Reconnaissance Exploration For Gold In The Misaki Area Within The Iramba-Sekenke Greenstone Belt, Central Tanzania

ABSTRACT

Combinations of geological, geophysical and geochemical techniques have been

used to explore gold deposits at Misaki within the Iramba-Sekenke Greenstone Belt

(ISGB) in Singida region. The Misaki area is occupied by different rocks including

homogeneous coarse-grained granite containing numerous xenoliths (> 5 vol. %),

tonalite, K-rich granite and pegmatite, and dolerite dykes. All granitic rocks have

been intruded by dolerite dykes, cut by epidote veins and are found juxtaposed to a

tonalitic rock. Granitic rocks contain mainly anhedral to subhedral K-feldspar,

plagioclase, quartz, biotite, hornblende, muscovite and opaque minerals, whereas

tonalite contains similar minerals with relatively large amounts of plagioclase, biotite

and hornblende (> 10 wt. %) and no K-feldspar. The rocks are weakly foliated to

massive and poikilitic. K-feldspar is perthitic, whereas plagioclases have cores with

rim overgrowths. Chlorite, plagioclase, epidote and sericite in the rock formed at the

expense of primary minerals under greenschist facies conditions. Aeromagnetic data

managed to identify lineaments that crosscut different rocks, from which NE-SW,

NW-SE and ESE-WNW trends have been recognized. Results from radiometric data

mapped different lithological units by their different K, U and Th contents

distinguishing areas occupied by sediments or sedimentary rocks and those underlain

by granitoid rocks. Soil geochemical survey has identified gold anomalies of up to

0.2 ppm Au that in parts associated with NE-SW trending lineaments. A follow-up

detailed geological mapping work is recommended that would involve trenching and

sampling of unweathered rocks, and documentation of geological structures to

uncover potential gold deposits of the Misaki area within the Iramba-Senkenke

Greenstone Belt (ISGB).