The Geology of the Nelson and adjoining part of Salmo map areas, British Columbia.
Institution: | McGill University |
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Department: | Department of Geological Sciences. |
Degree: | PhD |
Year: | 1951 |
Keywords: | Geological Sciences. |
Record ID: | 1539978 |
Full text PDF: | http://digitool.library.mcgill.ca/thesisfile124149.pdf |
The "Rossland volcanic group" is subdivided into two volcanic formations, separated by a dominantly sedimentary formation of Jurassic age. These rocks were folded along north-south axes and subsequently faulted and bent into an arc around a protuberance of the Cretaceous(?) Nelson granodiorite batholith during or just prior to its intrusion. A quartz-diorite stock and tongues, partly sheared, antedate the batholithic stage. Metadiorite, a feldspar-hornblende gneiss with coarse pyroxene-hornblende border facies, was formed by assimilation or metasomatic reconstitution of chiefly volcanic rocks prior to the batholithic stage. Syenite intrudes it in places, in others a gradational contact shows evidence of metasomatic action. The syenite may be Tertiary. Porphyry, aplite, lamprophyre and diabase dykes cut the granodiorite and some veins. These and monzonite chonoliths may be Tertiary. Gold-quartz, and gold and silver bearing copperlead- zinc sulphide deposits occur in bedded rocks, metadiorite, and quartz diorite tongues.