It Will Take 131 Years To Replace Oil, And We've Only Got 10

According to a new paper by two researchers at the University of California – Davis, it would take 131 years for replacement of gasoline and diesel given the current pace of research and development; however, world's oil could run dry almost a century before that.

The research was published on Nov. 8 at Environmental Science & Technology, which is based on the theory that market expectations are good predictors reflected in prices of publicly traded securities.

By incorporating market expectations into the model, the authors, Nataliya Malyshkina and Deb Niemeier, indicated that based on their calculation, the peak of oil production could occur between 2010 and 2030, before renewable replacement technologies become viable at around 2140.

The estimates not only delayed the alternative energy timeline, but also pushed up the peak oil deadline. The researchers suggest some previous estimates that pegged year 2040 as the time frame when alternatives would start to replace oil, could be “overly optimistic".

As I pointed out before, despite the excitement and hype surrounding a future of clean energy, a majority of the current technology simply does not make economic sense for regular consumers and lack the infrastructure for a mass deployment….even with government subsidies, tax breaks, and outright mandates.

In addition, the supply chain of renewable technologies is not as green as people might think. Most alternative technologies rely on rare earths for efficiency. However, the radioactive waste produced by rare earths mining process makes oil sands look like a green energy. This overlooked (or ignored) fact just now received some attention due to the sudden shortage caused by China’s embargo and export quotas on rare earths.

Why then does virtually every oil sample examined contain microfossils consistent with the age of the sediment in which it is buried?.>>>>>>>>>>>>

This is not true.Its a myth.

And why is petroleum not found naturally in metamorphic of igneous environments?>>>>>>>>>>>>>>>>

It is found in metamorphic amd igneous environments far below the stratified surface of the earths crust.

It´s a sedimentary phenomena.>>>>>>>>>>>>>>

Then why are replenished oil reserves filled from the bottom up, not from the sides of top?

The earth has an oil based ciculatory system which is deep below the earths crust, and it seeps upward innto the sedimetary areas which are oil permeable.Helium is a byproduct of the process. Helium coud never be created thryugh just a sedimentary process.There i s much more involved than simple processing of sedimentary microfossiles. The microfossile material is only an ingrediant in a larger process.Heat both from the mantle and from radioactive materials also play a part. We just do not know the full process yet.

You think you know the full process. No one does, yet.
But we do know it is not a strictly sedimentary process.

Oil reserves renew themselves over time.

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Dr Thomas Gold:

Recharging of oil and gas fields.

There have been numerous reports in recent times, of oil and gas fields not running out at the expected time, but instead showing a higher content of hydrocarbons after they had already produced more than the initially estimated amount. This has been seen in the Middle East, in the deep gas wells of Oklahoma, on the Gulf of Mexico coast, and in other places. It is this apparent refilling during production that has been responsible for the series of gross underestimate of reserves that have been published time and again, the most memorable being the one in the early seventies that firmly predicted the end of oil and gas globally by 1987, a prediction which produced an energy crisis and with that a huge shift in the wealth of nations. Refilling is an item of the greatest economic significance, and also a key to understanding what the sources of all this petroleum had been. It is also of practical engineering importance, since we may be able to exercise some control over the refilling process.
The debate about the origin of all the petroleum on Earth lies in the center of the subject. If we really knew that it is only biological materials, which, in their decay, could produce hydrocarbons, then the quanities that could ever be produced would be limited by the biological content of the sediments. But then the clear and strong association of petroleum with the inert gas helium would have no explanation; the finding of hydrocarbon gases, liquids and solids on most other planetary bodies in our solar system which have surface conditions quite unsuitable for surface life, could not be understood; the presence of hydrocarbons which we now find in abundance in basement rocks would also remained unexplained.
If we accept the fact, now known full well, that hydrocarbons are a common constituent of the cosmos and the planetary condensations that formed in it, then we have a totally different viewpoint. Hydrocarbons are stable down to great depths and the high temperatures there, contrary to many statements that have been made that the temperature reached at depths between 30,000 and 40,000 ft would dissociate most of the hydrocarbons. But these calculations are seriously in error, because they ignored the strong stabilizing effect of pressure at depth, that had been calculated by Soviet (Ukrainian and Russian) thermodynamicists. The existence of diamonds, crystals of pure carbon that form at pressures which are not reached on earth at depths of less than 140 kilometers, proves that unoxidized carbon exists at such depths, and also carbon-bearing liquids must flow there that can deposit carbon at high purity. High pressure fluid inclusions in diamonds prove that liquid or gaseous hydrocarbons were present at their formation. Present day meteorites give us examples of the solids responsible for the building up of the Earth; among those only one class, the carbonaceous chondrites, contain much carbon, mostly in unoxidized form. That this material is present in the Earth’s interior in large abundance is shown by the distribution of noble gases and their isotopes that have emerged into our atmosphere and show distributions that are strikingly similar to those in carbonaceous chondrites, but dissimilar to those of any other class of meteorites. The presence of this type of material would account for a continuous supply of hydrocarbons to the atmosphere, as the outer layers of the mantle heat up over time and make fluids form from the solid hydrocarbons that were included in the forming Earth (as also in most of the other planets and their satellites, in the asteroids, comets and interplanetary dust grains). Such fluids are less dense than the rocks, and buoyancy forces will propel them upwards.

