Bulletin of the Marine Geology, Vol. 36, No. 1, June 2021, pp. 15 to 26 15 DISTRIBUTION OF SUBSURFACE SEDIMENTATION AS A POTENTIAL MINERAL PLACER DEPOSITS IN SOUTH BINTAN ISLAND WATERS SEBARAN SEDIMENTASI BAWAH PERMUKAAN SEBAGAI POTENSI ENDAPAN MINERAL PLACER DI PERAIRAN SELATAN PULAU BINTAN Muhammad Zulfikar 1,2 , Nazar Nurdin 2 , Noor Cahyo Dwi Ariyanto 2 , Ildrem Syafri 3 , Budi Mulyana 3 , Andi Agus Nur 3 1 Study Program of Master, Faculty of Geological Engineering, Padjadjaran University Jl. Raya Jatinangor Km. 21 Bandung, Indonesia 2 Marine Geological Institute of Indonesia Jl. Dr. Djunjunan No.236 Bandung, Indonesia 3 Faculty of Geological Engineering, Padjadjaran University Jl. Raya Jatinangor Km. 21 Bandung, Indonesia Corresponding author: muhammad20389@mail.unpad.ac.id; muhammad.zulfikar@esdm.go.id (Received 7 June 2021; in revised from 18 June 2021; accepted 26 July 2021) ABSTRACT: Bintan Island is one of the areas traversed by the Southeast Asian granitoid belt which is known to have the potential for heavy mineral placer deposits. Due to the dwindling presence of heavy mineral placer deposits in land areas, it is necessary to explore in water areas. Delineation of deposits accommodation of heavy mineral placer in the defined area are requires subsurface imaging investigations. The method used in this subsurface mapping is a single channel seismic method with a total of 179 lines from northeast-southwest and west - east directions. The results of this seismic record are then interpreted as the boundaries of the seismic facies unit and distributed using the kriging method. Furthermore, the thickness calculates by using the assumption velocity of 1600 m/s. Based on the facies unit boundaries that have been interpreted, the quaternary sediments that formed in the study area are divided into 2 types of units, namely: Unit 2 which is estimated to be fluvial - transitional sediment, and Unit 1 which is estimated to be transitional - shallow marine sediment. There is also a difference in thickness patterns in these two units, where Unit 2 shows a pattern of sediment thickening that resembles a paleochannel trending northeast - southwest, while Unit 1 is relatively uniform. From the results of this study, it can be said that the area that has potential of heavy mineral placer deposits is in the west-center of the southern waters of Bintan Island. Where the potential for heavy mineral placer deposits should be in the paleochannel deposits that are part of Unit 2. Keywords: Quaternary Sediments, Heavy Mineral Placer Deposits, Rare Earth Elements, Southern Waters of Bintan ABSTRAK: Pulau Bintan merupakan salah satu wilayah yang dilalui oleh jalur granitoid Asia Tenggara yang dikenal memiliki potensi keterdapatan mineral berat plaser. Akibat keberadaan mineral berat plaser di wilayah daratan semakin menipis, maka dilakukan pencarian potensi tersebut di wilayah perairan. Delineasi wadah mineral berat plaser pada area ini memerlukan penyelidikan citra bawah permukaan. Pemetaan bawah permukaan ini menggunakan metode seismik single channel dengan jumlah lintasan sebanyak 179 lintasan dari timurlaut - baratdaya dan barat - timur. Hasil rekaman seismik ini kemudian diinterpretasi batas-batas unit fasiesnya dan disebar dengan menggunakan metode kriging. Selanjutnya dihitung ketebalannya dengan menggunakan asumsi cepat rambat 1600 m/s. Berdasarkan batas unit fasies yang telah diinterpretasi sedimen kuarter yang terbentuk di daerah penelitian terbagi menjadi 2 jenis unit yaitu: Unit 2 yang diperkirakan merupakan sedimen fluvial - transisi, dan Unit 1 yang diperkirakan sebagai sedimen transisi - laut dangkal. Terlihat pula adanya perbedaan pola ketebalan sedimen pada kedua Unit ini, dimana Unit 2 menunjukkan adanya pola penebalan sedimen menyerupai paleochannel berarah timurlaut - baratdaya sedangkan pada Unit 1 relatif terlihat seragam.