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OCCURRENCE OF PHILLIPSITE MINERAL IN SUB- SEAFLOOR OF ROO RISE-INDIAN OCEAN : A TECTONIC EROSION SYNTHESIS
No full textA single deep-sea core (MD982156) of 30.30 meters long which is obtained during the MD III-IMAGES IV Expedition from Roo Rise - Indian Ocean in 1998 was studied. Down to 30 meters of the core length, the sediment consists of abundance planktonic foraminiferas. Below 30 meters, it is mostly composed of phillipsite mineral-rich sediment that is associated with nannoplanktons.The Paleocene authigenic phillipsite minerals associated with nannoplanktons is separated from Late Miocene to Holocene planktonic foraminiferas rich-sediments by hiatus. This hiatus or non deposi- tional in Roo Rise suggest be triggered by long Cenozoic tectonic erosion
MARINE GEOMAGNETIC ANOMALY BELT AND ITS RELATIONSHIP TO THE REMNANT ARCS IN THE NORTHWESTERN JAVA SEA, INDONESIA
Get PDFThe continuous marine geomagneticsurvey within a timeintervalof1-secondsampling and a precision of 0.1 nT was conducted in the northwestern Java Sea to identify and interpret the general trend of total marine magnetic anomalies and the possibility related to thegeological resourcepotential. These magnetic data were then processed according to the formula corrected and applied to marine magnetic data. The total marine magnetic anomalies of the northwestern Java Sea indicate a well-defined lateral trend belt of anomaly contours. Anomalies are divided into four delineation zones: Zones I, II, III, and IV. A preliminary analysis of these anomalies led to the interpretation, reflecting the residual of a slightly east-west trending geological body underneath.Examination of magnetic anomalies suggests Zone I and IV characterize a basinalarea, Zone II depicts a granitic belt, and Zone III describes a Cretaceousmagmatic arc system in the east that extends from Middle Java across the Java SeathroughSouthern Kalimantan. These magnetic anomalies seem to coincide with the free air gravity anomalies data derived from TOPEX satellite data.
KARAKTERISTIK DAN PROSES PENGENDAPAN SEDIMEN DASAR LAUT DI PERAIRAN GOSONG BUNGA, KUALANAMU KAB. SERDANG BEDAGEI, PROV. SUMATERA UTARA
Get PDFDaerah penelitian terletak di perairan Gosong Bunga, lepas pantai Kualanamu dengan kedalaman antara 10 – 20 meter dan di bagian tengah hanya 2 - 3 meter pada saat air laut surut. Hasil analisis besar butir di daerah penelitian diperoleh beberapa jenis satuan tekstur sedimen dasar laut, yaitu: pasir lanauan, pasir, pasir lumpuran sedikit krikilan, lumpur pasiran, lanau pasiran, krikil pasiran, lumpur pasiran sedikit krikilan dan pasir sedikit krikilan. Berdasarkan hubungan antara besar butir dan persentase jumlah/frekuensi butiran; pengendapan sedimen dipengaruhi oleh arus sungai dan arus pantai dengan pola pergerakan butiran adalah saltasi, rolling (gulungan) dan sliding (dorongan) serta suspensi, dan secara umum membentuk pola saltasi.
Sedangkan hasil analisis kimia pada beberapa contoh sedimen terpilih menunjukkan kandungan kuarsa (SiO2) berkisar antara 66,33 - 74,21% dan kandungan rata-rata sebesar 69,88%. Analisis fotomikro memperlihatkan komposisi utama adalah butiran kuarsa hampir 85%, mineral berat (magnetit, ilmenit, hematit dan limonit) 10% dan cangkang foram dalam keadaan utuh 5%. Hasil interpretasi rekaman seismik menujukkan ketebalan sedimen Kuarter di daerah penelitian antara 7 – 15 meter, di bagian tengah mencapai 20 meter.
