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The AAPG/Datapages Combined Publications Database

CSPG Bulletin


Journal of the Alberta Society of Petroleum Geologists
Special Guide Book Issue
Vol. 10 (1962), No. 7. (July/August), Pages 428-437

Refraction Profiles Over the Southern Rocky Mountain Trench Area of British Columbia

A. T. Lamb, D. W. Smith


Two broadside refraction profiles were shot across the Rocky Mountain Trench near Elko, British Columbia. Due to the very poor signal to noise ratio in this locality only first arrival data were obtained. The Previous HitvelocityNext Hit of the broadside first arrivals was identified and controlled by three inline refraction profiles and seven cross spreads oriented parallel to the Trench. Excluding a small amount of near surface weathering material, the inline profiles identified three main Previous HitvelocityNext Hit layers. In the central portion of the Trench 7,500, 11,000 and 17,000 feet per second layers were observed. Near the east and west edges of the Trench the 17,000 feet per second layer was overlain by an 11,000 feet per second layer but the 7,500 feet per second layer was absent. Based on surrounding Previous HitvelocityTop measurements, the 17,000 feet per second layer is believed to be Precambrian Purcell strata. A depth plot of this layer shows a relatively smooth drop off from the Purcell outcrops on either side of the Trench at an elevation of about 3,000 feet above sea level to about 2,000 feet below sea level in the center of the Trench. These data are in general agreement with the gravity depth estimates by Garland, Kanasewich and Thompson.

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