The Protolith of the Carbonate Rich Rocks of the Larder Lake Break

Abstract

<p>The rocks of the Larder Lake Break at the Misema River road cut are predominantly schists, green carbonates, porphyries, lamprophyres, quartz and an iron formation. The schists and green carbonates have been metamorphosed, altered, and intruded by feldspar rich porphyries, lamprophyres, and quartz veins and stringers. The schists and green carbonates are komatiitic in composition and are characterized by concentrations of iridium, nickel, and chromium which are similar to known values for relatively unaltered Precambrian ultramafic flows.</p> <p>The presence of spinifex texture in schists and green carbonates suggests that these rocks were rapidly cooled crystal free ultramafic lavas.</p> <p>Gold is preferentially concentrated in sulphur rich felsic porphyritic intrusions.</p>