Abiogenic petroleum origin
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The hypothesis of '''abiogenic petroleum origin''' is an alternative hypothesis to the [[Petroleum#Formation|biological origin theory]] held by a majority of petroleum geologists and engineers.<ref name=glasby2006> {{cite journal
|last= Glasby
|first=Geoffrey P.
|date=2006
|title= Abiogenic origin of hydrocarbons: an historical overview
|journal= Resource Geology
|volume=56
|issue=1
|pages=83–96
|url=http://static.scribd.com/docs/j79lhbgbjbqrb.pdf
|format=PDF
|accessdate=2008-02-17}}
</ref> It states that natural [[petroleum]] was formed from deep carbon deposits, perhaps dating to the [[formation and evolution of the solar system|formation of the Earth]]. The presence of [[methane]] in the solar system is taken as evidence. Supporters of the abiogenic hypothesis suggest that there may be a great deal more petroleum on Earth than commonly thought, and that petroleum may originate from carbon-bearing fluids which migrate upward from the [[mantle (geology)|mantle]]. The abiogenic petroleum hypothesis predicts that oil is formed in the mantle at temperatures and pressures consistent with the laws of thermodynamics.{{huh?}}{{Fact|date=July 2008}}
Although the abiogenic hypothesis is accepted by some geologists in Russia, geologists consider the [[Petroleum#Formation|'''biogenic''' formation of petroleum]] to be supported scientifically. Though evidence exists for abiogenic creation of methane and hydrocarbon gases within the Earth<ref>Lollar, Sherwood et al. 2002. Abiogenic formation of alkanes in the Earth's crust as a minor source for global hydrocarbon reservoirs. ''Nature'', '''416''', pp522-524. [http://adsabs.harvard.edu/abs/2002Natur.416..522S Abstract]</ref><ref name="lollar2006">{{cite journal | author = B. Sherwood Lollar | coauthors = G. Lacrampe-Couloume, G.F. Slater, J. Ward, D.P. Moser, T.M. Gihring, L.-H. Lin, T.C. Onstott | year = 2006 | month = February | title = Unravelling abiogenic and biogenic sources of methane in the Earth's deep subsurface | journal = Chemical Geology | volume = 226 | issue = 3-4 | pages = 328–339 | doi = 10.1016/j.chemgeo.2005.09.027 }}</ref>, studies indicate that they are not produced in commercially significant quantities.<ref>http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=7052010</ref> All hydrocarbon gases that are extracted for use as fuel or raw materials for industrial production contain a median abiogenic hydrocarbon content of only 200 parts per million (ppm) or one fiftieth of one percent. The abiogenic origin of petroleum has also recently been reviewed in detail by Glasby, who raises a number of objections, including that there is no direct evidence to date of abiogenic petroleum (liquid crude oil and long-chain hydrocarbon compounds). <ref name=glasby2006>{{cite journal |author= Glasby GP |date=2006 |title= Abiogenic origin of hydrocarbons: an historical overview |journal= Resour Geol |volume=56 |issue=1 |pages=83–96 |url=http://static.scribd.com/docs/j79lhbgbjbqrb.pdf |format=PDF |accessdate=2008-01-29}}</ref>
Various abiogenic hypotheses were first proposed after advances in science in the nineteenth century, most notably by [[Alexander Von Humboldt|Alexander von Humboldt]], the Russian chemist [[Dmitri Mendeleev]] and the French chemist [[Marcellin Berthelot]]. Since that time, these hypotheses have lost ground to the more popular view that petroleum is a [[fossil fuel]]. The biogenic hypothesis for petroleum is much older and was first proposed by [[Georg Agricola]] in the 16th century.
Abiogenic hypotheses saw a revival in the last half of the twentieth century by Russian and Ukrainian scientists, and more interest has been generated in the West after the publication in 1999 of ''[[The Deep Hot Biosphere]]'' by [[Thomas Gold]]. Gold's version of the hypothesis partly is based on the existence of a [[biosphere]] composed of [[thermophile]] bacteria in the earth's crust, which may explain the existence of certain [[Biomarker (petroleum)|biomarker]]s in extracted petroleum.<ref name="gold1999">{{cite book | author=Gold, Thomas | year=1999 | title=The deep, hot biosphere | publisher=Copernicus Books|id=ISBN 0-387-98546-8}}</ref>
== History of abiogenic hypothesis ==
[[Alexander von Humboldt]] was the first to propose an inorganic abiogenic hypothesis for petroleum formation after he observed petroleum springs in the Bay of Cumaux (Cumana) on the Northeast coast of Venezuela.<ref>[http://books.google.com/books?id=IQkDAAAAIAAJ&pg=PA93&lpg=PA93 Sadtler, The Genesis and Chemical Relations of Petroleum and Natural Gas, 1897]</ref>
In 1804 [[von Humboldt]] said, "petroleum is the product of a distillation from great depth and issues from the primitive rocks beneath which the forces of all volcanic action lie."
The magmatic hypothesis, in the opinion of George F. Becker <ref>[http://books.google.com/books?hl=en&id=mKkPAAAAIAAJ&dq=becker+relations+between+local+magnetic+disturbances&printsec=frontcover&source=web&ots=-g6J28hk9R&sig=jseEVBdSmiF5iuva6q5RMS4Ifw8 Becker, Relations Between Local Magnetic Disturbances and the Genesis of Petroleum, 1909]</ref>, is entitled to high respect because of its advocacy by very great men of science. According to Becker:
"On [[August 12]] [[1805]], [[von Humboldt]] and [[Gay-Lussac]] witnessed a great eruption of [[Vesuvius]]; and at times they found the prevailing smell wafted from the crater bituminous."
Indeed, [[Abraham Gottlob Werner|Wernerian]] appreciation of basalts at times saw them as solidified oils or bitumen. While these notions have been disabused, the basic notion that petroleum is associated with magmatism has persisted. The chief proponents of what would become the abiogenic hypothesis were [[von Humboldt]], [[Mendeleev]]<ref>Mendeleev, D., 1877. L'origine du petrole. Revue Scientifique, 2e Ser., VIII, p. 409-416.</ref> and [[Marcellin Berthelot|Berthelot]].
Russian geologist [[Nikolai Kudryavtsev|Nikolai Alexandrovitch Kudryavtsev]] was the first to propose the modern abiotic hypothesis of petroleum in 1951. He analyzed the geology of the [[Athabasca Tar Sands]] in [[Alberta, Canada]] and concluded that no "source rocks" could form the enormous volume of hydrocarbons (estimated today 1.7 trillion barrels), and that therefore the most plausible explanation is abiotic deep petroleum. However, humic coals have been proposed for the source rocks by [http://www.searchanddiscovery.com/documents/2004/stanton/index.htm Stanton (2005)].
Although this hypothesis is supported by geologists in [[Russia]] and [[Ukraine]]{{Fact|date=July 2008}}, it has recently begun to receive attention in the West{{Fact|date=July 2008}}, where the biogenic petroleum theory is accepted by the vast majority of petroleum [[geologist]]s. Kudryavtsev's work was continued by many Russian researchers — [[Petr N. Kropotkin]], [[Vladimir B. Porfir'ev]], [[Emmanuil B. Chekaliuk]], Vladilen A. Krayushkin, [[Georgi E. Boyko]], [[Georgi I. Voitov]], [[Grygori N. Dolenko]], Iona V. Greenberg, Nikolai S. Beskrovny, [[Victor F. Linetsky]] and many others.
Astrophysicist [[Thomas Gold]] <ref name="gold1999" /> was one of the abiogenic hypothesis's most prominent proponents in recent years in the West, until his death in 2004. Dr. Jack Kenney of Gas Resources Corporation<ref name="kenney2">{{cite web| url = http://www.gasresources.net/ThrmcCnstrnts.htm| title = The Constraints of the Laws of Thermodynamics upon the Evolution of Hydrocarbons: The Prohibition of Hydrocarbon Genesis at Low Pressures.| accessdate = 2006-08-16| author = Kenney, J.F.| coauthors = I. K. Karpov I.K., Shnyukov Ac. Ye. F., Krayushkin V.A., Chebanenko I.I., Klochko V.P.| year = 2002}}</ref><ref name="kenney2001">{{cite journal | author=Kenney, J., Shnyukov, A., Krayushkin, V., Karpov, I., Kutcherov, V. and Plotnikova, I. | title= Dismissal of the claims of a biological connection for natural petroleum | journal=Energia | volume=22 | issue=3 | year=2001 | pages=26–34}} [http://www.gasresources.net/DisposalBioClaims.htm Article link]</ref><ref name="kenney2002">{{cite journal | author=Kenney, J., Kutcherov, V., Bendeliani, N. and Alekseev, V. | title= The evolution of multicomponent systems at high pressures: VI. The thermodynamic stability of the hydrogen–carbon system: The genesis of hydrocarbons and the origin of petroleum | journal=Proceedings of the National Academy of Sciences | volume=99 | year=2002 | pages=10976–10981 | url=http://www.pnas.org/cgi/content/full/99/17/10976 | accessdate=2006-10-04 | doi=10.1073/pnas.172376899 | pmid= 12177438 }}</ref> is perhaps the foremost proponent in the West. The hypothesis receives continued attention [http://321energy.com/editorials/engdahl/engdahl092607.html in oil industry media].
== Foundations of the hypotheses ==
Within the mantle, carbon may exist as hydrocarbon molecules, chiefly [[methane]], and as elemental carbon, carbon dioxide and carbonates. The abiotic hypothesis is that a full suite of hydrocarbons found in petroleum can be generated in the mantle by abiogenic processes,<ref name="kenney2002" /> and these hydrocarbons can migrate out of the mantle, into the crust until they escape to the surface or are trapped by impermeable strata, forming petroleum reservoirs.
