Abstract

Metallic ores of economic values often occur within profiles above basement rocks in tropical regions due to weathering and secondary enrichment. This study is carried out to determine the geochemistry and appraise the potential for metallic ore enrichment in the weathered profiles over Syenite and Younger Granite in Pankshin area. Top-soil, laterite and rock samples are collected from two lateritic profiles above Syenite and Younger Granite. The syenite rock is composed of alkali feldspars (perthite), nepheline, clinopyroxene, with minor amount of orthopyroxene, hornblende, plagioclase and few quartz grains, indicating oversaturation. The Younger Granite contains plagioclase feldspars, microcline, quartz, biotite, hornblende and reibeckite. Quartz (61.0%), kaolinite (32.0%) and microcline (7.0%) are the dominant minerals in the X-ray diffraction (XRD) of the decomposed rocks. The Chemical Index of Alteration (CIA) of both rocks is generally >90. There are enhancements of V, Sc, Zr and TiO₂ in the Syenite profile and Fe₂O₃, Zr, V and TiO₂ in the Younger Granite profile as reflected in the Accumulation Factor (AF), loss and gain of elements (K), though the values were too low for ore mineralization except for iron and titanium in the Younger Granite profile.

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