GEOCHEMICAL STUDY OF STREAM SEDIMENTS IN EAST HALMAHERA, NORTH MALUKU PROVINCE

• Main Author: Budiaji Nugroho, Irfan
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/32362
• Institution: Institut Teknologi Bandung

The research area administratively located in East Halmahera District, North Maluku Province. The coordinates of the study area are at 128°0'0"-128°40'0" East Longitude and 0°25'0"-0°55'0" North Latitude or 57100-92400 mN and 401000-462000 mE zone 52N datum WGS 1984, with a research area of 850 km2. According to the physiographic zones division of Halmahera Island, the research area was included in the East Halmahera Mandala zone which consists of steep slopes, karst, and sloping hills. Stratigraphy of the research area based on literature from old to young consists of 5 rock units, namely Ultrabasic Rocks Complex, Conglomerate Unit, Weda Formation, Tingteng Formation, and Alluvium and Coastal Deposit Units. The study aims to determine the potential and prospects of metal elements in the research area by analyzing the relationship between geology and geochemistry of the research area. The geochemical data analyzed in this study were concentration of Cu, Pb, Zn, Co, Ni, Mn, Ag, Fe, Cr, and Au elements from stream sediment samples and mineralogical data from the pan-concentrate samples. Geochemical analysis is carried out in two stages, univariate analysis which aims to determine the anomalies or threshold values of metal elements and multivariate analysis which aims to determine the element association group. Univariate analysis carried out produces element anomalies as follows; Cu is 30 ppm, Pb is 27 ppm, Zn is 127 ppm, Co is 407 ppm, Ni is 3,388 ppm, Mn is 3,249 ppm, Ag is 2.8 ppm, Fe is 183,200 ppm, Cr is 3,851 ppm, and Au 26 ppb. While the results of multivariate analysis show that there are two groups of elemental associations in the research area namely; Mn-Co-Ni-Fe-Au and Zn-Cr-Cu-Ag-Pb. Analysis of mineralogy from the pan-concentrate samples shows the presence of heavy minerals in the form of ilmenite, magnetite, hematite, garnet, pyrite, and rutile. The relation between the results of geochemical analysis and the geological conditions of the research area are being used to determine the prospect zone. The prospect zone in this research area is divided into several groups, namely; the association prospect zone of Mn-Co-Ni-Fe-Au which is located upstream of Ake Sangaji and Ake Fai, the prospect zone of Ag which is located upstream of Ake Nop and Ake Semlowos, the Cr prospect zone located in the upper reaches of Ake Sangaji and Ake Wotema, the Cu-Pb-Zn prospect zone located at the head of Ake Bim.