Matano Fault was a strike-slip fault with ESE – WNW orientation which located on the northern par... more Matano Fault was a strike-slip fault with ESE – WNW orientation which located on the northern part of Sulawesi's Southeast Arm. The fault is connected to Palu-Koro Fault on the western part and Sorong Fault on the eastern part. The Digital Elevation Model and the geological map shows that Matano Fault was a left stepping left-lateral fault that formed Matano's Lake pull-apart basin. The Offset of the Tokala Formation shows Matano Fault have at least 60 km displacement. The tectonic stress inversion from earthquake focal mechanism data showsMatano Fault was a strike-slip faultwith N 38 ° E/ 30 ° maximum compressive principal stress axes.
Bencana gempabumi di Indonesia adalah suatu keniscayaan, tidak hanya pada daerah yang selama ini ... more Bencana gempabumi di Indonesia adalah suatu keniscayaan, tidak hanya pada daerah yang selama ini diketahui seringkali mengalaminya, namun juga pada daerah yang dahulu diduga relatif aman. Kondisi demikian dikontrol oleh konfigurasi tektonis Indonesia di masa lampau dan di masa sekarang ini. Banyak sudah peristiwa gempabumi yang menelan korban ribuan jiwa dan kerugian harta benda yang sangat besar. Kenyataan ini menuntut kemauan kita untuk belajar memahami fenomena gempabumi dengan lebih baik lagi, agar dapat mengurangi resiko bencana. Gempabumi ditimbulkan oleh pergeseran patahan, sehingga keberadaan patahan baik di permukaan maupun di bawah permukaan harus bisa dipetakan dengan baik dan akurat. Energi gempabumi merambat dari sumber pergeseran patahan dalam beberapa jenis gelombang, yang menuntut pengukuran secara tepat dan cepat. Kerusakan infrastruktur tidak hanya disebabkan oleh besaran energi, namun juga bagaimana percepatan gelombang gempabumi diterima di lokasi tersebut. Perioda dan frekuensi batuan di permukaan serta bangunan turut pula menentukan derajat kerusakan, bila terjadi fenomena resonansi dan amplifikasi getaran gempabumi yang memiliki kesamaan karakter gelombang. Ketika terjadi gempabumi, informasi berupa intensitas getaran harus segera kita catat dan sampaikan kepada generasi penerus, sebagai data yang sangat berharga agar mereka kelak lebih siap lagi dalam menghadapi bencana gempabumi yang senantiasa berulang ini.
High-pressure low-temperature metamorphic rocks are considered as fossil subduction zones from th... more High-pressure low-temperature metamorphic rocks are considered as fossil subduction zones from the interpretation of progressive and retrogressive metamorphism, metamorphic facies series, protolith, role of fluid, geochronology of the various stages of metamorphism, P-T-t path, and exhumation model during regional metamorphism. Worldwide discovery of these rock types (e.g., Kokchetav, Dabie Shan, Indonesia, Franciscan, and Sanbagawa) have received much attention from earth scientists to demonstrate the exhumation of the rocks that have been metamorphosed at great depths in subduction zones that are exhumed at the surface.High-pressure metamorphic rocks expose in the South Sulawesi, Central Java, and South Kalimantan, which considered as central part of Indonesia. Northwesterly-directed Cretaceous subduction was suggested responsible to build these formations. Most of the metamorphic rocks occur in limited areas and are bounded by thrust fault with other units such as dismembered ophiolites, cherts, mélanges, and serpentinites. This contribution is implementation of published-exhumation concepts and processes, which are focus on the high-pressure metamorphic rocks in central part of Indonesia. The published- exhumation models on the high-pressure low-temperature metamorphic rocks in subduction zones suggest that buoyancy is the only effective force to exhume rocks from the deeply subducted levels to the base of the crust. Serpentinites are extremely buoyant with respect to the oceanic crust that has been transformed to eclogites during subduction and increasing their density, which are denser than average mantle rocks. Indeed, serpentinites have restricted P-T limit in the subduction zone. However the general P-T metamorphism of eclogites are within the range of serpentinites stability field. Thus, serpentinites might be counter-balancing the negative buoyancy, decouple, and facilitate exhumation of the high-pressure metamorphic rocks. Only rapid uplift accompanied by relatively low temperature rapid cooling maintains the high-pressure minerals in rocks. Furthermore, the presence of mélange units intercalated with high-pressure metamorphic rocks and chaotic occurrence of different metamorphic facies (e.g., eclogite, blueschist, greenschist) are typically formed in the subduction channel environment.
Penentuan paleogeografi suatu daerah sangat penting dalam suatu eksplorasi hidrokarbon. hal terse... more Penentuan paleogeografi suatu daerah sangat penting dalam suatu eksplorasi hidrokarbon. hal tersebut mempunyai dua arti penting, yang pertama untuk mengetahui arah sumber batuan dan yang kedua untuk mengetahui geometri batuan. Salah satu cara untuk mrngetahui paleogeografi adalah dengan menggunakan struktur slump. Struktur slump dapat menunjukkan dimana arah tinggian purba dan dimana arah cekungan purba. Lokasi penelitian berada pada tebing vertikal singkapan Formasi Halang di Desa Wonosari, Kecamatan Selang, Kabupaten Kebumen. Pada singkapan tersebut dilakukan pengukuran stratigrafi 1:100, pengukuran arah slump, dan pengambilan sampel batuan untuk analisis petrografi. Susunan batuan di daerah penelitian dapat dibagi menjadi dua asosiasi fasies, yang pertama yaitu asosiasi fasies perselingan batupasir dan napal sedangkan yang kedua yaitu asosiasi fasies napal sisipan batupasir. Daerah tersebut pada kisaran Miosen-Pliosen merupakan sebuah paparan laut dangkal yang dikelilingi oleh tinggian karbonat di sebelah utara dan selatannya. Tidak jauh dari paparan tersebut terdapat gunungapi aktif. Selama proses pengendapan terjadi dua kali transgresi dan sekali regresi.
Formasi Seloredjo yang umumnya banyak diteliti terletak di daerah Gunem sedangkan Anggota Dander ... more Formasi Seloredjo yang umumnya banyak diteliti terletak di daerah Gunem sedangkan Anggota Dander yang sudah diteliti terletak pada lokasi tipenya yaitu di Kecamatan Dander. Stratigrafi Anggota Dander di Kecamatan Bubulan terutama di Sungai Banyurejo (sebagaimana tergambar dalam peta geologi Lembar Bojonegoro sekala 1:100.000) belum pernah dipublikasikan. Penelitian ini dilakukan dengan membuat kolom stratigrafi terukur bersekala 1: 50 berdasarkan kenampakan lapangan, dengan tujuan mendapatkan gambaran fasies litologi, umur dan lingkungan pengendapan dari Anggota Dander. Dalam peta geologi Lembar Bojonegoro, Anggota Dander ditulis sebagai batugamping terumbu. Namun di Kecamatan Bubulan, litologinya terdiri dari perulangan grainstone dengan sisipan packestone pada bagian bawah, moluska rudstone – grainstone pada bagian tengah dan massive packestone pada bagian atas. Hal ini menggambarkan lingkungan lagun yang dinamis yang dipengaruhi oleh naik dan turunnya air laut. Kemudian, Anggota Dander di Kecamatan Bubulan ditumpangi secara tidak selaras oleh sedimen molasse berupa konglomerat polimik yang menggambarkan lingkungan yang berubah dari endapan lagun – estuarine menjadi channel mouthbar– fluvial, seiring dengan terangkatnya Pegunungan Kendeng dan Intrusi Bukit Pati Ayam di utara Nganjuk.
Berdasarkan analisis kandungan zirkon pada batuan volkanik berumur Miosen, Pegunungan Selatan Jaw... more Berdasarkan analisis kandungan zirkon pada batuan volkanik berumur Miosen, Pegunungan Selatan Jawa Timur (PSJT) dianggap sebuah fragmen Gondwana yang terpisah dari mikrokontinen Jawa Timur – Sulawesi Barat. Kajian tomografi seismik juga berhasil menunjukkan sebaran mikrokontinen PSJT tersebut. Model rekonstruksi tektonik yang ada selama ini menempatkan kolisi dan amalgamasi Pegunungan Selatan terhadap Sundaland terjadi pada akhir Kapur. Meski demikian, studi paleomagnetisme mengindikasikan posisi paleolatitude PSJT pada umur Eosen masih berada pada jarak sekitar 16o selatan dari posisinya saat ini. Dengan asumsi posisi Sundaland tidak banyak berubah semenjak akhir Kapur, hal ini memunculkan pertanyaan kapan sebenarnya kolisi PSJT terhadap tepian tenggara Sundaland. Makalah ini mengusulkan kolisi tersebut terjadi secara menyerong di akhir Oligosen dan berlangsung hingga Miosen Tengah, yang diakomodir oleh subduksi ganda dan patahan transform yang kelak menjadi Patahan Progo-Muria, serta memerangkapkan kerak samudera di bawah Cekungan Kendeng.
Zona Rembang tersusun atas Antiklinorium Rembang Utara dan Antiklinorium Rembang Selatan. Antikli... more Zona Rembang tersusun atas Antiklinorium Rembang Utara dan Antiklinorium Rembang Selatan. Antiklinorium Rembang Utara dibangun oleh beberapa perlipatan bersumbu timur-barat dengan pola en-echelon ke arah timur-timurlaut dan barat-baratdaya. Konfigurasi perlipatan demikian menunjukkan kontrol patahan basement geser mengiri berjurus timur-timurlaut dan barat-baratdaya. Makalah ini mencoba menampilkan data-data lapangan yang membuka mekanisme perlipatan, dengan lokasi daerah kajian pada Antiklin Braholo, sekitar 10 km di utara kota Blora. Struktur gores-garis, sesar minor, kekar, dan kedudukan perlapisan batuan menunjukkan deformasi tektonik terjadi dalam dua fase. Fase pertama dibentuk oleh gaya kompresif berarah baratlaut-tenggara yang disebabkan oleh pergeseran patahan basement berjurus timur-timurlaut dan barat-baratdaya, dengan kemungkinan adanya reorientasi stress lokal. Fase pertama ini terjadi pada Kala Plio-Pleistosen dan menyebabkan terbentuknya Antiklinorium Rembang dan beberapa sesar geser sinistral berarah timurlaur-baratdaya. Fase kedua yang menyusul kemudian sebagai relaksasi terhadap gaya kompresi fase pertama, dengan gaya regangan ke arah baratlaut-tenggara. Hasil temuan ini memberikan kontribusi ilmiah terhadap kajian tektonika Rembang yang jarang dilakukan, terutama berbasis data lapangan, terhadap konfigurasi antiklinorium yang menyimpan banyak perangkap hidrokarbon di kawasan tersebut.
