Hubungan Kumpulan Mineral Berat Pada Sedimen Pantai Dan Lepas Pantai Dengan Batuan Asal Darat Di Perairan Teluk Pelabuhan Ratu, Jawa Barat

DOI: 10.17014/ijog.v5i1.93Based on the depth contour, the sea bottom morphology in southern part of the researched area is very steep, while in the northern area it is sloped slightly. It shows that sedimentation process is from south to the north and continues to the west. It is supported by the current process in studied area. Rock slope stability of hilly morphology in the Cimandiri River area is related to weathering, erosion, and transportation process in coastal and nearshore areas. The presence of mineral in the studied area caused by those processes, was accumulated in the mouth of Cimandiri River, coastal, and nearshore areas. Those minerals were deposited in Cibelendung to Karangbeureum nearshore area by the longshore current. Magnetite and pyroxene minerals are dominant along the coastal and offshore areas of Pelabuhan Ratu Bay. The presence of augite and diopside shows that the source rock is basic igneous rocks (basalt), while the presence of hornblende and biotite minerals tend to indicate that the source rock is intermediate igneous rocks (andesite)

Mineral Content of Surficial Sediment of the Rangsang Island and Its Surrounding Area, Meranti Regency, Archipelago Riau Province

According to the regulation No 4 of 2009 of Mineral and Coal Mining Management stated that the requirement of an inventory for mineral resources data was created to support the establishment of mining area. This study is intended to obtain mineral resources content and surficial sediment data, Geographically the study area belongs to Meranti Archipelago Regency, Riau Province. it is located between 102o00'00" - 103o 15'00" E and 00o35'00" - 01o28'00" N. Grain size analyses result show that surficial sediment in the study area consists of silt, silty sand and sand which is dominated by silt. Based on the mineral identification, some of the minerals such as quartz, cassiterite, magnetite, hematite, dolonite, biotite and zircon have been found. Silt distribution is very wide started from estuarine southeast part northen part of Rangsang Island toward southeast of rangsang island. Sandy silt only found at the southeast of Rangsang Island, while sand sediment is found at the south and southeast of Rangsang Island. The presence of silt and sand grains is influenced by moderate to strong currents and wave patterns, so that the silt and sand grains sediment was transported along coastal to offsore area, while the fine grained (clay - silt) are deposited in the valley at the western part of Rangsang Island.Keywords: mineral, surficial sediment, Rangsang Island Berdasarkan Undang Undang Nomor 4 tahun 2009 tentang Pengelolaan Pertambangan Mineral dan Batubara, disebutkan bahwa inventarisasi data sumber daya mineral diperlukan dalam rangka mendukung penetapan Wilayah Pertambangan (WP). Penelitian ini dimaksudkan untuk memperoleh data kandungan sumber daya mineral dan sedimen dasar laut. Daerah penelitian, secara geografis termasuk dalam Kabupaten Kepulauan Meranti, Provinsi Riau, dan terletak pada koordinat antara 102o00'00" - 103o15'00" BT dan 00o35'00" - 01o28'00" LU. Hasil analisis besar butir menunjukkan sedimen permukaan dasar laut di daerah penelitian terdiri atas lanau, lanau pasiran dan pasir yang didominasi oleh lanau. Berdasarkan identifikasi mineral pada sedimen permukaan dasar lautnya menunjukkan kehadiran mineral kasiterit, magnetit, hematit, dolomit, biotit, zirkon dan kuarsa. Penyebaran lanau sangat luas dimulai dari daerah estuari barat laut dan bagian utara Pulau Rangsang, hingga ke sebelah tenggara Pulau Rangsang. Lanau pasiran hanya terdapat di tenggara Pulau rangsang, sedangkan pasir hanya terdapat di daerah di bagian selatan - tenggara Pulau Rangsang. Adanya butiran lanau - pasir dipengaruhi oleh pola arus dan gelombang yang sedang sampai kuat, sehingga butiran berukuran lanau - pasir dapat terangkut ke arah lepas pantai, sedangkan butiran halus (lempung) mengendap di daerah lembah di bagian barat Pulau Rangsang

Pembentukan Prisma Akresi Di Teluk Ciletuh Kaitannya Dengan Sesar Cimandiri, Jawa Barat