Abiogenic theories reject the supposition that certain molecules found within petroleum, known as "biomarkers," are indicative of the biological origin of petroleum. They contend that some of these molecules could have come from the microbes that the petroleum encounters in its upward migration through the crust, and that some of them are found in meteorites, which have presumably never contacted living material, and that some can be generated by plausible reactions in petroleum abiogenically.<ref name="kenney2001" />
The hypothesis is founded primarily upon: <!-- Comments are noting major theories rather than first sources; work in progress! -->
{| class="wikitable"
!Proponents
!Item
|-
| Gold
| The ubiquity of methane within the solar system
|-
| Gold
| The presence of hydrocarbons in extraterrestrial bodies including meteors, moons and comets <ref>{{cite journal | author=Hodgson, G. and Baker, B. | title=Evidence for porphyrins in the Orgueil meteorite | journal = Nature | volume=202 | year=1964 | pages=125–131 | doi=10.1038/202125a0}}</ref><ref>{{cite journal | author=Hodgson, G. and Baker, B. | title=Porphyrin abiogenesis from pyrole and formaldehyde under simulated geochemical conditions | journal=Nature | volume=216 | year=1964 | pages=29–32 | doi=10.1038/216029a0}}</ref>
|-
| Gold, Kenney <!-- Gold: temp+pressure, and primordial -->
| Plausible mechanisms of abiotically chemically synthesizing hydrocarbons within the mantle <ref name="kenney2">{{cite web| url = http://www.gasresources.net/ThrmcCnstrnts.htm| title = The Constraints of the Laws of Thermodynamics upon the Evolution of Hydrocarbons: The Prohibition of Hydrocarbon Genesis at Low Pressures.| accessdate = 2006-08-16| author = Kenney, J.F.| coauthors = I. K. Karpov I.K., Shnyukov Ac. Ye. F., Krayushkin V.A., Chebanenko I.I., Klochko V.P.| year = 2002}}</ref><ref name="kenney2001">{{cite journal | author=Kenney, J., Shnyukov, A., Krayushkin, V., Karpov, I., Kutcherov, V. and Plotnikova, I. | title= Dismissal of the claims of a biological connection for natural petroleum | journal=Energia | volume=22 | issue=3 | year=2001 | pages=26–34}} [http://www.gasresources.net/DisposalBioClaims.htm Article link]</ref><ref name="kenney2002">{{cite journal | author=Kenney, J., Kutcherov, V., Bendeliani, N. and Alekseev, V. | title= The evolution of multicomponent systems at high pressures: VI. The thermodynamic stability of the hydrogen–carbon system: The genesis of hydrocarbons and the origin of petroleum | journal=Proceedings of the National Academy of Sciences | volume=99 | year=2002 | pages=10976–10981 | url=http://www.pnas.org/cgi/content/full/99/17/10976 | accessdate=2006-10-04 | doi=10.1073/pnas.172376899 | pmid= 12177438 }}</ref>
|-
| Kudryavtsev, Gold
| Hydrocarbon-rich areas tend to be hydrocarbon-rich at many different levels ([[Kudryavtsev's Rule]])
|-
| Kudryavtsev, Gold
| Petroleum and methane deposits are found in large patterns related to deep-seated large-scale structural features of the crust rather than to the patchwork of sedimentary deposits
|-
| Gold <!-- Gold: similarity across large areas, calcite related, fractionation -->
| Interpretations of the chemical and isotopic composition of natural petroleum
|-
| Kudryavtsev, Gold
| The presence of oil and methane within non-[[sedimentary rock]]s upon the Earth <ref name="brown2005">{{cite journal | author=Brown, David | title= Vietnam finds oil in the basement| journal=AAPG Explorer | year=2005 | volume=26| issue=2 | pages=8–11}} [http://www.aapg.org/explorer/2005/02feb/vietnam.cfm Abstract]</ref>
|-
| Gold
| The existence of [[methane clathrate|methane hydrate]] deposits
|-
| Gold <!-- Gold (lack biological: Optical and odd-even; source may be association) -->
| Perceived ambiguity in some assumptions and key evidence used in the orthodox [[Petroleum#Formation|biogenic petroleum theories]] <ref name="kenney2" />
|-
| Gold
| [[Bituminous coal]] creation is based upon deep hydrocarbon [[seep]]s
|-
| Kudryavtsev
| Inability to create petroleum-like material from organic material at the time the theories were created
|-
| Gold <!-- Gold: constant carbon, no oxygen buildup -->
| Surface carbon budget and oxygen levels stable over geologic time scales
|-
| Kudryavtsev<!-- Kudryatsev: Ni&V porphyrins, 60+km depths -->, Gold <!-- Gold: Nickel and vanadium porphyrins, depths of 60 to 160 km, too much hydrogen -->
| Biogenic theories do not explain some hydrocarbon deposit characteristics
|-
| Szatmari
| The distribution of metals in crude oils fits better with upper serpentinized mantle, primitive mantle and chondrite patterns than oceanic and continental crust, and show no correlation with sea water<ref name="szatmari">Szatmari, P, Da Fonseca, T, and Miekeley, N. Trace Element Evidence for Major Contribution to Commercial Oils by Serpentinizing Mantle Peridotites. ''AAPG Research Conference'', Calgary, Canada, 2005. [http://www.searchanddiscovery.com/documents/abstracts/2005research_calgary/abstracts/short/szatmari.htm Abstract]</ref>
|-
| Gold
| The association of hydrocarbons with helium, a noble gas
|-
| Gold
| Deep microbial hypothesis of hydrocarbon generation
|}
==Conventional theories==
Most [[petroleum geology|petroleum geologists]] prefer theories of [[oil reservoir|oil formation]] which hold that oil originated in [[Western Interior Seaway|shallow seas]] as vast quantities of marine [[plankton]] or plant materials which died and sank into the [[bay mud|mud]] at the bottom under [[hypoxia (environmental)|anaerobic conditions]] that prevented [[biodegradation]]. Under these conditions, [[anaerobic organism|anaerobic bacteria]] converted the [[lipid]]s (fats, oils and waxes) into a waxy substance called [[kerogen]].
As the [[source rock]] was buried deeper, [[overburden pressure]] raised temperatures into the [[oil window]], between 60 and 120 °C, in which [[thermal depolymerization]] broke up the [[cracking (chemistry)|kerogen]] molecules into the [[alkane|straight-chain '''hydrocarbons]] that make up most of petroleum. This setting is called generation kitchen. Once crude oil formed, it became very [[fluid dynamics|fluid]], and migrated upward through the [[stratum|rock strata]]. This setting is called oil expulsion. Eventually it was either trapped in an [[oil reservoir]] or oil [[seep|escaped to the surface]] and was [[biodegradation|biodegraded]] by soil bacteria.
Any oil buried deeper entered the [[gas window]] of 120 °C to 220 °C and was converted into [[natural gas]] by [[cracking (chemistry)|thermal cracking]]. Thus, below a certain depth, the theories predicts that no oil will be found, only [[natural gas field|unassociated gas]]. If it went [[metamorphic rock|even deeper]], even natural gas would be destroyed by [[pyrolysis|high temperatures]].'''
== Proposed mechanisms of abiogenic petroleum ==
=== Primordial deposits ===
Thomas Gold's work was focused on hydrocarbon deposits of primordial origin. Meteorites are believed to represent the major composition of material from which the Earth was formed. Some meteorites, such as [[carbonaceous chondrite]]s, contain carbonaceous material. If a large amount of this material is still within the Earth, it could have been leaking upward for billions of years. The thermodynamic conditions within the mantle would allow many hydrocarbon molecules to be at equilibrium under high pressure and high temperature. Although molecules in these conditions may disassociate, resulting fragments would be reformed due to the pressure. An average equilibrium of various molecules would exist depending upon conditions and the carbon-hydrogen ratio of the material. <ref name="goldusgs">{{cite paper | author = Thomas Gold | title = The Origin of Methane (and Oil) in the Crust of the Earth, U.S.G.S. Professional Paper 1570, The Future of Energy Gases | publisher = USGS | date = 1993 | url = http://web.archive.org/web/20021015163818/www.people.cornell.edu/pages/tg21/usgs.html | accessdate = 2006-10-10}}</ref>
=== Creation within the mantle ===
Russian researchers performed the above calculations of thermodynamic equilibrium and concluded that hydrocarbon mixes would be created within the mantle. Experiments under high temperatures and pressures produced many hydrocarbons, including n-alkanes through C<sub>10</sub>H<sub>22</sub>, from iron oxide, calcium carbonate, and water. <ref name="kenney2002" /> Because such materials are in the mantle and in subducted crust, there is no requirement that all hydrocarbons be produced from primordial deposits.
