Geology, geochemistry and geochronology of the Hemlo East property, Schreiber-Hemlo Greenstone Belt, Ontario

Abstract

The Hemlo East property is located approximately 50 kilometres east of the town of Marathon, Ontario and is situated within the Schreiber-Hemlo greenstone belt of the Wawa-Abitibi Terrane of the Archean Superior Province. Lithologies within the Hemlo East Property are broadly divided into mafic metavolcanic, felsic metavolcanic, metasedimentary, intrusive and metaintrusive rocks. Stratigraphic continuity within the study area is demonstrated by the large number of drill holes in the area. Rock staining indicates that the K-feldspar present in felsic metavolcanic rocks in the Gouda-Thor-Carroll area of the Hemlo East Property is a product of alteration likely associated with base metal and gold mineralization. New major and trace element, Sm-Nd isotope, and geochronology data are presented for volcanic, plutonic, and metasedimentary rocks of the Hemlo East property to investigate their origins. Positive to negative εNd (-1.14 to 2.15) for tholeiitic basalts indicate that they were derived from depleted to moderately contaminated sources. FI rhyolites with steep trace element patterns (La/Ybn = 16 to 44) and fractionated HREE (Gd/Ybn = 2.1 to 7.5) are interpreted to have been derived from a deep mantle source. Metasedimentary rocks are geochemically similar to felsic metavolcanic rocks and are interpreted to be derived wholly, or in part, from a felsic source.