Geology & Mineralization
Regional Geologic Setting
The Cobar mining district occurs along the eastern margin of the Early Devonian age Cobar Basin, which lies within the northern part of the Central Belt of the Lachlan Orogen, and is marked by the regional scale Rookery Fault system.
District Geologic Setting & Mineralization
The Peak Gold Mines operation occupies a 10-kilometre section of the Rookery Fault system, referred to as the “Peak Mine Corridor.” To date, five separate gold-copper deposits have been developed into underground mines. Listed from south to north they include: Perseverance, Peak, New Occidental, Chesney and New Cobar. A sixth deposit, Great Cobar, which was mined from circa World War I until the mid-1940s, lies at the northern end of the Peak corridor and represents an area of renewed exploration focus.
Individual deposits occur as steeply dipping lodes with uniformly short strike lengths (less than 300 metres), narrow widths (10 to 30 metres), and long vertical dimensions. For example, the Peak and Perseverance deposits have been defined to vertical depths of 500 to 700 metres. The Chesney and New Cobar deposits are currently defined over shorter vertical ranges and, like all of the deposits along the Peak Mine Corridor, remain open at depth. Mineralization is characterized by polymetallic sulphides, which vary from gold-copper-lead-zinc assemblages at Peak and Perseverance, to simpler copper-gold at New Cobar, Chesney, and Great Cobar. In general, gold mineralization occurs as discrete lenses within broader envelopes of base metal mineralization.
Cobar Gold Field – Metal Zonation & Distribution – Long-Section
Including commercial mining production from Great Cobar and the resurgence of mining in 1991, the Peak Mines Corridor has produced in excess of 3.7 million ounces of gold and 200 million pounds of copper.
Since the start of commercial production in 1991, underground exploration around the known ore bodies along the Peak corridor has consistently added new reserves to replace its annual production. For example, beginning with a mineral reserve of 936 thousand ounces of gold in the Peak deposit in 1991, sustained exploration and development to replace mined reserves has resulted in the delineation of mineral reserves and resources totaling nearly three times that amount as of the end of 2014. With a twenty-four-year track record of successful reserves replacement and control of more than 75 kilometres of prospective geology along the greater Rookery fault trend, exploration at Peak continues to offer significant upside toward future exploration success.