=== Hydrogen generation ===
Hydrogen gas and water have been found more than 6 kilometers deep in the upper crust, including in the Siljan Ring boreholes and the [[Kola Superdeep Borehole]]. There are data in the western United States that [[aquifer]]s from near the surface may extend to depths of 10 to 20 km. Hydrogen gas can be created by water reacting with [[silicate]]s, [[quartz]] and [[feldspar]], in temperatures in the 25° to 270°C range. These minerals are common in crustal rocks such as [[granite]]. Hydrogen may react with dissolved carbon compounds in water to form methane and higher carbon compounds. <ref>{{cite conference | author = G.J. MacDonald | year = 1988 | title = Major Questions About Deep Continental Structures | booktitle = Deep drilling in crystalline bedrock, v. 1 | editor = A. Bodén and K.G. Eriksson | publisher = Springer-Verlag | location = Berlin | pages = 28-48 | id = ISBN 3-540-18995-5}}</ref>
One reaction not involving silicates which can create hydrogen is:
''Ferrous oxide + Water → Magnetite + hydrogen''<br>
:<math>3FeO + H_2O \rarr Fe_3O_4 + H_2</math>
The above reaction operates best at low pressures. At pressures greater than 5 GPa almost no hydrogen is created. <ref name="scott2004">{{cite journal | author = Scott HP | coauthors = Hemley RJ, Mao HK, Herschbach DR, Fried LE, Howard WM, Bastea S. | year = 2004 | month = September | title = Generation of methane in the Earth's mantle: in situ high pressure-temperature measurements of carbonate reduction | journal = Proc Natl Acad Sci | volume = 101 | issue = 39 | pages = 14023–6 | doi = 10.1073/pnas.0405930101 | url = http://www.pnas.org/cgi/content/abstract/0405930101v1 | accessdate = 2006-08-16 | pmid = 15381767 }}</ref>
=== Serpentinite mechanism ===
One proposed mechanism by which abiogenic petroleum is formed was first proposed by the [[Ukrainians|Ukrainian]] scientist, Prof. [[Emmanuil B. Chekaliuk]] in 1967. He proposed that petroleum could be formed at high temperatures and pressures from inorganic carbon in the form of carbon dioxide, hydrogen and/or methane.
This mechanism is supported by several lines of evidence which are accepted by modern scientific literature. This involves synthesis of oil within the crust via catalysis by chemically reductive rocks. A proposed mechanism for the formation of inorganic hydrocarbons<ref name="keith2005">Keith, S., Swan, M. 2005. Hydrothermal Hydrocarbons. ''AAPG Research Conference'', Calgary, Canada, 2005. [http://www.searchanddiscovery.com/documents/abstracts/2005research_calgary/abstracts/extended/keith/keith.htm Abstract]</ref> is via natural analogs of the [[Fischer-Tropsch process]] known as the ''serpentinite mechanism'' or the serpentinite process <ref name="szatmari" /><ref name="charlou2005">J. L. Charlou, J. P. Donval, P. Jean-Baptiste, D. Levaché, Y. Fouquet, J. P. Foucher, P. Cochonat, 2005. Abiogenic Petroleum Generated by Serpentinization of Oceanic Mantellic Rocks. ''AAPG Research Conference'', Calgary, Canada, 2005.</ref>.
:<math>CH_4 + \begin{matrix} \frac{1}{2} \end{matrix}O_2 \rarr 2 H_2 + CO</math>
:<math>(2n+1)H_2 + nCO \rarr C_nH_{2n+2} + nH_2O</math>
Serpentinites are ideal rocks to host this process as they are formed from [[peridotite]]s and [[dunite]]s, rocks which contain greater than 80% [[olivine]] and usually a percentage of Fe-Ti spinel minerals. Most olivines also contain high nickel concentrations (up to several percent) and may also contain chromite or chromium as a contaminant in olivine, providing the needed transition metals.
However, serpentinite synthesis and spinel cracking reactions require hydrothermal alteration of pristine peridotite-dunite, which is a finite process intrinsically related to metamorphism, and further, requires significant addition of water. Serpentinite is unstable at mantle temperatures and is readily dehydrated to [[granulite]], [[amphibolite]], [[talc]]-[[schist]] and even [[eclogite]]. This suggests that methanogenesis in the presence of serpentinites is restricted in space and time to mid-ocean ridges and upper levels of subduction zones. However, water has been found as deep as 12 km,<ref>{{cite journal | author = S. B. Smithson | coauthors = F. Wenzel, Y. V. Ganchin and I. B. Morozov | date = 2000-12-31 | title = Seismic results at Kola and KTB deep scientific boreholes: velocities, reflections, fluids, and crustal composition | journal = Tectonophysics | volume = 329 | issue = 1-4 | pages = 301–317 | doi = 10.1016/S0040-1951(00)00200-6 }}</ref> so water-based reactions are dependent upon the local conditions. Oil being created by this process in intracratonic regions is limited by the materials and temperature.
==== Serpentinite synthesis ====
A chemical basis for the abiotic petroleum process is the [[serpentinite|serpentinization]] of [[peridotite]], beginning with methanogenesis via hydrolysis of olivine into serpentine in the presence of carbon dioxide<ref name="charlou2005" />. Olivine, composed of Forsterite and Fayalite metamorphoses into serpentine, magnetite and silica by the following reactions, with silica from fayalite decomposition (reaction 1a) feeding into the forsterite reaction (1b).
'''Reaction 1a''':<br>
''Fayalite + water → Magnetite + aqueous silica + Hydrogen''
:<math>3Fe_2SiO_4 + 2H_2O \rarr 2Fe_3O_4 + 3SiO_2 + 2H_2 </math>
'''Reaction 1b''':<br>
''Forsterite + aqueous silica → Serpentinite''
:<math>3Mg_2SiO_4 + SiO_2 + 4H_2O \rarr 2Mg_3Si_2O_5(OH)_4</math>
When this reaction occurs in the presence of dissolved carbon dioxide (carbonic acid) at temperatures above 500 °C Reaction 2a takes place.
'''Reaction 2a''':<br>
''Olivine + Water + Carbonic acid → Serpentine + Magnetite + Methane ''
:<math>(Fe,Mg)_2SiO_4 + nH_2O + CO_2 \rarr Mg_3Si_2O_5(OH)_4 + Fe_3O_4 + CH_4</math>
or, in balanced form: <math>18 Mg_2SiO_4 + 6 Fe_2SiO_4 + 26 H_2O + CO_2</math> → <math>12 Mg_3Si_2O_5(OH)_4 + 4 Fe_3O_4 + CH_4</math>
However, reaction 2(b) is just as likely, and supported by the presence of abundant talc-carbonate schists and magnesite stringer veins in many serpentinised peridotites;
'''Reaction 2b''':<br>
''Olivine + Water + Carbonic acid → Serpentine + Magnetite + Magnesite + Silica ''
:<math>(Fe,Mg)_2SiO_4 + nH_2O + CO_2 \rarr Mg_3Si_2O_5(OH)_4 + Fe_3O_4 + MgCO_3 + SiO_2</math>
<!-- nothing is being reduced here to counterbalance Fe being oxidized, so something is obviously missing -->
The upgrading of methane to higher n-alkane hydrocarbons is via [[dehydrogenation]] of methane in the presence of catalyst transition metals (e.g. Fe, Ni). This can be termed spinel hydrolysis.
=== Spinel polymerization mechanism ===
[[Magnetite]], [[chromite]] and [[ilmenite]] are Fe-spinel group minerals found in many rocks but rarely as a major component in non-[[ultramafic]] rocks. In these rocks, high concentrations of magmatic magnetite, chromite and ilmenite provide a reduced matrix which may allow abiotic cracking of methane to higher hydrocarbons during [[hydrothermal]] events.
Chemically reduced rocks are required to drive this reaction and high temperatures are required to allow methane to be polymerized to ethane. Note that reaction 1a, above, also creates magnetite.
'''Reaction 3''':<br>
''Methane + Magnetite → Ethane + Hematite ''<br>
:<math>nCH_4 + nFe_3O_4 + nH_2O \rarr C_2H_6 + Fe_2O_3 + HCO_3 + H^+</math>
<!-- nothing is being reduced here to counterbalance the oxidation of both C and Fe, so something is obviously wrong -->
Reaction 3 results in n-alkane hydrocarbons, including linear saturated hydrocarbons, [[alcohol]]s, [[aldehyde]]s, [[ketone]]s, [[aromatic]]s, and cyclic compounds.<ref name="charlou2005" />
=== Carbonate decomposition ===
Calcium carbonate may decompose at around 500 °C through the following reaction: <ref name="scott2004" />
'''Reaction 5''':<br>
''Hydrogen + Calcium carbonate → Methane + Calcium oxide + Water ''<br>
:<math>4H_2 + CaCO_3 \rarr CH_4 + CaO + 2H_2O</math>
=== Laboratory experiments ===
Some research and laboratory experiments explore possible mechanisms, but there is little related geological evidence.
==== Carbonate reduction ====
Methane has been formed in laboratory conditions via carbonate reduction at pressures and temperatures similar to that in the upper mantle, but a large amount of water was provided to the reaction in excess of that which is typical in mantle lithology. Likely reactions include:
'''Reaction 6a''':<br>
''Ferrous oxide + Calcium carbonate + Water → Hematite + Methane + Calcium oxide ''<br>
:<math>8FeO + CaCO_3 + 2H_2O \rarr 4Fe_2O_3 + CH_4 + CaO</math>
:and
'''Reaction 6b''':<br>
''Ferrous oxide + Calcium carbonate + Water → Magnetite + Methane + Calcium oxide ''<br>
:<math>12FeO + CaCO_3 + 2H_2O \rarr 4Fe_3O_4 + CH_4 + CaO</math>
Methane formation is favored under 1,200 °C at 1 GPa. At 1,500 °C hydrogen production was prevalent. Methane production is most favored at 500 °C and pressures <7 GPa; higher temperatures are expected to lead to carbon dioxide and carbon monoxide production through a reforming equilibrium with methane.
This is cited as evidence of the ''plausibility'' of methanogenesis under mantle conditions.<ref name="scott2004" />
==== Calcite decomposition ====
One carbon compound, carbon dioxide, can be created by calcite decomposition at 1,500 °C: <ref name="scott2004" />
'''Reaction 7''':<br>
''Calcium carbonate → Calcium oxide + Carbon dioxide''<br>
:<math>CaCO_3 \rarr CaO + CO_2</math>
[[Calcite]] is likely molten at these temperatures, being a mixture of CaO ions and CO<sup>2</sub>.
