MAGNETIC AND GEOCHEMICAL CHARACTERIZATIONS OF IRONSAND DEPOSITS FROM CIREBON COASTAL AREA, WEST JAVA

Abstract

Cirebon is a densely populated port city which has ironsand deposits at its coastal area. Due to its vicinity to the port and the estuary, these deposits might contain anthropogenic pollutants including, heavy metals. Magnetic measurements, X-Ray diffraction (XRD) as well as X-Ray fluorescence (XRF) analyses were carried out on iron sand samples from three sites along the Cirebon coastal area to identify the anthropogenic pollutants. The samples were separated based on the grain size before the measurement and analyses. Preliminary results show that the ironsand is less magnetic and has smaller frequency-dependent magnetic susceptibility values than ironsand found on Bayuran Beach in Central Java. Combined XRD result and the regional geological map shows that most of the minerals were originated from eroded volcanic rocks. The XRF results show that the samples have a relatively high content of Si. XRF analyses also show relatively high concentrations of Cr and Zn, the Geoaccumulation Index shows that the sediment is moderately to heavily polluted by Cr and Zn indicating the possibility of anthropogenic origin. The Cr and Zn content exceeds the stipulated value in the Sediment Quality Guidelines (SQGS).