The Canadian dollar, shouldered aside by a surging American dollar, plunged through the 78-U.S.-cent barrier yesterday to close at another record low.

The Canadian currency finished the day at 77.90 U.S. cents--the third straight record-low close--after trading at 77.87 U.S. cents at one point.

Gold closed slightly higher after a concerted effort failed to push it down. In Zurich, it rose $2 to $317.50 an ounce; in London it ended at $317.25 against $315.50 Tuesday. In New York gold increased $1 to $317, and the New York Commodity Exchange settled it up 50 cents at $316.50. Silver closed at $5.48 an ounce, up from $5.44; it settled on the Comex at $5.485, up from $5.427.

The dollar set highs on some markets yesterday, closing in Paris at a record 6.7435 francs, up from 6.70 Tuesday. It was quoted at 6.7425 in New York. Paris bankers said speculation against the devalued franc appeared to be tapering off. Before last Saturday's devaluation, one dollar bought 6.31 francs. The British pound fell sharply, closing in London at $1.7505, down from $1.7615. It was trading at $1.7560 in New York.