UBC Theses and Dissertations
The relationship between lamprophyre dykes and ore deposits with special reference to British Columbia Young, John W.
Some conceptions by Bowen regarding the processes apparently involved in the formation of ultra-basic lamprophyres have been applied to observations made on reaction-rims in the rocks of this thesis. An attempt has been made to find, in the reaction-rims surrounding basic minerals, phenomena that might indicate that reactions took place, during the time the rock was forming, between the basic minerals and an alkaline liquid. No conclusive evidence of such reactions was found but the suggestion is made that there is an unusually great development of reaction rims, especially in the more basic lamprophyres, that may be due to the effect of an alkaline liquid. Another theory by Bowen, dealing with the possible origin of ore-bearing solutions, has been amplified to present possible reasons for a close relation between lamprophyres and ore. On the more practical side, a petrographic study of lamprophyres and associated ore has revealed an intra-mineralization age for lamprophyres whose field relations do not conclusively indicate contemporaneity with ore. A compilation from the literature, of facts pertaining to most of the lamprophyre occurrences in British Columbia, has provided interesting statistics on the geographical and geological distribution of lamprophyres, and on their relations to different types of ore. The majority of lamprophyres occur in the Rossland-Ymir-Nelson-Slocan belt, near the eastern contact of the Nelson series of batholiths, while most of the remainder are confined to the eastern contact of the Coast Range batholith. The lamprophyres of the Nelson batholith region are associated with ores which, in the Rossland, Salmo, Ymir and Nelson areas are almost half of the Pb, Zn, Ag type and in the Ainsworth-Slocan districts, entirely of the Pb, Zn, Ag type. It is in the Ainsworth-Slocan districts furthermore, that lamprophyres are perhaps most densely concentrated and show the closest time relation to ore. The lamprophyres along the east-side of the Coast Range batholith provide most of the evidence indicating that post-ore lamprophyres are predominantly associated with ores containing Au and Cu. The conclusion seems inescapable that lamprophyres are concentrated in the two most intensely mineralized zones of the province. Furthermore, a marked affinity is shown by lamprophyres for those areas in which Pb, Zn, Ag mineralization either is prominent or, at least, is present along with other metals. These statistical facts suggest that the relation between ore and lamprophyres is not purely one of chance and they arouse our curiosity as to what reasons may exist for such a relationship.
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