Delineating Gravity Anomaly Sources Using Derivative Analysis for Gold Exploration in the Kluet Formation

Frederic Steven (1), Syafrizal (2), Arie Naftali Hawu Hede (2), Petryan Paulus Pangihutan (2), Raden Ferianggoro Supriadi (3)

Delineating Gravity Anomaly Sources Using Derivative Analysis for Gold Exploration in the Kluet Formation
Frederic Steven (1), Syafrizal (2), Arie Naftali Hawu Hede (2), Petryan Paulus Pangihutan (2), Raden Ferianggoro Supriadi (3)

(1) Master Program of Mining Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Indonesia 40132
(2) Earth Resources Exploration Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Indonesia 40132
(3) Undergraduate Program of Geophysics, Faculty of Exact Sciences and Natural Sciences, Universitas Indonesia, Indonesia 16424

Abstract

This study investigates the efficacy of integrating gravity derivative analysis with existing geological data for targeting gold exploration within the Kluet Formation, Aceh - North Sumatra. The Kluet Formation, known for its complex geological history and potential for hosting gold mineralization, is characterized by a series of faults, fractures, intrusive bodies, and various lithologies. Complete Bouguer Anomaly (CBA) data are analyzed using First Vertical Derivative (FVD), Second Vertical Derivative (SVD), and Total Horizontal Derivative (THD) filters to enhance subsurface structural features commonly associated with gold deposition. FVD and SVD maps effectively highlight the locations of gravity anomaly sources, while THD maps delineate their boundaries. These derivative maps are then integrated with existing geological maps, including fault traces, fracture systems, and the distribution of intrusive bodies and lithologies, to delineate areas where these features spatially correlate with gravity anomalies. This integrated analysis was applied to the Kuta Usang artisanal gold mining area within the Dairi Regency. Several prominent gravity anomalies were identified and their spatial correlation with known faults, fracture zones, and altered rock units was established. To validate the results, samples were collected from locations proximal to these identified gravity anomalies. Analysis of these samples revealed altered rocks associated with fractures, containing gold concentrations up to 4.29 ppm and silver concentrations up to 27 ppm, as determined by Atomic Absorption Spectrometry. This study demonstrates that integrating gravity derivative analysis with detailed geological mapping significantly improves the efficiency of targeting and prioritizing gold exploration efforts within structurally complex terrains like the Kluet Formation.

Keywords: Complete Bouguer Anomaly, Gold Mineralization, Kluet Formation, Kuta Usang

Topic: Mineralogy, petrology, and volcanology