The study of Quaternary deposits was conducted using analyses of sedimentology and stratigraphy of thirteen boreholes obtained along the west to the east traverse, which was approximately parallel to the valley of Duren river, not far from the Duren Village between Bikang and Gadung villages, District of South Bangka, Province of Bangka-Belitung. The depth of each borehole varies from 2.20 to 30.10 m.Studies on Quaternary deposits revealed five facies which represented, encompassing alluvial fan (FKa), river channel (FAs), floodplain (FDb), lake/lacustrine (FDn), and swamp (FRw) depositional environments. Based on the result of correlation of the lateral and vertical variation of the facies, four intervals of the deposition (IP I-IV) were recognised. Each of the interval exhibits the variation of the depositional environment under the control of tectonic and climatic changes. The tectonic activities and climatic changes which controlled the deposition were recorded as four episode stages. These respective episodes were, (1) dry climate with tectonic effects, (2) sub humid climate which was influenced by fault in the west, (3) humid to sub-humid climate which was followed by active of the three faults on the basin, and (4) dry climate without being influenced by tectonics.

Penentuan Karakteristik reservoir merupakan suatu upaya untuk mengetahui kualitas reservoir dari suatu tubuh batuan dalam perkiraan prospek atau tidaknya lapisan reservoir tersebut. Penelitian ini dilakukan pada formasi Talang Akar yang masuk kedalam Sub-Cekungan Palembang Selatan, Cekungan Sumatera Selatan, dengan menggunakan data well, data seismik, data SWC dan data Mudlog. Formasi talang akar menunjukan lingkungan delta plain dimana zona reservoirnya yang merupakan bagian bawah dari formasi tersebut termasuk dalam lingkungan fluvial. Pada klasifikasi parasekuen formasi talang akar terdapat siklus regresi-transgresi yang membentuk pola pengendapan progradasi dan retrogradasidalam skala kecil dengan rincian Sumur X1, X2, dan X3 terdapat 4 parasekuen, sedangkan sumur X4 dan X5 berjumlah 5 parasekuen, secara kuantitatif, nilai-nilai perhitungan petrofisika menunjukan bahwa pada zona hidrokarbon mempunyai Sw berkisar 8-46%, porositas 13-30%, sedangkan zona air memiliki Sw 65-100 %, dan porositas 8-25%. Berdasarkan peta kontur struktur dan peta net san top zona C3, ke lima lapisan batupasirnya pada tiap sumur terletak pada antiklin, dimana arah pengendapan yang relative berarah Timur Laut – BaratDaya. Berdasarkan paparan diatas, pada langkah eksplorasinya telah ditentukan bahwa zona reservoir yang ekonomis pada daerah penelitian terdapat pada zona C3 sumur X5. Katakuci : Batupasir, Formasi Talang Akar, Parasekuen, Petrofisika, Prospek, Reservoir.

ABSTRAKDaerah penelitian di wilayah Majalengka, Provinsi Jawa Barat tersusun oleh batuan hasil endapan gunungapi tua (Qtvs), dan Formasi Kaliwangu (Tpkw). Hasil pelapukan batuan tersebut berupa tanah lempung dengan potensi mengembang. Tujuan dari penelitian ini adalah untuk mengetahui tingkat mengembang, dan bahaya yang ditimbulkan dari tanah lempung yang ada diwilayah penelitian berkaitan dengan gerakan tanah yang sering terjadi di wilayah ini. Tingkat potensi mengembang tanah lempung ini dapat dianalisis menggunakan data mekanika tanah, yaitu indek plastisitas dan persen lempung. Data mekanika tanah tersebut digunakan untuk menghitung nilai aktifitas dari lempung. Berdasarkan klasifikasi skempton nilai aktiftitas lempung yang didapat adalah 0,62 sampai 1,35. Jenis mineral lempung Illite dan Monmorilonite (Ca), dan tingkat potensi mengembang tinggi sampai sangat tinggi. Sedangkan berdasarkan klasifikasi Bowles dan Seed menunjukkan nilai aktifitas sebesar 0,79 sampai 1,80, dengan jenis mineral lempung Illite dan Monmorilonite, dan potensi mengembang tanah lempung ini adalah tinggi sampai sangat tinggi. Kata kunci: Potensi mengembang, lempung, nilai aktiftitas, indek plastisitas, persen lempung. ABSTRACTThe research area in Majalengka, West Java consist are older volcanic (Qvts) and Formation Kaliwangu (Tpkw). Result weathering of the rock is clay with potential to swelling. The purpose of this study is to determine the rate of swelling and the hazard potential at the area posed from clay. Swelling potential of this clay soil analyzed using by soil mechanical data with the index of plasticity and percentage of clay. The soil mechanical data used to calculate the activity value of clay. Based on skempton analysis results of analysis is 0.62 to 1.35, with Illite and Monmorilonite (Ca) clay minerals and swelling clay potential high up to very high. Based on the Bowles and seed classification showing activity values of 0.79 to 1.80, with the type of clay minerals Illite and Montmorillonite and swelling clay potential is high to very high. Keywords: Potential of Swelling, clay, value of activity, plastisity indeks, percent of clays.

