The Ackley high-silica magmatic/metallogenic system and associated post-tectonic granites, southeast Newfoundland.

摘要

The Ackley Granite Suite occupies 2,415 km;Much of the Ackley Granite Suite exhibits geochemical signatures of A-type granites, and a muscovite-bearing phase occurs in the north. Geochemical enrichment/depletion trends culminate at significant, endocontact, spatially separate, aplite-pegmatite Mo deposits at Recontre Lake, and quartz-topaz-Sn greisen deposits at Sage Pond. Hydrothermal muscovites from the deposits provide almost identical ;The southern Ackley Granite Suite is the frozen equivalent of high-silica, chemically zoned, magma chambers responsible for the formation of large ash flows. Convective fractionation may have operated to produce the observed chemical zonations. An emplacement model based on available geophysical data indicates stoping of large (20 km x 10 km) blocks from the upper to middle crust in response to regional crustal extension and lower crustal melting.;The H