Rocks and lower density fluids can co-exist at any level in a solid planetary body, provided that the pressure of the pore fluids is sufficiently high to make the differential pressure between rocks and fluids less than the crushing strength of the rocks. For a static case (with no upward flow of the fluid), this would result in pressure domains, within which the fluid pressure shows a pressure gradient with depth given just by the density of the fluid (the “head”), and where the bottom of each domain is at the level at which the fluid pressure is insufficient to maintain pore spaces against the higher pressure of the rock. (See Figure 1.) It is assumed here (for the static case) that this makes a complete barrier. As for the top of any domain, this cannot be at a level higher than that at which the fluid pressure equals the rock pressure, since fluid pressures in excess of this value cannot be maintained in rocks that on a large scale and in long time- intervals, have no tensile strength and therefore cannot resist the intrusion of the fluids and the generation of new pores.

If we consider the case of a slow upward migration of fluids (liquids or gases), then this picture changes to one in which each domain will be stacked on another one below, all the way down to the level of origin of the fluid. The fluid pressure would thus make a stepwise approximation to the pressure in the rocks. Now none of the barriers can be absolute, since they would be torn open by the fluids that arise from deeper and higher pressured domains. But the barriers would be torn open in each case only to the point at which the flow to the overlying domain causes it to suffer a pressure drop resembling that of the static case. This rule will apply whatever the nature of the rock. The heights of the domains will be determined by the rock and fluid densities and the crushing strength of the rocks; this height has been found to be between 10,000 ft and 15,000 ft in many sedimentary rocks, and in excess of 20,000 ft in granitic basement rocks. The upward seepage of methane is very widespread all over the Earth, as is shown by the great extent of methane hydrates on the ocean floors and in permafrost regions on land, where mostly no shallow source of methane can be invoked.
Vertically stacked domains of hydrocarbons have been found in all cases where drilling was sufficient to display them. The consistent tendency to find hydrocarbons below any producing region has been given the name of “Koudyavtsev’s Rule”, after the important Russian petroleum investigator who discovered this effect and collected a very large number of examples of it from all parts of the world. This rule would be the consequence of a deep origin of hydrocarbons and a steady process of outgassing.
With this picture in mind we would readily understand that refilling of hydrocarbon fields is possible and even probable. But if merely the steady upward flow from deep sources had been responsible, the refilling time scales would be much too slow to be of commercial interest, or to match the speed that appears to have been observed. A limit to the global average of that flow speed can be derived from the approximately known supply of carbon to the atmosphere over time. On that basis a large gas field may be recharging in times reckoned in tens of thousands of years, still very short compared with many millions of years, as had been the widespread belief. But observed refill times of just a few tens of years cannot be explained by this. However another effect will set in when a field is under production and the pressure in its domain is thereby diminished. The pressure difference between the producing domain and the one below it will then be increased, resulting in a higher rate of flow through the low permeability layer that divides these domains, or it may even result in a physical rupture of that layer.

There is an analogous case known in Kuwait. The extraction of goundwater at the shallow levels results in the disintegration of the barrier to the oil levels just below, and the water in the wells is suddenly replaced by oil. The delicate pressure balance that had established itself, just up to the level that the strength of the rock could bear, had been upset. Similarly in stacked domains of hydrocarbons, the lower domains will be opened quickly, once the upper ones had been depleted and the fluid pressure thereby reduced sufficiently. This process can be fast, just as it is in Kuwait, where we had the advantage that a different liquid (water) filled the upper domain, so that one could identify the rupture to the oil filled domain below.

This type of refilling process thus allows exploitation of the domain below that from which production had been obtained before. In turn, when this lower domain had suffered a sufficient pressure loss, the process may continue to the next lower domain. How much more than the original content of a hydrocarbon field can be produced in any one case will depend on numerous details of the formation, but present indications are that it is often at least double. The present global gas and oil glut appears to be due to this effect, and we have not yet seen the end of it, or any indication that it will end soon. Gas fields will be subject to faster refilling than oil fields, and moreover the volumes of gas in lower domains will in general be greater due to the higher pressures there and the higher compressibility of gas. Gas will thus become more plentiful than oil for this reason alone, but gas seems to be generally more plentiful and more widespread than oil. The environmental advantages of changing from coal or oil to gas, by far the cleanest of all combustible fuels, are very large, and the changeover is at present still handicapped by the mistaken belief that the supplies of gas will run out soon.

