Nurcahyo Indro Basuki
Institut Teknologi Bandung

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STUDI GEOKIMIA TANAH DAN HUBUNGANNYA DENGAN MINERALISASI LOGAM DAERAH KETUNGAU HULU, KABUPATEN SINTANG, PROVINSI KALIMANTAN BARAT: STUDY OF SOIL GEOCHEMISTRY AND IT’S RELATIONSHIP WITH THE PRESENCE OF METAL MINERALIZATION IN KETUNGAU HULU AREA, SINTANG REGENCY, WEST KALIMANTAN PROVINCE Nicolaus Bagus Krismantoro; Nurcahyo Indro Basuki; Hartaja Hatta Wicaksono; John Mauritz
Buletin Sumber Daya Geologi Vol. 17 No. 2 (2022): Buletin Sumber Daya Geologi
Publisher : Pusat Sumber Daya Mineral Batubara dan Panas Bumi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47599/bsdg.v17i2.352

Abstract

Ketungau Hulu is a gold prospect plan area in Sintang-Silantek Block on the island of Kalimantan which is a collaboration program between Indonesia (Geological Agency) and Malaysia (Jabatan Mineral and Geoscience). Administratively, the research area is located in Sintang Regency, West Kalimantan with an area of 18 km2. This study aims to identify the geological conditions, structure, alteration, and mineralization of the study area as well as potential anomalies for metal elements (Au, Cu, Pb, Zn, and Mn) based on soil geochemistry data and its relationship with the presence of mineralization. The study was conducted using soil samples from 84 points in the ridge and spur areas. In addition to soil samples, 48 rock samples and one sample from pan concentrate were also obtained. Furthermore, all samples were analyzed for chemical, geochemistry, statistic, petrology, petrographic, and mineragraphy. The research area consists of Greywacke Sandstone Unit, Arenite Sandstone Unit, and Diorite Intrusion Unit. Geological structure that developed in the area has relatively NNW-SSE and NW-SE trends. The alteration zones present in the research area are argillic zone and propylitic zone. Mineralization is found in dogtooth, crustiform, colloform, and assicular textured quartz veins with relative orientation directions NW-SE and NNE-SSW that presence of ore minerals such as native Au, chalcopyrite, pyrite, sphalerite, covellite, and from base metal contents abundance in the rock samples. The results of soil sample analysis showed that the Au had an anomaly value of log 1.90 ppb, Pb of sqrt 7.44 ppm, Zn of log 1.92 ppm, Cu of log 1.69 ppm, and Mn of log 2.46 ppm. Base metal elements anomaly is controlled by lithology, structure, and topography. Analysis using Pearson's product on base metal elements states that there are two groups of elements i.e., Au and Pb-Zn-Cu-Mn. Based on the anomaly distribution of base metal elements in soil and the presence of mineralization, it can be interpreted that there are four prospect area i.e., KU-1, KU-2, BE-1, and BE-2 prospects.
DISTRIBUSI UNSUR UTAMA DAN UNSUR TANAH JARANG PADA PELAPUKAN BATUAN GRANITOID DI DAERAH PARMONANGAN, KABUPATEN TAPANULI UTARA: DISTRIBUTION OF MAJOR ELEMENTS AND RARE EARTH ELEMENTS IN THE WEATHERED GRANITOID ROCKS IN THE PARMONANGAN AREA, NORTH TAPANULI REGENCY Ana Nurul Hidayati; Nurcahyo Indro Basuki; Sulaeman; Bayu Sayekti
Buletin Sumber Daya Geologi Vol. 17 No. 3 (2022): Buletin Sumber Daya Geologi
Publisher : Pusat Sumber Daya Mineral Batubara dan Panas Bumi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47599/bsdg.v17i3.371

Abstract

The results of an investigation by PSDMBP in 2011 showed that the REE content in weathered granitoid at Parmonangan contained several elements with significant anomalies such as Ce (600 to 1400 ppm), La (400 to 1000 ppm), and Pr (600 to 1400 ppm). Therefore, further investigation needs to be carried out to determine the distribution of REE to the west of the previous investigation area. This study aims to determine the characteristics of the granitoid, weathering pattern, and profile of the REE content in the investigation area. The weathering of granitoid in the Parmonangan area comes from biotite granite and hornblende biotite granite. The geochemical characteristics of weathering indicate that Na2O, CaO, K2O, SiO2, P2O5, and MnO dissolve and are mobile during weathering, indicating a decrease in soil content compared to bedrock. Meanwhile, Al2O3, Fe2O3, TiO2, and LOI showed an increase in weathering results due to residual enrichment. The content of the weathered granitoid in the Parmonangan area shows the relative enrichment of LREE to HREE. The content of LREE is influenced by the distribution of La and Ce elements contained in monazite. The content of HREE is controlled by the distribution of element Y. Based on the Spearman correlation, titanite and apatite also affect the abundance of LREE. While the mineral-bearing HREE is zircon. The sample interval is in the REE leaching zone so that the concentration of REE obtained in the soil is lower than in the bedrock.