<p>Atmospheric pressure affects the bubbles that form in lava, and this effect can be used to estimate paleopressure at the time of emplacement of a lava flow. You might need some special conditions, but it is possible to make such a study. The technique is described in Sahagian et al. (2002).</p>

<hr>

<p>Sahagian, D. L., Proussevitch, A. A., &amp; Carlson, W. D. (2002). Analysis of vesicular basalts and lava emplacement processes for application as a paleobarometer/paleoaltimeter. The Journal of Geology, 110(6), 671-685. [<a href="http://www.jstor.org/stable/10.1086/342627" rel="nofollow">JSTOR link</a>, <a href="http://www.geo.mtu.edu/~raman/papers2/SahagianJG.pdf" rel="nofollow">free PDF link</a>]</p>

CC BY-SA 3.0
2015-08-24T13:28:54.350Z
2015-08-26T05:16:59.253Z
2015-08-26T05:16:59.253Z
Jesus Rojas Parra
<p><a href="http://en.wikipedia.org/wiki/K%E2%80%93Ar_dating" rel="nofollow">Potassium–argon (K-Ar) dating</a> specifically and <em>only</em> works with igneous rocks. The idea being that when molten magma solidifies into, say, granite or basalt, any potassium ends up locked into crystaline forms. Some of that potassium will be the unstable K-40 isotope, decaying into A-40 with a half-life of 1.26 billion years. Since virtually <em>no</em> A-40 would have been present at time of crystalisation, the K-40:A-40 ratio gives a good indication of when solidification occurred.</p>

<p>There are of course other "radioactive clocks" based on other elements/isotopes with longer or short half-lives, which may be more suitable depending on how far back you're trying to look. And although we're not likely to find much in the way of organic material (fossils, etc.) in igneous rocks, information from different sources can usefully be collated.</p>

<p>I don't know of any specific case, but I'd have thought there would be many situations where sedimentary rock has been laid down over precisely-dated igneous rocks. And I don't know the exact limitations of <a href="http://en.wikipedia.org/wiki/Dendrochronology" rel="nofollow">dendrochronology</a>, but it seems at least <em>possible</em> that you could detect identifiable "pattern sequences" in ancient annual tree-trunk ring growth patterns that suddenly become far more meaningful if you know <em>when</em> those patterns were formed.</p>

<p>Some seasonal growth variation will be down to local factors, and some will reflect "global" events. But given enough data, they could be distinguished. It should be possible to collate information from, say, K-Ar dating and dendrochronology to derive <em>more</em> information that is directly available from either source. And the whole is greater than the sum of the parts, as they say.</p>

