Geology, petrography and geochemistry of Appalachian granites in New Brunswick and Gaspesie, Quebec / Геология, петрография и геохимия аппалачских гранитов в Нью-Брансуике и Гаспеси, Квебек

All major Appalachian tectonostratographic zones in Gaspesie, Quebec and New Brunswick (i.e. Humber, Dunnage, Gander, and Avalon) are intruded by Paleozoic granites. Granite petrological and geochemical data assist in evaluating the economic potential of the plutons and provide insight into the crustal and tectonic evolution of the orogen.
Based on Na2O and Al index values (generally >3.2 wt.% and <1.1 respectively) and high-field strength element contents, most of the granites are 1-types; some have "А-type affinities". Granite chemical and isotopic characteristics distinguish three contrasting groups of granites: Humber-Dunnage, Gander, and Avalon. Positive eNd values for Humber, Dunnage, and Avalon granites indicate melting of predominately juvenile sources. Negative e Nd and elevated 201РЫШРЬ and 518 values for Gander granites are consistent with reworking of older (1.1-1.8 Ga) crust containing a significant supracrustal component. Neodymium isotopic data effectively rules out Grenville basement as a source for Humber-Dunnage granites. Gander zone is apparently the autochthonous surface expression of a distinct lower crustal block. Contrasting e Nd signatures from Avalon and Gander granites indicates that Gander and Avalon zones are underlain by different crustal blocks, i.e. Precambrian Avalon basement is not a suitable protolith for Gander granites.<...>