Site plan of coal mining at Sorolangun, Jambi, is required geotechnical study for cut slope design. Mining plan. In open pit plan, to take stable slope, is required slope mass rating (SMR). SMR method is requiring rock mass rating value. According to soil and weak-rock mass properties of Muaraenim Formation, stable

Analisis tekanan pori dan gradien rekah adalah proses penting dalam pengeboran minyak dan gas untuk memprediksi tekanan yang terjadi di dalam sumur dan mencegah kejadian bencana pengeboran. Analisis ini berlokasi di lapangan RZZ sebagai salah satu lapangan produksi minyak dan gas alam pada Kalimantan Timur. Tujuan penelitian ini untuk mengetahui karakterisitik tekanan pori agar dapat menentukan metode yang tepat dalam optimasi berat lumpur pengeboran. Penelitian ini menggunakan data dari 14 sumur, berupa data log tali kawat, PTFA, LOT atau FIT, laporan pengeboran, mud log, interval velocity, dan Ro. Penelitian ini menggunakan metode Eaton (Eaton, 1975) pada analisis tekanan pori dan gradien rekah serta metode statistika pada optimasi berat lumpur. Hasil penelitian menunjukkan bahwa kedalaman top overpressure berada pada rentang 9,850 – 11,000 ftTVD pada Formasi Balikpapan dan top hard overpressure pada rentang 12,000 – 13,000 ftTVD pada Formasi Balikpapan juga. Hasil korelasi menunjukkan distribusi overpressure mengikuti struktur geologi yang berkembang yakni antiklin. Overpressure pada daerah penelitian disebabkan oleh mekanisme loading dan unloading. Mekanisme loading dibuktikan berdasarkan analisis sejarah pemendaman, sedangkan mekanisme unloading dibuktikan oleh plot silang Dutta (Dutta, 2002) dan nilai Ro. Optimasi berat lumpur pada section 12 ¼” dilakukan dengan cara menaikkan berat lumpur menjadi 2.65 ppg dari tekanan pori untuk menanggulangi permasalahan tight spot dan overpull. Sedangkan pada section 8 ½” dengan cara menurunkan berat lumpur menjadi 2.5-3.5 ppg dari tekanan pori untuk menanggulangi high gas. Penggunaan berat lumpur optimum ini akan meminimalisir terjadi permasalahan saat pengeboran sehingga pengeboran menjadi lebih efektif dan efisien.Kata Kunci: Tekanan Pori, Overpressure, Berat Lumpur, Mekanisme, Optimasi

The research uses two kinds of microfossils for an aim to produce more precision, which Palinomorph as a main object and foraminifera as the support object. Pollen analysis has the main role in paleo-environment reconstruction, based on ecological characteristics plants association. Using palinomorph and foraminifera together in one research can only be conducted through sediments transition. Coals are included in the category, where coal samples were taken from Sungai Perian near Pulaubalang-Pamaluan formation boundary.From four samples that were analyzed (1R / claystone, 3R / claystone, 5R / claystone carbonaceous, and 7R / claystone) 53 genera and only 5 foraminifera species was founded. Both microfossils have yielded the same interpretation. The relative ages of the pollen indicator are from Middle-Early Miocene, and the relative ages of the foraminifera are from Late-Early Miocene. Based on the palinomorph and foraminifera data the research area was on regressions environment during the geologic period mentioned.