CC BY-SA 3.0
2014-11-28T17:33:01.470Z
While I see your point here that we can use dating of volcanic beds to constrain sedimentary rocks in time, this is not what I was asking. I was asking about directly deriving paleoclimate data from igneous rocks.
Gimelist
CC BY-SA 3.0
2014-11-28T18:11:45.573Z
@Michael: oic. Well, I only joined earthscience yesterday, and it just so happened when I saw your question on my second visit today, it was moments after reading a passage in Richard Dawkins *The Greatest Show on Earth* where he specifically makes the point that such crystalisation in igneous rocks is invaluable for cross-referencing across broader timeframes than can be accessed using direct C-14 dating of organic material. Your *the time resolution [from igneous rocks] will obviously not be as good as dating individual [sedimentary] beds from the lake floor* doesn't match what *he* says.
FumbleFingers
CC BY-SA 3.0
2014-11-28T18:37:37.860Z
Welcome to the site! Notice that I was referring to intrusive rocks, for example granites. While dating volcanic beds can be used to constrain the timing of sedimentation (given that said beds are interbedded), this is no possible in the case of plutonic rocks.
Gimelist
CC BY-SA 3.0
2014-11-28T19:47:18.430Z
@Michael: Thank you. The honest truth is I wouldn't have dreamt of posting an answer ordinarily (this stuff is *way* past my pay grade! :) But despite having no God to believe in or ascribe it to, I was lulled into supposing there must be some connection between the stuff I was reading by Dawkins and the question I saw immediately afterwards here. My god-that-I-don't-believe-in compelled me to assume it was my duty to share what little knowledge I had.
FumbleFingers
CC BY-SA 3.0
2014-11-28T19:49:57.807Z
...but actually, now I know [the difference between volcanic and plutonic](http://education-portal.com/academy/lesson/volcanic-vs-plutonic-igneous-rocks-definition-and-differences.html), it occurs to me maybe the distribution of plutonic rocks, their formation and appearance *over time* should show patterns of subsurface activity that would be relevant to paleoclimatology.
FumbleFingers
CC BY-SA 3.0
2014-11-28T21:02:26.200Z
... and this is exactly what I am asking. However, your answer is not related to my question.
Gimelist
CC BY-SA 3.0
2014-11-29T00:35:47.603Z
@Michael: I understand. I won't try to delete my own answer, especially since it's got a couple of upvotes, but others may vote as they see fit. I'll be interested to see if anyone else can address your exact question though.
FumbleFingers
CC BY-SA 3.0
2014-11-28T16:02:14.820Z
2014-11-28T16:02:14.820Z
FumbleFingers
<p>Stable isotope signatures in igneous rock (primarily $\delta$<sup>18</sup>O) can be affected by climate, but the effect is complicated and unreliable enough that I doubt it can really be used to say much about palaeoclimate. You might be interested in my friend Lara Owens' <a href="http://www.ees.nmt.edu/outside/alumni/papers/2013d_owens_lb.pdf" rel="nofollow">dissertation</a> in which she considers the influence of climate on $\delta$<sup>18</sup>O in lava from Mt Erebus, Antarctica. Oxygen isotopes in Erebus precipitation are some of the lightest in the world, and she suggests that this water, after incorporation into a hydrothermal system whose rocks were later assimilated into magma, caused the anomalous $\delta$<sup>18</sup>O in some of the samples.</p>

<p>It would be interesting to see if there is a global geographic trend in similar anomalies, but I haven't heard of anyone trying that.</p>

<p>A more direct way that igneous rocks can record paleoclimate is through the effects that the atmosphere can have on pyroclastic deposits. Isopleth maps often can reveal the direction the wind was blowing during the eruption. Clast morphologies might even tell you the weather -- I'm thinking of accretionary lapilli, which form when an ash-rich eruption plume encounters a rain storm.</p>

<p>In conclusion, you might be able to glean a few data points here and there, but nothing comparable to the amazing records available in sedimentary rocks.</p>

<p><strong>Edit to add:</strong> I just went to a lecture by Jay Quade about figuring out the timing of uplift in the Andes, and whether it came before or after the Atacama became hyperarid. Among many other geochemical tools, he used $\delta$<sup>2</sup>H in hydration waters on tephra, primarily to figure out palaeoaltitudes. He said he thinks the relationship between $\delta$<sup>2</sup>H and altitude has been fairly constant over the period of investigation (back to 50 mya).</p>

<p><strong>Edit to add:</strong> I had forgotten to point out that subglacial eruption deposits are often distinctive (tuyas, hyaloclastites, pillow basalts). Wherever these deposits are found, you know a glacier or ice sheet was present and if you can date the rock then you know when there was a glacier there. Some recent work has suggested that you can even figure out the thickness of the glacier using the concentration of dissolved gasses in melt inclusions in the subglacially erupted lava flow.</p>

CC BY-SA 3.0
2015-03-28T21:13:15.480Z
2015-08-25T01:45:39.267Z
2015-08-25T01:45:39.267Z
foobarbecue
<p>Paleoclimate data often derives from sedimentary rocks. Metamorphic rocks can also contribute to paleoclimate information in a wide variety of ways.</p>

<p>What about igneous rocks? I guess that this can question be divided into two, about intrusive and extrusive rocks.</p>

<p>Extrusive rocks will have direct contact with the climate. They may exchange geochemical signals with the atmosphere or water they've erupted to. The cooling rate may be dependent on ambient temperature. Lava flows may fossilise the soil.</p>