Thomas Gold September 1999

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Natural Gas and Oil Thomas Gold January 1997 Natural gas and oil are widely considered to originate on Earth from the chemical evolution of biological debris. A view, widespread in earlier times and entertained by Mendeleev among others, was instead that these substances originated in materials laid down in the formation process of the Earth, and later percolated towards the surface.
Similar hydrocarbons are widespread on many other planetary bodies, as well as on comets and generally in deep galactic space, clearly not related to biological materials there. Thermodynamic considerations show that in the high-pressure, high-temperature regime of the outer mantle of the Earth, hydrogen and carbon will readily form hydrocarbon molecules, and some of those will be stable during ascent into the outer crust. There is no reason now for invoking the unique origin of biology for the Earth’s hydrocarbons, different from the origin of similar materials on the other planetary bodies.
The many molecules of unquestionably biological origin in petroleum - hopanes, pristine, phytane, steranes, certain porphyrins - can all be produced by bacteria, and such microbial life at depth is indeed now seen to be widespread. The presence of these molecules can no longer be taken to be indicative of a biological origin of petroleum, but merely of the widespread presence of a microflora at depth. The presence of helium and of numerous trace metals, often in far higher concentrations in petroleum than in its present host rock, has then an explanation in the scavenging action of hydrocarbon fluids on their long way up. Many mineral deposits may be due to the formation and transportation of organo-metallic compounds in such streams, often interacting with microbial life in the outer crust.
A 6.6 km deep well drilled in the granite of Sweden shows petroleum and gas, and bacteria that can be cultured, all in the complete absence of any sediments, and hence of any biological debris. Combustible gas in large sample containers has been brought to the surface from a depth of more than 6.5 km. It will readily burn, and it shows a composition which includes methane and heavier hydrocarbons up to C-7, as well as free hydrogen. The greatest concentrations of this gas are in and close to the various intrusions of volcanic rocks (dolerite), indicating that the gases have used the pathways from depth that the volcanic rock created or used in its ascent.

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The Origin of Methane (and Oil) in the Crust of the Earth Thomas Gold U.S.G.S. Professional Paper 1570, The Future of Energy Gases, 1993 Abstract The deposits of hydrocarbons in the crust of the Earth have long been regarded by many investigators as deriving from materials incorporated in the mantle at the time of the Earth’s formation. Outgassing processes, active in all geological epochs, then transported the liquids
and gases liberated there into porous rocks of the crust. The alternative viewpoint, that biological debris was the source material for all crustal hydrocarbons, gained widespread acceptance when molecules of clearly biological origin were found to be present in most commercial crude oils.

Modern information re-directs attention to the theories of a non-biological, primeval origin. Among this information is the prominence of hydrocarbons—gases, liquids and solids—on many other bodies of the solar system, as well as in interstellar space. Advances in high-pressure thermodynamics have shown that the pressure-temperature regime of the Earth would allow hydrocarbon molecules to be formed and to survive between the surface and a depth of 100 to 300 km. Outgassing from such depth would bring up other gases present in trace amounts in the rocks, thus accounting for the well known association of hydrocarbons with helium. Recent discoveries of the widespread presence of bacterial life at depth point to this as the origin of the biological content of petroleum. The carbon budget of the crust requires an outgassing process to have been active throughout the geologic record, and information from planets and meteorites, as well as from mantle samples, would suggest that methane rather than CO2 could be the major souce of surface carbon. Isotopic fractionation of methane in its migration through rocks is indicated by numerous observations, providing an alternative to biological processes that have been held responsible for such fractionation. Information from deep boreholes in granitic and volcanic rock of Sweden has given support to the theory of the migration of gas and oil from depth, to the occurrence of isotopic fractionation in migration, to an association with helium, and to the presence of microbiology below 4 km depth.

Introduction

The gas methane, CH4, the principal component of natural gas, does not contain sufficient evidence in itself from which to deduce its origin on the Earth. There is some evidence from its isotopic composition, but interpretations of that are not unique. Information, however, exists in the mode of occurrence of natural gas reservoirs, in the geographic and geological relationships, in associated chemicals, and, above all, in the frequent association with other hydrocarbons, specifically crude petroleum and bituminous coal. Although there are numerous occurrences of natural gas without the heavier hydrocarbons, the association is generally so clear that one cannot contemplate an origin for the natural gas deposits independent of those of petroleum. We shall therefore first consider the origin of the whole set of hydrocarbons
including natural gas, and then discuss aspects that are specific to methane.

Debate about the Origin of Petroleum

It is remarkable that in spite of its widespread occurrence, its great economic importance, and the immense amount of fine research devoted to it, there perhaps still remain more uncertainties concerning the origin of petroleum than that of any other commonly occurring natural substance. (H.D.Hedberg, 1964)

Actually it cannot be too strongly emphasized that petroleum does not present the composition picture expected from modified biogenic products, and all the arguments from the constituents of ancient oils fit equally well, or better, with the conception of a primordial hydrocarbon mixture to which bio-products have been added. (Sir Robert Robinson, President, Royal Society, 1963)

The capital fact to note is that petroleum was born in the depths of the Earth, and it is only there that we must seek its origin. (D. Mendeleev, 1877) The origin of petroleum has been a subject of many intense and heated debates, ever since this black fluid was first discovered to be present in large quantities in the pore spaces of many rocks. Is it something brought in from space when the Earth was formed? Or is it a fluid concentrated from huge amounts of vegetation and animal remains that may have been buried in the sediments over hundreds of millions of years?

