Mount Endut is a volcano located in the eastern part of Banten Province. Previous studies revealed that Mount Endut consists mainly of Quaternary volcanic and Tertiary plutonic igneous rocks respectively. This research focuses on the petrology of igneous rocks found in the southern region of Mount Endut in order to determine the type of igneous rocks, evolution of magma, and reconfirming historical geological process occurring in Mount Endut area. Petrographic analysis was performed on 11 samples and geochemical analysis was performed on 30 samples. Petrographic analysis revealed three types of igneous rocks, andesite porphyry, diorite porphyry, and dacite porphyry. Furthermore, geochemical analysis revealed that the igneous rocks in Mount Endut are comprised of basaltic andesite, andesite, dacite, basaltic trachy-andesite, trachy-andesite, and trachyte or trachydacite which originated from calc-alkaline magma series. The integration of petrographic and geochemical analysis supports the regional geological process where Mount Endut was formed either in an island arc or an active continental margin. The first section in your paper.
Micro X-ray fluorescence (µXRF) is an advanced analysis technique from conventional XRF (X-Ray Fluorescence) that allows analysis of smaller areas even inclusions with irregular shapes and non-homogeneous elements. This method has a spatial resolution up to 10 µm depends on the energy by X-rays so that the excitation beam at the smallest point of the sample surface can be detected. This study explains the application of µXRF to determine the type of deposit and the formation of uranium contained in Takandeang Village, Tapalang District, Mamuju Regency, West Sulawesi. The study began with surface geological and radiometry mapping, continued with geological drilling. Collected samples then undergo petrology, petrographic, and geochemical analysis. Three collected samples from drilling sample were analysed using the µXRF. From the analyses we found that the highest uranium anomaly is found in leucitite autobreccias. The anomaly that occurred in the study area was in the form of reconcentration of uranium elements in autobreccia rocks caused by hydrothermal activity which was also supported by magma type and structural control in the study area. In this study case we found that µXRF is usefull for uranium exploration.
Sebuku Island is located in Kotabaru Regency, South Kalimantan and is known as one of the main sources of laterite iron in Indonesia. Based on its tectonic setting, Sebuku Island is located within the suture zone that connects Southwest Borneo Block (SWB) and East Java West Sulawesi Block (EJWB). Due to its tectonic setting, Sebuku Island is composed of various rocks associated with suture zone, such as ophiolite rocks. The ophiolite rocks could host mineralization that occurred in Sebuku Island. The aim of this study is to determine the characteristics of lithology and mineralization as determinants of geological processes that influence the formation of rocks and mineral deposits in Sebuku Island. This study was carried out through petrological, petrographic, ore microscopy analysis, and geochemical analysis (x-ray fluorescence). 22 rock samples from Sebuku Island were collected and the result of this research shows that the chromite host rocks are composed of serpentinized dunite and serpentinite. Chromite minerals (FeCr2O4) were found in massive forms with cataclastic, brecciated texture and disseminated with pull-apart texture. Based on observation of the polished sections, it is known that the associated mineral of chromite is magnetite which is an alteration of chromite minerals. Chromitite chemical data shows the chromite composition is Al-rich (Cr# = 0.6) and classified as podiform chromitite formed by fractional crystallization. There are two magma series of igneous rock in the study area i.e. tholeiitic series consists of ultramafic-mafic rocks and calc-alkaline consists of micro-diorite. The abundance of Al2O3 and TiO2 in chromitite shows that Al-rich chromitite has formed in Supra Subduction Zone (SSZ) and has occurred near or above the Moho-transition zone.
In the coal mining industry, the coal quality is as crucial as the coal quantity because it can impact the coal usefulness. The quality of coal itself can be influenced by several factors, such as moisture content, ash, sulfur, and volatile matter. This study tries to understand the coal quality and its variation in the Muara Enim Formation of South Sumatra Basin. The research was conducted in the West Banko field, PT. Bukit Asam, Tbk., Tanjung Enim, South Sumatra. By using linear regression, this study found that increasing ash and total moisture content will lead to a decreasing amount of the calorific value. Additionally, the value of coal quality content such as ash and total moisture can be affected by the depositional environment, sedimentation rate, and coal characteristics in the study area thus affecting the calorific value. Transitional lower delta plain depositional environment with low sedimentation rate and coarsening upward sandstone sequence indicates lower ash and total moisture content in the study area. The highest calorific value found in the study area is in C1 seam, this can be seen from the ash quality and total moisture distribution map which inversely proportional to the calorific value.
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