<p>Intrusive rocks may be harder to interpret in that manner, if at all. The time resolution will obviously not be as good as dating individual beds from the lake floor, but I still think something can be gained from it. Maybe some igneous rocks can form only after a special sedimentary rock (derived from a specific climate) has been buried and remelted? What about isotopes? Sedimentay systems often fractionate various isotopic systems. Can this variability be later traced in igneous rocks?</p>

CC BY-SA 3.0
2014-11-28T13:07:17.833Z
@SabreTooth not dumb. Although I've read somewhere that these rocks are "igneous going up, sedimentary doing down", they still represent some kind of interaction occurring between a magmatic system (especially when they're still hot in the "up" stage) and the atmospheric system.
Gimelist
<volcanology><geochemistry><paleoclimatology><igneous>
What, if any, paleoclimate data can be derived from igneous rocks?
Gimelist
# What, if any, paleoclimate data can be derived from igneous rocks?

(Asked by: username_0 on 2014-11-27)

Paleoclimate data often derives from sedimentary rocks. Metamorphic rocks can also contribute to paleoclimate information in a wide variety of ways.

What about igneous rocks? I guess that this can question be divided into two, about intrusive and extrusive rocks.

Extrusive rocks will have direct contact with the climate. They may exchange geochemical signals with the atmosphere or water they've erupted to. The cooling rate may be dependent on ambient temperature. Lava flows may fossilise the soil.

Intrusive rocks may be harder to interpret in that manner, if at all. The time resolution will obviously not be as good as dating individual beds from the lake floor, but I still think something can be gained from it. Maybe some igneous rocks can form only after a special sedimentary rock (derived from a specific climate) has been buried and remelted? What about isotopes? Sedimentay systems often fractionate various isotopic systems. Can this variability be later traced in igneous rocks?

**Tags:** volcanology, geochemistry, paleoclimatology, igneous

> **Comments:**
> **username_0**: @SabreTooth not dumb. Although I've read somewhere that these rocks are "igneous going up, sedimentary doing down", they still represent some kind of interaction occurring between a magmatic system (especially when they're still hot in the "up" stage) and the atmospheric system.  

---

## 3 answers

### Answer by username_3 on 2015-03-28. Score: 7 | Accepted answer

Stable isotope signatures in igneous rock (primarily $\delta$18O) can be affected by climate, but the effect is complicated and unreliable enough that I doubt it can really be used to say much about palaeoclimate. You might be interested in my friend Lara Owens' [dissertation](http://www.ees.nmt.edu/outside/alumni/papers/2013d_owens_lb.pdf) in which she considers the influence of climate on $\delta$18O in lava from Mt Erebus, Antarctica. Oxygen isotopes in Erebus precipitation are some of the lightest in the world, and she suggests that this water, after incorporation into a hydrothermal system whose rocks were later assimilated into magma, caused the anomalous $\delta$18O in some of the samples.

It would be interesting to see if there is a global geographic trend in similar anomalies, but I haven't heard of anyone trying that.

A more direct way that igneous rocks can record paleoclimate is through the effects that the atmosphere can have on pyroclastic deposits. Isopleth maps often can reveal the direction the wind was blowing during the eruption. Clast morphologies might even tell you the weather -- I'm thinking of accretionary lapilli, which form when an ash-rich eruption plume encounters a rain storm.

In conclusion, you might be able to glean a few data points here and there, but nothing comparable to the amazing records available in sedimentary rocks.

**Edit to add:** I just went to a lecture by Jay Quade about figuring out the timing of uplift in the Andes, and whether it came before or after the Atacama became hyperarid. Among many other geochemical tools, he used $\delta$2H in hydration waters on tephra, primarily to figure out palaeoaltitudes. He said he thinks the relationship between $\delta$2H and altitude has been fairly constant over the period of investigation (back to 50 mya).

**Edit to add:** I had forgotten to point out that subglacial eruption deposits are often distinctive (tuyas, hyaloclastites, pillow basalts). Wherever these deposits are found, you know a glacier or ice sheet was present and if you can date the rock then you know when there was a glacier there. Some recent work has suggested that you can even figure out the thickness of the glacier using the concentration of dissolved gasses in melt inclusions in the subglacially erupted lava flow.


