I love that you said the "little settlement of Carlin' so cute. I've been a time or too, work just south of there in the Super Springs Range and in the West Pequop Mountains, I am geologist there
yes, nevada was once the pacific shore line of the north american shield/plate group, where the pacific plate subducted beneath it, with countless volcanic intrusions that broke through the sedimentary basement rock over and over during the geological development of what is nevada today, good video
Good presentation in general, but there are a few things worth mentioning. 6:40 Carlin deposits were recognized in the sixties, but the Getchell mine was mined in the late '30's. They didn't know what the deposit model was but they had gold from assays and were able to build a mine on that. It was the first Carlin deposit gold mine. 7:45 The discovery hole at Red Hill was drilled by Placer Dome around the same time as they discovered Cortez Hills, but the Cortez Hills discovery was so much better Red Hill didn't see much action until after Barrick took over. Barrick outlined the deposit, but arguably did not discover it. The carbonate rocks are more commonly silty than clayey. 13:50 Whether a subduction zone was responsible for the Antler Orogeny is still debated. The absence of contemporaneous magmatism is problematic to that model, as is the absence of an accreted arc terrane. 20:53 It is more likely that slab roll back from the north and south allowed asthenospheric mantle to move in, accounting for decreasing ages of magmatism from Arizona and Idaho over time progressing toward the youngest magmatism in the system in Central Nevada during the Oligocene. The interval associated with Carlin deposits seems to have been about 41-35Ma. 22:54 The fluids were near neutral pH until they reached the carbonic acid dissociation depth, decomposing to H+ and HCO3-, and thus acidifying the waters. But the acidification does not appear to have been as strong as in epithermal deposits. The apparent stability of dolomite places limits on the acidity of the fluids. 24:50 It is reactable iron in the limestones that provides iron for sulfidation. The dissolution and sulfidation processes are generally penecontemporaneous. This is why reduced, slope facies limestones are such good hosts. They have iron as siderite component in the calcite of the limestones which is liberated on dissolution and available to react with sulfide in the solution, forming pyrite. 36:50 It's by no means certain, nor even likely, that the Post fault was active since the Cambrian. There is no arch there, and upper slope limestones are more easily related to the depositional system than supposed tectonic activity. 38:56 Same thing with the Cortez fault - probably not syn- or pre-depositional. There are not depositional changes adequate to make that statement. The margin was tectonically quite passive during carbonate deposition. In addition, at 39:19, the emplacement of the Mill Canyon stock long postdates the Antler orogeny, which is plain from any geologic map. There is no contemporaneous Antler age magmatism in the region. I suggest you become familiar with carbonate sequence stratigraphy to improve your understanding of Great Basin stratigraphy and its relation to Carlin deposits, and acquaint yourself with more of the current literature on Carlin gold deposition mechanisms. Some of your ideas are outdated.
i did not know that the getchell mine was the first to mine carlin type ore, but what you say makes sense, i've been studying nevada geology and it's many ore types for almost 13 years, and still learning things, one ore type that has always fascinated me is the carbonate hosted type, and carlin is one of them, and in many cases, prospectors walk right past them because of one thing, the stone appearance dose not fit their model of gold in quartz veins, another thing no one has shown them what to look for in carbonate ore types, the main reason i know to collect carbonate grab samples is because i accidentally stumbled onto some fantastic ore samples by blindly taking random samples of rocks to different labs for assay/spectral analysis, now i don't bother getting samples assayed for evaluation of values, i use optics, the trusty pan and a shaker table, some carbonate hosted rock/s where i live has visible grains of electrum 50% au 50% ag on average, other types have invisible disseminated grains probably similar to carlin type, and the volcanic hosted rock/s here consists mainly the exact same ratio of gold to silver 50% au 50% ag as free electrum in oxides and grains formed inside individual pyrite cubes in rhyolite for the sulfides, as the main ore types mined in this mining district of nevada, i appreciate your educated post as i have learned much from it, regards
The Carlin Trend was produced by the Yucatan Peninsula Asteroid's tectonic plate push through the Gulf of Mexico with ending thrust at the Pacific Plate near Seattle, Washington. This re-vulcanized the earlier Yellowstone Caldera that started near the Baja Peninsula while traveling through Nevada to the present day location. Yucatan is the latter episode than Yellowstone, so the Carlin Trend follows the Yucatan tectonic plate thrust fault lines while being recharged with crossing the previous Yellowstone minerlized thrust fault zone. Being a physical on-ground dowsing prospector I need to keep track of both tectonic plate minerlized fault lines, so I have named Yellowstone as the "positive plat tectonics", because it was the first and is the largest. Yucatan is named the "negative plat tectonics".