==== Ethane and Ethylene synthesis ====
[[Image:Deep sea vent chemistry diagram.jpg|thumb|right|400px|Deep sea vent [[biogeochemical]] cycle diagram]]
The synthesis of ethane and ethylene has been done at 800 °C, using electric discharges in laboratory experiments. This experiment was in a hot gas, rather than hot mantle fluids. The calculated reactions are: <ref>{{cite journal | author = Chang-jun Liu | coauthors = Gen-hui Xu and Timing Wang | year = 1999 | month = March | title = Non-thermal plasma approaches in CO<sub>2</sub> utilization | journal = Fuel Processing Technology | volume = 58 | issue = 2-3 | pages = 119–134 | doi = 10.1016/S0378-3820(98)00091-5 }}</ref>
''Carbon dioxide + Methane → Carbon monoxide + Ethane + Water''<br>
:<math>CO_2 + 2CH_4 \rarr CO + C_2H_6 + H_2O</math>
: and
''Carbon dioxide + Ethane → Carbon monoxide + Ethylene + Water''<br>
:<math>CO_2 + C_2H_6 \rarr CO + C_2H_4 + H_2O</math>
=== Fischer-Tropsch process analogs ===
The [[Fischer-Tropsch process]] and similar reactions can create hydrocarbons through direct reactions or reactions with catalysts. Fischer-Tropsch synthesis proceeds from carbon monoxide and hydrogen, while CO<sub>2</sub> hydrogenation proceeds from carbon dioxide and hydrogen. Artificial catalytic materials often use rare materials, but some catalysts use somewhat more common materials such as silicon dioxide, aluminum oxide, iron or nickel. Methane production is most common although more complex products such as ethane, propene, propane, and butane <!-- only most common products, don't list all F-T & CO2+H stuff from lab work --> have also appeared. The high temperatures needed for direct reactions are reduced to lower temperatures when a catalyst is present.
Although reactions similar to the Fischer-Tropsch process can create hydrocarbons, laboratory and commercial experience has found that catalytic surfaces fail due to [[carbide]] formation, catalyst oxidation, sulfur poisoning or being covered with carbon deposits (such as through the [[Boudouard reaction]]). Natural formations where such reactions take place continuously would require conditions which avoid such problems. Spreading centers are a special case where new material is being added, so additional catalytic surfaces may (or may not) be created.
=== Evidence of abiogenic mechanisms ===
* Scaled particle theory for a simplified perturbed hard-chain, statistical mechanical model predicts that methane compressed to 30 or 40 kbar at 1000 °C (conditions in the mantle) yields hydrocarbons having properties similar to petroleum <ref name="kenney2001" /><ref name="kenney2002" />
* Experiments in diamond anvil high pressure cells have confirmed this theory<ref name="kenney2002" />
== Biotic (microbial) hydrocarbons ==
The "deep biotic petroleum hypothesis", similar to the abiogenic petroleum origin hypothesis, holds that not all [[petroleum]] deposits within the Earth's rocks can be explained purely according to the orthodox view of [[petroleum geology]]. [[Thomas Gold]] used the term ''the deep hot biosphere'' to describe the microbes which live underground.<ref name="gold1999" /><ref>{{cite journal | author = Thomas Gold | title = The Deep, Hot Biosphere | journal = PNAS | date = 1992 | url = http://www.pnas.org/cgi/content/abstract/89/13/6045 | accessdate = 2006-09-27 | volume = 89 | pages = 6045–6049 | doi = 10.1073/pnas.89.13.6045 | pmid = 1631089}}</ref><ref>{{cite web| url = http://web.archive.org/web/20021004123112/http://www.people.cornell.edu/pages/tg21/DHB.html| title = The Deep, Hot Biosphere| accessdate = 2006-09-27| last = Gold| first = Thomas| authorlink = Thomas Gold| year = 1992| month = July}}</ref>
This hypothesis is different from biogenic oil in that the role of deep-dwelling microbes is a biological source for oil which is not of a sedimentary origin and is not sourced from surface carbon. Deep microbial life is only contaminant of primordial hydrocarbons. Parts of microbes yield molecules as biomarkers.
Deep biotic oil is considered to be formed as a byproduct of the life cycle of deep microbes.
Shallow biotic oil is considered to be formed as a byproduct of the life cycles of shallow microbes.
The 2nd Law of thermodynamics prohibits petroleum formation at low pressure and temperature. Petroleum is stable within earth's mantle at depths around 150-200 km. At low pressure levels (for instance sedimentary basins) may occur bacterial contamination that leave their fingerprints in oil. It's impossible to form petroleum from biogenic [[detritus]].<ref>{{cite web| url = http://www.gasresources.net/ThrmcCnstrnts.htm| title = The Constraints of the Laws of Thermodynamics upon the Evolution of Hydrocarbons: The Prohibition of Hydrocarbon Genesis at Low Pressures.| accessdate = 2006-08-16| author = Kenney, J.F.| coauthors = I. K. Karpov I.K., Shnyukov Ac. Ye. F., Krayushkin V.A., Chebanenko I.I., Klochko V.P.| year = 2002}}</ref><ref name="kenney2001">{{cite journal | author=Kenney, J., Shnyukov, A., Krayushkin, V., Karpov, I., Kutcherov, V. and Plotnikova, I. | title= Dismissal of the claims of a biological connection for natural petroleum | journal=Energia | volume=22 | issue=3 | year=2001 | pages=26–34}} [http://www.gasresources.net/DisposalBioClaims.htm Article link]</ref><ref name="kenney2002">{{cite journal | author=Kenney, J., Kutcherov, V., Bendeliani, N. and Alekseev, V. | title= The evolution of multicomponent systems at high pressures: VI. The thermodynamic stability of the hydrogen–carbon system: The genesis of hydrocarbons and the origin of petroleum | journal=Proceedings of the National Academy of Sciences | volume=99 | year=2002 | pages=10976–10981 | url=http://www.pnas.org/cgi/content/full/99/17/10976 | accessdate=2006-10-04 | doi=10.1073/pnas.172376899 | pmid= 12177438 }}</ref>
=== Deep microbes ===
Microbial life has been discovered 4.2 kilometers deep in [[Alaska]] and 5.2 kilometers deep in [[Sweden]].{{Fact|date=February 2007}} [[Methanophile]] organisms have been known for some time, and recently it was found that microbial life in [[Yellowstone National Park]] is based on [[hydrogen metabolism]]. Other deep and hot [[extremophile]] organisms continue to be discovered. Proponents of abiogenic petroleum origin contend that deep microbial life is responsible for the biomarkers (see below) that are generally cited as evidence of biogenic origin. [[U.S. Geological Survey]] (USGS) scientist Frank Chapelle and his colleagues from the USGS and the [[University of Massachusetts]] have discovered a potential analog for life on other planets. A community of [[Archaea]] [[bacteria]] is thriving deep in the subsurface source of a hot spring in [[Idaho]]. Geothermal hydrogen, not organic carbon, is the primary energy source for this methanogen-dominated microbial community. This is the first documented case of a microbial community completely dominated by Archaea.
Deep microbial sources for petroleum and hydrocarbon chemicals within some sedimentary basins and within some crystalline rocks may explain some contradictory evidence as to the source of these oils.
Specifically, the presence of [[biomarker]]s in the extremely rare examples of [[Proterozoic]] oils and within oils found in [[Mesozoic]] and younger crystalline reservoirs, could be explained as coming from [[endolith|deep-dwelling bacteria]].
The abiogenic hypothesis of oil sees the role of deep microbes as providing these biomarkers as contaminants of abiogenic petroleum accumulations, not as products of plant and plankton detritus which have been converted to petroleum via orthodox biogenic processes.
=== Microbial biomarkers ===
[[Extremophile]] organisms living within the crust (deep heat-loving bacteria [[thermophiles]]) are considered a plausible source of biomarkers which are not sourced from kerogen.
[[Hopanoids]], called the "most abundant natural products on Earth", were believed to be indicators of oil derived from [[fern]]s and [[lichen]]s but are now known to be created by many bacteria, including archaea.
[[Sterane]] was thought to have come from processes involving surface deposits but is now known to be produced by several [[prokaryote]]s including [[methanotroph]]ic [[proteobacteria]].
The case for shallow bacterial life creating petroleum is apparent from circumstantial evidence at "tar seeps" in sandstone outcrops where live oil is encountered down-dip (e.g. [[Midway-Sunset Oil Field|Midway-Sunset]] field, San Joaquin Valley, California). Bacteria are considered to have "degraded" higher gravity oil to bitumens.
Extrapolation of bacterial degradation to still higher gravity oils and finally to methane leads to the suggestion that all petroleum up to tar and most of the carbon in coal are derivatives of methane, which is progressively stripped of its hydrogen by bacteria and archaea. The resultant partial methane molecules, CH<sub>3</sub>, CH<sub>2</sub>, CH, may be called ''"an-hydrides"''. Anhydride hypothesis, a New Theory of Petroleum and Coal Generation, is offered by C. Warren Hunt (1999).{{{Fact|date=July 2008}}
Due to the difficulty in culturing and sampling thermophilic bacteria little was known of their chemistry. As more is learned of bacterial chemistry, more biomarker chemicals can be attributed to bacterial sources. Although [[extremophile]] micro-organisms exist deep underground and some metabolize carbon, some of these biomarkers are so far only known from surface plants and remain the most reliable chemical evidence of biogenic genesis of petroleum.
This evidence is consistent with the biogenic hypothesis, although it might be true that these hydrocarbons have merely been in contact with ancient plant residues. There also is evidence that low-temperature relatives of hyperthermophiles are widespread, so it is also possible for biological deposits to have been altered by low-temperature bacteria which are similar to deeper heat-loving relatives.
It must also be acknowledged that, if extremophilic bacteria prove to be the source of some parts of known oils, that this remains a ''biological'' process.