Understanding the tectonic history of Central Java has long been recognized as critical to succes... more Understanding the tectonic history of Central Java has long been recognized as critical to successful petroleum exploration over the area. Most of the geologic setting and its product in Central Java are intimately linked with subduction tectonics. This paper attempts to analyze the deformation process of Bukit Bajangan, Kebumen, Central Java.
The lithology of Halang Formation of Miocene Age, evidenced in outcrop by alternating layers of competent tuffaceous sandstones and siltstones. The association of normal fault and high-angle reverse faulting is of critical interest in this paper. Association of normal and reverse faults can occur when the normal fault has highly-dipping strata that tectonically lock the movement of the other block. Reverse faulting occurs when extension progresses while tectonic locking occurs. Relative sense of movement is determined from slickensides and striation and drag folds. The main fault has an identifiable zone of brecciation. Methods used in this study are structural measurement, paleo stress analysis, and clay modeling.
Structural measurement was employed to determine the orientation of structural planes and the dynamics
of the structures. The results of study show that paleo stress direction of main fault came from N – S direction. This result follows the regional tectonic forces originating from subduction. Clay modeling was used to demonstrate the structures formed based on interpreted basement movement of Bukit Bajangan.
Way Panas is part of Ulubelu geothermal field, which is situated at the southern end of Sumatera ... more Way Panas is part of Ulubelu geothermal field, which is situated at the southern end of Sumatera Island, Indonesia. This geothermal field is built along the active Sumatera Fault Zone, which also had acted as the main control on the development of geothermal system on the area. Abundant surface thermal manifestation were observed in the Way Panas, such as hot springs, fumaroles, gas discharges, mud pots, steaming grounds, and altered rocks. Several geologic and geophysic studies have been conducted, and some geothermal system model were proposed. However, since this area were strongly controlled by tectonic processes, it is noticed that the role of geologic structures have never been put in considerable study. This paper presents recent findings on tectonic and structural geology based on geologic mapping and remote sensing interpretation. A number of 1938 lineaments were extracted from digital elevation model, which were analyzed according to their respective rock ages. A number of 220 tectonic joints and fault kinematic were analyzed from field data. It is observed that those surface manifestations were associated with major NW-SE normal fault, which acting as boundary fault of Early Pliocene structural graben that filled by Plio-Pleistocene volcanic complex. This NW-SE structural trend was part of the Sumatran Fault system, and its reactivation produced extensional faults and joints controlled the outflow of geothermal system. Another significance finding was arcuate geologic structures produced by volcanic load that influenced the existing geothermal system.
The Dieng field is located in Central Java, Indonesia with a 63 km2 concession area. This field i... more The Dieng field is located in Central Java, Indonesia with a 63 km2 concession area. This field is also known as the vulcan complex area. About 47 wells were drilled to prove that the potential geothermal resources of this field can generate enough electricity for Unit 1 (60 MW). For Units 2 and 3, created for development purposes, resource assessment was done in the Dieng field. This included reservoir modeling and the evaluation of surface and subsurface structural mapping. Detailed surface structural mapping was conducted to evaluate the surface structural pattern and to reconstruct the volcano-tectonic structural play in the Dieng field. Detailed surface structural mapping consisted of two phases: the presurvey analysis phase and the postsurvey analysis phase. In
presurvey analysis phase, structural analysis derived from IFSAR-DEM was conducted. IFSAR-DEM was chosen because of its spatial accuracy which can reach up to 8 m. The three steps of IFSAR-DEM structural analysis was conducted. This included
IFSAR-DEM interpretation, including hillshade analysis, manually lineament delineation, and digitally extraction lineament; statistic analysis; and kinematics analysis. In the postsurvey phase, an analysis of structural geology data derived from field data was conducted to reconstruct the volcano-tectonic structural play. The result of this study indicated that Dieng field was located in the NE Flank of Serayu Geanticline, which was elongated in the E-W direction. The structural play consisted of three main orientations, which are NW-SE, N-S, and E-W. This structural play was believed to be responsible for controlling the permeability zone in the Dieng field.
Kompleks struktur Trembono berada di wilayah Dusun Bentengwareng, Desa Tancep, Kecamatan Ngawen, ... more Kompleks struktur Trembono berada di wilayah Dusun Bentengwareng, Desa Tancep, Kecamatan Ngawen, Kabupaten Gunung Kidul, Provinsi Daerah Istimewa Yogyakarta. Daerah penelitian tersusun oleh batuan yang termasuk ke dalam Formasi Kebo-Butak berumur Oligosen Akhir hingga awal Miosen Awal yang telah mengalami deformasi sehingga menciptakan suatu kompleks struktur geologi. Kompleks struktur geologi Trembono mungkin menjadi bukti salah satu dari beberapa proses deformasi yang terjadi di Pegunungan Selatan. Penelitian dilakukan dengan melakukan pemetaan struktur geologi serta aspek geologi permukaan lain, seperti data petrologi, petrografi dan paleontologi. Litologi penyusun daerah penelitian dapat dibagi menjadi dua satuan, yaitu satuan batulanau tufandan satuan lapili.Struktur geologi yang berkembang pada daerah penelitian berupa kekar dan sesar yang dapat dibagi ke dalam beberapa kelompok berdasarkan arah orientasinya, yaitu struktur yang cenderung berarah utara-selatan, barat-timur,timurlaut-baratdaya dan tenggara-baratlaut. Kekar yang memotong satuan batulanau tufan lebih banyak dibandingkan dengan yang ada pada satuan lapili, sedangkan sesar lebih banyak memotong satuan lapili. Sesar yang berkembang pada daerah penelitian umumnya berupa sesar turunKompleks struktur Trembono terbentuk akibat regim regangan dengan tegasan ekstensi berarah 03°/N246°E. Waktu pembentukan kompleks struktur Trembono tidak dapat ditentukan secara pasti. Pembentukan sesar menimbulkan ketidakstabilan sehingga memicu terbentuknya gravitational structure. Jenis dan karakteristik litologi memiliki pengaruh terhadap jenis struktur geologi yang terbentuk akibat proses deformasi yang sama pada daerah penelitian. Hasil penelitian ini diharapkan dapat menambah pemahaman mengenai kondisi geologi di Pegunungan Selatan, khususnya mengenai struktur-struktur geologi dan tektoniknya.
Rocksquare merupakan piranti lunak berupa aplikasi android yang dibuat untuk recording data lapan... more Rocksquare merupakan piranti lunak berupa aplikasi android yang dibuat untuk recording data lapangan dengan praktis via tablet sistem android.Menimbang populernya Android sebagai OS no.1 dunia dan meluasnya penggunaan tablet di semua kalangan, maka tercetuslah ide untuk membuat suatu aplikasi dengan fungsi untuk menggantikan buku catatan lapangan konvesional dengan keunggulan praktis dan inovatif. Aplikasi ini dikembangkan bersama mitra dalam kegiatan PKM-T 2013. Pembuatan aplikasi ini menggunakan software development bernama Eclipse versi Indigo dan Juno pada Windows. Aplikasi ini terdiri dari beberapa bahasa pemrograman dalam pembuatannya diantaranya adalah xml, java, php, dll. Xml digunakan untuk membangun interface dari aplikasi ini. Java digunakan untuk bahasa algoritma dalam aplikasi ini atau dapat dikatakan
sebagai otak atau penggerak dari aplikasi ini yang membuat semua komponen dalam aplikasi bersinergi satu dengan yang lainnya. Sedangkan, php biasa digunakan untuk media penyimpanan atau database di dalam aplikasi itu sendiri.Rocksquare telah selesai dibuat untuk versi pertama dan memiliki beberapa fitur yang menarik yaitu note, informasi cuaca, keterangan pengambilan data, keterangan lokasi, kompas digital, GPS, kamera,voice note.Aplikasi ini telah uji coba lapangan di uji coba aplikasi android dilaksanakan pada hari jumat 3 oktober 2014 dengan koordinat - 7.7673020 110.6779556 yaitu Desa Bawak – gunung Temas, Bayat – Klaten. Harapan kami aplikasi ini mendapat respon positif di kalangan pekerja lapangan khususnya geologist untuk selanjutkan dapat membuat aplikasi versi berbayar.
In this study, we investigated the underground structure at Prambanan area, Yogyakarta. We perfor... more In this study, we investigated the underground structure at Prambanan area, Yogyakarta. We performed single observations of microtremor at 124 sites in Prambanan area. The results enabled us to estimate the site-dependent shaking characteristics of earthquake ground motion. We also conducted 2-site bore holes investigation to gain a representative determination of the soil condition of subsurface structures in Prambanan. From the SPT of borehole observations, the prambanan area corresponds to relatively soil condition with Vs ≤ 298 m/s, the predominant periods due to horizontal vertical ratios (HVSRs) are in the range of 0.48 to 1.19 s and the frequency are in the range of 0.95 to 1.92 Hz. By making these observations, we can obtain a relationship between the predominant periods, frequency and distribution of the first layer thickness of the sediment.
Hydrocarbons explorations is being deeply fundamental nowadays as the mature fields which has bee... more Hydrocarbons explorations is being deeply fundamental nowadays as the mature fields which has been exploited have come to the declining stage of its production. In any hydrocarbon explorations, there are many uncertainities in estimating the petroleum prospects. Sealing capacity is considered as the most common uncertainty occured; fault is necessary to be whether sealing or leaking for hydrocarbons to flow.