Arguments have been advanced for each viewpoint, and although they conflict with each other, each line of argument sounds strangely convincing. In favor of the biogenic origin of petroleum, the following four observations have been advanced:

(1) Petroleum contains groups of molecules which are clearly identified as the breakdown products of complex, but common, organic molecules that occur in plants, and that could not have been built up in a non-biological process.

(2) Petroleum frequently shows the phenomenon of optical activity, i.e. a rotation of the plane of polarization when polarized light is passed through it. This implies that molecules which can have either a right-handed or a left-handed symmetry are not equally represented, but that one symmetry is preferred. This is normally a characteristic of biological materials and absent in fluids of non-biological origin.

(3) Some petroleums show a clear preference for molecules with an odd number of carbon atoms over those with an even number. Such an odd-even effect can be understood as arising from the breakdown of a class of molecules that are common in biological substances, and may be difficult to account for in other ways.

(4) Petroleum is mostly found in sedimentary deposits and only rarely in the primary rocks of the crust below; even among the sediment, it favors those that are geologically young. In many cases such sediment appears to be rich in carbonaceous materials that were interpreted as of biological origin, and as source material for the petroleum deposit.

On the other side of the argument, in favor of an origin from deeply buried materials incorporated in the Earth when it formed, the following observations have been cited: (1) Petroleum and methane are found frequently in geographic patterns of long lines or arcs, which are related more to deep-seated large-scale structural features of the crust, than to the smaller scale patchwork of the sedimentary deposits.

(2) Hydrocarbon-rich areas tend to be hydrocarbon-rich at many different levels, corresponding to quite different geological epochs, and extending down to the crystalline basement that underlies the sediment. An invasion of an area by hydrocarbon fluids from below could better account for this than the chance of successive deposition.

(3) Some petroleums from deeper and hotter levels lack almost completely the biological evidence . Optical activity and the odd-even carbon number effect are sometimes totally absent, and it would be difficult to suppose that such a thorough destruction of the biological molecules had occurred as would be required to account for this, yet leaving the bulk substance quite similar to other crude oils.

(4) Methane is found in many locations where a biogenic origin is improbable or where biological deposits seem inadequate: in great ocean rifts in the absence of any substantial sediments; in fissures in igneous and metamorphic rocks, even at great depth; in active volcanic regions, even where there is a minimum of sediments; and there are massive amounts of methane hydrates (methane-water ice combinations) in permafrost and ocean deposits, where it is doubtful that an adequate quantity and distribution of biological source material is present.

(5) The hydrocarbon deposits of a large area often show common chemical or isotopic features, quite independent of the varied composition or the geological ages of the formations in which they are found. Such chemical signatures may be seen in the abundance ratios of some minor constituents such as traces of certain metals that are carried in petroleum; or a common tendency may be seen in the ratio of isotopes of some elements, or in the abundance ratio of some of the different molecules that make up petroleum. Thus a chemical analysis of a sample of petroleum could often allow the general area of its origin to be identified, even though quite different formations in that area may be producing petroleum. For example a crude oil from anywhere in the Middle East can be distinguished from an oil originating in any part of South
America, or from the oils of West Africa; almost any of the oils from California can be distinguished from that of other regions by the carbon isotope ratio. (6) The regional association of hydrocarbons with the inert gas helium, and a higher level of natural helium seepage in petroleum-bearing regions, has no explanation in the theories of biological origin of peroleum.
Advocates of the Abiogenic Theory Among the early advocates of a non-biological origin of petroleum was the great Russian chemist Mendeleev, the originator of the periodic table of the elements. His arguments, presented in a paper on the origin of petroleum (Mendeleev, 1877) are still valid today. He already knew of the large-scale patterns of hydrocarbon occurrence, but his information on the processes that shaped the Earth was not our present understanding, and made his explanations much more complex than would need to be the case now.
Sokoloff (1889) discussed the “cosmic origin of bitumina” (carbonaceous substances from petroleum to pitch and tar), and he related these to the meteorites, knowing then already about their hydrocarbon content. He stressed that oil and tar occur in basement rocks, such as in the gneiss of Sweden. He could find no relationship to the fossil content of rocks, and he stressed that porosity was the sole circumstance which relates to the accumulation of bituminous substances.

Vernadsky (1933) gave reasons why he considered that with increased pressure and deceased oxygen availability with depth, hydrocarbons would be stable and largely replace carbon dioxide as the chief carbon-bearing fluid.

