STUDY OF MAGNETIC AND GEOCHEMISTRY OF IRON SAND IN TAMBORA MOUNTAIN AREA, SUMBAWA ISLAND, WEST NUSA TENGGARA

• Main Author: Ulyandana Jayatri, Adella
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/48624
• Institution: Institut Teknologi Bandung

Tambora volcano is known for its devastating eruption in the world in 1815 with where more than 50 km3 of materials were ejected. These ejected materials, in turn, contain valuable and economic minerals deposited in its vicinity in various forms that include iron sand deposits. This study was conducted to determine the characteristics of iron sand deposits around Mount Tambora through analyses of grain size distribution, magnetic susceptibility and geochemistry (in the form of XRD, XRF and ICP-OES analyses). Sampling was carried out in three locations namely Nanga Miro, Baringin Jaya and Hodo. The Nanga miro and Baringin jaya areas are pyroclastic sedimentation zones of fallout from the eruption of 1815 and previous eruptions while the Hodo area is older rock deposits. The results showed that the size distribution of iron sand grains in Nanga Miro and Baringin Jaya MS and FS areas, while in the Hodo area it was dominant CS and FS. The Nanga Miro and Baringin Jaya regions have high magnetic susceptibility while Hodo has a low magnetic susceptibility value. The values of at Baringin Jaya are ((1148,87±59,75) - (25187,97±68,62)) x 10-8m3kg-1, while that of Nanga Miro are ((1970,80 ± 78,34) – (4766,00±923,27) x 10-8m3kg-1 and that of Hodo are ((1054,33±28,29) ? (1419,57±8,33)) x 10-8m3kg-1. The variation in the value of is also influenced by the magnetic mineral content. The results of the XRF and XRD geochemical tests show that the Baringin Jaya and Nanga Miro samples areas have high iron (Fe) concentrations and they contain magnetite and hematite. In addition, REE concentrations (such as Ce, Gd, Pr and Sc) are higher in the iron sand of pyroclastic fall zone. Combination of these methods have successfully different characteristics of iron sand deposits in the vicinity of Mount Tambora