Proceedings of the 2014 International Conference on Physics, 2014
Pegunungan Bintang district with the capital Oksibil, almost all of its territory is mountains of... more Pegunungan Bintang district with the capital Oksibil, almost all of its territory is mountains of karst, especially in the west area, people living in the mountain slopes and small valleys in small groups, scattered and isolated. Karst areas, in general, has a lot of subsurface cavities at a developed stage to form subsurface rivers. Therefore, as the capital of the District Oksibil need to know the local subsurface conditions, how much growth cavities that exist in Oksibil. So that the study was carried out by very low frequency electromagnetic (VLF) method. Based on the field measurement and VLF data analysis, the interpretation and the dolina correlation, the Oksibil area is still safe, by considering that there is no indication of dolina or subsurface river that continued relatively horizontal, and the subsurface doline at relatively quite deep (> 40 meters).
Luwuk at the eastern end of Sulawesi’s East Arm has been recognized to be formed under obductiona... more Luwuk at the eastern end of Sulawesi’s East Arm has been recognized to be formed under obductional tectonic where the East Sulawesi Ophiolite Complex thrusted southward over the Banggai-Sula microcontinent during Late Neogene event. At the southern section, a gas field of Tomori has been
developed with reservoirs distributed in the precollisional
Miocene carbonates. To date, explorational work over the area has been incorporating collisional structures such as thrusts and wrench faults into the petroleum systems, e.g.
hydrocarbon maturation and trap formation. Most of the structural concept based on the existing model of southeastward vergeance thick-skinned (ophiolitic basement involved) thrust-fold belt.
A geologic field work has been conducted transecting north-south section and east-west section of Luwuk. Satellite imagery interpretation and field observation suggest the existance of three structural compartments, i.e.: (i) the northern extensional, block-faulting, tectonic regime on the
ophiolite complex, (ii) the central compressional, northwestward vergeance thrust-fold belt, tectonic regime on the Tertiary carbonates, and (iii) the southern, locally gravitational sliding, tectonic regime on the Pliocene molasse. Each compartment exhibits distinct structural style and diverse tectonic control.
The northern extensional compartment were controlled by rifting of Siuna Bay along the Late-Miocene right-lateral movement of Balantak Fault. The central compressional compartment were developed by the Late Pliocene northwestward shortening due to activation of Sorong Fault. The southern gravitational Molasse sliding were induced
by the Late Pliocene uplift along the existing weak zone of north-south transtensional strike-slip fault. Implication of this research to petroleum exploration is a revision of Luwuk thrust-fold belt model, which is proposed to be thin-skinned
(basement uninvolved) northwestward vergeance.
The Province of Yogyakarta is an area with high level of seismic activity in Indonesia. One of th... more The Province of Yogyakarta is an area with high level of seismic activity in Indonesia. One of the active faults in this provice is Opak Fault, which was regarded as responsible for Yogyakarta earthquake of May 27, 2006. It is necessary to establish geodetic network for monitoring around the fault, with more detailed geologic mapping.
The research was conducted with several stages since the literature review, discussions with colleagues in the Laboratories of Geodesy and Geodynamic, Faculty of Engineering, Universitas Gadjah Mada. The first research procedure includes planning for bench-mark (BM) installation, and Global Navigation Satellite System (GNSS) data acquisition, Linux Centos V. 6.5 as Operating System and
GAMIT/GLOBK V 10.5 as scientific software for data proccesing. Measurement of monitoring network in
this area was carried out on 18 November 2013. The second research percedure was Geological observation and mapping which were conducted for about three weeks in the August 2013.
The research has established 10 BMs for monitoring network point using 3D Cartesian coordinates system. Pasive stations were labelled OPK 3, OPK 4, OPK 6, OPK 7, OPK 8, TGD 2, and active stations were labelled GK1_,KPG1,SLM1and BTL1. Distance between network monitoring stations ranges from
6,045.67385 m for the shortest distance OPK 6 to GK1_ and 4,3603.16313 m for longest distance of OPK 6 to KPG1, with precision of base lines varies from 3.94 mm to 10.61 mm, standard deviation of on the X-as (x) , Y-as (y) and Z-axis as (z) are varies. Standard deviations of 3D Cartesian coordinates system for pasive and active stations have similar pattern where y lesser than x dan z. Geological
mapping and field observation on the suspected area for the seismogenic fault suggest that the Mangunan-Muntuk region was influenced by similar tectonic forces as in 2006 earthquake.
Strata of the Middle Miocene Balikpapan Formation from the Lower Kutai basin are well exposed in ... more Strata of the Middle Miocene Balikpapan Formation from the Lower Kutai basin are well exposed in a section near the Samarinda city, East Kalimantan, Indonesia. The succession is characterized by thick sandstone bodies alternating with shales and coal beds. A 250 m thick composite section of exposed sediments (not including the soil interval) was measured, from which 25 coal samples were collected. Petrographic, microlithotype, and maceral analyses were performed in order to determine the depositional environment of the Samarinda coals. In order to assess the development of paleomires, coal facies diagrams were obtained from microlithotype and maceral composition. According to the organic petrologic results, the Samarinda coals represent a highly degraded humodetrinite-rich group deposited from terrestrial into telmatic condition of peat formation with vegetation characteristics of highly degraded woody forest type evolved under alternate oxic to anoxic moor conditions. These formed with intermittent moderate to high flooding as the paleopeat environment shifted from mesotrophic to ombrotrophic.
Cekungan Serayu Utara merupakan salah satu dari dua cekungan yang menyusun Jawa Tengah.Di Cekunga... more Cekungan Serayu Utara merupakan salah satu dari dua cekungan yang menyusun Jawa Tengah.Di Cekungan ini, banyak dijumpai rembesan hidrokarbon (minyak dan gas bumi) di permukaan, sebagai salah satu tanda aktifnya sistem petroleum.Meski demikian, kompleksitas geologi yang dimiliki cekungan ini membuatnya dikenal sebagai “terra incognita” dalam dunia eksplorasi migas di Pulau Jawa.Sebagai salah
satu manifestasi permukaan, rembesan hidrokarbon dapat menjadi jendela dan titik tolak pendekatan dalam mempelajari kondisi geologi bawah permukaan bagi unsur-unsur penting dalam sistem petroleum.Berlandaskan pemahaman tersebut, penelitian ini bermaksud untuk mempelajari faktor-faktor geologi yang pernah bekerja di Cekungan Serayu Utara yang mengontrol terjadinya rembesan hidrokarbon di Desa Sijenggung, Kecamatan Banjarmangu, Kabupaten Banjarnegara, Jawa Tengah.Di permukaan, rembesan tersebut terjadi pada singkapan Formasi Rambatan yang berumur Miosen Awal - Miosen Tengah.Pendekatan yang dipergunakan adalah pengumpulan data-data geologi permukaan, berupa data stratigrafi dan struktur geologi.
Penurunan Cekungan Serayu Utara sebagai cekungan belakang busur (back-arc basin) di Miosen Awal mempengaruhi pengendapan Formasi Rambatan, yang diisi oleh perselingan serpih, napal, dan tuff. Kandungan material volkaniklastik halus diduga berasal dari volkanisme Waturanda di Busur Volkanik
Serayu Selatan.Mekanisme pengendapan litologi Rambatan tersebut terpengaruh kondisi cekungan yang terus menurun, menghasilkan gangguan-gangguan sedimentasi (soft sediment deformation) akibat luncuran gravitasi di lereng cekungan. Memasuki Miosen Akhir, busur volkanik Jawa Tengah berpindah ke cekungan belakang busur, menghasilkan endapan-endapan vulkaniklastika kasar yang berselingan dengan klastika halus laut pada formasi-formasi Halang, Tapak, dan Pemali.
Deformasi yang dominan pada Formasi Rambatan adalah luncuran gravitasi (gravity sliding) ke arah utara-timurlaut dalam rejim ekstensional, yang secara lokal menghasilkan sesar anjak pada bagian ujung luncuran (toe-thrusting). Selanjutnya, saat aktifitas volkanisme menjadi dominan di Cekungan Serayu Utara, pembebanan tubuh gunungapi (volcanic load) juga menghasilkan deformasi luncuran gravitasi ke arah lateral, terutama bergerak ke arah selatan-baratdaya, yang tidak hanya bekerja pada dormasi-formasi Neogen Akhir tetapi juga mempengaruhi Formasi Rambatan yang lebih tua.
Rembesan hidrokarbon di Desa Sijenggung pada Formasi Rambatan yang memiliki potensi sebagai batuan penyimpan (reservoar) dan batuan penyekat (seal) sekaligus, diduga melalui mekanisme pecahnya batuan penyekat (seal failure). Hal ini terjadi karena rendahnya kualitasnya litologi penyekat yang rendah akibat deformasi luncuran gravitasi, sehingga hidrokarbon dapat mencapai permukaan.
Matano Fault was a strike-slip fault with ESE – WNW orientation which located on the northern par... more Matano Fault was a strike-slip fault with ESE – WNW orientation which located on the northern part of Sulawesi's Southeast Arm. The fault is connected to Palu-Koro Fault on the western part and Sorong Fault on the eastern part. The Digital Elevation Model and the geological map shows that Matano Fault was a left stepping left-lateral fault that formed Matano's Lake pull-apart basin. The Offset of the Tokala Formation shows Matano Fault have at least 60 km displacement. The tectonic stress inversion from earthquake focal mechanism data showsMatano Fault was a strike-slip faultwith N 38 ° E/ 30 ° maximum compressive principal stress axes.
