Observation on the Tanjung Enim coal outcrops has been conducted to evaluate coal and cleat characteristics, particularly those occurring at Suban and Air Laya Putih (ALP) sites. Tectonically, the region is located in the South Palembang Sub-basin. In this region, there are four to five coal seams dipping to the SW direction. The dips of coal beds in ALP are commonly steeper than those in Suban, implying that the ALP seams had been more deformed tectonically and hence underwent more shortening. The samples analyzed reveal that the coals are medium in rank with the ash content relatively constant along strike, but distinctive vertically. Most seams have high values of inherent moisture, fixed carbon, and volatile matter. Deformation of the seams has resulted in two types of fractures known as face and butt cleats. The present study employed a scanline method to measure cleat attributes such as spacing, aperture, and bedding orientation. A total of 3,241 face and butt cleats were measured from 12 scanlines. The face cleats predominantly have NNE-SSW orientation, suggesting paleostress direction. The general trend of butt cleats is NW-SE, likely coincident with the releasing stresses. Face cleats have spacing and aperture more tightly than butt cleats. This suggests that face cleats developed in response to the maximum stresses, and butt cleats formed due to the minimum in situ stresses. Scanning Electron Microscope (SEM) analysis revealed that microcleats in seam show a number of apertures that were connected to form a network system within the analyzed samples.

Cleat on coal seam is a slope stability controller, as well as permeability and porosity for fluidal flows. It also has become an interesting issue on coal mining, nevertheless the finite quantitative data. As a matter of facts, there is actually some available data about cleat as attributes, but this study only objecting on the orientation, cleat spacing, and cleat aperture. Cleat attributes measurement through field observation at two coalfields;Baturona and PMC in the area of Sungai Lilin, MusiBanyuasin Region. Next, those 667 faces and butt cleats were measured from 8 scanlines being analyzed using geostatistic methods. The purpose of geostatisticanalysis in this study is to see the relation between variables (cleat attributes) to evaluate data quantitatively until the normal distribution is obtained. The data filter was done as a treatment until valid data is reached through the boxplot model. Early boxplot result that almost entirely had outliers data in each seam. In fact, it is commonly seen some extreme outlier data. This suggests that outlier data filter is treated as a treatment until a normal distribution system is achieved on each cleat attribute. Identification of cleat outliers has been affected by mining activity, or due to weathering processes in the coal seams that have been exposed.

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