Gold occurrences in the Kolmozero-Voronya Archean greenstone belt, Kola region: Geological, mineralogical, geochronological and isotope-geochemical characteristics

2015

Литосфера, Vol 0, Iss 6, Pp 83-100 (2015)

A multidisciplinary study of the Oleninskoe and Nyalm-1 gold occurrences located in the Kolmozero-Voronya greenstone belt (Kola region) has been carried out. These gold occurrences are interpreted as orogenic and connected with a complex of gabbrodiorite-diorite-granodiorite-quartz porphyry minor intrusions. U-Pb age of zircon from a quartz porphyry dyke in the Oleninskoe occurrence is 2828 ± 8 Ma. An identical age of 2825 ± 7 Ma has been yielded by zircon from a granodiorite porphyry hosting the Nyalm-1 gold mineralization. The gold mineralization was formed in the Neoarchean time after the crystallization of minor intrusions ≈2.83 Ga ago and before the formation of tourmaline-bearing granites and rare-metal pegmatite veins (both dated at ≈2.5 Ga), during hydrothermal alteration of rocks at the retrograde stage of regional metamorphism. Rb-Sr isochron age 2779 ± 72 Ma, obtained for the whole rock samples and apatite from the Nyalm-1 granodiorite porphyry, probably is close to the age of this event. Values of εNd( t ) calculated for granodiorite-porphyries from the Oleninskoe and Nyalm-1 gold occurrences vary from +0.01 to +2.63, suggesting that their parental magma originated from a mantle source and that an addition of crust material was not significant.

article

English
Russian

A.N. Zavaritsky Institute of Geology and Geochemistry, 2015.

рудопроявления золота, геохронология, изотопная геохимия, зеленокаменный пояс колмозеро-воронья, фенноскандинавский щит, неоархей, gold, isotope-geochronological study, greenstone belt kolmozero-voronya, fennoscandian shield, neoarchean, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712