Integrated Geologic-Magnetic Interpretation For Determining Structural Zone Controlled Base-Precious Metal Zone On Skarn Deposit, Sukabumi West Java
Faiz Akbar Prihutama [1], Eka Haris Setiawan [2], Ilham Ilmawan [3], Dzulfikar Faruqi [3]

[1]Magister Geology of Hasanuddin University
[2]Magister Geology of Gadjah Mada University
[3]PT Generasi Muda Bersatu

Abstract

The Simpenan Pb-Zn-Ag Replacement Skarn deposit is located near the Palabuhan Ratu, the capital region of Sukabumi District, West Java Regency, Indonsia, about 100 km southwest from Bandung. This deposit also located in 4 km of the northside from Ciletuh Melange Complex. The occurances of Pb-Zn-Ag replacement skarn deposit was recorded during several shallow drilling actvitiees had been conducted approximately 20 m below the surface. From geological data, NW-SE and N-S structural trend become favour zones that filled by hydrothermal fluid forming base-precious metal skarn deposit.
The ground magnetic survey has been conducted with 25 m point spacing and 50 m line spacing with N80E orientation that is perpendicular to the regional geological structure trend. This detailed geophysical survey is conducted to find and delineate the Pb-Zn ore bodies. The total magnetic intensity (TMI) map is then processed using reduction to pole (RTP), tilt derivative (TDR), and analytic signal (AS) filter that generates 2D magnetic anomaly maps. The reduction to pole process shows that the area of interest has a magnetic anomaly value of -342.3 &#9472- -47 nT. The northern and northwestern parts of the study area show relatively low magnetic anomalies whereas the eastern and northeastern parts show relatively high anomalies. The tilt derivative process generates the magnetic anomaly lineaments with N-S- NW-SE- E-W- and NE-SW directions. These magnetic lineaments are interpreted as a shallow geological structure. The analytic signal filter applied on the RTP map specifically highlights the peak and gives the boundary of high magnetic anomaly. It can be interpreted the ore body can be found in the high anomaly area on the reduced-to-pole map that also has high magnetic anomaly amplitudes on the analytic signal map based on the geological condition, magnetic properties of the ore body and wallrock, and drilling result. In terms of the geological structure framework, the ore body should be found

Keywords: Skarn Deposit, Ground Magnetic Survey, Geological Structure

Topic: Geodynamic and subsurface geology