-
The coastal and offshore areas around the Sunda Strait will be developed to be a submarine cable corridor connecting between Java and Sumatra Islands. There are some requirements that should be considered before laying the underwater cables. One of these considerations is to understand the seafloor morphology of the Sunda Strait. The study was conducted based on six of track lines with 1 km line spacing and 4 Cross lines. The water depth obtained then was corrected to the depth of water from the Lowest Water Level (LWL). The seabed condition in the near shore area of Sumatra side is very flat and is influenced by 2 km offshore tide activity. The coast line is characterized by mangrove and fine fraction of sediments (mud and clay). At the Java side, the coastal morphology is characterized by the very steep slope and most of the area is occupied by the industrial activities.
Keywords: seafloor morphology, under water cables, Sunda Strait
Area pantai dan perairan Selat Sunda akan dikembangkan sebagai bagian dalam penempatan kabel bawah laut yang menghubungkan Pulau Jawa dan Pulau Sumatera. Rencana penempatan kabel bawah laut ini membutuhkan beberapa persyaratan teknis yang harus dipertimbangkan. Salah satu pertimbangan untuk peletakan kabel bawah laut adalah memahami morfologi dasar laut selat Sunda. Penelitian dilakukan berdasarkan 6 lintasan pemeruman dengan jarak antar lintasan 1 km, dan 4 lintasan memotong lintasan utama. Kedalaman laut yang diperoleh kemudian dikoreksi dengan muka laut terendah. Kondisi permukaan dasar laut di sisi pantai Sumatra sangat datar serta sejauh 2 km ke arah laut lepas masih dipengaruhi oleh aktifitas pasang surut. Garis pantainya dicirikan oleh tanaman bakau dan fraksi sedimen halus (lumpur dan lempung). Pada sisi Jawa, morfologi pantai dicirikan oleh kemiringan lereng yang curam dan kebanyakan area ditempati oleh aktivitas industri.
Kata kunci: morfologi dasar laut, kabel bawah laut, Selat Sunda
-
Study 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.
-
The main objective of this study is to identify and to determine the variation and content of heavy mineral placer of Kendawangan coastal, offshore and its surrounding area. Sediment samples were taken from 18 locations, such as 12 samples from offshore and 6 samples from coastal area. For this analysis the heavy metals were identified and analyzed using isodynamic separator and binocular microscopic. The result indicates that heavy minerals consist of zircon, cassiterite, rutile, ilmenite, topaz, chalcopyrite, epidote, pyrite, hematite, hornblende and magnetite. Cassiterite and zircon are also found in sediment samples in all locations and potentially to be further developed. Keywords: Heavy minerals placer, Zircon, Cassiterite, Kendawangan, West Kalimantan Tujuan penelitian ini adalah untuk mengidentifikasi dan menentukan variasi kandungan mineral berat plaser pada sedimen pantai dan lepas pantai Kendawangan dan sekitarnya. Sampel sedimen diambil dari 18 lokasi yang terdiri atas 12 sampel sedimen lepas pantai dan 6 sampel sedimen pantai. Analisis dilakukan dengan menggunakan isodinamik separator dan mikroskop binokular. Hasil analisis menunjukkan bahwa mineral berat terdiri atas zircon, kasiterit, rutil, ilmenit, topas, kalkopirit, epidot, pirit, hematit, hornblende, dan magnetit. Kasiterit dan zircon juga dijumpai pada sampel sedimen di semua lokasi yang dianalisis dan berpotensi untuk dikembangkan lebih lanjut. Kata kunci: Mineral berat plaser, Zirkon, Kasiterit, Kendawangan, Kalimantan Barat
-
The GSSI Ground Penetrating radar have been used to profile the shallow depth of subsurface geology of several area of Land Coastal zone in Indonesia Analysis of a large data base of GPR profile from natural subsurface geological condition along the land coast line have allowed identification of reflection configuration that characterize this type of sub surface geological environment. In many contamination problem, the geological information of coastal area is sparse and drill-core description only gives a limited picture of the geometry of inhomogeneties. The Ground-Probing Radar (GPR) method is a promising tool for resolving changes of physical properties in subsurface geological condition at the scale of natural inhomogeneties arising from changing lithology composition. The objective of present work are to examine whether and to what extent the characteristic lithofacies of subsurface lithology can be recognised as mapable reflection pattern on ground probing radar (GPR) reflection profiles in order to gain information about the subsurface geometry of subsurface geology in coastal area.
