Alluvial gold was discovered along the banks of the Bendigo Creek in 1851 and resulted in a major gold rush. The discovery is usually attributed to Mrs Kennedy and Mrs Farrell, the wives of two of workers on the Mt Alexander North pastoral property. In Christmas 1851 there were 800 people on the field and by the following June, 20,000 diggers had arrived in the alluvial field. Alluvial gold production was dominant in the first ten years of the field to 1860 and is estimated to account for up to four million ounces or almost one fifth of the total gold won from the Bendigo Goldfield.Sourcing the alluvial gold back to the quartz reefs was easily recognised and outcropping quartz reefs were soon brought into production. The appointment of government geologists from 1852 and the formation of the Geological Survey of Victoria in 1856 assisted in the rapid understanding of the controls of gold mineralisation.The close association of all types of reefs with the anticline axis was recognised early in the development of the field. The reefs were found to be persistent along the anticlinal axes forming ribbons which repeated with depth. This early breakthrough in the predictability of ore gave mine management and investors confidence in the practice of deep shaft sinking on productive anticlines as the main exploration tool. Deep, often speculative, shaft sinking remained the pre-eminent exploration tool throughout the early productive life of the field (1851 to 1954).
Throughout the mining history of the Bendigo Goldfield in excess of 5,000 shafts were sunk (90 km of shaft sinking in total). At least 140 shafts exceeded 300 m in depth, 67 exceeded 600 m, and 11 were over 1,000 m deep. Shafts below 1000 m occur on three separate anticlines and the two deepest shafts are the New Chum Railway at 1,312 m deep and the Victoria Quartz at 1,406 m. Both shafts intersected significant gold mineralisation below 1 km depth. Despite this amount of shaft sinking the vast majority of the field is tested to depths of less than 200 m due to the physical and technical constraints on mining and exploration in the 19th Century. The Bendigo Goldfield represents the largest concentration of deep shafts anywhere in the world.
đang được dịch, vui lòng đợi..