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hawkeye

Why So Many Big Nuggets In Oz

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As I read the amazing "Reg Wilson" threads about the numerous large nuggets found in Australia I began thinking about the amazing depositional situation that created them.  I have "Googled" a bit to try and find any literature on the subject, but have not found anything to satisfy my curiosity.

 .  Can anyone recommend any papers or books that describes the creation of the Australian deposits.  I understand how gold is deposited, but what is unique about the Australian situation that resulted in so much large gold?

 

 

 

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Unlike most U.S. geologic information Australia reports and publications are largely private fee access type reports. Pub,ic reports are rare. Here is a start.

Victorian Gold Deposits 1998

“The Palaeozoic succession of Victoria represents a major world gold province with a total production of 2500 t of gold (i.e. 78 million oz). On a global scale, central Victoria represents one of the most gold mineralized areas outside the Witwatersrand of South Africa, and remains the prime example of a ‘slate belt’ gold province (also known as ‘turbidite-hosted’, or ‘shale-greywacke’ gold province).”

Victorian Geology

Geology of Victorian Gold Occurances 1908

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Thank you Steve.  I will certainly check these out.  

Geology is very interesting to me.  I graduated from Montana School of Mines (so named in 1963), but with a degree in Petroleum Engineering.  Nevertheless I did take courses in geology, petrology and mineralogy.  I forgot most it of over the years as I was more involved with the drilling and production of oil and wells.  I have renewed my interest in geology since taking up the hobby  of detecting for gold.  I missed out on the "golden age" of detecting while pursuing my career in Petroleum and raising a family in areas not even close to gold.  So be it.

 

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I always liked geology from a young age, and once thought I might go to college for it, but instead just learned from reading it for decades. Fascinating stuff. Here is a presentation that has some good maps, etc....

https://www.smedg.org.au/Bendigo Ionex Aug07.pdf

As far as "why" questions go it is always good to remember that even now most of what is presented are just theories. These guys for instance have a completely new theory as to the ultimate gold source for some Australian gold.

My old geology teacher put it thus when asked a "why" question - "the conditions were favorable". Prospectors simplify even that into "gold is where you find it"!

This one is not Australia but is one of my favorite recent summaries of gold deposit models:

Models and Exploration Methods for Major Gold Deposit Types." Ore Deposits and Exploration Technology, Paper 48. By Robert, F., Brommecker, R., Bourne, B. T., Dobak, P. J., McEwan, C. .J., Rowe and R. R., Zhou, X.

From the conclusion:

"There has been significant progress in the last decade in the understanding of the geology, settings and controls of the diverse types of gold deposits, including the recognition of new deposit types in new environments. Such progress has been paralleled with the development of data integration, processing and visualization techniques, and of advances in geophysical, geochemical and spectral detection techniques. Geologists are now better equipped than ever to face the increasingly difficult challenge of finding gold. However, one of the key lessons of the last decade, as reminded by Sillitoe and Thompson (2006), is that the exploration work needs to remain grounded in geology, especially in the field, and the elaborate detection techniques and tools available will only find their full power when closely integrated with a good geological framework."

Sounds like a prescription for successful nugget detecting to me!

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I struck it rich! With this site that has a huge number of free downloads

http://earthresources.efirst.com.au/product.asp?pID=49&cID=15

http://earthresources.efirst.com.au/categories.asp?cID=42

Lots more there to explore.

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