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Earthquakes Deposit Gold In Fault Zones

samzenpus posted about 2 years ago | from the shake-rattle-and-gold dept.

Earth 55

sciencehabit writes "Gold deposits may be created in a flash—literally. Along fault zones deep within Earth's crust, small cavities filled with fluids rich in dissolved substances such as gold and silicate minerals can expand suddenly to as much as 130,000 times their former size during a major earthquake, a new analysis suggests. In such circumstances, pressure drops accordingly, driving a process the scientists call flash evaporation. And when the pressure in the cavity suddenly drops, so does the solubility of minerals in the water there. Along with substantial quantities of quartz, large earthquakes could deposit as much as 0.1 milligrams of gold along each square meter of a fault zone's surface in just a fraction of a second Typical rates of seismicity along a fault, such as the San Andreas fault zone shown in the main image, could generate a 100-metric-ton deposit of gold in less than 100,000 years."

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I smell a future James Bond plot... (4, Funny)

jfalcon (163956) | about 2 years ago | (#43202621)

Much like a cross between Goldfinger and View to a Kill.

Re:I smell a future James Bond plot... (0)

Anonymous Coward | about 2 years ago | (#43202923)

More like a Action Comics story arc. You forget, Lex Luthor *is* the greatest criminal mind the world has ever known.

Re:I smell a future James Bond plot... (0)

Anonymous Coward | about 2 years ago | (#43203219)

A criminal? How dare you cast aspersions on the man who saved us from the Reach, and from numerous other aliens when the Justice League was off-gallivanting?

Secretary-General Lex Luthor is the greatest leader the Earth has ever known.

He is a hero, a true human hero.

Re:I smell a future James Bond plot... (5, Funny)

Jeremiah Cornelius (137) | about 2 years ago | (#43202947)

Man to God: What is a million years like to you, God?

God: A million years? To me that's just like one of your seconds

Man: I see! Then... What is a million DOLLARS like to you, God?

God: I'm feeling you, man. You can guess, a million dollars to me is just like one of your pennies.

Man: OK, God! Can I ask you for a penny, then?

God: Sure! Just hold for a second...

Re:I smell a future James Bond plot... (0)

Anonymous Coward | about 2 years ago | (#43203453)

God: Yeah, well, you know, that's just, like, your opinion, man.

Re:I smell a future James Bond plot... (1)

wiredlogic (135348) | about 2 years ago | (#43203079)

You mean something like ST: Nemesis?

Re:I smell a future James Bond plot... (0)

Anonymous Coward | about 2 years ago | (#43206001)

Or a new discovery show

1kg a year (3, Informative)

RichMan (8097) | about 2 years ago | (#43202631)

100 metric tons/ 100,000 years
1 metric tonne/1000 years
1000kg /1000 years

1kg/year

Re:1kg a year (4, Informative)

schneidafunk (795759) | about 2 years ago | (#43202719)

Which turns out to be worth $51,740 according to today's price of gold [24hgold.com] .

Re:1kg a year (3, Informative)

tgeller (10260) | about 2 years ago | (#43202891)

...over the *entire San Andreas Fault*. So $50,000 isn't enough to survey and extract it all.

Still: it's interesting in its own right. Congrats to the researchers!

Re:1kg a year (2)

ShanghaiBill (739463) | about 2 years ago | (#43204279)

...over the *entire San Andreas Fault*. So $50,000 isn't enough to survey and extract it all.

Why would you only want to extract one year's deposit? The San Andreas Fault has been around for 30 million years [wikipedia.org] . So the total value of gold should be worth about $1.5 trillion. That is about $1.9 billion for each of its 810 miles.

Of course dumping that much gold on the market may depress prices slightly.

 

Re:1kg a year (0)

Anonymous Coward | about 2 years ago | (#43202721)

That's an issue that should be raised with human lifespans, not with earthquakes.

Re:1kg a year (0)

Anonymous Coward | about 2 years ago | (#43206373)

100 metric tons/ 100,000 years
1 metric tonne/1000 years
1000kg /1000 years

1kg/year

It reminds me of the half full/half empty glass. At first glance they seem to be the same but there is a reason to why the words are different. half full and half empty only means the same when observing a state but the expression implies an ongoing change.

100 metric tons/ 100,000 years and 1kg/year appears to be the same thing but 1kg/year implies a mass that is more evenly distributed in time.
100 metric tons once every 100,000 years vs. 1kg once every year

You have died of Cholera. There is nothing you... (1)

jellomizer (103300) | about 2 years ago | (#43202637)

It is like a modern day Gold Rush.

Re:You have died of Cholera. There is nothing you. (1)

RevWaldo (1186281) | about 2 years ago | (#43202781)

There's gold in them dar crevices!

.

