By Reuters (Bloomberg) — Gold producers in Australia are outperforming their global competitors, prompting investors to encourage them to expand their horizons and acquire struggling North American rivals. Boosted by some of the sector’s best margins, low debt and swelling cash piles, miners in the world’s No. 2 producer are defying a wider lull in gold equities. Saracen Mineral Holdings Ltd. and Northern Star Resources Ltd. have surged in the past year as rivals in Canada, the U.S. and South Africa faltered.