<p>The process you're describing in the question is the one at the origin of coal. Although coal deposits are known from the Devonian to the Quaternary, they have been 3 major periods of depositions (see <strong>Thomas 2013</strong>): the Carboniferous-Early Permian, the Jurassic-Cretaceous and during the Cenozoic. So, indeed the Carboniferous is one of the main period of coal deposit but I couldn't find any numerical evidence in the literature that this is the "main" period of deposit. The idea that it is is most likely due to the fact that the western Europe and eastern USA coal mines (hence historically the most noteworthy) all happen to be Carboniferous.<br>
But as far as oil (petroleum) is concerned, according to <strong>Klemme &amp; Ulmishek 1991</strong> (straight from the abstract):</p>

<blockquote>
  <p>Six stratigraphic intervals, representing one-third of Phanerozoic
  time, contain petroleum source rocks that have provided more than 90%
  of the world's discovered original reserves of oil and gas (in barrels
  of oil equivalent). The six intervals are (1) Silurian (generated 9%
  of the world's reserves), (2) Upper Devonian-Tournaisian (8% of
  reserves), (3) Pennsylvanian-Lower Permian (8% of reserves), (4) Upper
  Jurassic (25% of reserves), (5) middle Cretaceous (29% of reserves),
  and (6) Oligocene-Miocene (12.5% of reserves)</p>
</blockquote>

<p>See <strong>Klemme 1994</strong> for a detailed explanation on the origins of the Jurassic source rocks (i. e. 25% of the world's reserve at the time): most of them are marine, but some are fluvial or from lagoonal inland seas (table 3.2).</p>

<p><sub>References:<br>
Klemme, 1994. Petroleum systems of the world involving Upper Jurassic source rocks. In Maggon &amp; Dow (Eds), <em>The petroleum system - from source to trap</em>, AAPG Memoir, 60: 51-72.<br>
Klemme &amp; Ulmishek, 1991. Effective petroleum source rocks of the world; stratigraphic distribution and controlling depositional factors
<em>AAPG Bulletin</em>, 75: 1809-1851.<br>
Thomas, 2013. <em>Coal Geology, 2nd Edition.</em> Wiley-Blackwell, 444pp.
</sub></p>

CC BY-SA 3.0
2014-09-18T13:47:37.047Z
2014-09-18T14:07:06.687Z
2014-09-18T14:07:06.687Z
plannapus
<p>It is said that <a href="http://www.energyquest.ca.gov/story/chapter08.html">most of the fossil fuels</a> in existence today (coal, oil, gas) came from the <a href="https://en.wikipedia.org/wiki/Carboniferous#Rocks_and_coal">Carboniferous period</a>. A unique set of circumstances lead to the creation of fossil fuels, which depends on anaerobic decomposition:</p>

<ul>
<li>Plants evolved bark as an effective defense against insect herbivores</li>
<li>Very few organisms at the time could digest or decompose the bark fiber <a href="https://en.wikipedia.org/wiki/Lignin">lignin</a></li>
</ul>

<p>Suppose that the Carboniferous period never happened, or for whatever reason the period never produced fossil fuels. How much fossil fuel would we have today instead? How much of today's fossil fuel deposits were created during the Carboniferous?</p>

CC BY-SA 3.0
2014-09-18T06:44:21.523Z
This might be true for coal (though probably overstated) but oil does not derive from land plants, it has a marine origin (hence the offshore oil rig).
plannapus
CC BY-SA 3.0
2014-09-18T12:07:40.600Z
@plannapus: Offshore rigs are offshore because that's where the oil and gas are today. The source rocks that produced the hydrocarbons are often continental (lacustrine, say), as they are often from a relatively early phase of the basin's history, such as early rifting in a rift basin or passive margin's case.
Matt Hall
CC BY-SA 3.0
2014-09-18T13:08:03.650Z
Just as an example, most of [the oil from the northern North Sea](https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/197333/TR_SEA2_Geology.pdf) is Jurassic and was deposited in marine mudstones. The point of my previous comment was that the phenomenon the OP was describing is the one producing specifically coal, not all fossil fuel.
plannapus
<geology><fossil-fuel>
How much fossil fuel came from the Carboniferous?
congusbongus
# How much fossil fuel came from the Carboniferous?