Kudryavtsev (1959) the most prominent and strongest advocate of the abiogenic theory in modern times, argued that no petroleum resembling the chemical composition of natural crudes has ever been made from genuine plant material in the laboratory, and in conditions resembling those in nature. He gave many examples of of substantial and sometimes commercial quantities of petroleum being found in crystalline or metamorphic basements, or in sediments directly overlying those. He cited cases in Kansas, California, Western Venezuela and Morocco. He pointed out that oil pools in sedimentary strata are often related to fractures in the basement directly below. The Lost Soldier Field in Wyoming has oil pools, he stated, at every horizon of the geological section, from the Cambrian sandstone overlying the basement to the upper Cretaceous deposits. A flow of oil was also obtained from the basement itself.

Hydrocarbon gases, he noted, are not rare in igneous and metamorphic rocks of the Canadian Shield. Petroleum in Precambrian gneiss is encountered in wells on the eastern shore of Lake Baikal. He stressed that petroleum is present, in large or small quantity, but in all horizons below any petroleum accumulation, apparently totally independent of the varied conditions of formation of these horizons. This statement has since become known as “Kudryavtsev’s Rule” and many examples of it have been noted in different parts of the world. Commercial accumulations are simply found where permeable zones are overlaid by impermeable ones, he concluded.

Kudryavtsev introduced a number of other relevant considerations into the argument. Columns of flames have been seen during the eruptions of some volcanoes, sometimes reaching 500 meters in height, such as during the eruption of Merapi in Sumatra in 1932. (We since know of several other instances.) The eruptions of mud-volcanoes have liberated such quantities of methane, that even the most prolific gasfield underneath should have been exhausted long ago. Also the quantities of mud deposited in some cases would have required eruptions of much more gas than is known in any gasfield anywhere. The water coming up in some instances carries such substances as iodine, bromine and boron that could not have been derived from local sediments, and that exceed the concentrations in seawater one hundred fold. Mud volcanoes are often associated with lava volcanoes, and the typical relationship is that where they are close, the mud volcanoes emit incombustible gases, while the ones further away emit methane. He knew of the occurrence of oil in basement rocks of the Kola Peninsula,

and of the surface seeps of oil in the Siljan Ring formation of Central Sweden (which we shall discuss later). He noted that the enormous quantities of hydrocarbons in the Athabasca tar sands in Canada would have required vast amounts of source rocks for their generation in the conventional discussion, when in fact no source rocks have been found.
Beskrovny and Tikhomirov (1968) noted, as did Anders, Hayatsu and Studier (1973), that of the many possible isomers of petroleum molecules, the particular sub-set found in natural petroleum is also the one singled out in artificial oil production from hydrogen and carbon rather than from biological substances.
Profir’ev (1974) argued that so-called source rocks have no identification that proves their hydrocarbons to be primarily biogenic. He also discounted the hypothesis, often advanced, that the transport and deposition of oil from supposed source rocks to the final reservoir was accomplished by solution in gas: the quantities of gas that would be required would exceed by orders of magnitude the quantities that could be derived from the supposed source materials.
Levin (1958) concerned himself with the formation process of the Earth, claiming that the class of meteorites called carbonaceous chondrites, a low-temperature condensate that was probably responsible for bringing in solids that contained water, could have brought to the forming Earth several times larger quantities of carbonaceous materials than all the ocean water.
Kravtsov (1975) presented much observational material. He showed that the natural seepage of methane in many areas was far more than could be supplied by any kind of gasfield known. If the volcanic gases of the Kurile Islands, for example, are typical of the gases emitted over the time-span of the volcanic activity there, the amount of methane emitted would far exceed the conventional estimate of the present-day total world reserves. He also gave many examples of “Kudryavtsev’s Rule.”

Kropotkin and Valyaev (1976, 1984) and Kropotkin (1985) developed many aspects of the theory of deep-seated, inorganic origin of hydrocarbons. They concluded that petroleum deposits were formed where pressure conditions permitted the condensation of heavier hydrocarbons, transferred from great depth by rapidly rising streams of compressed gases. In volcanic regions, they noted, decomposition of hydrocarbons would be favored, resulting in the formation of carbon dioxide and water, while in “cool” regions hydrocarbons would be preserved, and could accumulate in alluvial cover and highly fractured beds, depending on the presence of adequate reservoirs and covers. According to these authors “vertical migration of hydrocarbons from levels far below formations rich in biogenic organic matter, which have been considered the source material for the oil, can be demonstrated in a majority of deposits.” Kropotkin also presented numerous examples where Kudryavtsev’s Rule is satisfied in a striking way.