Bencana gempabumi di Indonesia adalah suatu keniscayaan, tidak hanya pada daerah yang selama ini ... more Bencana gempabumi di Indonesia adalah suatu keniscayaan, tidak hanya pada daerah yang selama ini diketahui seringkali mengalaminya, namun juga pada daerah yang dahulu diduga relatif aman. Kondisi demikian dikontrol oleh konfigurasi tektonis Indonesia di masa lampau dan di masa sekarang ini. Banyak sudah peristiwa gempabumi yang menelan korban ribuan jiwa dan kerugian harta benda yang sangat besar. Kenyataan ini menuntut kemauan kita untuk belajar memahami fenomena gempabumi dengan lebih baik lagi, agar dapat mengurangi resiko bencana. Gempabumi ditimbulkan oleh pergeseran patahan, sehingga keberadaan patahan baik di permukaan maupun di bawah permukaan harus bisa dipetakan dengan baik dan akurat. Energi gempabumi merambat dari sumber pergeseran patahan dalam beberapa jenis gelombang, yang menuntut pengukuran secara tepat dan cepat. Kerusakan infrastruktur tidak hanya disebabkan oleh besaran energi, namun juga bagaimana percepatan gelombang gempabumi diterima di lokasi tersebut. Perioda dan frekuensi batuan di permukaan serta bangunan turut pula menentukan derajat kerusakan, bila terjadi fenomena resonansi dan amplifikasi getaran gempabumi yang memiliki kesamaan karakter gelombang. Ketika terjadi gempabumi, informasi berupa intensitas getaran harus segera kita catat dan sampaikan kepada generasi penerus, sebagai data yang sangat berharga agar mereka kelak lebih siap lagi dalam menghadapi bencana gempabumi yang senantiasa berulang ini.
High-pressure low-temperature metamorphic rocks are considered as fossil subduction zones from th... more High-pressure low-temperature metamorphic rocks are considered as fossil subduction zones from the interpretation of progressive and retrogressive metamorphism, metamorphic facies series, protolith, role of fluid, geochronology of the various stages of metamorphism, P-T-t path, and exhumation model during regional metamorphism. Worldwide discovery of these rock types (e.g., Kokchetav, Dabie Shan, Indonesia, Franciscan, and Sanbagawa) have received much attention from earth scientists to demonstrate the exhumation of the rocks that have been metamorphosed at great depths in subduction zones that are exhumed at the surface.High-pressure metamorphic rocks expose in the South Sulawesi, Central Java, and South Kalimantan, which considered as central part of Indonesia. Northwesterly-directed Cretaceous subduction was suggested responsible to build these formations. Most of the metamorphic rocks occur in limited areas and are bounded by thrust fault with other units such as dismembered ophiolites, cherts, mélanges, and serpentinites. This contribution is implementation of published-exhumation concepts and processes, which are focus on the high-pressure metamorphic rocks in central part of Indonesia. The published- exhumation models on the high-pressure low-temperature metamorphic rocks in subduction zones suggest that buoyancy is the only effective force to exhume rocks from the deeply subducted levels to the base of the crust. Serpentinites are extremely buoyant with respect to the oceanic crust that has been transformed to eclogites during subduction and increasing their density, which are denser than average mantle rocks. Indeed, serpentinites have restricted P-T limit in the subduction zone. However the general P-T metamorphism of eclogites are within the range of serpentinites stability field. Thus, serpentinites might be counter-balancing the negative buoyancy, decouple, and facilitate exhumation of the high-pressure metamorphic rocks. Only rapid uplift accompanied by relatively low temperature rapid cooling maintains the high-pressure minerals in rocks. Furthermore, the presence of mélange units intercalated with high-pressure metamorphic rocks and chaotic occurrence of different metamorphic facies (e.g., eclogite, blueschist, greenschist) are typically formed in the subduction channel environment.
Penentuan paleogeografi suatu daerah sangat penting dalam suatu eksplorasi hidrokarbon. hal terse... more Penentuan paleogeografi suatu daerah sangat penting dalam suatu eksplorasi hidrokarbon. hal tersebut mempunyai dua arti penting, yang pertama untuk mengetahui arah sumber batuan dan yang kedua untuk mengetahui geometri batuan. Salah satu cara untuk mrngetahui paleogeografi adalah dengan menggunakan struktur slump. Struktur slump dapat menunjukkan dimana arah tinggian purba dan dimana arah cekungan purba. Lokasi penelitian berada pada tebing vertikal singkapan Formasi Halang di Desa Wonosari, Kecamatan Selang, Kabupaten Kebumen. Pada singkapan tersebut dilakukan pengukuran stratigrafi 1:100, pengukuran arah slump, dan pengambilan sampel batuan untuk analisis petrografi. Susunan batuan di daerah penelitian dapat dibagi menjadi dua asosiasi fasies, yang pertama yaitu asosiasi fasies perselingan batupasir dan napal sedangkan yang kedua yaitu asosiasi fasies napal sisipan batupasir. Daerah tersebut pada kisaran Miosen-Pliosen merupakan sebuah paparan laut dangkal yang dikelilingi oleh tinggian karbonat di sebelah utara dan selatannya. Tidak jauh dari paparan tersebut terdapat gunungapi aktif. Selama proses pengendapan terjadi dua kali transgresi dan sekali regresi.
Formasi Seloredjo yang umumnya banyak diteliti terletak di daerah Gunem sedangkan Anggota Dander ... more Formasi Seloredjo yang umumnya banyak diteliti terletak di daerah Gunem sedangkan Anggota Dander yang sudah diteliti terletak pada lokasi tipenya yaitu di Kecamatan Dander. Stratigrafi Anggota Dander di Kecamatan Bubulan terutama di Sungai Banyurejo (sebagaimana tergambar dalam peta geologi Lembar Bojonegoro sekala 1:100.000) belum pernah dipublikasikan. Penelitian ini dilakukan dengan membuat kolom stratigrafi terukur bersekala 1: 50 berdasarkan kenampakan lapangan, dengan tujuan mendapatkan gambaran fasies litologi, umur dan lingkungan pengendapan dari Anggota Dander. Dalam peta geologi Lembar Bojonegoro, Anggota Dander ditulis sebagai batugamping terumbu. Namun di Kecamatan Bubulan, litologinya terdiri dari perulangan grainstone dengan sisipan packestone pada bagian bawah, moluska rudstone – grainstone pada bagian tengah dan massive packestone pada bagian atas. Hal ini menggambarkan lingkungan lagun yang dinamis yang dipengaruhi oleh naik dan turunnya air laut. Kemudian, Anggota Dander di Kecamatan Bubulan ditumpangi secara tidak selaras oleh sedimen molasse berupa konglomerat polimik yang menggambarkan lingkungan yang berubah dari endapan lagun – estuarine menjadi channel mouthbar– fluvial, seiring dengan terangkatnya Pegunungan Kendeng dan Intrusi Bukit Pati Ayam di utara Nganjuk.
Berdasarkan analisis kandungan zirkon pada batuan volkanik berumur Miosen, Pegunungan Selatan Jaw... more Berdasarkan analisis kandungan zirkon pada batuan volkanik berumur Miosen, Pegunungan Selatan Jawa Timur (PSJT) dianggap sebuah fragmen Gondwana yang terpisah dari mikrokontinen Jawa Timur – Sulawesi Barat. Kajian tomografi seismik juga berhasil menunjukkan sebaran mikrokontinen PSJT tersebut. Model rekonstruksi tektonik yang ada selama ini menempatkan kolisi dan amalgamasi Pegunungan Selatan terhadap Sundaland terjadi pada akhir Kapur. Meski demikian, studi paleomagnetisme mengindikasikan posisi paleolatitude PSJT pada umur Eosen masih berada pada jarak sekitar 16o selatan dari posisinya saat ini. Dengan asumsi posisi Sundaland tidak banyak berubah semenjak akhir Kapur, hal ini memunculkan pertanyaan kapan sebenarnya kolisi PSJT terhadap tepian tenggara Sundaland. Makalah ini mengusulkan kolisi tersebut terjadi secara menyerong di akhir Oligosen dan berlangsung hingga Miosen Tengah, yang diakomodir oleh subduksi ganda dan patahan transform yang kelak menjadi Patahan Progo-Muria, serta memerangkapkan kerak samudera di bawah Cekungan Kendeng.
Zona Rembang tersusun atas Antiklinorium Rembang Utara dan Antiklinorium Rembang Selatan. Antikli... more Zona Rembang tersusun atas Antiklinorium Rembang Utara dan Antiklinorium Rembang Selatan. Antiklinorium Rembang Utara dibangun oleh beberapa perlipatan bersumbu timur-barat dengan pola en-echelon ke arah timur-timurlaut dan barat-baratdaya. Konfigurasi perlipatan demikian menunjukkan kontrol patahan basement geser mengiri berjurus timur-timurlaut dan barat-baratdaya. Makalah ini mencoba menampilkan data-data lapangan yang membuka mekanisme perlipatan, dengan lokasi daerah kajian pada Antiklin Braholo, sekitar 10 km di utara kota Blora. Struktur gores-garis, sesar minor, kekar, dan kedudukan perlapisan batuan menunjukkan deformasi tektonik terjadi dalam dua fase. Fase pertama dibentuk oleh gaya kompresif berarah baratlaut-tenggara yang disebabkan oleh pergeseran patahan basement berjurus timur-timurlaut dan barat-baratdaya, dengan kemungkinan adanya reorientasi stress lokal. Fase pertama ini terjadi pada Kala Plio-Pleistosen dan menyebabkan terbentuknya Antiklinorium Rembang dan beberapa sesar geser sinistral berarah timurlaur-baratdaya. Fase kedua yang menyusul kemudian sebagai relaksasi terhadap gaya kompresi fase pertama, dengan gaya regangan ke arah baratlaut-tenggara. Hasil temuan ini memberikan kontribusi ilmiah terhadap kajian tektonika Rembang yang jarang dilakukan, terutama berbasis data lapangan, terhadap konfigurasi antiklinorium yang menyimpan banyak perangkap hidrokarbon di kawasan tersebut.
Understanding the tectonic history of Central Java has long been recognized as critical to succes... more Understanding the tectonic history of Central Java has long been recognized as critical to successful petroleum exploration over the area. Most of the geologic setting and its product in Central Java are intimately linked with subduction tectonics. This paper attempts to analyze the deformation process of Bukit Bajangan, Kebumen, Central Java.
