<blockquote>
<p>What is the role of trace elements in magmatic crystallization?</p>
</blockquote>
<p>They don't really have a role in magmatic crystallisation. Trace elements are useful because they are (sometimes) more sensitive to changes in crystallisation conditions, when they are measured.</p>
<p>For example, a basalt crystallising plagioclase wouldn't change its Al, Ca, Na, and Si contents too much. They will change a bit, but nothing serious. On the other hand, strontium and europium are two trace elements that are extremely compatible in plagioclase. Seeing a rock with a strong depletion of Eu and Sr compared to average crust (for example) indicates that plagioclase has crystallised in its crystallisation history. This is less obvious when considering only major elements (although can be deduced by the experienced petrologist).</p>

CC BY-SA 4.0
2021-11-27T11:07:35.893Z
2021-11-27T11:07:35.893Z
Gimelist
<p>Not much of anything, trace elements are found in low concentrations in the mantle because they are lithophobic. During crystallisation they end up in the residue of silica, and incompatible elements like gold etc..., that is squeezed out into the country rock around the margins of igneous intrusions.</p>

CC BY-SA 4.0
2021-11-08T10:51:44.503Z
I would argue this is a major impact because it tends to concentrate the elements involved into ore veins. Chalcophilic matter, especially, shows this property.
Oscar Lanzi
CC BY-SA 4.0
2021-11-09T04:42:18.040Z
@OscarLanzi That is *outside* of the magma crystallisation process though, the result of their presence in a melt is that they are concentrated outside the subsequent batholith, they don't play a role in the crystallisation of the magma body.
Ash
CC BY-SA 4.0
2021-11-08T04:31:17.530Z
2021-11-08T04:31:17.530Z
Ash
<p>I understand that trace element behavior in a system depends on whether they are compatible or not. But , if that question is asked in an examination , what could be the points that one should write to answer that?</p>

CC BY-SA 4.0
2021-11-07T13:57:10.750Z
Hello there - could you clarify your question and make it more precise? Most of us are not going to take this exam, so we are requiring context to answer in the scope of what you are asking. Like, what is compatible with what? And could you provide a couple of point example about what you already know?
marsisalie
<geochemistry>
What is the role of trace elements in magmatic crystallization?
Knight
# What is the role of trace elements in magmatic crystallization?

(Asked by: username_0 on 2021-11-07)

I understand that trace element behavior in a system depends on whether they are compatible or not. But , if that question is asked in an examination , what could be the points that one should write to answer that?

**Tags:** geochemistry

> **Comments:**
> **username_1**: Hello there - could you clarify your question and make it more precise? Most of us are not going to take this exam, so we are requiring context to answer in the scope of what you are asking. Like, what is compatible with what? And could you provide a couple of point example about what you already know?  

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## 2 answers

### Answer by username_2 on 2021-11-27. Score: 3

> What is the role of trace elements in magmatic crystallization?

They don't really have a role in magmatic crystallisation. Trace elements are useful because they are (sometimes) more sensitive to changes in crystallisation conditions, when they are measured.

For example, a basalt crystallising plagioclase wouldn't change its Al, Ca, Na, and Si contents too much. They will change a bit, but nothing serious. On the other hand, strontium and europium are two trace elements that are extremely compatible in plagioclase. Seeing a rock with a strong depletion of Eu and Sr compared to average crust (for example) indicates that plagioclase has crystallised in its crystallisation history. This is less obvious when considering only major elements (although can be deduced by the experienced petrologist).


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### Answer by username_3 on 2021-11-08. Score: 3

Not much of anything, trace elements are found in low concentrations in the mantle because they are lithophobic. During crystallisation they end up in the residue of silica, and incompatible elements like gold etc..., that is squeezed out into the country rock around the margins of igneous intrusions.

> **Comments:**
> **username_4**: I would argue this is a major impact because it tends to concentrate the elements involved into ore veins. Chalcophilic matter, especially, shows this property.  
> **username_3**: @username_4 That is *outside* of the magma crystallisation process though, the result of their presence in a melt is that they are concentrated outside the subsequent batholith, they don't play a role in the crystallisation of the magma body.  

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