Thorough rebuttal of biogenic origins based on biomarkers has been offered by Kenney, et al. (2001).<ref name="kenney2001" />
=== Microbial evidence from petroleum geochemistry ===
If the above mechanism for microbial petroleum genesis is active and prevalent within the Earth crust and the hypothesis holds true, the geochemistry of petroleum deposits within the Earth’s crust should reflect this mechanism of formation.
The geochemistry of petroleum deposits has been widely and deeply studied by oil companies and academia for more than a century in order to elucidate the origin of petroleum and develop predictive scientific models. Certain findings of this research can be used to interpret petroleum as being either of biogenic or abiogenic origin. These include biomarker chemicals, the optical activity of oils, chirality and the trace metal abundances of oils.
==== Isotopic evidence ====
[[Methane]] is ubiquitous in crustal fluid and gas <ref name="lollar2006" />. Research continues to attempt to characterise crustal sources of methane as biogenic or abiogenic using carbon isotope fractionation of observed gases (Lollar & Sherwood 2006). There are few clear examples of abiogenic methane-ethane-butane, as the same processes favor enrichment of light isotopes in all chemical reactions, whether organic or inorganic. δ<sup>13</sup>C of methane overlaps that of inorganic carbonate and graphite in the crust, which are heavily depleted in <sup>12</sup>C, and attain this by isotopic fractionation during metamorphic reactions.
One argument for abiogenic oil cites the high carbon depletion of methane as stemming from the observed carbon isotope depletion with depth in the crust. However, diamonds, which are definitively of mantle origin, are not as depleted as methane, which implies that methane carbon isotope fractionation is not controlled by mantle values. <ref name="mello2005">M. R. Mello and J. M. Moldowan (2005). Petroleum: To Be Or Not To Be Abiogenic. ''AAPG Research Conference'', Calgary, Canada, 2005. [http://www.searchanddiscovery.com/documents/abstracts/2005research_calgary/abstracts/extended/mello/mello.htm Abstract]</ref>
[[Helium]] [[Isotope geochemistry#Noble Gas Isotopes|isotope geochemistry]] is a clear indicator of mantle source within gases. Within the major precambrian shield there is no evidence of mantle helium in gases or groundwaters, which disproves the theory of continued outgassing of primordial methane and helium along structures in the Precambrian basement.{{Fact|date=July 2008}} Furthermore, there are few examples of primordial helium or mantle helium trapped within oil and gas occurrences. Helium gas has close association with petroleum. Although [[Helium-3|³He]] is primordial, much He gas is from radioactive decay of uranium. Helium gas is associated with light oils, sometimes accompanied by nitrogen that allow petroleum to reach shallow levels in crust. Because helium is a very light gas, commercial accumulations are not (un?)common at Panhandle-Hugoton in USA, Algerian and Russian gas fields.
Panhandle-Hugoton field (Anadarko Basin) in Texas-Oklahoma, USA is the most important gas field with commercial helium content. Helium trapped with hydrocarbons (mainly methane) and nitrogen is possible if there is an efficient seal overlying the reservoir such as salt. Helium trapped within most petroleum occurrences, such as the occurrence in Texas, is of a distinctly crustal character with an ''Ra'' ratio of less than 0.0001 that of the atmosphere.<ref>{{cite journal | author = Weinlich, F.H. | coauthors = Brauer K., Kampf H., Strauch G., J Tesar and S.M. Weise | year = 1999 | title = An active subcontinental mantle volatile system in the western Eger rift, Central Europe: Gas flux, isotopic (He, C and N) and compositional fingerprints - Implications with respect to the degassing processes | journal = Geochimica et Cosmochimica Acta | volume = 63 | issue = 21 | pages = 3653–3671 | doi = 10.1016/S0016-7037(99)00187-8 }}</ref><ref>{{cite journal | author = B.G.Polyak | coauthors = I.N. Tolstikhin, I.L. Kamensky, L.E. Yakovlev, B. Marty and A.L. Cheshko | year = 2000 | title = Helium isotopes, tectonics and heat flow in the Northern Caucasus | journal = Geochimica et Cosmochimica Acta | volume = 64 | issue = 11 | pages = 1924–1944 | doi = 10.1016/S0016-7037(00)00342-2 }}</ref>
=== Biomarker chemicals===
Certain chemicals found in naturally occurring petroleum contain chemical and structural similarities to compounds found within many living organisms. These include [[terpenoid]]s, [[terpene]]s, [[pristane]], [[phytane]], [[cholestane]], [[chlorin]]s and [[porphyrin]]s, which are large, [[chelate|chelating]] molecules in the same family as [[heme]] and [[chlorophyll]]. Materials which suggest certain biological processes include tetracyclic diterpane and oleanane.
The presence of these chemicals in crude oil is assumed to be as a result of the inclusion of biological material in the oil. This is predicated upon the theory that these chemicals are released by [[kerogen]] during the production of hydrocarbon oils.
However, since the advent of abiogenic hypothesis, the veracity of these assumptions has been called into question and new lines of evidence used to provide alternative explanations. Some are provided by many scientists from around the world including Russia.
===Odd-number carbon abundance===
Members of the [[alkane|n-alkane]] series found in petroleum have a slightly greater abundance of odd-numbered carbon chains ([[propane]], [[pentane]], etc.) Likewise, linear carbohydrate molecules in living systems exhibit the same preference for odd carbon numbers.
All mixtures of linear hydrocarbon chains, be they artificial, natural or biological, exhibit this tendency. It arises from the geometry of the [[covalent bond]] in linear molecules, so the greater abundances of odd-numbered hydrocarbons need not be of biological origin.
=== Trace metals ===
[[Nickel]] (Ni), [[vanadium]] (V), [[lead]] (Pb), [[arsenic]] (As), [[cadmium]] (Cd), [[mercury (element)|mercury]] (Hg) and others metals frequently occur in oils. Some heavy crude oils, such as Venezuelan heavy crude have up to 45% [[vanadium]] pentoxide content in their ash, high enough that it is a commercial source for vanadium. These metals are common in Earth's mantle, thus their compounds in oils are often called as ''abiomarkers''.
Analysis of 22 trace elements in 77 oils correlate significantly better with [[chondrite]], serpentinized fertile mantle peridotite, and the primitive mantle than with oceanic or continental crust, and shows no correlation with seawater. <ref name="szatmari" />
=== Reduced carbon ===
Petroleum is composed mainly of [[Alkane|n-alkanes]]. Sir [[Robert Robinson (scientist)|Robert Robinson]] studied the chemical makeup of natural petroleum oils in great detail, and concluded that they were mostly far too hydrogen-rich to be a likely product of the decay of plant debris.<ref name="goldusgs" /> However, several processes which generate hydrogen could supply kerogen hydrogenation which is compatible with conventional petroleum generation theories.<ref>{{cite journal | author = Zhijun Jin | coauthors = Liuping Zhang, Lei Yang and Wenxuan Hu | year = 2004 | month = January | title = A preliminary study of mantle-derived fluids and their effects on oil/gas generation in sedimentary basins | journal = Journal of Petroleum Science and Engineering | volume = 41 | issue = 1-3 | pages = 45–55 | doi = 10.1016/S0920-4105(03)00142-6 }}</ref>
[[Olefin]]s, the unsaturated hydrocarbons, would have been expected to predominate by far in any material that was derived in that way. He also wrote: "Petroleum ... [seems to be] a primordial hydrocarbon mixture into which bio-products have been added."
The presence of low-oxygen and hydroxyl-poor hydrocarbons in natural living media is supported by the presence of natural waxes (n=30+), oils (n=20+) and lipids in both plant matter and animal matter, for instance fats in phytoplankton, zooplankton and so on. These oils and waxes, however, occur in quantities too small to significantly affect the overall hydrogen/carbon ratio of biological materials.
== Geological framework ==
The proposed mechanism for abiogenic petroleum production is robust in hypothesis,{{Fact|date=July 2008}} leaving aside ambiguous geochemical evidence. The abiogenic hypothesis on the origin of petroleum seeks to explain the origin of commercial accumulations of petrochemicals via chemical mechanisms such as serpentinite catalysis.
The geological observations which are used to support the abiogenic origin of petrochemical deposits should be evaluated on a case-by-case basis for each hydrocarbon deposit, with the presence of no one line of evidence used in isolation to infer genetic conclusions when equivocal or contradictory evidence is available.
The geological observations proposed for the abiogenic hypothesis are presented below, followed by investigation of several key deposits on a case by case basis to evaluate their genesis.
== Direct observations ==
The following are the direct tests of the abiogenic hypothesis of petroleum or impartial evidence generated by observations of the Earth which can be used to argue the hypothesis for or against, and are presented as such.
* The [[Lost City (hydrothermal field)|Lost City Hydrothermal Vent Field]] was determined to have abiogenic hydrocarbon production. Proskurowski et al. wrote, "Radiocarbon evidence rules out seawater bicarbonate as the carbon source for [[Fisher-Tropsch process|FTT reactions]], suggesting that a mantle-derived inorganic carbon source is leached from the host rocks. Our findings illustrate that the abiotic synthesis of hydrocarbons in nature may occur in the presence of ultramafic rocks, water, and moderate amounts of heat."<ref>Proskurowski, Giora et al. 2008 [http://www.sciencemag.org/cgi/content/short/319/5863/604 Abiogenic Hydrocarbon Production at Lost City Hydrothermal Field.] ''Science'', 319(5863) 604-607</ref>
* The [[Siljan (lake)|Siljan Ring]] meteorite crater, Sweden, was proposed by [[Thomas Gold]] as the most likely place to test the hypothesis because it was one of the few places in the world where the granite basement was cracked sufficiently (by meteorite impact) to allow oil to seep up from the mantle; furthermore it is infilled with a relatively thin veneer of sediment, which was sufficient to trap any abiogenic oil but was modelled as untenable for a biogenic origin of any oil (it had not developed the 'oil window' and structural traps typical of biogenic plays).