The lithology of Halang Formation of Miocene Age, evidenced in outcrop by alternating layers of competent tuffaceous sandstones and siltstones. The association of normal fault and high-angle reverse faulting is of critical interest in this paper. Association of normal and reverse faults can occur when the normal fault has highly-dipping strata that tectonically lock the movement of the other block. Reverse faulting occurs when extension progresses while tectonic locking occurs. Relative sense of movement is determined from slickensides and striation and drag folds. The main fault has an identifiable zone of brecciation. Methods used in this study are structural measurement, paleo stress analysis, and clay modeling.
Structural measurement was employed to determine the orientation of structural planes and the dynamics
of the structures. The results of study show that paleo stress direction of main fault came from N – S direction. This result follows the regional tectonic forces originating from subduction. Clay modeling was used to demonstrate the structures formed based on interpreted basement movement of Bukit Bajangan.
Way Panas is part of Ulubelu geothermal field, which is situated at the southern end of Sumatera ... more Way Panas is part of Ulubelu geothermal field, which is situated at the southern end of Sumatera Island, Indonesia. This geothermal field is built along the active Sumatera Fault Zone, which also had acted as the main control on the development of geothermal system on the area. Abundant surface thermal manifestation were observed in the Way Panas, such as hot springs, fumaroles, gas discharges, mud pots, steaming grounds, and altered rocks. Several geologic and geophysic studies have been conducted, and some geothermal system model were proposed. However, since this area were strongly controlled by tectonic processes, it is noticed that the role of geologic structures have never been put in considerable study. This paper presents recent findings on tectonic and structural geology based on geologic mapping and remote sensing interpretation. A number of 1938 lineaments were extracted from digital elevation model, which were analyzed according to their respective rock ages. A number of 220 tectonic joints and fault kinematic were analyzed from field data. It is observed that those surface manifestations were associated with major NW-SE normal fault, which acting as boundary fault of Early Pliocene structural graben that filled by Plio-Pleistocene volcanic complex. This NW-SE structural trend was part of the Sumatran Fault system, and its reactivation produced extensional faults and joints controlled the outflow of geothermal system. Another significance finding was arcuate geologic structures produced by volcanic load that influenced the existing geothermal system.
The Dieng field is located in Central Java, Indonesia with a 63 km2 concession area. This field i... more The Dieng field is located in Central Java, Indonesia with a 63 km2 concession area. This field is also known as the vulcan complex area. About 47 wells were drilled to prove that the potential geothermal resources of this field can generate enough electricity for Unit 1 (60 MW). For Units 2 and 3, created for development purposes, resource assessment was done in the Dieng field. This included reservoir modeling and the evaluation of surface and subsurface structural mapping. Detailed surface structural mapping was conducted to evaluate the surface structural pattern and to reconstruct the volcano-tectonic structural play in the Dieng field. Detailed surface structural mapping consisted of two phases: the presurvey analysis phase and the postsurvey analysis phase. In
presurvey analysis phase, structural analysis derived from IFSAR-DEM was conducted. IFSAR-DEM was chosen because of its spatial accuracy which can reach up to 8 m. The three steps of IFSAR-DEM structural analysis was conducted. This included
IFSAR-DEM interpretation, including hillshade analysis, manually lineament delineation, and digitally extraction lineament; statistic analysis; and kinematics analysis. In the postsurvey phase, an analysis of structural geology data derived from field data was conducted to reconstruct the volcano-tectonic structural play. The result of this study indicated that Dieng field was located in the NE Flank of Serayu Geanticline, which was elongated in the E-W direction. The structural play consisted of three main orientations, which are NW-SE, N-S, and E-W. This structural play was believed to be responsible for controlling the permeability zone in the Dieng field.
Kompleks struktur Trembono berada di wilayah Dusun Bentengwareng, Desa Tancep, Kecamatan Ngawen, ... more Kompleks struktur Trembono berada di wilayah Dusun Bentengwareng, Desa Tancep, Kecamatan Ngawen, Kabupaten Gunung Kidul, Provinsi Daerah Istimewa Yogyakarta. Daerah penelitian tersusun oleh batuan yang termasuk ke dalam Formasi Kebo-Butak berumur Oligosen Akhir hingga awal Miosen Awal yang telah mengalami deformasi sehingga menciptakan suatu kompleks struktur geologi. Kompleks struktur geologi Trembono mungkin menjadi bukti salah satu dari beberapa proses deformasi yang terjadi di Pegunungan Selatan. Penelitian dilakukan dengan melakukan pemetaan struktur geologi serta aspek geologi permukaan lain, seperti data petrologi, petrografi dan paleontologi. Litologi penyusun daerah penelitian dapat dibagi menjadi dua satuan, yaitu satuan batulanau tufandan satuan lapili.Struktur geologi yang berkembang pada daerah penelitian berupa kekar dan sesar yang dapat dibagi ke dalam beberapa kelompok berdasarkan arah orientasinya, yaitu struktur yang cenderung berarah utara-selatan, barat-timur,timurlaut-baratdaya dan tenggara-baratlaut. Kekar yang memotong satuan batulanau tufan lebih banyak dibandingkan dengan yang ada pada satuan lapili, sedangkan sesar lebih banyak memotong satuan lapili. Sesar yang berkembang pada daerah penelitian umumnya berupa sesar turunKompleks struktur Trembono terbentuk akibat regim regangan dengan tegasan ekstensi berarah 03°/N246°E. Waktu pembentukan kompleks struktur Trembono tidak dapat ditentukan secara pasti. Pembentukan sesar menimbulkan ketidakstabilan sehingga memicu terbentuknya gravitational structure. Jenis dan karakteristik litologi memiliki pengaruh terhadap jenis struktur geologi yang terbentuk akibat proses deformasi yang sama pada daerah penelitian. Hasil penelitian ini diharapkan dapat menambah pemahaman mengenai kondisi geologi di Pegunungan Selatan, khususnya mengenai struktur-struktur geologi dan tektoniknya.
Rocksquare merupakan piranti lunak berupa aplikasi android yang dibuat untuk recording data lapan... more Rocksquare merupakan piranti lunak berupa aplikasi android yang dibuat untuk recording data lapangan dengan praktis via tablet sistem android.Menimbang populernya Android sebagai OS no.1 dunia dan meluasnya penggunaan tablet di semua kalangan, maka tercetuslah ide untuk membuat suatu aplikasi dengan fungsi untuk menggantikan buku catatan lapangan konvesional dengan keunggulan praktis dan inovatif. Aplikasi ini dikembangkan bersama mitra dalam kegiatan PKM-T 2013. Pembuatan aplikasi ini menggunakan software development bernama Eclipse versi Indigo dan Juno pada Windows. Aplikasi ini terdiri dari beberapa bahasa pemrograman dalam pembuatannya diantaranya adalah xml, java, php, dll. Xml digunakan untuk membangun interface dari aplikasi ini. Java digunakan untuk bahasa algoritma dalam aplikasi ini atau dapat dikatakan
sebagai otak atau penggerak dari aplikasi ini yang membuat semua komponen dalam aplikasi bersinergi satu dengan yang lainnya. Sedangkan, php biasa digunakan untuk media penyimpanan atau database di dalam aplikasi itu sendiri.Rocksquare telah selesai dibuat untuk versi pertama dan memiliki beberapa fitur yang menarik yaitu note, informasi cuaca, keterangan pengambilan data, keterangan lokasi, kompas digital, GPS, kamera,voice note.Aplikasi ini telah uji coba lapangan di uji coba aplikasi android dilaksanakan pada hari jumat 3 oktober 2014 dengan koordinat - 7.7673020 110.6779556 yaitu Desa Bawak – gunung Temas, Bayat – Klaten. Harapan kami aplikasi ini mendapat respon positif di kalangan pekerja lapangan khususnya geologist untuk selanjutkan dapat membuat aplikasi versi berbayar.
In this study, we investigated the underground structure at Prambanan area, Yogyakarta. We perfor... more In this study, we investigated the underground structure at Prambanan area, Yogyakarta. We performed single observations of microtremor at 124 sites in Prambanan area. The results enabled us to estimate the site-dependent shaking characteristics of earthquake ground motion. We also conducted 2-site bore holes investigation to gain a representative determination of the soil condition of subsurface structures in Prambanan. From the SPT of borehole observations, the prambanan area corresponds to relatively soil condition with Vs ≤ 298 m/s, the predominant periods due to horizontal vertical ratios (HVSRs) are in the range of 0.48 to 1.19 s and the frequency are in the range of 0.95 to 1.92 Hz. By making these observations, we can obtain a relationship between the predominant periods, frequency and distribution of the first layer thickness of the sediment.
Hydrocarbons explorations is being deeply fundamental nowadays as the mature fields which has bee... more Hydrocarbons explorations is being deeply fundamental nowadays as the mature fields which has been exploited have come to the declining stage of its production. In any hydrocarbon explorations, there are many uncertainities in estimating the petroleum prospects. Sealing capacity is considered as the most common uncertainty occured; fault is necessary to be whether sealing or leaking for hydrocarbons to flow.
Proceedings of the 2014 International Conference on Physics, 2014
Pegunungan Bintang district with the capital Oksibil, almost all of its territory is mountains of... more Pegunungan Bintang district with the capital Oksibil, almost all of its territory is mountains of karst, especially in the west area, people living in the mountain slopes and small valleys in small groups, scattered and isolated. Karst areas, in general, has a lot of subsurface cavities at a developed stage to form subsurface rivers. Therefore, as the capital of the District Oksibil need to know the local subsurface conditions, how much growth cavities that exist in Oksibil. So that the study was carried out by very low frequency electromagnetic (VLF) method. Based on the field measurement and VLF data analysis, the interpretation and the dolina correlation, the Oksibil area is still safe, by considering that there is no indication of dolina or subsurface river that continued relatively horizontal, and the subsurface doline at relatively quite deep (> 40 meters).