Daerah penelitian adalah DAS Cipeles yang terletak di Kabupaten Sumedang. Penelitian dilakukan untuk mengetahui karakteristik morfometri DAS Cipeles, khususnya subDAS yang ada di dalamnya. Penelitian dilakukan menggunakan Sistem Informasi Geografis dan dukungan perangkat lunak MapInfo untuk mengidentifikasi aspek morfometri DAS di daerah penelitian. Aspek morfometri DAS yang diteliti terdiri dari aspek linear (orde sungai (u), panjang sungai orde “u” (Lu), rata-rata panjang sungai (Lsm), rasio panjang sungai (RL), rasio cabang sungai (Rb), rata-rata rasio cabang sungai (Rbm)), areal (kerapatan drainase (Dd), frekuensi sungai (Fs), tekstur drainase (Rt), faktor bentuk (Rf), rasio sirkularitas (Rc), rasio elongasi (Re), panjang aliran permukaan (Lg)), serta relief (relief DAS (R), rasio relief (Rh)). Berdasarkan hasil penelitian, DAS Cipeles terdiri dari 38 subDAS yang tersebar di bagian utara dan selatan Sungai Cipeles dengan karakteristik morfometri beragam. Secara umum, 38 subDAS tersebut terdiri dari DAS memanjang yang berada pada relief tinggi dan DAS membulat yang berada pada relief rendah dengan tingkat geomorfik muda hingga lanjut. Meskipun di beberapa tempat ditemukan DAS memanjang pada relief rendah dan tingkat geomorfik lanjut serta DAS membulat pada relief tinggi dan tingkat geomorfik muda. Kontrol struktur relatif tidak ada cenderung lemah kecuali indikasi pada subDAS Cpl_06. Selain itu, kenaikan muka banjir di daerah penelitian cenderung lambat hingga tidak terlalu cepat sehingga DAS Cipeles tidak termasuk daerah rawan banjir.

Studies on the distribution of chemical elements Lawangdora limestone area has been conducted to determine the depositional environment is based on the chemical characteristics . The purpose of this study was to apply the theory of Chilingar who stating that Mg levels will decrease when deposited away from the beach. The results showed that the study area is dominated by calcite limestone, and the type is low magnesium calcite . This is a type of calcite carbonate in deep marine sediments. Based on the cross section of the direction and distance relative to the content of the element magnesium ( Mg ) is seen that the direction of deepening moves relative to the north.

The Quaternary volcanic terrain has unique characteristic. Those phenomena are reflected by basin morphometry. Some morphometry variables can used are basin dimention, azimuth of river segment, azimuth of terrain lineament, river length (Ls), drainage density (Dd), and bifurcation ratio (Rb).Upper Citarum River area is the research area, exactly on Cijoho Basin, Cihejo Basin, Cigalugah Basin, and Barugbug Basin. Base on literature study result and field survey, those four basins have difference geological setting. Probabilistic approach used for know difference and similarity of basins. Statistic tests used are distribution normality of data and average difference tests.Result of research show highest Dd value exist on Cijoho Basin (3.78), otherwise its lowest exist on Barugbug Basin (2.35). That’s phenomena reflect difference of its volcanic rock characteristic. Commonly Rb values < 3 show that deformed basins. Rb values increase to downstream of Cihejo Basin, meanwhile on the other basins they are decrease. The Rb values escalation to downstream indicate strongly deformation at downstream of Cihejo Basin. The rivers of Cijoho Basin direct the-90o until 179o controlled by active tectonic. Meanwhile, the rivers pattern of Basins of Cihejo, Barugbug, and Cigalugah are controlled by active tectonic.

