The discovery of the Pebble giant porphyry Cu-Au-Mo deposit in Southwest Alska, USA, and its enlightenment significance

The Pebble deposit is located 320km southwest of Anchorage, Alaska, USA. It is one of the newly discovered supergiant porphyry copper-gold-molybdenum deposits. A total resource of 10.78 billion tons (Bt) has been defined, making it the fourth largest porphyry copper deposit and the first porphyry gold deposit in the world. The Pebble deposit consists of two ore zones: East and west ore zones which are approximately equal in size. The east and west zones have been regarded as two coeval hydrothermal centers within a single system. Previous studies indicate that the Pebble deposit was formed from the mixing of magmatic fluids with meteoric water. The deposit is, therefore, believed to be a product of Mesozoic multiphase tectonic-magmatic event caused by coeval subduction of the Pacific oceanic plate under the northern American continent. The easternmost section of the Sino-Mongolian border region is located at the intersection of several crustal-scale structures. The Jurassic-Cretaceous intrusive and extrusive rocks are widely distributed and hosted a number of molybdenum, gold and copper-polymetallic prospective areas and anomalous zones. This setting is similar to fertile porphyry environments in southwestern Alaska of USA and suggests that the easternmost section of the Sino-Mongolian border region is highly favorable for porphyry copper-polymetallic deposit exploration.