ANALYSIS OF LIMESTONE DISTRIBUTION IN TANIMBAR ISLANDS BASED ON GRAVITY DATA
Tanimbar Islands, Maluku Province utm is located at coordinates 784747.68 s.d. 693471.55 and 9077659.9 to 9227259.96. Tanimbar Islands are located in the north of Seram Island which is proven to be a petroleum production field (Masela PSC block). This study aims to interpret the geological structure and modeling and analyze the distribution of limestone in the research area. The geophysical exploration method used in this study is the gravity method, namely knowing the distribution of gravitational field values below the ground surface to find the distribution of density values, anomalous separation with the Lowpass Filter method, derivative analysis with First Horizontal Derivative (FHD) and First Vertical Derivative (FVD), as well as conducting 2D modeling of subsurface structures in the research area. The results of the study obtained that the Tanimbar Islands area has a distribution of low to high anomalous values with a value of -49.4 mGal – 3.6 mGal. Interpretation of residual analysis and derivative analysis shows that the study area is indicated by faults and folds. The results of 2D modeling using the Montaj GM-SYS Oasis obtained density distribution values with a value range of 1.9 g / cm 3 to 3.08 g / cm3 High density value areas with the predominance of Batimafudi rock formations which are rock formations consisting of calcarenite and calcilutite interspersions inserted by calcidurite and or napal and Tangustabun formations consisting of sandstone interspersions and also interspersions between clay and limestone. An area of medium density value, with a predominance of rock formations of the Molu, Batimafudi and Batilembuti Complexes consisting of limestone-inserted napals. And areas with low density values are dominated by Saumlaki rock formations in the form of coral limestone and coarse-grained calcarenite limestones to very coarse containing coral fragments, gastropods and palecipodes.
Keywords : Tanimbar Islands, PSC-Masela, Gravity Method, 2D Modeling.