Kata kunci: sedimen dasar laut, proses pengendapan, pola pergerakan, lepas pantai Kualanamu
The survey area is located on the Gosong Bunga waters, offshore of Kualanamu coast with waters depth between 10 – 20 meters, and part of central area only 2 – 3 meters depth on low sea level. Grain size analysis result from the survey area is several types of seafloor sediment textures silty sand, sand, slightly gravelly muddy sand, sandy mud, sandy silt, sandy gravel, slightly gravelly sandy mud and slightly gravelly sand. Based on relation between size, and cumulative and frequency percent of grains; depositional process of sediment influenced by river and coastal current with movement pattern are saltation, rolling, sliding and suspension, and generally to form a saltation pattern.
While, result of chemical analysis on some the samples indicates that the quartz content (SiO2) content are between 66,73 – 74,21%, and the average content is 69,88%. Microphoto analysis indicates that the main content are quartz approximately 85%, 10% heavy minerals (magnetite, ilmenite, hematite and limonite) and good condition foram shell 5%. Seismic interpretation shows that the thickness of Quaternary sediments are about 7 to 15 meters except in the centre of the study area which is 20 meters.
Keywords: seafloor sediment, depositional process, movement pattern, offshore of Kualanam
INTRUSI VULKANIK DI PERAIRAN SEKOTONG LOMBOK BARAT
Get PDFRekaman seismik pantul dangkal menunjukkan adanya terobosan batuan ke permukaan dasar laut. Terobosan batuan tersebut berupa intrusi vulkanik seperti yang terdapat di darat, yaitu di bagian barat dan timur daerah telitian.
Disekitar intrusi batuan vulkanik ini dapat diamati adanya sesar sesar yang berkembang. Adanya intrusi vulkanik dan sesar sesar di daerah telitian ini, perlu diwaspadai sebagai bahaya geologi yang perlu dipertimbangkan dalam pengembangan dan pembangunan di sekitar pantai.
Shallow seismic reflection record indicate an intrusion body to sea floor surface. This intrusion suggested to be a vulcanic rock that occur in the western and eastern part of study area.
Around in this intrusion vulcanic rock, the development of faults can be observed. The occurrence of this vulcanic intrusion should be paid attention as geological hazard that have to be consider for coastal development
KARAKTERISTIK AKUSTIK DAN FENOMENA GEOLOGI ENDAPAN SEDIMEN KUARTER DELTA MAHAKAM - KALIMANTAN TIMUR
Get PDFTeknik stratigrafi sekuen resolusi tinggi yang dikembangkan dari konsep stratigrafi seismik, digunakan untuk mengidentifikasi sekuen pengendapan dalam runtunan sedimen Kuarter di Delta Mahakam, Kalimantan Timur. Dalam studi ini dilakukan usaha untuk menghubungkan pola umum refleksi endapan delta terhadap sifat-sifat akustik. Lapisan sedimen mengandung gas secara akustik biasanya dicirikan oleh zona yang bersifat keruh, diperkirakan berupa diapir lumpur dan/atau akumulasi gas biogenik menghasilkan kontras akustik relatif terhadap batuan sekitarnya. Data penampang seismik di lepas pantai menunjukan sedikitnya empat interval akustik (sekuen pengendapan) yang dipisahkan oleh bidang ketidakselarasan serta menunjukan fenomena akustik yang menyertainya.
Kata kunci : Delta Mahakam, akustik, erosi, stratigrafi seismik, sedimen, diapir.
High-resolution sequence stratigraphic technique, which is originally derived from the concepts of seismic stratigraphy, is applied to identify depositional sequences within Quaternary strata in Mahakam Delta, East Kalimantan. In this study an effort is made to relate the general pattern of reflection obtained over the submerged delta to the acoustical characteristics. Sediment bearing gas in particular acoustically is indicated by their turbid zones, suspected as mud diapirs and/or accumulation of biogenic gas produce acoustical contrasts with respect to country rock. Offshore seismic profile data indicate at least four acoustic intervals (depositional sequences) separated by unconformities and its associated acoustical phenomena.