:Drilling of the Siljan Ring with the Gravberg-1 7,500 m borehole penetrated the lowest reservoirs. Hydrocarbons were found, though in an economically unviable form of sludge. It was proposed that the eight barrels of oil produced were from the diesel fuel based drilling fluid used to do the drilling, but the diesel was demonstrated to be not of the kind of oil found in the shaft. This well also sampled over 13,000 feet of methane-bearing inclusions. [http://www.geology.wisc.edu/~pbrown/fi/pac6/mikesmith.html] To be safe, a second hole was drilled a few miles away with no diesel fuel based drilling fluid and this produced 15 tons of oil. [http://web.archive.org/web/20021015163818/www.people.cornell.edu/pages/tg21/usgs.html]
* Methanogenesis of groundwaters associated with ultramafic dykes and serpentinites, South Island of [[New Zealand]]
* Methane outflows are common from drillholes within large Archaean serpentinised [[olivine]] [[cumulate rocks|adcumulate]] bodies, such as the Honeymoon Well complex, Yakabindie ultramafic, Mt Clifford dunite, in the [[Yilgarn Craton]], Western Australia.
* Direct observation of bacterial mats and fracture-fill carbonate and humin of bacterial origin in deep boreholes in Iran, Australia<ref>Bons P., et al. 2004. Fossil microbes in late proterozoic fibrous calcite veins from Arkaroola, South Australia. ''Geological Society of America Abstracts with Programs'', '''Vol. 36''', No. 5, p. 475</ref>, Sweden and Canada
* Presence of deep-dwelling microbes in the [[Lechuguilla Cave]] complex, New Mexico
<!-- please discuss your evidence for oil in the second drillhole on the talk page, and provide ref links if possible, because it would be good to see the evidence and close up this issue. cheers, Rolinator -->
=== Example abiogenic deposits ===
Supergiant fields such as the [[Athabasca Tar Sands]] ([[Canada]]), [http://www.eoearth.org/article/Orinoco_Heavy_Oil_Belt,_Venezuela Orinoco Heavy Oil Belt] ([[Venezuela]]) and the [[Ghawar Field]] ([[Saudi Arabia]]) are interpreted by some as having been formed by abiogenic oils. This interpretation is based mostly on perceived deficiency in source rock volumes.{{Fact|date=February 2008}}
Panhandle-Hugoton field (Anadarko Basin) in Texas-Oklahoma, [[USA]] is the most important gas field with commercial helium content.
The [[White Tiger oil field]] in [[Vietnam]] has been proposed as an example of abiogenic oil because it is 4,000 m of fractured basement granite, at a depth of 5,000 m. <ref>{{cite journal | author = Anirbid Sircar | date = 2004-07-25 | title = Hydrocarbon production from fractured basement formations | journal = Current Science | volume = 87 | issue = 2 | pages = 147–151 | url = http://www.ias.ac.in/currsci/jul252004/147.pdf | format = pdf }}</ref>. However, others argue that it contains biogenic oil which leaked into the basement horst from conventional source rocks within the [[Cuu Long]] basin <ref>White Tiger oilfield, Vietnam. AAPG Review of [http://www.aapg.org/explorer/2005/02feb/vietnam.cfm CuuLong Basin] and [http://www.aapg.org/explorer/2005/02feb/vietnamseismic01.jpg Seismic profile] showing basement horst as trap for biogeic oil.</ref> <ref name="brown2005" />. <!-- ([[Talk:Abiogenic petroleum origin#Going over the evidence again|(discussion)]] -->
A major component of mantle-derived carbon is indicated in commercial gas reservoirs in the [[Pannonian Basin|Pannonian]] and [[Vienna basin]]s of Hungary and Austria.<ref> {{cite journal|title=The fate of mantle-derived carbon in a continental sedimentary basin: Integration of C/He relationships and stable isotope signatures|journal=Geochimica et Cosmochimica Acta|date=1997-06|first=B. Sherwood|last=Lollara|coauthors=C. J. Ballentineb and R. K. Onions|volume=61|issue=11|pages=2295–2307|doi= 10.1016/S0016-7037(97)00083-5|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V66-3SWJH68-1T&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=bee722ceefac8870c425e31888931977|format=|accessdate=2008-06-06 }}</ref>
There are mantle-derived natural gas pools in the [[Shengli Field]]<ref> {{cite journal|title=Multi-origin alkanes related to CO2-rich, mantle-derived fluid in Dongying Sag, Bohai Bay Basin|journal=Chinese Science Bulletin|date=2002-10-30|first=Zhijun|last=JIN|coauthors=ZHANG Liuping, ZENG Jianhui|volume=47|issue=20|pages=1756–1760|id= |url=http://scholar.ilib.cn/A-ddgzyckx-e200402006.html|format=PDF|accessdate=2008-06-06|doi=10.1360/02tb9384 }}</ref> and Songliao Basin, northeastern China.<ref> {{cite journal|title=Geochemistry And Tectonic Environment And Reservoir Formation Of Mantle-Derived Natural Gas In The Songliao Basin, Northeastern China|journal=Geotectonica et Metallogenia|date=2004|first=Zian|last=Li|coauthors=GUO Zhanqian , BAI Zhenguo , LIN Ge |volume=|issue=|pages=|id= |url=http://scholar.ilib.cn/A-ddgzyckx-e200402006.html|format=|accessdate=2008-06-06 }}</ref><ref> {{cite web|url=http://www.magnet.fsu.edu/mediacenter/publications/reports/2006annualreport/2006-NHMFL-Report431.pdf |title=ABIOGENIC HYDROCARBON ACCUMULATIONS IN THE SONGLIAO BASIN, CHINA |accessdate=2008-06-06 |date=2006 |format=PDF |publisher=NATIONAL HIGH MAGNETIC FIELD LABORATORY }}</ref>
=== The geological argument for abiogenic oil ===
Given the known occurrence of methane and the probable catalysis of methane into higher atomic weight hydrocarbon molecules, the abiogenic hypothesis considers the following to be key observations in support;
[[Image:USGS world oil endowment.png|thumb|Oil deposits are associated with tectonic structures]]
* The serpentinite synthesis, graphite synthesis and spinel catalysation models prove the process is viable <ref name="szatmari" /><ref name="charlou2005" />
* The association of oil deposits with key tectonic structures and plate boundaries, generally in arcs
* The likelihood that abiogenic oil seeping up from the mantle is trapped beneath sediments which effectively seal mantle-tapping faults <ref name="keith2005" />
* [[Kudryavtsev's Rule]] that states petroleum can be found in all layers of a sedimentary basin; subsequently proven to be of limited application; it has also been stated as applying to hydrocarbon deposits, including natural gas, petroleum, and coal. [[Nikolai Kudryavtsev]] pointed that the eruptions of mud-volcanoes have liberated such large quantities of methane that even the most prolific gasfield underneath should have been exhausted long ago and also provided several other geological arguments about abiotic and deep origin of petroleum.
* Mass-balance calculations for supergiant oilfields which argue that the calculated source rock could not have supplied the reservoir with the known accumulation of oil, implying deep recharge (Kudryavtsev, 1951)
* Ubiquitous presence of nickel and vanadium (Ni, V) in all oils of the world. Also including other trace elements such as Zn, Pb, Cu, Cd, Cr, Co, As, Sb, Te, Hg, Au, Ag. All these trace-elements settings are related to mantle rocks (dunite/peridotite and serpentinites).
* Common association of [[helium]] with hydrocarbons, mainly with methane and nitrogen in gas fields.
==== Incidental evidence ====
The proponents of abiogenic oil use several arguments which draw on a variety of natural phenomena in order to support the hypothesis
* The ubiquitous presence of carbon, methane, ammonia and a variety of amino acids within extraterrestrial bodies such as [[meteorites]], [[comets]] and on several moons within the Solar System. The Earth acquired much carbon during its creation.
** However, Earth has several anomalies which indicate a complex past which may have affected primordial material. The [[Giant impact theory|formation of the Moon]] was a geologically significant event. Unexplained ratios of elements suggest material has been lost, perhaps through gases being lost to space and through collisional erosion. <ref>{{cite conference | first = Palme | last = H. | coauthors = H. St. C. O'Neill and W. Benz | year = 2003 | month = March | title = Evidence for Collisional Erosion of the Earth | booktitle = 34th Annual Lunar and Planetary Science Conference, March 17-21, 2003, League City, Texas | editor = Mackwel, S. | others = Stansbery, E. | publisher = LPI}}</ref> However this argument is found to be highly speculative by some.
* The modelling of some researchers which shows the Earth was accreted at relatively low temperature, thereby perhaps preserving primordial carbon deposits within the mantle, to drive abiogenic hydrocarbon production <ref>{{cite journal | author=John W. Valley, William H. Peck, Elizabeth M.King, Simon A. Wilde | title=A Cool Early Earth | journal=Geology | year=2002 | volume=30 | pages=351–354 | doi=10.1130/0091-7613(2002)030<0351:ACEE>2.0.CO;2}} {{cite web | title= A Cool Early Earth | work= Zircons Are Forever | url=http://www.geology.wisc.edu/zircon/cool_early/cool_early_home.html | accessmonthday=11 April | accessyear=2005 }}</ref>
* The presence of natural gas eruptions, flames and explosions during earthquakes and during some volcanic eruptions, mainly in mud volcanoes.
* The presence of vast quantities of methane hydrate ([[methane clathrate]]) within deep pelagic oozes within the oceans of the Earth, cited as evidence of abiogenic methane generation from serpentinitisation of the oceanic crust.