Luwuk at the eastern end of Sulawesi’s East Arm has been recognized to be formed under obductiona... more Luwuk at the eastern end of Sulawesi’s East Arm has been recognized to be formed under obductional tectonic where the East Sulawesi Ophiolite Complex thrusted southward over the Banggai-Sula microcontinent during Late Neogene event. At the southern section, a gas field of Tomori has been
developed with reservoirs distributed in the precollisional
Miocene carbonates. To date, explorational work over the area has been incorporating collisional structures such as thrusts and wrench faults into the petroleum systems, e.g.
hydrocarbon maturation and trap formation. Most of the structural concept based on the existing model of southeastward vergeance thick-skinned (ophiolitic basement involved) thrust-fold belt.
A geologic field work has been conducted transecting north-south section and east-west section of Luwuk. Satellite imagery interpretation and field observation suggest the existance of three structural compartments, i.e.: (i) the northern extensional, block-faulting, tectonic regime on the
ophiolite complex, (ii) the central compressional, northwestward vergeance thrust-fold belt, tectonic regime on the Tertiary carbonates, and (iii) the southern, locally gravitational sliding, tectonic regime on the Pliocene molasse. Each compartment exhibits distinct structural style and diverse tectonic control.
The northern extensional compartment were controlled by rifting of Siuna Bay along the Late-Miocene right-lateral movement of Balantak Fault. The central compressional compartment were developed by the Late Pliocene northwestward shortening due to activation of Sorong Fault. The southern gravitational Molasse sliding were induced
by the Late Pliocene uplift along the existing weak zone of north-south transtensional strike-slip fault. Implication of this research to petroleum exploration is a revision of Luwuk thrust-fold belt model, which is proposed to be thin-skinned
(basement uninvolved) northwestward vergeance.
The Province of Yogyakarta is an area with high level of seismic activity in Indonesia. One of th... more The Province of Yogyakarta is an area with high level of seismic activity in Indonesia. One of the active faults in this provice is Opak Fault, which was regarded as responsible for Yogyakarta earthquake of May 27, 2006. It is necessary to establish geodetic network for monitoring around the fault, with more detailed geologic mapping.
The research was conducted with several stages since the literature review, discussions with colleagues in the Laboratories of Geodesy and Geodynamic, Faculty of Engineering, Universitas Gadjah Mada. The first research procedure includes planning for bench-mark (BM) installation, and Global Navigation Satellite System (GNSS) data acquisition, Linux Centos V. 6.5 as Operating System and
GAMIT/GLOBK V 10.5 as scientific software for data proccesing. Measurement of monitoring network in
this area was carried out on 18 November 2013. The second research percedure was Geological observation and mapping which were conducted for about three weeks in the August 2013.
The research has established 10 BMs for monitoring network point using 3D Cartesian coordinates system. Pasive stations were labelled OPK 3, OPK 4, OPK 6, OPK 7, OPK 8, TGD 2, and active stations were labelled GK1_,KPG1,SLM1and BTL1. Distance between network monitoring stations ranges from
6,045.67385 m for the shortest distance OPK 6 to GK1_ and 4,3603.16313 m for longest distance of OPK 6 to KPG1, with precision of base lines varies from 3.94 mm to 10.61 mm, standard deviation of on the X-as (x) , Y-as (y) and Z-axis as (z) are varies. Standard deviations of 3D Cartesian coordinates system for pasive and active stations have similar pattern where y lesser than x dan z. Geological
mapping and field observation on the suspected area for the seismogenic fault suggest that the Mangunan-Muntuk region was influenced by similar tectonic forces as in 2006 earthquake.
Strata of the Middle Miocene Balikpapan Formation from the Lower Kutai basin are well exposed in ... more Strata of the Middle Miocene Balikpapan Formation from the Lower Kutai basin are well exposed in a section near the Samarinda city, East Kalimantan, Indonesia. The succession is characterized by thick sandstone bodies alternating with shales and coal beds. A 250 m thick composite section of exposed sediments (not including the soil interval) was measured, from which 25 coal samples were collected. Petrographic, microlithotype, and maceral analyses were performed in order to determine the depositional environment of the Samarinda coals. In order to assess the development of paleomires, coal facies diagrams were obtained from microlithotype and maceral composition. According to the organic petrologic results, the Samarinda coals represent a highly degraded humodetrinite-rich group deposited from terrestrial into telmatic condition of peat formation with vegetation characteristics of highly degraded woody forest type evolved under alternate oxic to anoxic moor conditions. These formed with intermittent moderate to high flooding as the paleopeat environment shifted from mesotrophic to ombrotrophic.
Cekungan Serayu Utara merupakan salah satu dari dua cekungan yang menyusun Jawa Tengah.Di Cekunga... more Cekungan Serayu Utara merupakan salah satu dari dua cekungan yang menyusun Jawa Tengah.Di Cekungan ini, banyak dijumpai rembesan hidrokarbon (minyak dan gas bumi) di permukaan, sebagai salah satu tanda aktifnya sistem petroleum.Meski demikian, kompleksitas geologi yang dimiliki cekungan ini membuatnya dikenal sebagai “terra incognita” dalam dunia eksplorasi migas di Pulau Jawa.Sebagai salah
satu manifestasi permukaan, rembesan hidrokarbon dapat menjadi jendela dan titik tolak pendekatan dalam mempelajari kondisi geologi bawah permukaan bagi unsur-unsur penting dalam sistem petroleum.Berlandaskan pemahaman tersebut, penelitian ini bermaksud untuk mempelajari faktor-faktor geologi yang pernah bekerja di Cekungan Serayu Utara yang mengontrol terjadinya rembesan hidrokarbon di Desa Sijenggung, Kecamatan Banjarmangu, Kabupaten Banjarnegara, Jawa Tengah.Di permukaan, rembesan tersebut terjadi pada singkapan Formasi Rambatan yang berumur Miosen Awal - Miosen Tengah.Pendekatan yang dipergunakan adalah pengumpulan data-data geologi permukaan, berupa data stratigrafi dan struktur geologi.
Penurunan Cekungan Serayu Utara sebagai cekungan belakang busur (back-arc basin) di Miosen Awal mempengaruhi pengendapan Formasi Rambatan, yang diisi oleh perselingan serpih, napal, dan tuff. Kandungan material volkaniklastik halus diduga berasal dari volkanisme Waturanda di Busur Volkanik
Serayu Selatan.Mekanisme pengendapan litologi Rambatan tersebut terpengaruh kondisi cekungan yang terus menurun, menghasilkan gangguan-gangguan sedimentasi (soft sediment deformation) akibat luncuran gravitasi di lereng cekungan. Memasuki Miosen Akhir, busur volkanik Jawa Tengah berpindah ke cekungan belakang busur, menghasilkan endapan-endapan vulkaniklastika kasar yang berselingan dengan klastika halus laut pada formasi-formasi Halang, Tapak, dan Pemali.
Deformasi yang dominan pada Formasi Rambatan adalah luncuran gravitasi (gravity sliding) ke arah utara-timurlaut dalam rejim ekstensional, yang secara lokal menghasilkan sesar anjak pada bagian ujung luncuran (toe-thrusting). Selanjutnya, saat aktifitas volkanisme menjadi dominan di Cekungan Serayu Utara, pembebanan tubuh gunungapi (volcanic load) juga menghasilkan deformasi luncuran gravitasi ke arah lateral, terutama bergerak ke arah selatan-baratdaya, yang tidak hanya bekerja pada dormasi-formasi Neogen Akhir tetapi juga mempengaruhi Formasi Rambatan yang lebih tua.
Rembesan hidrokarbon di Desa Sijenggung pada Formasi Rambatan yang memiliki potensi sebagai batuan penyimpan (reservoar) dan batuan penyekat (seal) sekaligus, diduga melalui mekanisme pecahnya batuan penyekat (seal failure). Hal ini terjadi karena rendahnya kualitasnya litologi penyekat yang rendah akibat deformasi luncuran gravitasi, sehingga hidrokarbon dapat mencapai permukaan.
Mata kuliah Ekskursi Geologi Regional/EGR (TKG 3122) merupakan mata kuliah wajib bagi mahasiswa p... more Mata kuliah Ekskursi Geologi Regional/EGR (TKG 3122) merupakan mata kuliah wajib bagi mahasiswa program strata satu (S1) di Departemen Teknik Geologi FT UGM. Mata kuliah ini bersifat kegiatan lapangan, dengan bertujuan untuk mengenal zonasi fisiografi, urutan stratigrafi, pola struktur, kaitannya terhadap sejarah geologi regional, potensi sumber daya geologi, dan aspek bencana geologi.
This geologic excursion is crossing several physiographic zone of Java, perpendicular to major ea... more This geologic excursion is crossing several physiographic zone of Java, perpendicular to major east-west structural trends of the island. Therefore, studying physiographic expression is a transient approach to understand geological formation of a particular region and its tectonic history. This excursion starts at the northern fringe of Southern Mountains Zone, a peneplained Eocene-Miocene volcanic belt. Successively the excursion runs to the north, crosses the Solo Zone, a low land formed by modern volcanic belt of Java Island, on to Kendeng Zone, a rolling and hilly area composed of inverted deeper marine sediments. To the north, the journey continues to Randublatung Zone, a narrow depression formed at the edge of Sundaland continental platform, which is dotted by astonishing mud volcanism. The excursion will be concluded in the Rembang Zone, an inverted continental platform which hosts the Northeast Java Basin, a prolific basin in the Java Island.
Bayat, Klaten, Central Java, is one of three location1 in Java that has a complete types of rocks... more Bayat, Klaten, Central Java, is one of three location1 in Java that has a complete types of rocks exposed at the earth surface. In geoscience, rocks generally divided into three major groups based on their origin, i.e. igneous (crystallized from molten magmas), sedimentary (lithified from eroded surface materials), and metamorphic (compacted from other existing rocks). All of those rocks are scattered in a short distance in Bayat, revealing past processes of rock deformation (folding, fracturing and faulting) and present-day processes of rock weathering and erosion.