There were several voices also outside Russia (or the Soviet Union), who argued for a non- biogenic origin. Most notable among them was Sir Robert Robinson (1963, 1966) who, like Mendeleev, can be considered among the most distinguished chemists of his day. He studied the chemical make-up of natural petroleums in great detail, and concluded that they were mostly far too hydrogen-rich to be a likely product of the decay of plant debris. Olefins, the unsaturated hydrocarbons, would have been expected to predominate by far in any material that was derived in that way.
Sylvester-Bradley (1964, 1972) discussed that the meteorites have hydrocarbons, and that hydrocarbons on the Earth derived in major part from such material. He proposed that hydrocarbons streaming up through the crust from great depth would have provided energy sources for simple forms of life. He knew about the biological materials in petroleum, but, like Robert Robinson, he thought that they were due to contaminating additions from microbiology in such locations.

Before discussing further the possible origins of hydrocarbons on the Earth, it is necessary to discuss the present state of knowledge of the formation process of the Earth and the planetary system, and the materials that contributed to the formation.

The Formation Process of the Earth

The Earth is a body with a most complex history. None of its sister planets display signs of the processes that appear to have been the major ones to shape this planet of ours. On all the other solid bodies of the Solar System the effects of impact cratering can be seen very clearly. Craters spanning a range of size from a few kilometers to several thousand can be clearly recognized. Impacts of solid objects upon all the planetary bodies in the process of their formation must have been a common occurrence.

Strangely, on our Earth similar cratering events can only be seen, if at all, in a very subdued form. We see arcs of circles appearing in the midst of a topography shaped by other effects. It seems reasonable to interpret such circular features as the remains of impacts, now deeply buried but affecting the outer crust at a later stage in some way that makes the buried impacts recognizable again. One has to suppose that other events occurred here that obscured most of the evidence of this early bombardment.

Nevertheless, it is now quite clear that the Earth, like the other solid planetary bodies, also formed by the accretion of solid objects, probably largely in the form of small grains, but interspersed with occasional major pieces. It appears that then a partial melting took place, causing materials of lower density to make their way to the surface, while presumably melts of high density sank down towards the center. The heat for this melting was the result of radioactivity contained in the material, as well as just the heat resulting from compression. Once partial melting occurred, two other sources of heat came into play: firstly the gravitational energy that is released as materials can move and sort themselves out according to density. Secondly there is the chemical energy that results from all the chemical reactions that can then take place, either between different liquids or between liquids and solids. The original diverse materials accreted as cold objects would certainly not have been chemically equilibrated with each other, but would be left in an uneven distribution by the chances of the impact events. After gaining mobility by melting, many chemical reactions would take place that would, on average, release energy and thus provide more heat, as well as giving rise to volatile substances.

Both these last two sources of energy have the interesting property that they make the heating unstable: where more heating has occurred and more melt produced, more of these actions can take place and therefore still more heat will be produced there. One may well speculate that the very uneven distribution of internal heat sources which we recognize at the surface, derives from such an instability. The circumpacific “belt of fire” is the most striking example, but there are also many other lanes characterized by high heat flow and volcanic activity. They are also characterized by the outflow of fluids, gases and liquids, that are thought to have a deep origin. Deposits of hydrocarbons frequently show a clear association with such patterns. (An example is shown in Figure 3.)

If the major volume of the Earth has never been molten, the mantle of the Earth underneath the crust must still contain the diversity of chemistry, the chemical energy sources and the sources of gases and liquids that would be the legacy of an accretion process from diverse and initially cold solids. Major impacts would have thrown up ring patterns of mountains, which, as on the Moon, would convert vertical patterns of chemical inhomogeneity into regional patterns. Many arcuate patterns on the Earth of present surface topography and of chemical features or of heat flow may be a consequence of this.

The Theory of the Biological Origin of Hydrocarbons on Earth

Oil, hydrocarbon gases and coal on the Earth were thought to have derived entirely from biological debris for the following reasons: One reason was the belief in earlier times that hydrocarbons were specifically organic substances: hence the name “organic carbon” for all
forms of unoxidized carbon. The knowledge that hydrocarbons are abundant in the universe, and on many of the other planetary bodies of our solar system, was not available at that time. Now we know that carbon, the fourth most abundant element in the Universe after hydrogen, helium and oxygen, is almost certainly also the fourth most abundant in the planetary system; there it is predominantly in the form of hydrocarbons. The major planets Jupiter, Saturn, Uranus and Neptune, have large amounts of methane and other hydrocarbon gases in their atmospheres. Titan, a large satellite of Saturn, has methane and ethane in its atmosphere, and these gases form clouds and behave much like water does in the atmosphere of the Earth. Triton, a large satellite of Neptune, appears to have hydrocarbons mixed with water ices on its surface, as does the outermost planet known at this time, Pluto. A large fraction of all the asteroids show a surface reflectance closely resembling that of tar, and the comets have hydrocarbons among the gases they emit. The surface of the core of Comet Halley, recently observed by spacecraft, is most reasonably interpreted as one of tar. Complex, polycyclic hydrocarbon molecules, similar to those in natural petroleum have been observed to be a prominent component of interplanetary dust grains that currently enter the Earth’s upper atmosphere (Clemett and others, 1993).