Keywords : Mahakam Delta, acoustic, erosion, seismic stratigraphy, sediments, diapir
TINJAUAN GEOLOGI TERHADAP MODEL ELEVASI DIGITAL SISTEM PARIT-PRISMA AKRESI, SELATAN JAWA
Get PDFModel elevasi digital sistem parit-prisma akresi selatan Pulau Jawa menggambarkan keterwakilan topografi dasar laut seperti elevasi, lereng dan lain sebagainya secara tepat dan dengan mudah dapat dikuantifikasikan serta digambarkan sebagai output images. Sistem parit-prisma akresi selatan Pulau Jawa terletak di sebelah tenggara tepian Paparan Sunda dan diperkirakan dialasi oleh kerak samudera terakresi dan berada pada tahap awal evolusi. Analisis topografi rinci data model elevasi digital (DEM) dari daerah ini menunjukan hubungan yang erat antara struktur geologi dan batas satuan batuan.
Kata kunci : parit, prisma akresi, DEM, topografi, lereng.
Digital elevation model of the trench-accretionary prism system off south Java Island displays an accurate representation of seafloor topographic such as elevation, slope, etc and can easily be quantified and is displayed as output images. The trench-accretionary prism system off south Java Island lies on the southeast Sunda Shelf continental margin and it is suggested to be underlain by the basement of accreted oceanic crust, which is still in an early stage of evolution. Detailed topographic analysis of the digital elevation model (DEM) data from the area reveals a strong correlation between geological structures and rock unit boundaries.
Keywords : trench, accretionary prism, DEM, topography, slope
PENAFSIRAN STRUKTUR GEOLOGI SEMENANJUNG MURIA DARI DATA CITRA SATELIT
Get PDFPenafsiran data citra satelit yang ditunjang dengan data geologi sekunder, menunjukan bahwa Semenanjung Muria telah mengalami minimal dua rejim tektonik yaitu peregangan (rifting/extension) dan tektonik tekanan (inverse/compression). Keberadaan gunungapi Muria saat ini menunjukan pernah terjadi interaksi yang komplek antara rejim tekanan dan keberadaan struktur regangan di daerah ini. Proses tektonik tekanan ini mengakibatkan batuan dasar berumur lebih tua mengalami pemampatan yang memungkinkan keluarnya magma melalui bidang sesar yang teraktifkan kembali dan membentuk Komplek Gunungapi Muria.
Kata kunci : struktur patahan,citra satelit, Semenanjung Muria
Satellite imageries data interpretation complemented by secondary geological data, indicate that the Muria Peninsula has been undergone by at least two tectonic regimes, those are rifting/extension and inversion/compression tectonics. At present, the occurrence of Muria volcano indicates there was a complex interaction between compression regime and the occurrence of extensional structures in the area. These tectonic processes implies that the older basement in the study area is accomplished by lithosphere shortening which allows active upwelling of magma through the reactivated fault planes forming a Muria Volcano Complex.
Keyword : fault structures,satellite imageries, Muria Peninsul
TINJAUAN ASPEK-ASPEK PEMBANGUNAN YANG MEMPENGARUHI DAMPAK LINGKUNGAN KAWASAN PESISIR DAN LAUT
Get PDFUrbanisasi yang terjadi di hampir seluruh kota besar di Indonesia menambah beban daerah perkotaan menjadi lebih berat. Peningkatan jumlah penduduk selalu diikuti dengan peningkatan infrastruktur perkotaan seperti perumahan, sarana transportasi, air bersih, prasarana pendidikan, dan lain-lain.
Hal tersebut di atas akan menyebabkan dorongan luar biasa terhadap pengalihfungsian lahan-lahan pertanian di kawasan pesisir, di tempat mana akan terjadi suatu situasi kritis terhadap masalah limbah. Kebutuhan akan lahan untuk permukiman maupun kegiatan perekonomian akan semakin meningkat sehingga terjadi perubahan tataguna lahan yang mengakibatkan peningkatan aliran permukaan dan limbah. Pengendalian pencemaran dan pembuangan limbah, merupakan masalah krusial dalam kawasan ini dan tindakan langsung maupun tidak langsung diperlukan untuk menciptakan pengendalian terhadap kegiatan-kegiatan yang dapat merusak lingkungan.