Re:You have died of Cholera. There is nothing you. (0)

Anonymous Coward | about 2 years ago | (#43203665)

Yet another reason to date fatties.

Re:You have died of Cholera. There is nothing you. (1)

fazey (2806709) | about 2 years ago | (#43203851)

except fatties only have day old potato chips in them thar crevices.

Re:You have died of Cholera. There is nothing you. (1)

Gilmoure (18428) | about 2 years ago | (#43205511)

Pumas, too!

Re:You have died of Cholera. There is nothing you. (1)

cusco (717999) | about 2 years ago | (#43208541)

I'm going to move to California. There's lots of earthquakes, so I bet I'll find gold there.

What? Sutter's Mill? Never heard of it . . .

Sounds like... (0)

Anonymous Coward | about 2 years ago | (#43202651)

Artificial earthquakes in 3, 2, 1...

Re:Sounds like... (5, Funny)

jellomizer (103300) | about 2 years ago | (#43202669)

Dude, you found a way to popularize Fracking again!
Natural Gas and GOLD!!!

Re:Sounds like... (1)

Gilmoure (18428) | about 2 years ago | (#43205539)

Fracking major faults ROCKS!

So how do they keep the gold from dissolving? (4, Insightful)

khallow (566160) | about 2 years ago | (#43202711)

There doesn't seem to be much point to the observation since the gold can dissolve again, perhaps even within a few minutes of the end of the earthquake (it is hot down there, especially after a big earthquake).

Re:So how do they keep the gold from dissolving? (0)

Anonymous Coward | about 2 years ago | (#43202977)

Could the process be applied to surface lava by routing it through a specialized device to simulate flash evaporation?

Titanium pipes can carry lava.

Re:So how do they keep the gold from dissolving? (2)

PPH (736903) | about 2 years ago | (#43203179)

Lava? TFA says water. So the approach might be to circulate water through deep strata, dissolve the minerals out and pump them back to the surface. Flash evaporate that and pump the water back.

It might be interesting to revisit some old oil or natural gas wells that have been injected with water to increase their yield. The water has had time to dissolve minerals, so now we can bring it to the surface and see what settles out.

Re:So how do they keep the gold from dissolving? (0)

Anonymous Coward | about 2 years ago | (#43203327)

The summary didn't state what kind of fluid. It's not unusual to assume lava with articles like this [examiner.com] floating around.

Re:So how do they keep the gold from dissolving? (0)

Anonymous Coward | about 2 years ago | (#43203535)

And this [nature.com] .

Re:So how do they keep the gold from dissolving? (2)

khallow (566160) | about 2 years ago | (#43203709)

It's worth noting that geothermal plants already do this. And as a result, they tend to have a nasty scaling problem in their plumbing. I think it would be interesting to try this, say pump the working fluid through a bed of crushed limestone after the heat has been extracted. Then after a while, cart the results off to a mine and extract whatever metals have been left behind.

Re:So how do they keep the gold from dissolving? (2)

WindBourne (631190) | about 2 years ago | (#43204049)

Simbol Materials. However, at this time, recovering Au is not profitable enough. BUT, I am going to guess that with enough injections over and over that we will soon see the Au concentration rise to the point where it is profitable to look at it.

Re:So how do they keep the gold from dissolving? (1)

khallow (566160) | about 2 years ago | (#43204637)

Interesting tip. Glancing through their news releases, it sounds like they're putting in a prototype plant at the Salton Sea in California.

BUT, I am going to guess that with enough injections over and over that we will soon see the Au concentration rise to the point where it is profitable to look at it.

I guess it depends on location, volume, and whether gold is the primary resource extracted. There are mines specializing in extracting absurdly small amounts of gold per unit mass of material, but these require rather high volumes to be worth the bother.

But gold extraction can piggy back on other mining. Since Simbol is extracting zinc, there might be some gold (or near relatives, copper and silver) in the hydrothermal fluid that they're processing.

Re:So how do they keep the gold from dissolving? (1)

Anonymous Coward | about 2 years ago | (#43203147)

A single event is economically irrelevant for other reasons (see above comment about the huge volume over which it is spread), but it won't become soluble again very easily unless fluid pressures and temperatures rise considerably, and the gold will be trapped in the quartz anyway (i.e. the new fractures created by the next pulse of high pressure fluid will break the quartz rather than dissolve it significantly before it cools again). Even If there is any re-dissolution, it will probably re-precipitate out again shortly and nearby, so there's the potential to keep enriching the deposit through multiple cycles. This is more-or-less what's expected for any major economic deposit -- they result from persistent deposition of small concentrations of gold over a prolonged period of time and many successive delivery events. Ordinarily these deposits aren't made from a single event, as the linked article explains with the sentence "Because mineral-rich waters continually infiltrate cavities along the fault, ore deposits accumulate with each passing quake." The *individual* fluid injection events might be surprisingly brief (the point of the article), but it still takes a lot of them.

