<p>There are few studies of paleobarometry, but to my knowledge at least three different proxies have been used to infer past atmospheric pressures, and they pretty much agree:</p>
<ul>
<li><strong>Fossil raindrop imprints</strong>. <a href="https://doi.org/10.1038/nature10890" rel="nofollow noreferrer">Som et al. (2012)</a> used such imprints found in tuffs of the Ventersdorp Supergroup (South Africa), dated around 2.7 Ga, to determine the terminal velocity of raindrops and, finally, surface air density. They estimate that it was, at that time, less than twice modern levels (2.3 kg m<sup>−3</sup> compared 1.2 kg m<sup>−3</sup>).</li>
<li><strong><span class="math-container">$\ce{N2}/\ce{^36Ar}$</span> ratio</strong>. <a href="https://doi.org/10.1126/science.1240971" rel="nofollow noreferrer">Marty et al. (2013)</a> used fluid inclusions trapped in three different Archean hydrothermal quartz samples to determine the past partial pressure of nitrogen and carbon dioxide, finding <span class="math-container">$P_{\ce{N2}} \leq 1.1$</span> bar and <span class="math-container">$P_{\ce{CO2}} \leq 0.7$</span> bar.</li>
<li><strong>Lava flow vesicle size</strong>. <a href="https://doi.org/10.1038/ngeo2713" rel="nofollow noreferrer">Som et al. (2016)</a> used this proxy in a basaltic lava flow from the Pilbara Craton (Australia), emplaced around 2.7 Ga, finding that the late Archaean atmospheric pressure was likely less than 0.5 bar.</li>
</ul>
<p>But these are only a few data points giving a snapshot of a particular moment in time. I'm not aware that there has been efforts to reconstruct a more comprehensive paleobarometric record.</p>

CC BY-SA 4.0
2024-03-04T16:23:22.630Z
Thx! The wikipedia-page "paleo-atmosphere" to me suggests the empirical methods to determine abundance of atmospheric oxygen and carbon-dioxide should give estimates of their part. pressures (that would be sufficient to discuss most of the remarkable phenomena). So a sober scientific approach would have been to use graphs of these part. pressures. To go to fractional atm. comp., one needs additional info on nitrogen, argon, methane... and this would seem somewhat unnecessary (although the matter seems to be relevant to address the faint young sun paradox, suitable boiling point for water)
5th decile
CC BY-SA 4.0
2024-03-04T16:33:37.623Z
Ok, in my previous comment (and in my original question) I'm sloppily conflating partial pressure, partial number density, partial mass density... I'm obviously aware that the temperature mediates between them and that paleo-temperature is not constant and an interesting subject in itself.
5th decile
CC BY-SA 4.0
2024-03-04T13:32:46.807Z
2024-03-04T13:32:46.807Z
Jean-Marie Prival
<p>In many introductory geology courses, a great deal of time is spent on the historical composition of earth's atmosphere: the great oxygenation event, oxygen maximum during the carboniferous, ups and downs for the CO2 trend...</p>
<p>The graphs supporting those discussions always (according to my memory) show the fractional composition of the atmosphere. But given that for many of the phenomena one wants to explain with this composition trend it would rather be the partial pressures or total mass of each of the composing gases that would be relevant, my question is whether there is (in the scientific literature) an account of the total pressure and / or the total mass of earth's atmosphere on geological time scales?</p>

<geology><atmosphere>
The total pressure / total mass of earth's atmosphere on geological time scales
5th decile
# The total pressure / total mass of earth's atmosphere on geological time scales

(Asked by: username_0 on 2024-03-04)

In many introductory geology courses, a great deal of time is spent on the historical composition of earth's atmosphere: the great oxygenation event, oxygen maximum during the carboniferous, ups and downs for the CO2 trend...

The graphs supporting those discussions always (according to my memory) show the fractional composition of the atmosphere. But given that for many of the phenomena one wants to explain with this composition trend it would rather be the partial pressures or total mass of each of the composing gases that would be relevant, my question is whether there is (in the scientific literature) an account of the total pressure and / or the total mass of earth's atmosphere on geological time scales?

**Tags:** geology, atmosphere


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## 1 answers

### Answer by username_1 on 2024-03-04. Score: 3 | Accepted answer

There are few studies of paleobarometry, but to my knowledge at least three different proxies have been used to infer past atmospheric pressures, and they pretty much agree:

* **Fossil raindrop imprints**. [Som et al. (2012)](https://doi.org/10.1038/nature10890) used such imprints found in tuffs of the Ventersdorp Supergroup (South Africa), dated around 2.7 Ga, to determine the terminal velocity of raindrops and, finally, surface air density. They estimate that it was, at that time, less than twice modern levels (2.3 kg m−3 compared 1.2 kg m−3).
* **$\ce{N2}/\ce{^36Ar}$ ratio**. [Marty et al. (2013)](https://doi.org/10.1126/science.1240971) used fluid inclusions trapped in three different Archean hydrothermal quartz samples to determine the past partial pressure of nitrogen and carbon dioxide, finding $P\_{\ce{N2}} \leq 1.1$ bar and $P\_{\ce{CO2}} \leq 0.7$ bar.
* **Lava flow vesicle size**. [Som et al. (2016)](https://doi.org/10.1038/ngeo2713) used this proxy in a basaltic lava flow from the Pilbara Craton (Australia), emplaced around 2.7 Ga, finding that the late Archaean atmospheric pressure was likely less than 0.5 bar.

But these are only a few data points giving a snapshot of a particular moment in time. I'm not aware that there has been efforts to reconstruct a more comprehensive paleobarometric record.

> **Comments:**
> **username_0**: Thx! The wikipedia-page "paleo-atmosphere" to me suggests the empirical methods to determine abundance of atmospheric oxygen and carbon-dioxide should give estimates of their part. pressures (that would be sufficient to discuss most of the remarkable phenomena). So a sober scientific approach would have been to use graphs of these part. pressures. To go to fractional atm. comp., one needs additional info on nitrogen, argon, methane... and this would seem somewhat unnecessary (although the matter seems to be relevant to address the faint young sun paradox, suitable boiling point for water)  
> **username_0**: Ok, in my previous comment (and in my original question) I'm sloppily conflating partial pressure, partial number density, partial mass density... I'm obviously aware that the temperature mediates between them and that paleo-temperature is not constant and an interesting subject in itself.  

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