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Gold Prospecting
Gold localities & information
Creswick and Wedderburn - Golden Triangle Newbie
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<blockquote data-quote="Hawkear" data-source="post: 640688" data-attributes="member: 4728"><p>"There would have been plenty of opportunity to erode the kilometres (10 vertical Km) of rock necessary to expose the reefs on the surface".</p><p>Thought I should justify my assumption above in an earlier post. </p><p>The uppermost layers of the uplifted sea floor sediments which now form the bed rock of the goldfields would have would have been much newer and softer than the older, deeper metamorphised layers. Those softer sedimentary layers would have been the first to be exposed to erosion when uplifted.</p><p>In nature they may be compared to the "Badlands" of South Dakota which are similarly uplifted sedimentary marine deposits but of much younger age. A study in 2003 put the yearly rate of erosion of the Badlands at around 2.5 cm per year. </p><p>Plugging in a few numbers,10Km of Badlands type sediment if sufficiently uplifted could be eroded away in as little as 4 million years. </p><p>Of course there are many other factors involved such as hardening and metamorphism of the deeper rocks, climatic variation, uplift rates etc but I think my assumption that there would have been plenty of time to erode 10 vertical kilometres of rock could be justified.</p></blockquote><p></p>
[QUOTE="Hawkear, post: 640688, member: 4728"] "There would have been plenty of opportunity to erode the kilometres (10 vertical Km) of rock necessary to expose the reefs on the surface". Thought I should justify my assumption above in an earlier post. The uppermost layers of the uplifted sea floor sediments which now form the bed rock of the goldfields would have would have been much newer and softer than the older, deeper metamorphised layers. Those softer sedimentary layers would have been the first to be exposed to erosion when uplifted. In nature they may be compared to the "Badlands" of South Dakota which are similarly uplifted sedimentary marine deposits but of much younger age. A study in 2003 put the yearly rate of erosion of the Badlands at around 2.5 cm per year. Plugging in a few numbers,10Km of Badlands type sediment if sufficiently uplifted could be eroded away in as little as 4 million years. Of course there are many other factors involved such as hardening and metamorphism of the deeper rocks, climatic variation, uplift rates etc but I think my assumption that there would have been plenty of time to erode 10 vertical kilometres of rock could be justified. [/QUOTE]
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Gold Prospecting
Gold localities & information
Creswick and Wedderburn - Golden Triangle Newbie
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