* The presence of continuous methane upwelling through gas chimneys (gas vent) in oceans forming pockmark features, cold seeps, methane related diagenetic carbonates, bentonic ecosystems such as cold-water corals (deep-water corals), methane flares from sea bottom, shale diapirs formed by gas interaction, submarine and terrestrial mud-volcanoes. It is important to note that bacterial reworking of primordial methane that come from great depths yield biogenic methane at shallow levels in crust
* The presence of methane within the gases and fluids of mid-ocean ridge spreading centre [[hydrothermal]] fields<ref>{{cite journal | author=Chapelle, F.H., O'Neill, K., Bradley, P.M., Methe, B.A., Ciufo, S.A., Knobel, L.L., and Lovley, D.R. | title=A hydrogen-based subsurface microbial community dominated by methanogens | journal=Nature | volume=415 | year=2002 | pages=312–315|doi=10.1038/415312a}}</ref>
* The presence of intraplate earthquakes and deep focus earthquakes, apparently caused by movement of vast quantities of mantle methane and hydrocarbons
*The presence of tiny diamondoids in oils, gas and mainly in condensates. Diamondoids probably form at high pressures in the earth's mantle and they migrate together with oil and gas to low pressures in the crust.{{Fact|date=February 2007}}
=== The geological argument against ===
Key arguments against chemical reactions, such as the serpentinite mechanism, as being the major source of hydrocarbon deposits within the crust are;
* The lack of available pore space within rocks as depth increases <!-- ; especially within the mantle {{Fact|date=February 2008}} -->
** This is contradicted by numerous studies which have documented the existence of hydrologic systems operating over a range of scales and at all depths in the continental crust. <ref>{{cite journal | author = C. E. Manning | coauthors = S. E. Ingebritsen | date = 1999-02-01 | title = Permeability of the continental crust: implications of geothermal data and metamorphic systems | journal = Reviews of Geophysics | volume = 37 | issue = 1 | pages = 127–150 | doi = 10.1029/1998RG900002}}</ref>
* The presence of no commercial hydrocarbon deposits within the crystalline shield areas of the major [[craton]]s especially around key deep seated structures which are predicted to host oil by the abiogenic hypothesis <ref name="mello2005" />
* Limited evidence that major serpentinite belts underlie continental sedimentary basins which host oil
* Lack of conclusive proof that carbon isotope fractionation observed in crustal methane sources is entirely of abiogenic origin (Lollar et al. 2006)<ref name="lollar2006" />
* Mass balance problems of supplying enough carbon dioxide to serpentinite within the metamorphic event before the peridotite is fully reacted to serpentinite
* Drilling of the Siljan Ring failed to find commercial quantities of gas<ref name="mello2005" />, thus providing a counter example to [[Kudryavtsev's Rule]] and failing to locate the predicted abiogenic gas <!-- source of disproof of K's Rule? And it was a gas test well, so I changed "oil" to "gas" in this sentence. -->
** Helium in the Siljan Gravberg-1 well was depleted in [[Helium-3|<sup>3</sup>He]] and not consistent with a mantle origin<ref>{{cite conference | author = A. W.A. Jeffrey | coauthors = I. R. Kaplan and J. R. Castaño | year = 1988 | title = Analyses of Gases in the Gravberg-1 Well | booktitle = Deep drilling in crystalline bedrock, v. 1 | editor = A. Bodén and K.G. Eriksson | publisher = Springer-Verlag | location = Berlin | pages = 134-139 | url = | format = | accessdate = | doi = | id = ISBN 3-540-18995-5}}</ref>
<!-- ** The eight barrels of oil-like substance produced from the Siljan borehole were proven to be diesel sludge contamination --> <!-- Source? There were several drilling locations and patterns. -->
* The distribution of sedimentary basins is caused by plate tectonics, with sedimentary basins forming on either side of a [[volcanic arc]], which explains the distribution of oil within these sedimentary basins
* Kudryavtsev's Rule has been explained for oil and gas (not coal): Gas deposits which are below oil deposits can be created from that oil or its source rocks. Because natural gas is less dense than oil, as kerogen and hydrocarbons are generating gas the gas fills the top of the available space. Oil is forced down, and can reach the spill point where oil leaks around the edge(s) of the formation and flows upward. If the original formation becomes completely filled with gas then all the oil will have leaked above the original location.<ref>{{cite journal | last = Price | first = Leigh C. | title = Origins, Characteristics, Evidence For, and Economic Viabilities of Conventional and Unconventional Gas Resource Bases | journal = Geologic controls of deep natural gas resources in the United States (USGS Bulletin 2146) | pages = 181–207 | publisher = USGS | date = 1997 | url = http://pubs.er.usgs.gov/usgspubs/b/b2146 | accessdate = 2006-10-12 }}</ref>
==== Arguments against the incidental evidence ====
* Gas ruptures during earthquakes are more likely to be sourced from biogenic methane generated in unconsolidated sediment from existing organic matter, released by [[earthquake liquefaction]] of the reservoir during tremors
* The presence of methane hydrate is arguably produced by bacterial action upon organic detritus falling from the [[littoral]] zone and trapped in the depth due to pressure and temperature
* The likelihood of vast concentrations of methane in the mantle is very slim, given mantle xenoliths have negligible methane in their fluid inclusions; conventional plate tectonics explains deep focus quakes better, and the extreme confining pressures invalidate the hypothesis of gas pockets causing quakes
* Further evidence is the presence of diamond within [[kimberlite]]s and [[lamproite]]s which sample the mantle depths proposed as being the source region of mantle methane (by Gold et al). <ref name="goldusgs" /> It is arguable from oxygen fugacity and carbon phase stability models that reduced carbon in the mantle is either in the form of graphite or diamond, not methane, and that oxidized carbon is present as carbon dioxide.{{Fact|date=February 2007}}
== Petroleum origin, peak oil, and politics ==
{{Unreferencedsection|date=July 2007}}
Many aspects of the abiogenic hypothesis were developed in the former [[Soviet Union]] by [[Russia]]n and [[Ukraine|Ukrainian]] scientists during the [[Cold War]]. Some proponents see a pro-Western bias in the promotion of the biogenic theory. Thus, in addition to the scientific merits of competing hypothoses, political and economic considerations often influence discussions of petroleum origins.
The topic of the origin of petroleum is also linked to discussions of projected declines in petroleum production, variously referred to as "[[peak oil]]" or "[[M. King Hubbert|Hubbert's]] peak". The abiogenic hypothesis stands in contrast to that of [[Hubbert peak theory|Peak Oil]], which presumes a fixed and dwindling supply of oil that was formed through biological processes.
Some [[environmentalist]]s accuse abiogenic hypothesis supporters of a "[[cornucopian]]" worldview. They claim that such a view incorrectly sees no limits to exploitation of petroleum supplies while simultaneously ignoring potential consequences of petroleum consumption such as [[global warming]]. Conversely, some supporters of the abiogenic hypothesis accuse their opponents of an unwarranted [[Malthusian]] viewpoint that needlessly limits the use of hydrocarbons as an energy source and artificially inflates oil prices.
[[Image:USGS deep wells 1997.png|thumb|U.S. hydrocarbon wells deeper than 4.5 km in sedimentary deposits. (USGS 1997)]]
Independent of whether massive hydrocarbon reserves exist deep in the crust, they are unattainable in the short term. Additionally, oil wells are being drilled down to depths of 10 km, just shy of the world record of 12 km set by the [[Kola Superdeep Borehole]] in the East European Craton. Thus the "deep reservoirs" of Gold et al. are being tested successfully according to biogenic models of petroleum occurrence.
Considering the dominance of the biogenic origin theory in the exploration industry, new oil discoveries based on abiogenic hypothesis may be slow in coming. The [[ASPO]] predicts that global oil production will peak in 2011, while some other organizations such as the [[USGS]] pick as late as 20 years later. If that happened, there would be serious economic ramifications. For this reason, as well as concerns about global warming, development of [[nuclear power]] and [[renewable energy]] sources is being increasingly urged.
These aspects of the controversy may be seen in many of the online articles in the [[#External links|External links]] section below.
== State of current research ==
Currently there is little direct research on abiogenic petroleum or experimental studies into the synthesis of abiogenic methane. However, several research areas, mostly related to [[astrobiology]] and the deep microbial biosphere and serpentinite reactions, continue to provide insight into the contribution of abiogenic hydrocarbons into petroleum accumulations.