Hydrocarbons in our planetary system are certainly very abundant, and in all the extraterrestrial examples mentioned almost certainly not related to biology. Also hydrocarbons are prominent among the gases identified in the molecular clouds of the galaxy, and it is from such clouds that the solar system formed initially. The presence and great abundance of hydrocarbons is universal, and no special mechanism for their generation on the Earth needs to be invoked, unless one knew with certainty that they could not have survived the formation process here, although they did so on many of the other planetary bodies. (No evidence of hydrocarbons has yet been seen on Mars, Moon, Venus and Mercury. The atmosphere of Venus is too hot to have maintained gaseous or liquid hydrocarbons; the other three bodies lack an adequate protective atmosphere to have maintained them on their surfaces.)

In earlier times there was the belief that the Earth had formed as a hot, molten body. In that case no hydrocarbons or hydrogen would have survived against oxidation, nor would any of these substances have been maintained in the interior after solidification. With that belief, there seemed no other possibility of accounting for the hydrocarbons embedded in the crust than by the outgassing of carbon in the form of CO2, produced by materials that could have survived in a hot Earth, and subsequent photosynthesis by plants that converted this CO2 into unoxidized carbon compounds. This consideration is irrelevant now that we know that a cold formation process assembled the Earth and that hydrocarbons could have been maintained, and could be here for the same reasons as they are on the other planetary bodies.

The common existence of molecules of clearly biological origin in most petroleum and bituminous coal is no longer an argument for a biological origin of hydrocarbons, now that we know of the wide reach of microbiology in the crust (Jannasch, 1983; Yayanos, 1986; Gold, 1992). Before this had been identified, the possibility of widespread biological contamination at depth had not been considered. Now, especially after the discovery of the volcanic vents on the ocean floors and the profuse chemosynthetic life that exists there, the outlook is different. It is now seen as not only possible, but very likely, that microbiology is common in the crust down to depths of between 5 and 10 kilometers, a level below which the temperature will reach values too high for any microbial life we know, thought to be between 110 and 150 °C. This deep microbial life uses as its energy source the various chemical imbalances that the outgassing process creates as gases and liquids stream up through rocks with which they have never been chemically equilibrated. Knowing now of the occurrences of such deep microbial life, it seems likely that no location that could support such life has been kept sterile from it for the long periods of geologic time. Hydrocarbons, together with oxygen donors such as sulfates or metal (principally iron) oxides, substances that are common in the rocks or water, would provide a usable energy source for microorganisms. Hydrocarbon deposits would therefore acquire biological debris in the course of time. The molecules which are commonly regarded as proof of the biological origin of petroleum and of bituminous coal have all been found to be also produced by subsurface bacteria; indeed some of them can only be produced by bacteria (Ourisson and others, 1984). Pristane, phytane, steranes, hopanes are unquestionably of biological origin, but do not certify the biological origin of either petroleum, coal, kerogen or whatever other deposits in which they are seen. With the photosynthetic theory of their origin,they seemed to certify that these materials were all once at the surface. But this is no longer a valid inference. Many other conclusions in geology were based on this, and should also be reconsidered now.

Origin of the Carbon on the Earth

The surface and surface sediment on the Earth contain approximately one hundred times as much carbon as would have been derived from the grinding up of the basement rocks that contributed to the sediment. The surface is enormously enriched in carbon, and this needs an explanation.

The carbon we have on the surface or in the sediment of the Earth is estimated to be 4/5 in the form of carbonate rocks, and 1/5 in unoxidized form, frequently referred to as “organic.” (The word “organic” given then to all unoxidized carbon, is of course now a misleading misnomer.) The quantities are large: if expressed as the mass of the element carbon per square centimeter of total Earth surface area, the estimate is about 20 kilograms. (I will be referring to this quantity again later.)

During formation of the Earth by the accumulation of cold solids, very little gaseous material was incorporated. The knowledge of this comes from the extremely low level of the non- radiogenic noble gases in the atmosphere of the Earth. Among those, only helium could have escaped into space, and only xenon could have been significantly removed by absorption into rocks. Neon, argon, krypton would have been maintained as an atmospheric component. The noble gas proportions in the Sun and in space are known. Any acquisition of such a mix of gases in the formation process would not have been able to selectively exclude noble gases that have no significant chemical interactions. One is forced to conclude that the acquisition of gases, or substances that would be gaseous at the pressures and temperatures that ruled in the region of formation of the Earth, was limited to the small value implied by the low noble gas values. The carbon supply the Earth received initially could not have been in the form of hydrocarbon gases, high volatility hydrocarbon liquids, or CO or CO2.
Could meteoritic infall of carbon at later times be held responsible for the surface carbon excess? Such a massive infall would have left much other evidence in the geologic record, and this is absent. The only alternative is that carbon came up from the interior as a liquid or gas, just as is also true for the water of the oceans (approximately 300 kg/cm2) the nitrogen of the atmosphere (1 kg/cm2 approximately) and the (largely radiogenic) argon of the atmosphere.

