PETROGRAPHIC COAL STUDY TO DETERMINING PALEOMIRE IN MUARALAWA EAST BORNEO

PETROGRAPHIC COAL STUDY TO DETERMINING PALEOMIRE IN MUARALAWA EAST BORNEO

Petrographic coal

Petrographic Coal Study has many benefits, such as to solve geological problem including geological structure, coal seam correlation, thermal history,  determine depositional environment, and coal classification. Coal is in homogenous compound which is has basic component same as mineral in other organic rocks. Component that build coal is called maceral. Generally maceral is classified into three groups, there are vitrinite, liptinite, and inertinite. Study area is located in Muaralawa, part of Kutai Basin. Ariswara (2009) tell that research area including to homocline hills with slope 6⁰ – 25 ⁰ . Maximum elevation is 100 m. dendritic drainage pattern indicate that lithology in that area has homogenous resistance. Endogenic process produce joints in some part, so lithology that has low resistance is easier to be eroded.

            There are two coal seam based on Ariswara geological map (2009). Research study is focused on coal seam 8500. Organic matter or maceral that found in seam coal 8.500 is vitrinite and sclerotinite. Maceral I smore resistant from erosional process. In upper part, coal also consist of quartz, pyrit in small number. Based on facies, seam coal 8500 show progradation due to sea level drop. It can be seen by coarsening upward that indicate increasing depositional energy. Mire or wetlands is a place that enable to accumulated peat. Peat can be form in swamp, bog, fen moor, muskeg, and peatlands. Mire has special characterization depend on several factors like climate, structural position, and plants development. Interpretation based on macerals is a one of method to know paleoecosystem from peat formation. Classifications can cover groundwater influence, nutrient, ionic supply, PH, and vegetation type.

Source: Nevi Selvina & Donatus Hendra Amijaya ( Geological Engineering UGM)