Pegunungan Selatan - Zona Solo - Zona Kendeng - Zona Randublatung - Zona Rembang
Jawa Tengah - J... more Pegunungan Selatan - Zona Solo - Zona Kendeng - Zona Randublatung - Zona Rembang
Jawa Tengah - Jawa Timur
Uploads
Papers by Salahuddin Husein
Gempabumi ditimbulkan oleh pergeseran patahan, sehingga keberadaan patahan baik di permukaan maupun di bawah permukaan harus bisa dipetakan dengan baik dan akurat. Energi gempabumi merambat dari sumber pergeseran patahan dalam beberapa jenis gelombang, yang menuntut pengukuran secara tepat dan cepat. Kerusakan infrastruktur tidak hanya disebabkan oleh besaran energi, namun juga bagaimana percepatan gelombang gempabumi diterima di lokasi tersebut. Perioda dan frekuensi batuan di permukaan serta bangunan turut pula menentukan derajat kerusakan, bila terjadi fenomena resonansi dan amplifikasi getaran gempabumi yang memiliki kesamaan karakter gelombang. Ketika terjadi gempabumi, informasi berupa intensitas getaran harus segera kita catat dan sampaikan kepada generasi penerus, sebagai data yang sangat berharga agar mereka kelak lebih siap lagi dalam menghadapi bencana gempabumi yang senantiasa berulang ini.
Lokasi penelitian berada pada tebing vertikal singkapan Formasi Halang di Desa Wonosari, Kecamatan Selang, Kabupaten Kebumen. Pada singkapan tersebut dilakukan pengukuran stratigrafi 1:100, pengukuran arah slump, dan pengambilan sampel batuan untuk analisis petrografi.
Susunan batuan di daerah penelitian dapat dibagi menjadi dua asosiasi fasies, yang pertama yaitu asosiasi fasies perselingan batupasir dan napal sedangkan yang kedua yaitu asosiasi fasies napal sisipan batupasir. Daerah tersebut pada kisaran Miosen-Pliosen merupakan sebuah paparan laut dangkal yang dikelilingi oleh tinggian karbonat di sebelah utara dan selatannya. Tidak jauh dari paparan tersebut terdapat gunungapi aktif. Selama proses pengendapan terjadi dua kali transgresi dan sekali regresi.
The lithology of Halang Formation of Miocene Age, evidenced in outcrop by alternating layers of competent tuffaceous sandstones and siltstones. The association of normal fault and high-angle reverse faulting is of critical interest in this paper. Association of normal and reverse faults can occur when the normal fault has highly-dipping strata that tectonically lock the movement of the other block. Reverse faulting occurs when extension progresses while tectonic locking occurs. Relative sense of movement is determined from slickensides and striation and drag folds. The main fault has an identifiable zone of brecciation. Methods used in this study are structural measurement, paleo stress analysis, and clay modeling.
Structural measurement was employed to determine the orientation of structural planes and the dynamics
of the structures. The results of study show that paleo stress direction of main fault came from N – S direction. This result follows the regional tectonic forces originating from subduction. Clay modeling was used to demonstrate the structures formed based on interpreted basement movement of Bukit Bajangan.
presurvey analysis phase, structural analysis derived from IFSAR-DEM was conducted. IFSAR-DEM was chosen because of its spatial accuracy which can reach up to 8 m. The three steps of IFSAR-DEM structural analysis was conducted. This included
IFSAR-DEM interpretation, including hillshade analysis, manually lineament delineation, and digitally extraction lineament; statistic analysis; and kinematics analysis. In the postsurvey phase, an analysis of structural geology data derived from field data was conducted to reconstruct the volcano-tectonic structural play. The result of this study indicated that Dieng field was located in the NE Flank of Serayu Geanticline, which was elongated in the E-W direction. The structural play consisted of three main orientations, which are NW-SE, N-S, and E-W. This structural play was believed to be responsible for controlling the permeability zone in the Dieng field.
sebagai otak atau penggerak dari aplikasi ini yang membuat semua komponen dalam aplikasi bersinergi satu dengan yang lainnya. Sedangkan, php biasa digunakan untuk media penyimpanan atau database di dalam aplikasi itu sendiri.Rocksquare telah selesai dibuat untuk versi pertama dan memiliki beberapa fitur yang menarik yaitu note, informasi cuaca, keterangan pengambilan data, keterangan lokasi, kompas digital, GPS, kamera,voice note.Aplikasi ini telah uji coba lapangan di uji coba aplikasi android dilaksanakan pada hari jumat 3 oktober 2014 dengan koordinat - 7.7673020 110.6779556 yaitu Desa Bawak – gunung Temas, Bayat – Klaten. Harapan kami aplikasi ini mendapat respon positif di kalangan pekerja lapangan khususnya geologist untuk selanjutkan dapat membuat aplikasi versi berbayar.
developed with reservoirs distributed in the precollisional
Miocene carbonates. To date, explorational work over the area has been incorporating collisional structures such as thrusts and wrench faults into the petroleum systems, e.g.
hydrocarbon maturation and trap formation. Most of the structural concept based on the existing model of southeastward vergeance thick-skinned (ophiolitic basement involved) thrust-fold belt.
A geologic field work has been conducted transecting north-south section and east-west section of Luwuk. Satellite imagery interpretation and field observation suggest the existance of three structural compartments, i.e.: (i) the northern extensional, block-faulting, tectonic regime on the
ophiolite complex, (ii) the central compressional, northwestward vergeance thrust-fold belt, tectonic regime on the Tertiary carbonates, and (iii) the southern, locally gravitational sliding, tectonic regime on the Pliocene molasse. Each compartment exhibits distinct structural style and diverse tectonic control.
The northern extensional compartment were controlled by rifting of Siuna Bay along the Late-Miocene right-lateral movement of Balantak Fault. The central compressional compartment were developed by the Late Pliocene northwestward shortening due to activation of Sorong Fault. The southern gravitational Molasse sliding were induced
by the Late Pliocene uplift along the existing weak zone of north-south transtensional strike-slip fault. Implication of this research to petroleum exploration is a revision of Luwuk thrust-fold belt model, which is proposed to be thin-skinned
(basement uninvolved) northwestward vergeance.
The research was conducted with several stages since the literature review, discussions with colleagues in the Laboratories of Geodesy and Geodynamic, Faculty of Engineering, Universitas Gadjah Mada. The first research procedure includes planning for bench-mark (BM) installation, and Global Navigation Satellite System (GNSS) data acquisition, Linux Centos V. 6.5 as Operating System and
GAMIT/GLOBK V 10.5 as scientific software for data proccesing. Measurement of monitoring network in
this area was carried out on 18 November 2013. The second research percedure was Geological observation and mapping which were conducted for about three weeks in the August 2013.
The research has established 10 BMs for monitoring network point using 3D Cartesian coordinates system. Pasive stations were labelled OPK 3, OPK 4, OPK 6, OPK 7, OPK 8, TGD 2, and active stations were labelled GK1_,KPG1,SLM1and BTL1. Distance between network monitoring stations ranges from
6,045.67385 m for the shortest distance OPK 6 to GK1_ and 4,3603.16313 m for longest distance of OPK 6 to KPG1, with precision of base lines varies from 3.94 mm to 10.61 mm, standard deviation of on the X-as (x) , Y-as (y) and Z-axis as (z) are varies. Standard deviations of 3D Cartesian coordinates system for pasive and active stations have similar pattern where y lesser than x dan z. Geological
mapping and field observation on the suspected area for the seismogenic fault suggest that the Mangunan-Muntuk region was influenced by similar tectonic forces as in 2006 earthquake.
satu manifestasi permukaan, rembesan hidrokarbon dapat menjadi jendela dan titik tolak pendekatan dalam mempelajari kondisi geologi bawah permukaan bagi unsur-unsur penting dalam sistem petroleum.Berlandaskan pemahaman tersebut, penelitian ini bermaksud untuk mempelajari faktor-faktor geologi yang pernah bekerja di Cekungan Serayu Utara yang mengontrol terjadinya rembesan hidrokarbon di Desa Sijenggung, Kecamatan Banjarmangu, Kabupaten Banjarnegara, Jawa Tengah.Di permukaan, rembesan tersebut terjadi pada singkapan Formasi Rambatan yang berumur Miosen Awal - Miosen Tengah.Pendekatan yang dipergunakan adalah pengumpulan data-data geologi permukaan, berupa data stratigrafi dan struktur geologi.
Penurunan Cekungan Serayu Utara sebagai cekungan belakang busur (back-arc basin) di Miosen Awal mempengaruhi pengendapan Formasi Rambatan, yang diisi oleh perselingan serpih, napal, dan tuff. Kandungan material volkaniklastik halus diduga berasal dari volkanisme Waturanda di Busur Volkanik
Serayu Selatan.Mekanisme pengendapan litologi Rambatan tersebut terpengaruh kondisi cekungan yang terus menurun, menghasilkan gangguan-gangguan sedimentasi (soft sediment deformation) akibat luncuran gravitasi di lereng cekungan. Memasuki Miosen Akhir, busur volkanik Jawa Tengah berpindah ke cekungan belakang busur, menghasilkan endapan-endapan vulkaniklastika kasar yang berselingan dengan klastika halus laut pada formasi-formasi Halang, Tapak, dan Pemali.
Deformasi yang dominan pada Formasi Rambatan adalah luncuran gravitasi (gravity sliding) ke arah utara-timurlaut dalam rejim ekstensional, yang secara lokal menghasilkan sesar anjak pada bagian ujung luncuran (toe-thrusting). Selanjutnya, saat aktifitas volkanisme menjadi dominan di Cekungan Serayu Utara, pembebanan tubuh gunungapi (volcanic load) juga menghasilkan deformasi luncuran gravitasi ke arah lateral, terutama bergerak ke arah selatan-baratdaya, yang tidak hanya bekerja pada dormasi-formasi Neogen Akhir tetapi juga mempengaruhi Formasi Rambatan yang lebih tua.
Rembesan hidrokarbon di Desa Sijenggung pada Formasi Rambatan yang memiliki potensi sebagai batuan penyimpan (reservoar) dan batuan penyekat (seal) sekaligus, diduga melalui mekanisme pecahnya batuan penyekat (seal failure). Hal ini terjadi karena rendahnya kualitasnya litologi penyekat yang rendah akibat deformasi luncuran gravitasi, sehingga hidrokarbon dapat mencapai permukaan.