Key word: Subsurface geology, coastal zone, Ground Probing Radar
Ground probing radar produksi GSSI telah dipergunakan untuk membuat penampang geologi bawah permukaan dangkal di beberapa kawasan pantai Indonesia. Analisa data dasar penampang GPR dari geologi bawah permukaan di kawasan pantai dapat memperlihatkan konfigurasi reflector yang mencerminkan jenis lingkungan geologi bawah permukaan. Dalam masalah kontaminasi, informasi geologi di daerah pantai yang dihasilkan dari pemboran inti hanya dapat memperlihatkan gambaran yang sederhana tentang geometri ketidakseragaman. Metoda ground probing radar merupakan alat bantu yang menjanjikan untuk menanggulangi masalah sifat fisik kondisi geologi bawah permukaan pada skala ketidak seragaman yang sebenarnya dari perubahan komposisi litologi. Tujuan utama dari penelitian ini adalah untuk menguji sampai sejauh mana karakteristik litofasies dari litologi bawah permukaan dapat dilihat sebagai pola refleksi yang dapat dipetakan dalam penampang GPR dengan maksud untuk mendapatkan informasi geometri geologi bawah permukaan di daerah pantai.
Kata kunci: Geologi bawah permukaan, zona pantai, “Ground probing radarâ€
-
Analyses result of the heavy minerals that was took from beach sediments and sea floor surficial sediments was founded ten heavy minerals namely hematite, magnetite, limonite and rutile from oxide and hydroxide group, pyroxene, amphibol and zircon from silicate group, biotit from mica group, barite from sulfide group and dolomite from carbonate group. From 10 minerals identified, only magnetit distributes in the whole area, with the highest percentage of 34,15% in the sea and 35,14 % on beaches. Other heavy minerals distribute locally with the percentage of less than 0,01 %. Grain size analyses result of sea floor surficial sediment had identified six units sediment such as sand, sand with few gravel, sandy gravel, gravely sand, gravel and reef. Distribution area of the six units sediment as follows sand and sandy gravel are occupied 25 % respectively of the study area, reef 20%, sand 15 %, gravel 10 % and gravely sand occupied 5%. The best sediment for making art goods is sand sizes which is rich of heavy minerals such as magnetite, hematitre, limonite, zircon, pyroxene and amphibol. If will be exploited of the sand sediment on beach or sea floor surficial sediment, should be considering of the environment sustainable.
Keyword: grain size analyses, heavy mineral, seafloor surficial sediment, besach sediment, Karang Asem
Hasil analisis mineral berat dari sedimen pantai dan permukaan dasar laut dijumpai sepuluh jenis mineral berat yaitu magnetit, hematit, limonit, rutil dari kelompok oksida & hidroksida, piroksen, ampibol, sirkon dari kelompok silikat, biotit dari kelompok mika, barit dari kelompok sulfida dan dolomit dari kelompok karbonat. Dari sepuluh jenis mineral berat yang teridentifikasi hanya magnetit yang sebarannya merata di seluruh daerah penyelidikan baik di laut maupun di pantai dengan persentase tertinggi 34,15 % di laut dan 35,14% di pantai, sedangkan sembilan mineral lainnya sebarannya tidak merata atau setempat-setempat dengan persentase umumnya di bawah 0,01 %. Hasil analisis besar butir sedimen permukaan dasar laut dapat di bedakan menjadi 6 satuan yaitu pasir, pasir sedikit krikilan, pasir krikilan, krikil pasiran, krikil dan terumbu karang. Luas sebaran ke enam jenis sedimen tersebut terhadap luas daerah penelitian adalah pasir sedikit krikilan menempati 25%, pasir krikilan 25%, terumbu karang 20%, pasir 15%, krikil 10% dan menempati pasir krikilan 5%. Jenis sedimen yang baik untuk pembuatan benda seni adalah sedimen berukuran pasir dengan kandungan mineral berat yang tinggi seperti magnetit, hematit, limonit, sirkon, piroksen, dan ampibol. Bila akan dilakukan eksploitasi terhadap sedimen jenis pasir baik di laut maupun di pantai, harus memperhatikan kelestarian lingkungan.