Kumpulan sesar naik yang ditafsirkan dari penampang seismic refleksi di teluk Ciletuh mengindikasikan adanya prisma akresi di daerah penelitian. Prisma akresi di daerah penelitian terletak di perairan teluk Ciletuh yang ditandai olef kumpulan sesar naik akibat adanya zona tumbukan antara kerak benua dan kerak samudera. Kerak samudera yang terangkat dan tersingkap di daratan teluk Ciletuh berupa batuan basalt (lava bantal), batuan ultra basa dan batuan bancuh. Prima akresi ini diduga berumur lebih tua dari prisma akresi yang masih terjadi saat ini, diperkirakan umurnya Tersier. Posisi prisma akresi di daerah penelitian ini berada di utara zona subduksi yang masih aktif di selatan di pulau Jawa. Beberapa struktur sesar naik juga terdapat di utara teluk Pelabuhan Ratu. Kumpulan sesar naik di sekitar teluk Pelabuhan Ratu dapat dianggap sebagai prisma akresi tua, dan mempunyai kaitan dengan kumpulan sesar naik di teluk Ciletuh. Posisi sesar-sesar naik yang terpisah antara sesar naik di lokasi teluk Pelabuhan Ratu dan di teluk Ciletuh diperkirakan terpisah oleh suatu sesar. Sesar yang memisahkan kedua kumpulan sesar naik ini diduga adalah sesar Cimandiri dengan jenis sesar mendatar menganan Kata kunci prisma akresi, teluk Ciletuh, batuan ultra basa, sesar sisnistral Cimandiri. A series of thrust faults which is interpreted from seismic reflection profile at Ciletuh bay indicate the occurrence of accretionary prism in the study area. The accretionary Prism in the study area indicated by series of thrust faults as a product of the collision zone between continental crust and oceanic crust. Uplifted oceanic crust was exposed on Ciletuh mainland such as basaltic rocks, pillow lavas, ultra basic rocks and melange. The accretionary prism is thought to be older than the accretionary prism that is still occurs on south Java island, and it was estimated Tertiary in age. The position of accretionary prisms in this study area is in the northern active subduction zone in the south of Java island. Some thrust faults are also found in the northern of Pelabuhan Ratu Gulf. A series of these faults can be regarded as an old accretionary prism, and have a relationship with a series of thrust fault at Ciletuh bay. The position of these thrust faults separate between the thrust of Pelabuhan Ratu bay and the thrust of Ciletuh bay and estimated have been disturbed by a fault. Fault which separates these two sets thrust fault is interpreted due to Cimandiri dextral fault

Kandungan Mineral pada Sedimen Pantai dan Laut, Hubungannya dengan Batuan Sumber di Pesisir Kabupaten Rembang, Jawa Tengah

Sedimen di sepanjang pantai Kabupaten Rembang terdiri atas sedimen muda (aluvial) dan sedimen tua (breksi dan batugamping). Sedimen muda merupakan sedimen lepas dan terdapat di daerah sedimentasi. Sedimen tua berupa sedimen kompak yang secara fisik mempunyai resisitensi tinggi terhadap abrasi Batuan yang terdapat di kawasan pesisir adalah: pasir kuarsa, andesit, tras kaolin, batugamping, batubara dan lempung. Peta sebaran sedimen dasar laut perairan Kabupaten Rembang, menunjukkan dominasi endapan pasir, lanau (pasir halus) dan lanau pasiran (pasir halus - kasar). Kandungan mineral yang terdapat di perairan Kabupaten Rembang terdiri dari: magnetit, pirit, hematit, zirkon, ilmenit diopsid, augit, hornblende, kuarsa, biotit, muskovit dan dolomit Kata Kunci: sedimen, mineral, Rembang The coastal sediment along the coastal of Rembang District consists of young sediment (alluvium) and old sediment (breccias and limestones). Young sediment is placer sediment that occupies the sedimentation area. Old sediment is massive sediment that has a high resistance to abrasion Rocks content in the coastal zone area consist of quarzt sand, andesite, caoline, limestone, trass, coal and clay. Seafloor surficial sediments map of the Rembang water area shows the domination of sand deposits, silt (fine sand) and sandy silt (fine to medium sand). Mineral content in Rembang waters area consists of magnetites, pyrites, hematites, zircons, ilmenite diopsides, augitse, hornblendas, quartzs, biotitse, muskovites and dolomites. Keywords: sediment, mineral, Remban