Natuna is one of the regions in Indonesia that has potential in hydrocarbon with a siliciclastic reservoir which is generally characterized by a fluvial and deltaic environment. For this reason, it is important to identify the distribution channel to find out the distribution of the reservoir. This study using the well-logging and 3D seismic data interpretation methods. With the correlation between the horizon slicing method on seimsic data, lithology identification in well data, and also using seismic attributes, we can determine the distribution of reservoirs. In reseach area, reservoir distribution analysis in Arang and Muda Formation. Where Arang Formation identified 4 reservoirs, which 3 of them have oil content, with effective porosity value of 10-30%. Meanwhile, in Muda Formation, there are 3 reservoirs with effective porosity of Muda Formation is 20-27%

Terdapat indikasi adanya gejala kehilangan debit sungai yang bersifat alami (non-rekayasa) pada segmen zona transfer Cikapundung, yaitu pada jalur sungai antara daerah Maribaya dan Curug Dago. Karena segmen ini bersifat effluent (air tanah mengisi air sungai) maka gejala imbuhan yang terjadi pada segmen ini merupakan suatu anomali influent (air sungai mengisi air tanah). Bagian dasar sungai pada zona ini ditutupi oleh lapisan lava basal yang masif, sehingga proses imbuhan yang terjadi diduga melalui struktur rekahan batuan. Berdasarkan hasil pengujian statistik dapat disimpulkan bahwa pada zona transfer memang terjadi gejala anomali imbuhan, yaitu pada sub-segmen sungai yang bergradien rendah dan berdensitas kelurusan regional tinggi. Sub-segmen yang berdensitas kelurusan tinggi secara umum memiliki densitas rekahan batuan yang tinggi pula.Kata kunci: zona transfer, imbuhan, effluent, influent     There is an indication of a natural loss of discharge phenomenon within the zone transfer of Cikapundung which are located between Maribaya area and Curung Dago. Because this segment is effluent in nature, the symptom of recharge that happened in this segment is an anomaly. The river bed in this zone is covered by massive basalt layers. Therefore the recharge process that happened is through the fractured of basalt. The results of a statistical test conclude that in the transfer zone there is a recharge anomaly phenomenon which is in the sub-segment of the river which has both a low gradient and a high regional lineament density. In general, the sub-segment that is of a high lineament density also shows high fracture density.Keywords: transfer zone, recharge, effluent, influent

Bioclastic limestones from Baturaja Formation cropped out at Muaradua area, South Sumatera is a good object of research for studying microfacies of limestone. Based on the rock features under the polarization microscope of the bioclastic limestones taking from studied area could be predicted the limestones are predominantly deposited at reef-flank and back-reef local basin. The main components T-F-P test of the limestones showing a significant difference of the carbonate grains, terrigenous grains, and neomorphism materials between two depositional environments. The other side, matrix, cement, and rock porosity components have no significant difference.

This research was conducted in the Cikao sub-watershed, which is in Purwakarta Regency, West Java Province. Cikao Sub-Watershed is a part of the Citarum Watershed, which contributes the highest erosivity to Citarum Watershed. This is reinforced by the activity of sedimentation excavation in Cikao river area. This research was conducted to determine the erosion and sedimentation potential rate in Cikao Sub-Watershed using Soil and Water Assessment Tool (SWAT) which can be considered for watershed management plan. This SWAT model is quantitative analysis using climate, hydrology, land use, soil type, and slope data. The results show that erosion rates in the Cikao Sub-Watershed are 845.7 tons/ha/year and sedimentation rates are 653.62 tons/ha/year. The erosion levels in the Cikao Sub-Watershed consist of very slight class 2041.99 ha, slight class 1956.03 ha, and moderate class is 3027.32 ha. And the sedimentation levels consist of a very low class 3004.02 ha, a low class 134.78 ha, a moderate class 131.62 ha, and a very high class 3754.92 ha.Keywords: SWAT, Cikao Sub-Watershed, Erosion, Sedimentation