Kata kunci: analisis besar butir, mineral berat, sedimen permukaan dasar laut, sedimen pantai, Karang Asem
-
Sub bottom Profiling survey using strata box, a specially designed low penetration sub bottom Profiling (< 80 m) for coastal waters exploration, found out evidence of submarine volcanic activities in northern coastal waters of Weh Island, NanggroeAceh Darussalam Province. Gas bubbling could be observed at water columns of the digital sub bottom Profiling records as acoustic turbidity. There are at least 33 spots of volcanic gas bursts observed from the sub bottom Profiling. Examination of gas bursts at coastal area which show fumaroles and solfatara indicate reduce volcanic activity either at submarine or terrestrial. Identification of seafloor gas burst by diving team found out that center of such burst is occurred at a north - south opened lineation assumed as normal fault. It seems that the seafloor normal fault is the continuation of terrestrial fault of the same direction as observed from terrain earth google of Weh Island.Keywords: seafloor faulting, submarine volcanic activities, shallow sub bottom Profiling data, Weh Island Aceh Survei penampang bawah dasar laut (SBP) menggunakan strata box, suatu alat SBP penetrasi rendah yang didisain untuk eksplorasi perairan pantai, mendapatkan bukti-bukti aktivitas gunungapi bawah laut di perairan sebelah utara Pulau Weh, Provinsi Nanggroe Aceh Darussalam. Gelembung-gelembung gas dapat diamati pada kolom air rekaman digital penampang bawah dasar laut sebagai turbiditas akustik. Sedikitnya dijumpai 33 titik semburan gas volkanik yang teramati dari penampang bawah dasar laut tersebut. Pemeriksaan semburan-semburan gas pada wilayah pantai sebagai fumarola dan solfataramenunjukkan telah berkurangnya aktivitas volkanik apakah pada dasar laut maupun darat. Identifikasi semburan gas dasar laut oleh tim selam mendapatkan bahwa pusat semburan berada pada kelurusan berarah utara - selatan yang diduga sebagai sesar normal. Tampaknya adalah bahwa sesar normal dasar laut tersebut merupakan kelanjutan sesar darat yang berorientasi sama seperti teramati dari citra earthgoogle terrain Pulau Weh. Kata kunci: pensesaran dasar laut, aktivitas gunungapi bawah laut, data penampang bawah dasar laut, Pulau Weh Aceh
-
Semarang Flood Canals distinguished its merit to cope the flood, thus, the observation of sediment quality as one of environmental assessment is required. Those sediments hosted pollutants like heavy metals being a hazard to human. So, the aims of this study were to measure the concentration and to assess the sediment quality based on heavy metal in the flood canals. Responding to the objective, the sediment collection was carried out in April 2016. The collection core sediment samples were carried out up to 80 cm in depth and the sub-sample was collected within 5 cm interval. The laboratory analysis revealed the average concentrations of Cd, Cu, Fe, Ni, Pb, and Zn in the east flood canals were 0,1-0,43; 25,9-36,7; 40.933-76.942; 24,5-35,2; 5,8±13,4; 74,2±113,8 mg/kg dry, respectively. Meanwhile, the concentrations of Cd, Cu, Fe, Ni, Pb, and Zn in the west flood canals were 0,1-0,5; 25,6-59,5; 34.083-76.119; 24,3-33,2; 7,7±22,0; 75,5±173,4 mg/kg dry. East Flood Canal which hosted more intense anthropogenic activities was exhibiting higher metals concentration than West Flood Canal. Enrichment Factor (EF) was computed to assess sediment quality based on heavy metals and the result indicated no enrichment and minor enrichment of metals in the sediment except for Cd and Zn in east flood canal.
-
Morphologically, Singkawang and adjacent area consist of zones beaches, undulating hills, and steep hills. Granitic rocks and alluvium as a based rock of Singkawang coasts. Generally, Singkawang coasts was developed for coastal farms, fishery pond, and beach resorts, where most of these area have been eroded. Geological and physical oceanography condition are the aspects that build the characteristics of Singkawang coast. Human activities also play an important role in managing the equilibrium and dynamics of this coastal region. This research is to determine the dynamics and coastline changes of Singkawang coasts based on the characteristics of the coastal element and sediment. The high erosion was occurred at Semalagi–Cape Bajau. The Cape Bajau - Cape Banjar is relatively stable due to headlands of this coast is characterized by igneous rocks which resistant to the erosion. The Cape Banjar – South Coasts is very intensive erosion coast. Modern shorelines of the Singkawang coast might be as a shallow marine environment which were occurred thousands years ago (pre-Recent). The high of sedimentation process is generated by global sea level change, where was occurred at that time, and might be changed the area become part of the mainland coast of Singkawang.
