Spatial distribution of clay minerals using GIS-Based Mapping : continental shelf of East Johor

Abstract

This study was conducted to determine the spatial and temporal distribution of clay minerals of East Johar coastal sediments. 30 samples during the pre-monsoon and post-monsoon seasons were collected using the Smith McIntyre Grab in the study area. Identification of clay minerals and the composition of clay mineral were determined using X-Ray Diffractometer (XRD). Data on clay minerals were mapped using Geographical Information System (GIS). In general, the dominant clay minerals found in the study area are mostly illite and kaolinite during both seasons while quartz is the most dominant nonclay-mineral in all stations. Distribution of illite during both monsoonal seasons showed abundance further offshore, indicating that this mineral is transported by wave energy seaward. The dominance of quartz is due to its relative stability and due to the weathering product of granite, the dominant rock of east coast of Peninsular Malaysia. Feldspar, goethite, smectite and gibbsite were also present in the sediments while montmorillonite-chlorite is only present in trace amounts at stations 10 and 20 during post-monsoon. Climatological variation may influence the depositional conditions at the study area due to the prevailing monsoons. Therefore, monsoonal effect is one of the factors influencing the circulation of bottom sediments in the South China Sea, off east coast of Johor. GIS based mapping and analysis of clay minerals in this study is essential in the determination of distribution patterns of clay minerals and can be followed by modeling trends of their distribution in the future.