Gempabumi ditimbulkan oleh pergeseran patahan, sehingga keberadaan patahan baik di permukaan maupun di bawah permukaan harus bisa dipetakan dengan baik dan akurat. Energi gempabumi merambat dari sumber pergeseran patahan dalam beberapa jenis gelombang, yang menuntut pengukuran secara tepat dan cepat. Kerusakan infrastruktur tidak hanya disebabkan oleh besaran energi, namun juga bagaimana percepatan gelombang gempabumi diterima di lokasi tersebut. Perioda dan frekuensi batuan di permukaan serta bangunan turut pula menentukan derajat kerusakan, bila terjadi fenomena resonansi dan amplifikasi getaran gempabumi yang memiliki kesamaan karakter gelombang. Ketika terjadi gempabumi, informasi berupa intensitas getaran harus segera kita catat dan sampaikan kepada generasi penerus, sebagai data yang sangat berharga agar mereka kelak lebih siap lagi dalam menghadapi bencana gempabumi yang senantiasa berulang ini.
Lokasi penelitian berada pada tebing vertikal singkapan Formasi Halang di Desa Wonosari, Kecamatan Selang, Kabupaten Kebumen. Pada singkapan tersebut dilakukan pengukuran stratigrafi 1:100, pengukuran arah slump, dan pengambilan sampel batuan untuk analisis petrografi.
Susunan batuan di daerah penelitian dapat dibagi menjadi dua asosiasi fasies, yang pertama yaitu asosiasi fasies perselingan batupasir dan napal sedangkan yang kedua yaitu asosiasi fasies napal sisipan batupasir. Daerah tersebut pada kisaran Miosen-Pliosen merupakan sebuah paparan laut dangkal yang dikelilingi oleh tinggian karbonat di sebelah utara dan selatannya. Tidak jauh dari paparan tersebut terdapat gunungapi aktif. Selama proses pengendapan terjadi dua kali transgresi dan sekali regresi.
The lithology of Halang Formation of Miocene Age, evidenced in outcrop by alternating layers of competent tuffaceous sandstones and siltstones. The association of normal fault and high-angle reverse faulting is of critical interest in this paper. Association of normal and reverse faults can occur when the normal fault has highly-dipping strata that tectonically lock the movement of the other block. Reverse faulting occurs when extension progresses while tectonic locking occurs. Relative sense of movement is determined from slickensides and striation and drag folds. The main fault has an identifiable zone of brecciation. Methods used in this study are structural measurement, paleo stress analysis, and clay modeling.
Structural measurement was employed to determine the orientation of structural planes and the dynamics
of the structures. The results of study show that paleo stress direction of main fault came from N – S direction. This result follows the regional tectonic forces originating from subduction. Clay modeling was used to demonstrate the structures formed based on interpreted basement movement of Bukit Bajangan.
presurvey analysis phase, structural analysis derived from IFSAR-DEM was conducted. IFSAR-DEM was chosen because of its spatial accuracy which can reach up to 8 m. The three steps of IFSAR-DEM structural analysis was conducted. This included
IFSAR-DEM interpretation, including hillshade analysis, manually lineament delineation, and digitally extraction lineament; statistic analysis; and kinematics analysis. In the postsurvey phase, an analysis of structural geology data derived from field data was conducted to reconstruct the volcano-tectonic structural play. The result of this study indicated that Dieng field was located in the NE Flank of Serayu Geanticline, which was elongated in the E-W direction. The structural play consisted of three main orientations, which are NW-SE, N-S, and E-W. This structural play was believed to be responsible for controlling the permeability zone in the Dieng field.
sebagai otak atau penggerak dari aplikasi ini yang membuat semua komponen dalam aplikasi bersinergi satu dengan yang lainnya. Sedangkan, php biasa digunakan untuk media penyimpanan atau database di dalam aplikasi itu sendiri.Rocksquare telah selesai dibuat untuk versi pertama dan memiliki beberapa fitur yang menarik yaitu note, informasi cuaca, keterangan pengambilan data, keterangan lokasi, kompas digital, GPS, kamera,voice note.Aplikasi ini telah uji coba lapangan di uji coba aplikasi android dilaksanakan pada hari jumat 3 oktober 2014 dengan koordinat - 7.7673020 110.6779556 yaitu Desa Bawak – gunung Temas, Bayat – Klaten. Harapan kami aplikasi ini mendapat respon positif di kalangan pekerja lapangan khususnya geologist untuk selanjutkan dapat membuat aplikasi versi berbayar.
developed with reservoirs distributed in the precollisional
Miocene carbonates. To date, explorational work over the area has been incorporating collisional structures such as thrusts and wrench faults into the petroleum systems, e.g.
hydrocarbon maturation and trap formation. Most of the structural concept based on the existing model of southeastward vergeance thick-skinned (ophiolitic basement involved) thrust-fold belt.
A geologic field work has been conducted transecting north-south section and east-west section of Luwuk. Satellite imagery interpretation and field observation suggest the existance of three structural compartments, i.e.: (i) the northern extensional, block-faulting, tectonic regime on the
ophiolite complex, (ii) the central compressional, northwestward vergeance thrust-fold belt, tectonic regime on the Tertiary carbonates, and (iii) the southern, locally gravitational sliding, tectonic regime on the Pliocene molasse. Each compartment exhibits distinct structural style and diverse tectonic control.
The northern extensional compartment were controlled by rifting of Siuna Bay along the Late-Miocene right-lateral movement of Balantak Fault. The central compressional compartment were developed by the Late Pliocene northwestward shortening due to activation of Sorong Fault. The southern gravitational Molasse sliding were induced
by the Late Pliocene uplift along the existing weak zone of north-south transtensional strike-slip fault. Implication of this research to petroleum exploration is a revision of Luwuk thrust-fold belt model, which is proposed to be thin-skinned
(basement uninvolved) northwestward vergeance.
The research was conducted with several stages since the literature review, discussions with colleagues in the Laboratories of Geodesy and Geodynamic, Faculty of Engineering, Universitas Gadjah Mada. The first research procedure includes planning for bench-mark (BM) installation, and Global Navigation Satellite System (GNSS) data acquisition, Linux Centos V. 6.5 as Operating System and
GAMIT/GLOBK V 10.5 as scientific software for data proccesing. Measurement of monitoring network in
this area was carried out on 18 November 2013. The second research percedure was Geological observation and mapping which were conducted for about three weeks in the August 2013.
The research has established 10 BMs for monitoring network point using 3D Cartesian coordinates system. Pasive stations were labelled OPK 3, OPK 4, OPK 6, OPK 7, OPK 8, TGD 2, and active stations were labelled GK1_,KPG1,SLM1and BTL1. Distance between network monitoring stations ranges from
6,045.67385 m for the shortest distance OPK 6 to GK1_ and 4,3603.16313 m for longest distance of OPK 6 to KPG1, with precision of base lines varies from 3.94 mm to 10.61 mm, standard deviation of on the X-as (x) , Y-as (y) and Z-axis as (z) are varies. Standard deviations of 3D Cartesian coordinates system for pasive and active stations have similar pattern where y lesser than x dan z. Geological
mapping and field observation on the suspected area for the seismogenic fault suggest that the Mangunan-Muntuk region was influenced by similar tectonic forces as in 2006 earthquake.
satu manifestasi permukaan, rembesan hidrokarbon dapat menjadi jendela dan titik tolak pendekatan dalam mempelajari kondisi geologi bawah permukaan bagi unsur-unsur penting dalam sistem petroleum.Berlandaskan pemahaman tersebut, penelitian ini bermaksud untuk mempelajari faktor-faktor geologi yang pernah bekerja di Cekungan Serayu Utara yang mengontrol terjadinya rembesan hidrokarbon di Desa Sijenggung, Kecamatan Banjarmangu, Kabupaten Banjarnegara, Jawa Tengah.Di permukaan, rembesan tersebut terjadi pada singkapan Formasi Rambatan yang berumur Miosen Awal - Miosen Tengah.Pendekatan yang dipergunakan adalah pengumpulan data-data geologi permukaan, berupa data stratigrafi dan struktur geologi.
Penurunan Cekungan Serayu Utara sebagai cekungan belakang busur (back-arc basin) di Miosen Awal mempengaruhi pengendapan Formasi Rambatan, yang diisi oleh perselingan serpih, napal, dan tuff. Kandungan material volkaniklastik halus diduga berasal dari volkanisme Waturanda di Busur Volkanik
Serayu Selatan.Mekanisme pengendapan litologi Rambatan tersebut terpengaruh kondisi cekungan yang terus menurun, menghasilkan gangguan-gangguan sedimentasi (soft sediment deformation) akibat luncuran gravitasi di lereng cekungan. Memasuki Miosen Akhir, busur volkanik Jawa Tengah berpindah ke cekungan belakang busur, menghasilkan endapan-endapan vulkaniklastika kasar yang berselingan dengan klastika halus laut pada formasi-formasi Halang, Tapak, dan Pemali.
Deformasi yang dominan pada Formasi Rambatan adalah luncuran gravitasi (gravity sliding) ke arah utara-timurlaut dalam rejim ekstensional, yang secara lokal menghasilkan sesar anjak pada bagian ujung luncuran (toe-thrusting). Selanjutnya, saat aktifitas volkanisme menjadi dominan di Cekungan Serayu Utara, pembebanan tubuh gunungapi (volcanic load) juga menghasilkan deformasi luncuran gravitasi ke arah lateral, terutama bergerak ke arah selatan-baratdaya, yang tidak hanya bekerja pada dormasi-formasi Neogen Akhir tetapi juga mempengaruhi Formasi Rambatan yang lebih tua.
Rembesan hidrokarbon di Desa Sijenggung pada Formasi Rambatan yang memiliki potensi sebagai batuan penyimpan (reservoar) dan batuan penyekat (seal) sekaligus, diduga melalui mekanisme pecahnya batuan penyekat (seal failure). Hal ini terjadi karena rendahnya kualitasnya litologi penyekat yang rendah akibat deformasi luncuran gravitasi, sehingga hidrokarbon dapat mencapai permukaan.
Jawa Tengah - Jawa Timur