Keywords: coastal dynamics, erosion, sedimentation, Singkawang, West Kalimantan
Secara morfologi, Singkawang terdiri atas daerah patai, perbukitan bergelombang, dan perbukitan curam. Batuan granit dan alluvium mengalasi kawasan pesisir Singkawang. Pesisir Singkawang sebagian besar berupa daerah pertanian, tambak ikan, dan tempat wisata yang umumnya merupakan kawasan pantai erosi. Geologi dan oseanografi fisika merupakan aspek yang membentuk karakteristik pantai Singkawang. Aktifitas manusia juga memainkan peranan penting di dalam mengelola kesetimbangan dan dinamika pesisir daerah ini. Penelitian ini untuk mengetahui dinamika dan perubahan garispantai Singkawang berdasarkan karakteristik dan sedimen pantai. Pantai Semalagi – Tanjung Bajau merupakan kawasan pantai erosi kuat. Tanjung Bajau – Tanjung Banjar merupakan kawasan pantai nisbi stabil ujung-ujung TanjungTanjungnya dicirikan oleh batuan beku yang tahan terhadap erosi. Tanjung Banjar – Pantai Selatan merupakan kawasan pantai erosi sangat kuat. Garispantai Singkawang pada saat ribuan tahun sebelum sekarang (pra-Recent) diperkirakan berupa kawasan lingkungan laut dangkal. Karena proses sedimentasi cukup kuat yang ditimbulkan oleh perubahan muka laut global pada saat itu mengubah kawasan tersebut menjadi daratan pantai Singkawang.
Kata kunci: Dinamika pantai, erosi, sedimentasi, Singkawang, Kalimantan Barat.
-
Sulawesi Island is situated on the three major plates, namely the Indo-Australian plate together with Continent Australia (Australian Craton) plate moves towards the North - Northeast and crust Pacific - Philippines moves towards the West - Northwest, causing the collision with the Eurasian plate (Sunda Land) which more passive or stable. The Bone basin is located between South Sulawesi and Southeast Sulawesi arms. This basin is formed by several fault system, such as, Walanae, Palukoro, West and East Bone faults and others. Several active faults are likely to be extended each other into the openings structure and characterized by the accumulation of young sediment in the Bone basin. Keywords: Sulawesi, collision Bone basin, faults, sedimentation Pulau Sulawesi merupakan tempat pertemuan antara tiga lempeng besar, yaitu lempeng Indo-Australia bersama-sama dengan lempeng Benua Australia (Australian Craton) bergerak ke arah Utara - Timurlaut dan Kerak Pasifik - Filipina bergerak ke arah Barat - Baratlaut sehingga terjadi tumbukan dengan lempeng Eurasia (Daratan Sunda) lebih bersifat pasif atau diam. Secara geologi Cekungan Bone terletak diantara Lengan Sulawesi Selatan dan Lengan Sulawesi Tenggara. Cekungan ini terbentuk oleh beberapa sistem sesar yaitu sesar Walanae, Palukoro, Timur dan Barat Bone dan lainnya. Beberapa sesar aktif tersebut kemungkinannya saling tarik menarik menjadi struktur bukaan dan ditandai dengan adanya akumulasi sedimentasi muda di cekungan Bone. Kata kunci: Sulawesi, tumbukan, Cekungan Bone, Sesar, Sedimentasi
-
Multiple often and always appear in marine seismic data due to very high acoustic impedance contrasts. These events have undergone more than one reflection. This causes the signal to arrive back at the receiver at an erroneous time, which, in turn, causes false results and can result in data misinterpretation. Several types of multiple suppression have been studied in literature. Methods that attenuate multiples can be classified into three broad categories: deconvolution methods; filtering methods and wavefield prediction subtraction methods. The study area is situated on Seram Sea in between 131°15’E – 132°45’E and 3°0’S – 4°0’S, Seram Trough which is located beneath Seram Sea at northern part of the Banda-Arc – Australian collision zone and currently the site of contraction between Bird’s Head and Seram. This research uses predictive deconvolution and FK-filter to attenuate short period multiple from their move out, then continued by SRME method to predict multiple that cannot be attenuated from previous method, then followed by Radon transform to attenuate multiple that still left and cannot be attenuated by SRME method. The result of each method then compared to each other to see how well multiple attenuated. Predictive deconvolution and F-K filter could not give satisfactory result especially complex area where multiple in dipping event is not periodic, SRME method successfully attenuate multiple especially in near offset multiple without need subsurface information, while SRME method fails to attenuate long offset multiple, combination of SRME method and Radon transform can give satisfactory result with careful selection of the Radon transform parameters because it can obscure some primary reflectors. Based on geological interpretation, Seram Trough is built by dominant structural style of deposited fold and thrust belt. The deposited fold and thrust belt has a complexly fault geometry from western zone until eastern of seismic line.
