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The Kutai Basin contains prolific reserves of oil and gas. The study of depositional environments is one of the goals of oil and gas exploration. The location of this research is situated in the Tanah Merah area, Samarinda. The objective of this research was to analyse outcrops of the Pulau Balang Formation exposed in the Tanah Merah area to determine the depositional environment. Site specific studies were conducted at 3 localities in this area; TM1, TM2 and TM3. This study combines geological mapping, measured sections, facies analysis, petrography, ichnofacies analysis and microfossil analysis. Geological mapping was carried out to determine the distribution of rock units and geological structures. Measured sections were used for facies analysis and the identification of sedimentary structures and ichnofacies. Petrography was carried out to determine the mineral content of rocks and microfossil analysis for palaeobathymetric environmental analysis. The geological structure of the study area comprises a NE-SW trending anticline and syncline and a left lateral strike-slip fault with E-W direction. The study area is entirely within the Middle Miocene age Pulau Balang Formation and can be divided into three facies associations. The TM1 facies association comprises strata interpreted to be deposited in a supratidal marsh and intertidal flat environment. The TM2 facies association comprises strata interpreted to be deposited in a subtidal, intertidal, and supratidal environment. The TM3 facies association comprises strata interpreted to be deposited in a shoreface environment. The petrography of the study area indicates that rock units predominantly comprise quartz wacke and lithic wacke. Two ichnofacies were identified in the research area 2, namely the Skolithos ichnofacies and the Skolithos-Cruziana ichnofacies and contain ichnogenera namely Ophiomorpha, Skolithos, Planolites, Thalassinoides, Paaleophycus. Microfossil analysis found benthonic foraminifera species including Nodosaria lamellala, N. radicula, Vaginulinopsis tricarinata, Lagena costata, Striatissima vaginulina, Bulimina lappa, Planularia auris, Quinqueloculina seminulum, Bolivina punctata and Lahena laevis. Based on the presence of these microfossils and ichnofacies, it is interpreted that the research area was deposited in a neritic-bathyal environment.

Tujuan dari penelitian ini adalah untuk mengetahui tonase batubara berdasarkan tingkat kepercayaan geologi ke dalam kategori sumberdaya tereka, tertunjuk, dan terukur menggunakan metode Circular 891 USGS. Penelitian ini juga dilakukan melalui pemetaan geologi detail daerah penelitian yaitu di Desa Tanah Merah, Kota Samarinda, kemudian dilakukan korelasi antar singkapan batubara guna mengetahui sebaran batubara tersebut. Setelah mengetahui sebaran batubara dapat dilakukan perhitungan sumberdaya tereka, tertunjuk dan terukur. Data yang diperoleh dari penelitian ini yaitu data singkapan batubara yang ditemukan di daerah penelitian. Data hasil pengamatan lapangan yang telah didapatkan kemudian diolah menggunakan rumus perhitungan volume dan tonase batubara, untuk sumberdaya tereka diperoleh hasil 945.468,74 m3, tertunjuk diperoleh hasil 700.020,23 m3, sedangkan untuk sumberdaya terukur diperoleh hasil 349.335,77 m3, kemudian dikalikan dengan densitas batubara yaitu 1,3 ton/m3. Estimasi sumberdaya tereka dengan radius 750 m diperoleh tonase sebesar 1.229.109,36 ton, sumberdaya tertunjuk dengan radius 500 m diperoleh tonase sebesar 910.026,30 ton. Sedangkan sumberdaya terukur dengan radius 250 m diperoleh tonase sebesar 454.136,50 ton.