ABSTRACTThe Grasberg Block Cave (GBC) underground mine consists of multiple intrusion stages become into the Grasberg Intrusion Complex (GIC). The intrusion is consists of three intrusion stages, Dalam Intrusion Complex (DIC), Main Grasberg Intrusion (MGI) and Kali Intrusion (KI). The emplacement of intrusions occurred in a relatively short span between 3.51Ma (Dalam stage), 3.21Ma (Main Grasberg stage) and 3.1Ma (Kali stage). The existence of magmatic activity that occurs is the main control of mineral formation changes that affect the condition of rocks and quality of Cu-Au. Different type of alteration and mineralization on GIC rock can change its physical properties. Variations of mineral alterations that are formed due to the variation of intrusion causes the variation of mineral alteration that affect the value of rock strength. The value of rock strength affects the determination of rock support that will be mined in the Grasberg Block Cave underground mine (GBC). XRD analysis with mineral content dominance quartz 30.07%, sericite 22.72%, k-feldspar 13.38%, fe sulphide 9.80% and CaSulfate 5.72%. XRD analysis results are type of phyllic alteration. Point load analysis in the research area of 347 pieces of rock drill hole found rock strength value is dominated by weak (0.2 – 1 Mpa) - medium (1 – 2 Mpa). Rock Mass Rating (RMR) analysis calculation result value is RMR 20 - 60 (poor - fair). Keywords: Grasberg Block Cave, phyllic alteration, XRD Analysis, Point Load Test analysis,  ABSTRAKTambang bawah tanah Grasberg Block Cave (GBC) terdiri dari beberapa tahapan intrusi yang tergabung ke dalam jenis Komplek Batuan Beku Grasberg (GIC). Tahapan intrusi dari tua ke muda adalah Dalam Intrusion Complex (DIC), Main Grasberg Intrusion (MGI) dan Kali Intrusion (KI). Adanya aktifitas magmatik yang terjadi merupakan kontrol utama pembentukan mineral ubahan yang berpengaruh terhadap kondisi batuan. Variasi mineral ubahan yang terbentuk akibat dari adanya variasi intrusi menyebabkan adanya variasi mineral ubahan yang berpengaruh terhadap Tambang bawah tanah Grasberg Block Cave (GBC) terdiri dari beberapa tahapan intrusi yang tergabung ke dalam jenis Komplek Batuan Beku Grasberg (GIC). Tahapan intrusi dari tua ke muda adalah Dalam Intrusion Complex (DIC), Main Grasberg Intrusion (MGI) dan Kali Intrusion (KI). Adanya aktifitas magmatik yang terjadi merupakan kontrol utama pembentukan mineral ubahan yang berpengaruh terhadap kondisi batuan dan kualitas cebakan Cu-Au. Variasi mineral ubahan yang terbentuk akibat dari adanya variasi intrusi menyebabkan adanya variasi mineral ubahan yang berpengaruh terhadap nilai mekanika batuan. Analisa XRD dengan dominasi kandungan mineral quartz 30.07%, sericite 22.72%, k-feldspar 13.38%, fe sulphide 9.80% dan casulfate 5.72%. Hasil analisis XRD tersebut masuk ke dalam tipe phyllic alteration. Analisis uji kuat tekan batuan (Point Load Test) pada daerah penelitian terhadap 347 buah conto batuan lubang pemboran memberikan nilai kekuatan batuan didominasi oleh nilai kekuatan batuan lemah (weak, 0.2 – 1 Mpa) - sedang (medium, 1 – 2 Mpa). Kata kunci: Grasberg Block Cave, phyllic alteration, XRD Analysis, Point Load Test.

Physical development of the region will always be associated with infrastructure studies. Construction plans in Kertajati International Airport, will bring the study of the infrastructure related to public facilities, which supports the international airport in West Java. Including a study of infrastructures are the foundation for buildings, roads, bridges, buildings, dams, etc., also the slope which is the result of slope stability design. This study discusses the behavior of the activity of high plasticity clay (CH) toward safety factor of slope and soil bearing capacity. Safety factor of slope is represented by value of FS (Factor of Safety) with a specified slope angle, so the increasing soil activity (A) is known relationship with a decrease in the value of the slope safety factor (FS). Soil bearing capacity is represented by the value of qa (allowable soil bearing capacity) for square and circular foundation type, so that the relationship of soil bearing capacity is decreasing with increasing value of soil activity. The study is expected to be developed, to facilitate the safety factor is the estimated slope and soil bearing capacity estimated by examining the number of activity as an early indicator. The relationship between the allowable soil bearing capacity (qa) for shallow foundations (of a square type) with soil activity (Skempton, and Seed) shows the equation qa = 7.89890 A (-1.01759) a negative relationship with correlation coefficient R = - 0754, and qa = 8.81669 A (-0.83957) a negative relationship with correlation coefficient R = - 0722. The relationship between the allowable soil bearing capacity (qa) for shallow foundation (of a circular type) with soil activity (Skempton, and Seed) shows the equation qa = 7.80513 A (-1.06644) a negative relationship with correlation coefficient R = - 0780, and qa = 8.77028 A (-0.88473) a negative relationship with correlation coefficient R = - 0722, it indicates that bearing capacity land values decline with increasing soil activity. The relationship between the security factor (FS) with 15o slope angle A activity figures show the equation FS = 1.517 A -0.79 with R ² = 0.625; The relationship between the safety factor (FS) with 30o slope angle A activity figures show the equation FS = 1.721 A - 0.78 with R ² = 0.64. Handling of expansive soil can be through soil improvement. To planning the foundation and slope infrastructures, is required safe design in accordance with assessment of soil bearing capacity and Factor of Safety (FS) of slopes, in order to avoid design failure.

