AbstractsEarth & Environmental Science

The Geology of the Nelson and adjoining part of Salmo map areas, British Columbia.

by Robert. Mulligan




Institution: McGill University
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


Abstract

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.