SEDIMENTOLOGY OF THE UPPER MERAWU FORMATION, CIKADU AREA, NORTH SERAYU RANGE, CENTRAL JAVA: IMPLICATION FOR TECTONIC ACTIVITY AND HYDROCARBON EXPLORATION

Abstract

The Upper Merawu Formation in the Cikadu area of the North Serayu Range, Central Java, presents a complex geological and sedimentological framework shaped by tectonic and sedimentary processes. This study aims to analyze the stratigraphy, lithofacies, and depositional environments of the Upper Merawu Formation through detailed geological mapping, lithofacies analysis, and micropaleontological examination. The Upper Merawu Formation is composed primarily of alternating sequences of shale, fine-grained sandstone, and tuffaceous sandstones, with distinct sedimentary structures including parallel laminations, cross-stratifications, and hummocky cross-stratification. These lithofacies indicate deposition in a marine setting ranging from distal shelf to shoreface environments. Thrust faults and folds dominate the region's structural geology, consistent with regional tectonic activity. This research provides new insights into the sedimentation and tectonic history of the North Serayu Range, suggesting significant tectonic influence during the Miocene to Pliocene period. These findings contribute to the broader understanding of the depositional systems within the Serayu Basin, with implications for hydrocarbon exploration in the region.