Thanks for this video and I learned a lot, I metal detect and always look for good spots to metal detect and find a little nugget ...... This video makes me think of leaving Arizona and moving to Nevada......
Are there any of these types of deposits in the vast network of lime-stones in the east coast and south east ? Areas such as middle TN which lay near approximate distances from the free gold areas in the south, and which were also shallow seas ?
Carlin trend deposits aren’t really Ore deposits 101 simply because John Livermore didn’t discover the first Carlin trend deposit til 1961. So It’s fairly new to the mining world although alot of people seem to act like it was always known . Not true , it took a free thinking prospector type geologist to figure it out . Someone that isn’t blinded by the standard academic mind set that all we know or ever will is already written in the textbooks. Mining in Nevada owes a great debt to John Livermore.
Great information. I've studied this before but like your presentation. PLEASE stop saying Nev-odd-a and Nev-odd-er. Look up how to say it properly. It's extremely distracting and upsetting to people here when anyone says "odd" in the middle of the state's name.
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Truly excellent presentation. Thank you.
I love that you said the "little settlement of Carlin' so cute. I've been a time or too, work just south of there in the Super Springs Range and in the West Pequop Mountains, I am geologist there
yes, nevada was once the pacific shore line of the north american shield/plate group, where the pacific plate subducted beneath it, with countless volcanic intrusions that broke through the sedimentary basement rock over and over during the geological development of what is nevada today, good video
Such a great series. Thank you for uploading.
Wow! Brilliant presentation as always. Bravo!
Thank you for this update and well-done presentation. in Gratitude.
Good presentation in general, but there are a few things worth mentioning.
6:40 Carlin deposits were recognized in the sixties, but the Getchell mine was mined in the late '30's. They didn't know what the deposit model was but they had gold from assays and were able to build a mine on that. It was the first Carlin deposit gold mine.
7:45 The discovery hole at Red Hill was drilled by Placer Dome around the same time as they discovered Cortez Hills, but the Cortez Hills discovery was so much better Red Hill didn't see much action until after Barrick took over. Barrick outlined the deposit, but arguably did not discover it.
The carbonate rocks are more commonly silty than clayey.
13:50 Whether a subduction zone was responsible for the Antler Orogeny is still debated. The absence of contemporaneous magmatism is problematic to that model, as is the absence of an accreted arc terrane.
20:53 It is more likely that slab roll back from the north and south allowed asthenospheric mantle to move in, accounting for decreasing ages of magmatism from Arizona and Idaho over time progressing toward the youngest magmatism in the system in Central Nevada during the Oligocene. The interval associated with Carlin deposits seems to have been about 41-35Ma.
22:54 The fluids were near neutral pH until they reached the carbonic acid dissociation depth, decomposing to H+ and HCO3-, and thus acidifying the waters. But the acidification does not appear to have been as strong as in epithermal deposits. The apparent stability of dolomite places limits on the acidity of the fluids.
24:50 It is reactable iron in the limestones that provides iron for sulfidation. The dissolution and sulfidation processes are generally penecontemporaneous. This is why reduced, slope facies limestones are such good hosts. They have iron as siderite component in the calcite of the limestones which is liberated on dissolution and available to react with sulfide in the solution, forming pyrite.