Analisis polen dilakukan pada sampel yang diambil dari  singkapan  di Sungai Cijurai, Kabupaten Sumedang. Tujuan penelitian untuk merekonstruksikan palinomof pada masanya, umur relatif dan lingkungan pengendapan. Preparasi menggunakan metode hidrogen peroksida. Diperoleh palinomrorf yang terdiri dari  polen, spora pteridophya, foraminifera test linings, dan dinoflagellate cyst.  Secara garis besar asal palinomorf  dikelompokan menjadi dua yaitu palinomorf  marine dan terestrial. Terestrial  palinomorf terdiri dari polen dan spora kelompok  mangrove, back mangrove, freshwater swamp and mountain.   Palinomorf laut terdiri dari foraminifera test linings dan  dinoflagellate cyst. Komponen dinoflagellate cyst meliputi Peridinium, Protoperidinium  dan Spiniferites.  Ditemukan Polen penanda umur  Florschuetzia meridionalis, Florschuetzia levipoli,  Stenochlaenidites papuanus, Impatiensidites brevicolpus, dan Dacrycarpites australiensis. Sampel CJ-I  dengan umur relatif  Pliosen, sedangkan dua sampel diatasnya CJ2-02 dan CJ-3  adalah Pliosen akhir. Dari sampel bagian bawah ke posisi bagian atas sampel menunjukkan adanya perubahan  kuantitas palinomorf, keragaman maupun perbandingan jumlah palinomorf laut  dan terestrial. Nilai Index PMI berturu-turut dari CJ-1 sebesar 14,28, CJ-2 sebesar 13,63 dan CJ-3 sebesar 24,13. Seluruh nilai PMI kurang dari 51% yang mengindikasikan pengendapan berlangsung pada lingkungan  air payau, pada zona pasang surut air laut

Makalah ini menyajikan hasil penelitian terhadap salah satu endapan batubara yang belum banyak dikenal dalam literatur geologi Indonesia, yakni batubara Formasi Steenkool (akhir Miosen – Plistosen) yang ada di daerah Ransiki, Kepala Burung, Papua. Hasil penelitian lapangan menunjukkan bahwa batubara Formasi Steenkool dapat dibedakan menjadi tiga jenis, yakni bright coal, banded bright coal, dan dull coal. Batubara tersebut umumnya berwarna hitam dengan gores coklat, dan keras. Belerang kadang-kadang ditemukan mengisi bidang pecah planar hingga conchoidal yang berkembang didalamnya. Lapisan-lapisan batubara Formasi Steenkool di daerah Ransiki memiliki ketebalan yang sangat bervariasi, mulai dari beberapa centimeter hingga hampir 3 m. Sebagian diantaranya mengandung parting serpih karbonan dengan ketebalan umumnya kurang dari 20 cm. Lapisan-lapisan batubara umumnya diapit oleh lapisan serpih karbonan, meskipun ada sebagian diantaranya yang dialasi atau ditutupi oleh lapisan batupasir halus. Hasil penelitian laboratorium terhadap 13 sampel terpilih mengindikasikan bahwa batubara Formasi Steenkool umumnya memiliki kelembapan rata-rata < 3% adb, kadar abu rata-rata < 5%, kadar volatil rata-rata > 40%, kandungan karbon tertambat rata-rata > 45%, dan kadar belerang rata-rata < 1% dengan nilai kalor > 5000 kal/g. Penelitian ini mengungkapkan hasil yang berbeda dengan laporan yang selama ini diterima mengenai batubara Formasi Steenkool. Pertama, hasil penelitian ini menujukkan bahwa hampir semua batubara Formasi Steenkool di daerah penelitian merupakan high-volatile subbituminous coal, bukan lignit sebagaimana dilaporkan selama ini. Kedua, batubara Formasi Steenkool memiliki kualitas yang cukup baik. Hal itu terlihat dari bukti fisik sebagaimana terlihat di lapangan dan dari hasil penelitian laboratorium yang menunjukkan bahwa semua sampel memiliki nilai kalor lebih dari 5000 kal/g. Hasil penelitian ini mengindikasikan bahwa batubara Formasi Steenkool layak diteliti lebih lanjut dan seksama untuk mengetahui potensi endapan batubara di wilayah Kepala Burung, Papua, dan untuk mengkaji nilai ekonomis yang mungkin dimilikinya.Kata kunci: Formasi Steenkool, Batubara, Papua