* rock porosity and migration pathways for abiogenic petroleum <ref>Kitchka, A., 2005. Juvenile Petroleum Pathway: From Fluid Inclusions via Tectonic Pathways to Oil Fields. ''AAPG Research Conference'', Calgary, Canada, 2005.[http://www.searchanddiscovery.com/documents/abstracts/2005research_calgary/abstracts/extended/kitchka/kitchka.htm Abstract]</ref>
* ocean floor [[hydrothermal vent]]s as in the [[Lost City (hydrothermal field)|Lost City]] hydrothermal field;
* [[Mud volcano]]es and the volatile contents of deep pelagic oozes and deep formation brines
* mantle [[peridotite]] [[serpentinization]] reactions and other natural Fischer-Tropsch analogs
* Primoridal hydrocarbons in [[meteorite]]s, [[comet]]s, [[asteroids]] and the solid bodies of the [[solar system]]
** Primordial or ancient sources of hydrocarbons or carbon in Earth <ref name="scott2004" /><ref>{{cite journal | author = Thomas Stachel | coauthors = Anetta Banas, Karlis Muehlenbachs, Stephan Kurszlaukis and Edward C. Walker | year = 2006 | month = June | title = Archean diamonds from Wawa (Canada): samples from deep cratonic roots predating cratonization of the Superior Province | journal = Contributions to Mineralogy and Petrology | volume = 151 | issue = 6 | pages = 737–750 | doi = 10.1007/s00410-006-0090-7 }}</ref>
*** Primordial hydrocarbons formed from hydrolysis of metal carbides of the iron peak of cosmic elemental abundance (Cr, Fe, Ni, V, Mn, Co) <ref>{{cite journal | author = Franco Cataldo | year = 2003 | month = January | title = Organic matter formed from hydrolysis of metal carbides of the iron peak of cosmic elemental abundance | journal = International Journal of Astrobiology | volume = 2 | issue = 1 | pages = 51–63 | doi = 10.1017/S1473550403001393 }}</ref>
* isotopic studies of groundwater reservoirs, sedimentary cements, formation gases and the composition of the noble gases and nitrogen in many oil fields
* the geochemistry of petroleum and the presence of trace metals related to Earth's mantle (Ni, V, Cd, As, Pb, Zn, Hg and others)
Similarly, research into the deep microbial hypothesis of hydrocarbon generation is advancing as part of the attempt to investigate the concept of [[panspermia]] and [[astrobiology]], specifically using deep microbial life as an analog for [[life on Mars]]. Research applicable to deep microbial petroleum theories includes
* Research into how to sample deep reservoirs and rocks without contamination
* Sampling deep rocks and measuring chemistry and biological activity <ref>{{cite journal | author = Thomas L. Kieft | coauthors = Sean M. McCuddy, T. C. Onstott, Mark Davidson, Li-Hung Lin, Bianca Mislowack, Lisa Pratt, Erik Boice, Barbara Sherwood Lollar, Johanna Lippmann-Pipke, Susan M. Pfiffner, Tommy J. Phelps, Thomas Gihring, Duane Moser, Arnand van Heerden | year = 2005 | month = September | title = Geochemically Generated, Energy-Rich Substrates and Indigenous Microorganisms in Deep, Ancient Groundwater | journal = Geomicrobiology Journal | volume = 22 | issue = 6 | pages = 325–335 | doi = 10.1080/01490450500184876 }}</ref>
* Possible energy sources and metabolic pathways which may be used in a deep biosphere <ref>{{cite journal | author = Li-Hung Lin | coauthors = Greg F. Slater, Barbara Sherwood Lollar, Georges Lacrampe-Coulome, and T.C. Onstott | year = 2005 | month = February | title = The yield and isotopic composition of radiolytic H<sub>2</sub>, a potential energy source for the deep subsurface biosphere | journal = Geochimica et Cosmochimica Acta | volume = 69 | issue = 4 | pages = 893–903 | doi = 10.1016/j.gca.2004.07.032 }}</ref><ref name="lollar2006" />
* Investigations into the reworking primordial hydrocarbons by bacteria and their effects on carbon isotope fractionation
A 2006 review article by Glasby presented arguments against the abiogenic origin of petroleum on a number of counts.<ref name=glasby2006/>
An article on ''abiogenic hydrocarbon production'' in the February 2008 issue of [[Science Magazine]] used data from experiments at [[Lost City (hydrothermal field)]] to report how the abiotic synthesis of hydrocarbons in nature may occur in the presence of ultramafic rocks, water, and moderate amounts of heat.<ref>Science Magazine, ''Abiogenic Hydrocarbon Production at Lost City Hydrothermal Field'' February 2008 http://www.sciencemag.org/cgi/content/short/319/5863/604</ref>
== See also ==
* [[Eugene Island]]
* [[Fischer-Tropsch process]]
* [[Mineral fuel]], also known as [[Fossil fuel]]
* [[Nikolai Kudryavtsev|Nikolai Alexandrovitch Kudryavtsev]]
* [[Peak oil]]
* [[Thomas Gold]]
== References ==
{{Reflist|2}}
== Bibliography ==
* Kudryavtsev N.A., 1959. Geological proof of the deep origin of Petroleum. Trudy ''Vsesoyuz. Neftyan. Nauch. Issledovatel Geologoraz Vedoch. Inst.'' No.132, pp. 242-262 {{ru icon}}
<!-- Dead note "Mao2002": {{cite journal | author = Jingwen Mao | coauthors = Robert Kerrich, Hongyan Li and Yanhe Li | year = 2002 | title = High <sup>3</sup>He/<sup>4</sup>He ratios in the Wangu gold deposit, Hunan province, China: Implications for mantle fluids along the Tanlu deep fault zone | journal = Geochemical Journal | volume = 36 | pages = 197–208 }} -->
<!-- Dead note "Zhmur2002": Zhmur S.L., 2002. Shungites of Karelia as Model for Carbon Hondrites Formation. ''Journal of Astrobiology''. [http://biospace.nw.ru/astrobiology/Articles2002/Astrobio_zhmur_111.pdf Paper (pdf)] -->
<!-- Dead note "Dutkiewicz": Dutkiewicz, A., Volk A., Ridley J., George S., 2003. Biomarkers, brines, and oil in the Mesoproterozoic, Roper Superbasin, Australia. ''Geology''; '''v. 31'''; p. 981-984 [http://geology.geoscienceworld.org/cgi/content/abstract/31/11/981 Abstract] -->
<!-- Dead note "stanton2004": Stanton, M.S., 2004. Origin of the Lower Cretaceous Heavy Oils ("Tar Sands") of Alberta. ''AAPG Search and Discovery Article #10071'' (2004) [http://www.searchanddiscovery.com/documents/2004/stanton/images/stanton.pdf Article link (pdf)] -->
<!-- Dead note "Valyaev2005": B. M. Valyaev, S. A. Leonov, G. A. Titkov, and M. Yu. Chudetsky, 2005. Conceptions and Indicators of the Abiogenic Oil and Gas Origin and Its Significance. ''AAPG Conference, Calgary, Canada 2005''. [http://www.searchanddiscovery.com/documents/abstracts/2005research_calgary/abstracts/extended/valyaev/valyaev.htm Abstract] -->
<!-- Dead note "dow2005": Dow, W.G., 2005. The Petroleum System Paradigm and the Biogenic Origin of Oil and Gas. ''AAPG Conference, Calgary, Canada 2005.'' [http://www.searchanddiscovery.com/documents/abstracts/2005research_calgary/abstracts/extended/dow/dow.htm Abstract] discussion of oil genesis, optical axis shifts, and the CuuLong / White Tiger field. -->
<!-- Dead note "Seewald2005": Seewald J., Whelan J., 2005. Isotopic and Chemical Composition of Natural Gas from the Potato Hills Field, Southeastern Oklahoma: Evidence for an Abiogenic Origin? ''AAPG Conference, Calgary, Canada 2005.'' [http://www.searchanddiscovery.com/documents/abstracts/2005research_calgary/abstracts/extended/seewald/seewald.htm Abstract] -->
<!-- Dead note "Barker2005": Barker C., 2005. The Complementary Roles of Kinetics and Thermodynamics in the Generation and Preservation of Oil and Gas. ''AAPG Conference, Calgary, Canada 2005.'' [http://www.searchanddiscovery.com/documents/abstracts/2005research_calgary/abstracts/short/barker.htm Abstract] -->
== External links ==
*[http://web.archive.org/web/20021004123112/http://www.people.cornell.edu/pages/tg21/usgs.html The Origin of Methane (and Oil) in the Crust of the Earth (Thomas Gold)]
*[http://www.searchanddiscovery.net/documents/abstracts/2005research_calgary/index.htm abstracts from AAPG Origin of Petroleum Conference] 06/18/05 Calgary Alberta, Canada
*[http://www.wired.com/wired/archive/8.07/gold_pr.html Fuel's Paradise (Wired)]
*[http://www.aapg.org/explorer/2002/11nov/abiogenic.cfm Abiogenic Gas Debate 11:2002 (EXPLORER)]
*[http://www.gasresources.net/index.htm Gas Resources Corporation collection of documents]
*[http://eaps.mit.edu/geobiology/biomarkers.html Geobiology @ MIT about biomarkers]
*[http://www.fromthewilderness.com/free/ww3/102104_no_free_pt1.shtml "No Free Lunch, Part 1: A Critique of Thomas Gold's Claims for Abiotic Oil"], by Jean Laherrere, in ''[[From The Wilderness]]''
*[http://www.fromthewilderness.com/free/ww3/011205_no_free_pt2.shtml "No Free Lunch, Part 2: If Abiotic Oil Exists, Where Is It?"], by Dale Allen Pfeiffer, in ''From The Wilderness''
* [http://www.wnd.com/news/article.asp?ARTICLE_ID=38645 Sustainable Oil? (5-25-04 WorldNet Daily)]
* [http://www-cms.llnl.gov/s-t/cheetah_methane_str.html Experimental evidence for the Calcite-magnetite-aragonite-methane system at 500-700°C.]
<!-- Dead note "Protoil1": CSIRO Petroleum Research, [http://www.dpr.csiro.au/ourcapabilities/petroleumgeoscience/organicgeochemistry/projects/proterozoicoilinclusions/ Proterozoic oils] -->
<!-- Dead note "Protoil2": [http://www.ucmp.berkeley.edu/bacteria/cyanofr.html proterozoic stromatolite]. -->
* [http://www.geosci.usyd.edu.au/about/people/staff/dutkiewicz.html Publications of A. Dutkiewicz] on Proterozoil oils (reference list and bibliography).
* [http://www.sciencemag.org/cgi/content/abstract/319/5863/604 Abiogenic Hydrocarbon Production at Lost City Hydrothermal Field]
[[Category:Extremophiles]]
[[Category:Peak oil]]
[[Category:Fringe science]]
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[[es:Origen Inorgánico del Petróleo]]
[[pt:Origem inorgânica do petróleo]]
[[sv:Olja av icke-biologiskt ursprung]]