36:50 It's by no means certain, nor even likely, that the Post fault was active since the Cambrian. There is no arch there, and upper slope limestones are more easily related to the depositional system than supposed tectonic activity.
38:56 Same thing with the Cortez fault - probably not syn- or pre-depositional. There are not depositional changes adequate to make that statement. The margin was tectonically quite passive during carbonate deposition. In addition, at 39:19, the emplacement of the Mill Canyon stock long postdates the Antler orogeny, which is plain from any geologic map. There is no contemporaneous Antler age magmatism in the region.
I suggest you become familiar with carbonate sequence stratigraphy to improve your understanding of Great Basin stratigraphy and its relation to Carlin deposits, and acquaint yourself with more of the current literature on Carlin gold deposition mechanisms. Some of your ideas are outdated.
i did not know that the getchell mine was the first to mine carlin type ore, but what you say makes sense, i've been studying nevada geology and it's many ore types for almost 13 years, and still learning things, one ore type that has always fascinated me is the carbonate hosted type, and carlin is one of them, and in many cases, prospectors walk right past them because of one thing, the stone appearance dose not fit their model of gold in quartz veins, another thing no one has shown them what to look for in carbonate ore types, the main reason i know to collect carbonate grab samples is because i accidentally stumbled onto some fantastic ore samples by blindly taking random samples of rocks to different labs for assay/spectral analysis, now i don't bother getting samples assayed for evaluation of values, i use optics, the trusty pan and a shaker table, some carbonate hosted rock/s where i live has visible grains of electrum 50% au 50% ag on average, other types have invisible disseminated grains probably similar to carlin type, and the volcanic hosted rock/s here consists mainly the exact same ratio of gold to silver 50% au 50% ag as free electrum in oxides and grains formed inside individual pyrite cubes in rhyolite for the sulfides, as the main ore types mined in this mining district of nevada, i appreciate your educated post as i have learned much from it, regards
Thank you for your clear and bright presentation!
The Carlin Trend was produced by the Yucatan Peninsula Asteroid's tectonic plate push through the Gulf of Mexico with ending thrust at the Pacific Plate near Seattle, Washington. This re-vulcanized the earlier Yellowstone Caldera that started near the Baja Peninsula while traveling through Nevada to the present day location. Yucatan is the latter episode than Yellowstone, so the Carlin Trend follows the Yucatan tectonic plate thrust fault lines while being recharged with crossing the previous Yellowstone minerlized thrust fault zone. Being a physical on-ground dowsing prospector I need to keep track of both tectonic plate minerlized fault lines, so I have named Yellowstone as the "positive plat tectonics", because it was the first and is the largest. Yucatan is named the "negative plat tectonics".
Weird
Have loved every one I've seen! Thsnk you!
Thanks so much for this excellent video. Very helpful.
Thanks for this video and I learned a lot, I metal detect and always look for good spots to metal detect and find a little nugget ...... This video makes me think of leaving Arizona and moving to Nevada......
The Carlin gold is micron size. There is little significant free gold in the systems. Metal detecting for them would not be fruitful
Are there any of these types of deposits in the vast network of lime-stones in the east coast and south east ? Areas such as middle TN which lay near approximate distances from the free gold areas in the south, and which were also shallow seas ?
Great job
The geologic history here, particularly prior to 100 million years ago, is probably quite a bit more wrong than it is right.
Yes
❤
Carlin trend deposits aren’t really Ore deposits 101 simply because John Livermore didn’t discover the first Carlin trend deposit til 1961. So It’s fairly new to the mining world although alot of people seem to act like it was always known . Not true , it took a free thinking prospector type geologist to figure it out . Someone that isn’t blinded by the standard academic mind set that all we know or ever will is already written in the textbooks. Mining in Nevada owes a great debt to John Livermore.
Thanks
nice
Great information. I've studied this before but like your presentation. PLEASE stop saying Nev-odd-a and Nev-odd-er. Look up how to say it properly. It's extremely distracting and upsetting to people here when anyone says "odd" in the middle of the state's name.