Abstracts
Abstract
Controversy surrounds the question of origin of bedding-concordant auriferous quartz veins occurring In Meguma Croup rocks of Nova Scotia. Several origins have been proposed, most important among which are I) that the veins formed pretectonically due to precipitation from submarine hydrothermal hot springs, and 2) that the veins are syntectonic and due to precipitation into hydraulic fractures from aqueous solutions. The fundamental differences between these two proposed origins have obvious consequences for studies of quartz and gold genesis and their location In this area.
Microstructures of bedding-concordant veins from a number of localities in the Meguma Terrane show conclusive evidence of a syntectonic, multiple-hydraulic fracturing origin for the veins studied, and lend no support to the hot springs hypothesis.
RESUME
On retrouve, dans les roches du groupe Meguma de la Nouvelle-Ecosse, des veines de quartz auriferes, paralleles 3 la stratification, dont 1'origine demeure un sujet controversy. Plusieurs modes de formation ont St6 proposes dont les principaux sont: I) un emplacement prScfidant I'fivfinement tectonique, par precipitation 3 partir de sources chaudes hydro t her ma les sous-marines; et 2) un emplacement syntec-tonique le long de fractures hydrauliques, par precipitation a partir de solutions aqueuses. Les differences fondamentales marquant ces deux modes d'origlne ont des consequences import antes quant a l'Stude de la genese du quartz et de I'or afnsi qu'd leur presence dans cette region.
Plusieurs sites dans le terrain Meguma font voir des veines concordantes & la stratification caractfiri-sees par des microstructures qui indiquent de facon concluante I'orlgine syntectonique, par fractures hydrauliques multiples, de ces veines. L'hypothfise des sources chaudes est done Scartfee.
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