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

摘要

The Hemlo East property is located approximately 50 kilometres east of thetown of Marathon, Ontario and is situated within the Schreiber-Hemlo greenstone beltof the Wawa-Abitibi Terrane of the Archean Superior Province. Lithologies within theHemlo East Property are broadly divided into mafic metavolcanic, felsic metavolcanic,metasedimentary, intrusive and metaintrusive rocks. Stratigraphic continuity withinthe study area is demonstrated by the large number of drill holes in the area. Rockstaining indicates that the K-feldspar present in felsic metavolcanic rocks in theGouda-Thor-Carroll area of the Hemlo East Property is a product of alteration likelyassociated with base metal and gold mineralization.New major and trace element, Sm-Nd isotope, and geochronology data arepresented for volcanic, plutonic, and metasedimentary rocks of the Hemlo Eastproperty to investigate their origins. Positive to negative ?Nd (-1.14 to 2.15) for tholeiiticbasalts indicate that they were derived from depleted to moderately contaminatedsources. FI rhyolites with steep trace element patterns (La/Ybn = 16 to 44) andfractionated HREE (Gd/Ybn = 2.1 to 7.5) are interpreted to have been derived from adeep mantle source. Metasedimentary rocks are geochemically similar to felsicmetavolcanic rocks and are interpreted to be derived wholly, or in part, from a felsicsource.