Kata kunci : urbanisasi, infrastruktur, aliran permukaan, pencemaran dan limbah.
Urbanizations that occured in nearly all of the big cities in Indonesia had burdened city areas lately. The increasing of population always comes up with the improvement of infrastructures like residential area, transportation, clean water, educational facility etc.
These things may cause a stimulus and change the function of coastal farming lands and will reach a critical situation concerning the waste problem. The need of lands for settlement area and economical activity will increase and cause the change on land use and will increase the drainage and wastes. The pollution and waste dumping control are crucial problems in this area and the direct and indirect action is needed to create controls on activities that could damage the environment.
Key word : urbanization, infrastructure, drainage, pollution and waste
MUD DIAPIR DI PERAIRAN SELATAN PULAU MADURA
Get PDFShallow seismic reflection study along the southern water of Madura Island indicates the occurrence of diapir and sediment bearing gas. Normally, the occurrence of diapirism is associated with sediment bearing gas. These phenomena can be observed along the southern waters of Madura, from Sampang until Kalianget. Diapir, fault, and gas charged sediment are indicated as the geological hazard. Offshore infrastructures and drillings have to consider the present phenomena because they can destroy those infrastructures.
Key word: diapir, fault, gas, geological hazard, Sampang
Penelitian seismik pantul dangkal di perairan selatan P. Madura menunjukkan adanya diapir di dalam lapisan sedimen yang mengandung gas. Biasanya keberadaan diapir diikuti oleh adanya lapisan sedimen yang mengandung gas. Gejala ini dapat diamati di sekitar perairan pantai selatan Madura,mulai dari perairan Sampang hingga ke Kalianget. Diapir,sesar, dan gas dalam sedimen diindikasikan sebagai bahaya geologi. Pembangunan atau pemboran di pantai dan lepas pantai harus mewaspadai keberadaan diapir dan gas dalam lapisan sedimen. Di tempat ini struktur tanahnya labil dan dapat menimbulkan kerusakan bangunan di atasnya.
Kata kunci: diapir, sesar,gas, bahaya geologi, Sampan
LATE NEOGENE SEISMIC STRUCTURES OF THE SOUTH BATANTA BASIN, WEST PAPUA
Get PDFStudy on multi-channel seismic records from South Batanta Basin, West Papua acquired during RV Geomarin III cruise in 2013 were aimed to invent and map geological aspects and for geo-tectonic and geological history studies. Seismic data indicate that sediment sequences which can be observed from our seismic system in the study area are characterized by pre-extension sediments (Lower Early Miocene-Upper Early Pliocene), syn-extension sediments (Lower Middle Pliocene-Upper Late Pliocene), post-extension sediments (Early Pleistocene), and syn-inversion sediments (Late Pleistocene-Recent) typical of the West Papua tectonic system. In the study area, sediment sequences are possibly characterized by clastical sedimentary cover such as slumps, debrites and turbidites.
Key words: South Batanta Basin, seismic sequence, tectonic, faults, clastical sediments.
Studi rekaman seismik multi kanal dari Cekungan Batanta Selatan, Papua Barat yang diperoleh selama pelayaran KR Geomarin III pada tahun 2013 bertujuan untuk menginventarisir dan memetakan aspek-aspek geologi serta untuk studi geo-tektonik dan sejarah geologi. Data seismik menunjukkan bahwa urutan sedimen yang dapat diamati dari sistem seismik di daerah studi ditandai oleh sedimen pra-ekstensi (Miosen Awal Bagian Bawah-Pliosen Awal Bagian Atas), sedimen syn-ekstensi (Pliosen Tengah Bagian Bawah-Pliosen Akhir Bagian Atas), sedimen post-ekstensi (Plestosen Awal), dan sedimen syn-inversi (Pleistosen Akhir-Resen) tipikal sistem tektonik Papua Barat. Di daerah studi, urutan sedimen dicirikan oleh sedimen penutup klastika kemungkinan berupa slump, debrit dan turbidit.
Kata kunci: Cekungan Batanta Selatan, sekuen seismik, tektonik, sesar, sedimen klastika
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