(Asked by: username_0 on 2014-09-18)

It is said that [most of the fossil fuels](http://www.energyquest.ca.gov/story/chapter08.html) in existence today (coal, oil, gas) came from the [Carboniferous period](https://en.wikipedia.org/wiki/Carboniferous#Rocks_and_coal). A unique set of circumstances lead to the creation of fossil fuels, which depends on anaerobic decomposition:

* Plants evolved bark as an effective defense against insect herbivores
* Very few organisms at the time could digest or decompose the bark fiber [lignin](https://en.wikipedia.org/wiki/Lignin)

Suppose that the Carboniferous period never happened, or for whatever reason the period never produced fossil fuels. How much fossil fuel would we have today instead? How much of today's fossil fuel deposits were created during the Carboniferous?

**Tags:** geology, fossil-fuel

> **Comments:**
> **username_1**: This might be true for coal (though probably overstated) but oil does not derive from land plants, it has a marine origin (hence the offshore oil rig).  
> **username_2**: @username_1: Offshore rigs are offshore because that's where the oil and gas are today. The source rocks that produced the hydrocarbons are often continental (lacustrine, say), as they are often from a relatively early phase of the basin's history, such as early rifting in a rift basin or passive margin's case.  
> **username_1**: Just as an example, most of [the oil from the northern North Sea](https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/197333/TR_SEA2_Geology.pdf) is Jurassic and was deposited in marine mudstones. The point of my previous comment was that the phenomenon the OP was describing is the one producing specifically coal, not all fossil fuel.  

---

## 1 answers

### Answer by username_1 on 2014-09-18. Score: 8

The process you're describing in the question is the one at the origin of coal. Although coal deposits are known from the Devonian to the Quaternary, they have been 3 major periods of depositions (see **Thomas 2013**): the Carboniferous-Early Permian, the Jurassic-Cretaceous and during the Cenozoic. So, indeed the Carboniferous is one of the main period of coal deposit but I couldn't find any numerical evidence in the literature that this is the "main" period of deposit. The idea that it is is most likely due to the fact that the western Europe and eastern USA coal mines (hence historically the most noteworthy) all happen to be Carboniferous.  
But as far as oil (petroleum) is concerned, according to **Klemme & Ulmishek 1991** (straight from the abstract):

> Six stratigraphic intervals, representing one-third of Phanerozoic
> time, contain petroleum source rocks that have provided more than 90%
> of the world's discovered original reserves of oil and gas (in barrels
> of oil equivalent). The six intervals are (1) Silurian (generated 9%
> of the world's reserves), (2) Upper Devonian-Tournaisian (8% of
> reserves), (3) Pennsylvanian-Lower Permian (8% of reserves), (4) Upper
> Jurassic (25% of reserves), (5) middle Cretaceous (29% of reserves),
> and (6) Oligocene-Miocene (12.5% of reserves)

See **Klemme 1994** for a detailed explanation on the origins of the Jurassic source rocks (i. e. 25% of the world's reserve at the time): most of them are marine, but some are fluvial or from lagoonal inland seas (table 3.2).

References:  
Klemme, 1994. Petroleum systems of the world involving Upper Jurassic source rocks. In Maggon & Dow (Eds), *The petroleum system - from source to trap*, AAPG Memoir, 60: 51-72.  
Klemme & Ulmishek, 1991. Effective petroleum source rocks of the world; stratigraphic distribution and controlling depositional factors
*AAPG Bulletin*, 75: 1809-1851.  
Thomas, 2013. *Coal Geology, 2nd Edition.* Wiley-Blackwell, 444pp.


---