Re:So how do they keep the gold from dissolving? (2)

khallow (566160) | about 2 years ago | (#43203577)

unless fluid pressures and temperatures rise considerably

Let us recall, that was why the gold was there in the first place. It was originally dissolved in solution because of high fluid pressures and temperatures. I'm pretty sure temperature actually increases after an earthquake, so in order for precipitation to occur and stay, either the pressure has to drop and stay dropped, or gold becomes trapped as you claim.

Even If there is any re-dissolution, it will probably re-precipitate out again shortly and nearby

Why? Gold is no more likely to precipitate, if it's been in solution for a long time versus a short time. And why wouldn't have done so in the absence of the earthquake?

Gold can precipitate either if the temperature of the water cools down or its chemistry changes to something more basic in PH. A fault provides opportunities for both. It's a means for water to leak down, dissolve metals, and return to the cooler near surface.

It also moves different rock types around. So your gold-bearing igneous rock may end up next to limestone. Then fluids may circulate between the two rock types and slowly transfer gold and other metals to the limestone body.

Re:So how do they keep the gold from dissolving? (1)

Anonymous Coward | about 2 years ago | (#43203181)

It might not be practically useful information but at least now we might know why exactly so much gold is found around California and Alaska and other fault lines. Has Iceland ever had a gold rush?

Re:So how do they keep the gold from dissolving? (2)

MarkRose (820682) | about 2 years ago | (#43204813)

There is gold everywhere, but yes, fault lines are a great way to find certain kinds of gold deposits. If you want more information on why gold ends up where it does, I highly recommend a series of videos put out by the Sprott Group on ore deposists [youtube.com] .

This week on... SAN ANDREAS GOLD! (0)

Anonymous Coward | about 2 years ago | (#43202861)

I can't wait for the reality show.

Re:This week on... SAN ANDREAS GOLD! (1)

chromas (1085949) | about 2 years ago | (#43205649)

I think you mean plural. There'll be two shows each on at least Discovery, History and probably TLC. Maybe even National Geologic. Now, one show will consist of people going out to find the gold, while the second will have other people bringing it in. And they'll have stupid punny names like Goldie Luck's and AU Gratin.

So, buy land in California? (0)

Anonymous Coward | about 2 years ago | (#43202879)

Good thing it's so cheap!

gold rush... (1)

tresstatus (260408) | about 2 years ago | (#43202909)

quick... send that nasaly-voiced old man to look for the glory hole!

Re:gold rush... (0)

Anonymous Coward | about 2 years ago | (#43202987)

It's down there.

I can feel it!

Re:gold rush... (1)

fredrated (639554) | about 2 years ago | (#43203161)

Get your head out of there!

100,000 years? (0)

Anonymous Coward | about 2 years ago | (#43203379)

Not exactly a get-rich-quick scheme.....

That's all well and good.... (0)

Anonymous Coward | about 2 years ago | (#43203631)

How do I build an infinite gold farm in Minecraft using this information?

Miners Know (5, Interesting)

A10Mechanic (1056868) | about 2 years ago | (#43203637)

When I was younger, we'd explore the old 1800's silver mines at Alta, Utah. When the old miners hit a fault line (underground), they'd span out and mine that fault for all it was worth. It was pretty neat for us finding a rock face perfectly smooth and straight (the fault), that had been stoped out a hundred years ago, miles underground. It was like going back in time. In hindsight, it was probably dangerous... Ah, youth.

Gold is abundant. So are all other metals. (2)

140Mandak262Jamuna (970587) | about 2 years ago | (#43203745)

Sea water contains so much of salt of every metal there is. Thousands of tons of gold exists in the sea water. Just the cost of extraction far outweighs the value of the extracted metal.

Re:Gold is abundant. So are all other metals. (1)

ShanghaiBill (739463) | about 2 years ago | (#43204523)

Just the cost of extraction far outweighs the value of the extracted metal.

Indeed. The concentration of gold in seawater is about 50 ppq (parts per quadrillion). That is less than two ounces for every cubic mile of water. It is implausible that it will ever be economical to extract gold from seawater.

Re:Gold is abundant. So are all other metals. (1)

Anonymous Coward | about 2 years ago | (#43206417)

It's actually more like 92lbs/ mi^3. http://www.webelements.com/gold/ [webelements.com] quotes sea water values at 10 nanograms/Liter.

Re:Gold is abundant. So are all other metals. (1)

ShanghaiBill (739463) | about 2 years ago | (#43206939)

It's actually more like 92lbs/ mi^3. http://www.webelements.com/gold/ [webelements.com] quotes sea water values at 10 nanograms/Liter.

No, the page you reference just pulls that number out of thin air, and even admits to doing so by saying that "perhaps" that is the concentration. Much more detailed information is here: Gold in Seawater [wikipedia.org] , which quotes a figure about a thousand times less.

