Episode 77: What's up with the Witwatersrand? by The Northern Miner published on 2017-10-18T20:37:27Z This week we've got a geological bonananza! Lesley sits down with Dr. Hartwig Frimmel to chat about the genesis of the Witwatersrand (Wits) gold deposit in South Africa. The geological anomaly has received renewed attention thanks to a recent discovery by Novo Resources (TSXV: NVO; USOTC: NSRPF), which reported on July 12 that it had found gold nuggets up to 4 cm long during trenching at its Purdy’s Reward gold prospect in Western Australia. Novo (12:00) has traced the nugget-rich, 2.7-billion-year-old conglomeratic package almost continuously along an 8 km strike length. The rocks dip 10 degrees southeast under a cover of basalts. Dr. Frimmel explains that the "biggest controversy" behind the Wits remains the source of gold. He argues that acidic rain liberated gold from the crust and gold-rich streams flushed across the hinterland, depositing gold in chemically-reactive algal mats. Those algal mats only started to blossom around 2.9 billion years ago – which is why the richest part of the Wits is 2.9 billion years. He believes these algal matts were then eroded and flushed into the basin. Timeline Novo Resources 17:50 Greenstone belts across the world 33:45 Dating gold-porphyry deposits 36:55 Wits 2.0: Is there a twin? 40:00 Articles referenced: Novo Resources strikes gold at Purdy’s Reward in Australia: http://www.northernminer.com/news/novo-resources-strikes-gold-purdys-reward/1003788541/ Come See the Mine of the Future – October 23, 2017: www.northernminer.com/progressive-mine-forum/ Music Credits: "Cool Rock" Kevin MacLeod (incompetech.com) Licensed under Creative Commons: By Attribution 3.0 License creativecommons.org/licenses/by/3.0/ "Isolated" Kevin MacLeod (incompetech.com) Licensed under Creative Commons: By Attribution 3.0 License creativecommons.org/licenses/by/3.0/ Genre Science Comment by bilbo @user-938472678-34797352: I have since been informed that the large amount of conglomerate probably came from the erosion of the rift banks of the rift basin this area of the pilbara. 2017-10-19T18:07:39Z Comment by bilbo @user-938472678-34797352: further to last...where did all this conglomerate come from? What is its source? How did it come to cover so much area? 2017-10-19T16:48:29Z Comment by bilbo Excellent podcast. In trying to apply this info about the Wits micro-nuggets to Pilbara's watermelon seed nuggets I have concluded that the watermelon seed shaped nuggests must have formed directly on top of a bacterial colony in the shallows of the ancient sea as opposed to the banks of ancient rivers. The form and shape of the colonies must have given rise to the watermelon seed shape that is so widespread on Novo's/Artemis land. Perhaps something akin to large expanses of stromatolite colonies. These precipitous watermelon seeds were then somehow washed into pebble and gravel beds were they sank to the bottom of the gravel (conglomerate) layer before being carpeted by submarine lava. Exactly how the watermelon seeds wound up in the gravel beds is the part that still has me scratching my head. Truly a strange deposit that so far has eluded a convincing explanation. 2017-10-19T16:39:47Z
