong sections show more detailed illustration of the subsurface geology structures. Qualitative and quantitative gravity analyses that were supported by surface geological data, sediment thickness, and remote sensing data, estimate that the anomaly alignment reflects a fault that formed a big graben. The anomaly profiles also describe some fault forming some horsts and grebens. Based on erotion intensity esoect in the mountainous area, and geological structures, the land stability of this area is interpreted as very low. Keywords.' high, low, anomaly alignment, structure, Pangalengan-Subang Section, horst, graben, land stability
STRUKTUR GEOLOGI BAWAH PERMUKAAN DAERAH KEBUMEN BERDASARKAN ANALISIS POLA ANOMALI GAYA BERAT DAN GEOMAGNET Subagio Subagio
Jurnal Geologi dan Sumberdaya Mineral Vol. 18 No. 6 (2008): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v18i6.259

Abstract

The Gravity anomaly pattern of research area is devided into two groups  involving high and low anomalies. The high anomaly dominating at western and eastern area have positive circular pattern, and the value ranges from 90 mgal to 145 mgal. The east and west high anomalies are separated by low anomaly, having negative circular pattern, varies from 52 mgal to 89 mgal, and the low anomaly is located in the central area. The high anomaly patterns might be caused by andesite intrusive rocks in Karangbolong and Kulon Progo High areas, and Pratertier rock in Karangsambung area. Gravity value of Luk Ulo Complex (114 mgal) is lower than the value of intrusive rocks (145 mgal), meanwhile the negative anomaly indicates sedimentary basin. Karangbolong and Kulonprogo high and the basin are seperated by faults, such as Karangbolong and Purworejo Faults respectively. Keywords :  gravity anomaly, positive circular pattern, negative circular pattern, andesite intrusive rock, sedimentary basin, Luk Ulo Pratertier rocks, Karangbolong Fault, Purworejo Fault, Karangbolong High, Kulon Progo High.  
POTENSI PANAS BUMI DAERAH PANDEGLANG DAN SEKITARNYA BERDASARKAN EVALUASI DATA GEOLOGI DAN GEOFISIKA TERPADU Subagio Subagio; Bambang S.Widijono
Jurnal Geologi dan Sumberdaya Mineral Vol. 18 No. 3 (2008): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v18i3.261

Abstract

Intergrated geological and geophysical informations provide ilustration of subsurface geology of the researched area. Result of gravity modelling of the study area show several grabbens and intrusives. This structures would probably be act as trap of a geothermal potential. The young intrusive rocks beneath the Gunung Karang is interpretated as a heat sources, while the Tertiary sedimentary rocks could possibly be a reservoir. The altered volcanic rocks widely exposed in the study area may presence as a caprock. The possibility of geothermal energy potential is also indicated by the area.occurrence of several of springs exposed in the area. Keywords: intergrated geophysical information, subsurface geological structure, geothermal
Interpretasi Struktur Geologi Bawah Permukaan Berdasarkan Updating Data Gaya Berat Cekungan Banyumas, Jawa Tengah Hidayat Hidayat; Subagio Subagio; Zulimatul Safa'ah Praromadani
Jurnal Geologi dan Sumberdaya Mineral Vol. 21 No. 3 (2020): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v21i3.524

Abstract

Cekungan Banyumas adalah cekungan sedimen Paleogen-Neogen yang terdapat di Jawa Tengah bagian selatan dan merupakan salah satu cekungan sedimen dengan potensi hidrokarbon. Rembesan migas ditemukan di beberapa lokasi sekitar puncak Antiklin Cipari yang memisahkan sub-Cekungan Majenang dan sub-Cekungan Citanduy, dengan pola sebaran baratlaut – tenggara. Oil show juga ditemukan pada beberapa sumur eksplorasi di sekitar area studi yang merupakan indikasi terdapatnya sistem petroleum aktif di Cekungan Banyumas. Tujuan penelitian adalah melakukan analisis data gaya berat yang telah diperbarui oleh Pusat Survei Geologi dengan ketelitian dan kerapatan antar stasiun pengukuran lebih baik daripada data sebelumnya. Analisis data terdiri atas analisis spektrum untuk mengestimasi kedalaman batuan dasar dan filter Second Vertical Derivative (SVD) untuk mengetahui perubahan densitas dan orientasi kemiringan (dip) pada suatu lapisan. Band pass filter diterapkan pada anomali bouger lengkap untuk memperoleh anomali sisa gaya berat berdasarkan analisis spektrum. Anomali sisa gaya berat menunjukkan tren Antiklin Cipari yang relatif berarah baratlaut – tenggara. Analisis data selanjutnya disajikan dalam dua buah penampang, A – A' dan B – B' berupa pemodelan ke depan 2.5D dengan apriori: data pemboran Jati-1 dan penampang seismik serta informasi struktur peta geologi Lembar Majenang. Pola anomali tinggian dan rendahan di sekitar penampang ditafsirkan akibat adanya struktur geologi berupa patahan dan lipatan yang berkembang di sekitar area penelitian.Katakunci : Gaya berat, cekungan sedimen, SVD, analisis spektrum, Banyumas.