Jakarta, a very populated capital city of Indonesia, was built above alluvial deposit which is currently subsiding relative to sea level at a high rate. As a result Jakarta becomes more often to be flooded with water that delivered from other regions and also the sea level rises relative to land and shoreline move toward the ground are increasing feasibility of tidal flood to occur. Consolidation process of the ground acts as a cause to the land subsidence in Jakarta. The fact is water needs in Jakarta is high due to its high population. Therefore, large amount in withdrawal of groundwater occurs and causes the ground to settle. In order to decrease the rate of land subsidence, groundwater should be extracted in a proper, more effective and efficient way. Younger generation is advised to save water using a fresh approach which is easy to be understood and accepted. In the future, people in Jakarta will consider that saving water as a norm which brings great benefit to their environment, Jakarta.

Foraminifera analysis taken from 18 surface sample from sandstone unit and siltstone unit, Kali Bentur section, Ngawenan area, Blora.According quantitative analysis, foraminifera assemblages consist of 39 species (218.128 individu) planktonic and 53 species (16.384 individu) bentic , with abundance of Globigerinoides trilobus imaturus, Globigerinoides trilobus trilobus, Globoquadrina altispira, Globoquadrina dehiscens, Orbulina universa, Globorotalia menardii and Bolivina, Batisiphon, Cibicides, Robulus, Planulina, Uvigerina dan StilostomelaForaminifera planktonic distribution indicated tropical zone, warm water(24oC - 28oC ) salinity 34-36 ppm, and based on bentic foraminifera, there were paleoenvironment change that more deep from sandstone unit to silt unit.

Karangcegak Village, Kutasari District, Purbalingga Regency has high andesite rock potential. Andesite rock has been mined traditionally by the local community, but its utilization is still not optimal. This study aims to determine the distribution of andesite rocks based on the resistivity data of the Wenner-Schlumberger configuration. Resistivity data acquisition was done on four trajectories with a length of 195 m. The GL-01 trajectory is located at a geographical position of 07°19'23.3” S; 109°17'19.6” E, the GL-02 trajectory is located at position of 07°19'23.9” S; 109°17'21.1” E, the GL-03 trajectory is located at position of 07°19'24.3” S; 109°17'21.8” E, and the GL-04 trajectory is located at position of 07°19'25.1” S; 109°17'22.8” E. Calculation of field data (i.e. voltage and current) were carried out to obtain apparent resistivity data. The calculated data are stored in the notepad format, and are used as input data for resistivity data modeling. The resistivity data modeling were carried out in 2D and 3D using RES2DINV 3.54 and VOXLER 4.0. The structure of the subsurface rock layers obtained on the four trajectories consists of three types of rock, i.e. the lava breccia with a resistivity value of less than 1,510 m, weathered andesite rock with resistivity values ranging from 1.511 – 4,000 m, and andesite rock with resistivity values are more than 4,000 m. Andesite rocks are found in all trajectories with a depth of 0 – 36 m. Based on the results of the analysis of the 2D resistivity cross section in each trajectory and the 3D pseudo-resistivity, the potential of andesite rock in the study area is estimated to be very large. The study results also show that the direction of the distribution of andesite rocks is in accordance with the direction of the lava flow of Slamet Volcano, i.e. from southwest to southeast.