---

### Answer by username_1 on 2015-08-24. Score: 3

Atmospheric pressure affects the bubbles that form in lava, and this effect can be used to estimate paleopressure at the time of emplacement of a lava flow. You might need some special conditions, but it is possible to make such a study. The technique is described in Sahagian et al. (2002).

---

Sahagian, D. L., Proussevitch, A. A., & Carlson, W. D. (2002). Analysis of vesicular basalts and lava emplacement processes for application as a paleobarometer/paleoaltimeter. The Journal of Geology, 110(6), 671-685. [[JSTOR link](http://www.jstor.org/stable/10.1086/342627), [free PDF link](http://www.geo.mtu.edu/~raman/papers2/SahagianJG.pdf)]


---

### Answer by username_2 on 2014-11-28. Score: 3

[Potassium–argon (K-Ar) dating](http://en.wikipedia.org/wiki/K%E2%80%93Ar_dating) specifically and *only* works with igneous rocks. The idea being that when molten magma solidifies into, say, granite or basalt, any potassium ends up locked into crystaline forms. Some of that potassium will be the unstable K-40 isotope, decaying into A-40 with a half-life of 1.26 billion years. Since virtually *no* A-40 would have been present at time of crystalisation, the K-40:A-40 ratio gives a good indication of when solidification occurred.

There are of course other "radioactive clocks" based on other elements/isotopes with longer or short half-lives, which may be more suitable depending on how far back you're trying to look. And although we're not likely to find much in the way of organic material (fossils, etc.) in igneous rocks, information from different sources can usefully be collated.

I don't know of any specific case, but I'd have thought there would be many situations where sedimentary rock has been laid down over precisely-dated igneous rocks. And I don't know the exact limitations of [dendrochronology](http://en.wikipedia.org/wiki/Dendrochronology), but it seems at least *possible* that you could detect identifiable "pattern sequences" in ancient annual tree-trunk ring growth patterns that suddenly become far more meaningful if you know *when* those patterns were formed.

Some seasonal growth variation will be down to local factors, and some will reflect "global" events. But given enough data, they could be distinguished. It should be possible to collate information from, say, K-Ar dating and dendrochronology to derive *more* information that is directly available from either source. And the whole is greater than the sum of the parts, as they say.

> **Comments:**
> **username_0**: While I see your point here that we can use dating of volcanic beds to constrain sedimentary rocks in time, this is not what I was asking. I was asking about directly deriving paleoclimate data from igneous rocks.  
> **username_2**: @Michael: oic. Well, I only joined earthscience yesterday, and it just so happened when I saw your question on my second visit today, it was moments after reading a passage in Richard Dawkins *The Greatest Show on Earth* where he specifically makes the point that such crystalisation in igneous rocks is invaluable for cross-referencing across broader timeframes than can be accessed using direct C-14 dating of organic material. Your *the time resolution [from igneous rocks] will obviously not be as good as dating individual [sedimentary] beds from the lake floor* doesn't match what *he* says.  
> **username_0**: Welcome to the site! Notice that I was referring to intrusive rocks, for example granites. While dating volcanic beds can be used to constrain the timing of sedimentation (given that said beds are interbedded), this is no possible in the case of plutonic rocks.  
> **username_2**: @Michael: Thank you. The honest truth is I wouldn't have dreamt of posting an answer ordinarily (this stuff is *way* past my pay grade! :) But despite having no God to believe in or ascribe it to, I was lulled into supposing there must be some connection between the stuff I was reading by Dawkins and the question I saw immediately afterwards here. My god-that-I-don't-believe-in compelled me to assume it was my duty to share what little knowledge I had.  
> **username_2**: ...but actually, now I know [the difference between volcanic and plutonic](http://education-portal.com/academy/lesson/volcanic-vs-plutonic-igneous-rocks-definition-and-differences.html), it occurs to me maybe the distribution of plutonic rocks, their formation and appearance *over time* should show patterns of subsurface activity that would be relevant to paleoclimatology.  
> **username_0**: ... and this is exactly what I am asking. However, your answer is not related to my question.  
> **username_2**: @Michael: I understand. I won't try to delete my own answer, especially since it's got a couple of upvotes, but others may vote as they see fit. I'll be interested to see if anyone else can address your exact question though.  

---