This article [newscientist.com] states that people used to think seawater has much more gold than is estimated today, so that my explain your estimate.

But if you want to extract gold (or anything else) from seawater, you would probably start with the effluent brine from a desalination plant. That way it is already partially concentrated, and may already be pumped up above sea level so you could use gravity to move it through your extraction mechanism.

Re:Gold is abundant. So are all other metals. (1)

istartedi (132515) | about 2 years ago | (#43207675)

ut if you want to extract gold (or anything else) from seawater, you would probably start with the effluent brine from a desalination plant. That way it is already partially concentrated, and may already be pumped up above sea level so you could use gravity to move it through your extraction mechanism.

You could also find a natural salt flat left over from an ancient sea. These things exist of course, and they are mined... for salt. Even with all the water extracted, it's still not economical to separate the gold.

Re:Gold is abundant. So are all other metals. (2)

cusco (717999) | about 2 years ago | (#43208673)

Sewage is a considerably better source.

"http://pinktentacle.com/2009/01/gold-mined-from-sewage-sludge/"

A sewage plant in Japan's Nagano prefecture has started mining gold from sludge, earning a cool 5 million yen ($56,000) in its first month of operation.

Re:Gold is abundant. So are all other metals. (0)

Anonymous Coward | about 2 years ago | (#43210055)

Hanging out around the dome of the Georgia State (USA) capitol building is far more appealing. Sorry, can't find the link but I recall that the original gold leaf coating wasn't applied as well as it could have been, and supplied a slow but steady treasure to passers-bye.

Then there are the guys who sweep the dust up around jewelry making districts.

A century ago, the black sand on the beaches near San Francisco had extractable gold; but according to the sources I've read it would take 500 years to recharge from silt washed out through the aptly named gate. You can still see the magnetite sand there, it just doesn't have gold anymore, and mining it is probably illegal anyway.

And so on and so forth... gold traces everwhere...

Re:Gold is abundant. So are all other metals. (1)

cusco (717999) | about 2 years ago | (#43214871)

Back during the Alaska Gold Rush days, enough gold was panned out of the sands on the beaches at Nome to pay for Seward's original purchase of the entire state. I know way too much trivia . . .

so NK will nuke the flat line to speed it up as nu (0)

Anonymous Coward | about 2 years ago | (#43203749)

so NK will nuke the flat line to speed it up as radiation can speed stuff up.

Something for the goldbugs... (2, Interesting)

Anonymous Coward | about 2 years ago | (#43204233)

The oceans contain about 20 million tons [noaa.gov] of gold, dissolved in the seawater and on the seabed, eclipsing the worlds current stock of mined gold by more than 100 times.

Ironically, those promoting a gold standard for financial stability, would ensure that hyperinflation occurs in the future; as soon as innovations in nanotechnology, make the cost of extracting gold from seawater affordable/cheap, the value of gold itself will then plummet as its availability increases, causing inflation and eventually hyperinflation.

Why is this "news"? (0)

Anonymous Coward | about 2 years ago | (#43204565)

Read many many papers by Sibson and others from the 70's and later on processes like fault valving.

This is what they discovered (3, Interesting)

Diamonddavej (851495) | about 2 years ago | (#43206315)

Weatherley and Henley investigated a mesothermal gold deposit, the Revenge Mine in Australia (also known as orogenic gold deposits). These gold deposits form deep underground during mountain building events, generally 3 to 20 km deep, where greater hydrostatic pressures normally prevent fluids from boiling. Previously, geologists speculated that mesothermal gold ore was deposited when fluids cooled or interacted with other fluids with a different chemistry, not so it seems. Weatherley and Henley claim that, even at great depths and pressures, fluid pressure in a fault zone can momentarily approach zero during an earthquake, this is a great surprise. Also, the (normal) temperature and pressures during the formation of the Revenge Mine deposit was 1675 to 2075 bars and 425 to 525 C, this suggests the water was a Supercritical Fluid. I wonder if a phase change from supercritical fluid to a gas facilitated the precipitation of gold.

Also, it should be pointed out that role of Earthquakes in the formation of gold and other mineral deposits has been acknowledged for decades (in particular the near surface epithermal fault hosted gold-silver veins). Epithermal deposits are formed near the surface (generally less than 1 km), the frequent occurrence of breccias, broken rock fragments and voids in the faults attests to vigorous fluid boiling. One famous example of earthquake provoked mineralisation is the San Andreas fault, where hot springs issuing from the fault zone emit more arsenic and mercury after an earthquake, gold is presumably deposited at depth as well e.g.

Sibson, R.H. 1987. Earthquake rupturing as a mineralizing agent in hydrothermal systems. Geology 15(8), 701-704.

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