Perhaps one might consider the possibility that the Earth once had a massive atmosphere of carbon dioxide that evolved early on, from materials that could have survived the formation process, and that these then became converted in into the carbon deposits we now have; but that also does not seem an acceptable explanation, for in that case we should see incomparably more very early carbonate rocks than the amounts laid down later. This is not what the geologic record shows. What it does show is a reasonably continuous process of laying down carbonate rocks; no epoch having enormously more per unit time, nor enormously less. If outgassing from depth is responsible, then one has to discuss what the source material in the Earth might have been, what liquids or gases might have come from them, and what their fate would have been as they made their way up through the crust.

The meteorites represent some samples of leftover material from the formation of the planets. While they may not be representative of the quantities of the different types that made up the Earth, they appear to represent at least samples of all the major components. Only one type, the carbonaceous chondrites, contain significant amounts of carbon, and they contain it mainly in unoxidized form, a substantial fraction in the form of solid, heavy hydrocarbons. This material, when heated under pressure as it would be in the interior of the Earth, would indeed release hydrocarbon fluids, leaving behind deposits of solid carbon.

The quantitative information on carbonaceous chondrites is difficult to evaluate. They are much more friable than most other meteorites, and therefore survive the fall through the atmosphere less often than the others. Carbonaceous chondrites also are destroyed by erosion on the
ground much more rapidly. The result must be that far fewer than the original proportion are ever discovered. They may well represent even now the largest quantity of meteoritic material still available for collection by the Earth; the infall of interplanetary dust to which I have referred, contains similar carbonaceous material.

By contrast, carbonates, which would be a source material for CO2, exist in meteoritic materials only in very small concentrations, so that an origin of the carbon from an initial CO2 source seems unlikely. If the carbonaceous chondrite material is the principal source of the surface carbon we have, then the initial material that could be mobilized in the Earth at elevated temperatures and pressure would be a mix of carbon and hydrogen. What would be the fate of such a mix? Would it all be oxidized with oxygen from the rocks, as some chemical equilibrium calculations have suggested? Evidently not, for we have clear evidence that unoxidized carbon exists at depths between 150 km and 300 km in the diamonds. We know they come from there, because it is only in this depth range that the pressures would be adequate for their formation. Diamonds are known to have high-pressure inclusions that contain CH4 and heavier hydrocarbons, as well as CO2 and nitrogen (Melton and Giardini, 1974). The presence of at least centimeter-sized pieces of very pure carbon implies that carbon-bearing fluids exist there, and that they must be able to move through pore-spaces at that depth, so that a dissociation process may deposit selectively the pure carbon; a process akin to mineralization processes as we know them at shallower levels. The fluid responsible cannot be CO2, since this has a higher dissociation temperature than the hydrocarbons that co-exist in the diamonds; it must therefore have been a hydrocarbon that laid down the diamonds.

Diamonds will only survive a transport to the low pressure at the surface, if it is accompanied by rapid cooling; if they are taken through a slow cooling process they will turn to graphite, the equilibrium form of carbon at low pressure. Diamond is a metastable form of carbon at the low surface pressure, but the temperature is too low for a relaxation to the stable form. Indeed, diamonds are found predominately in the vicinity of sites of explosive gas eruptions, diamond pipes, where rapid gas expansion caused quick cooling. There is also evidence for pure carbon transported up from depth at a slow rate: pseudomorphs of diamonds. Spaces showing the octahedral symmetry of diamond have been found filled with graphite, in mantle rocks that have come to the surface in Morocco (Pearson and others, 1989). These rocks came up presumably in a slow ascent, and contained a dense array of octahedral spaces filled with graphite, clearly fitting the interpretation as pseudomorphs of diamond. This discovery suggests that a very high density of diamonds exists at least in some locations in the mantle, and that their rarity on the surface is to be attributed to the rarity of the explosive events that could bring them up sufficiently quickly. It is noteworthy that hydrocarbons are found in diamond pipes together with the diamonds, suggesting that the gases involved in the explosive events were not oxidizing (Kravtsov and others, 1976; 1981).

The Surface Carbon Budget

The deposition of carbonate rocks has been an ongoing process throughout the times of the geologic record. Most, but not all of this carbonate has been an oceanic deposit, deriving the necessary CO2 from the atmospheric-oceanic CO2 store. The amount that is at present in this store is, however, only a very small fraction of the amount required to lay down the carbonates present in the geologic record. The atmospheric-oceanic reservoir holds at present only about 0.01 kg of carbon per cm2 of the Earth’s surface area. If we take the figure quoted, of about 20 kg of carbon per cm2 laid down over the time of the identified geologic record, there must have been a supply renewing the atmospheric-oceanic CO2 gradually, but by an amount 2,000 times the present content. This amount of carbon, if calculated as a continuous and steady outgassing rate and initially all coming up as methane, would translate into a one meter deep layer of methane (at STP) being created all over the Earth every 2,700 years. If the rate is regionally variable so that, for example, one tenth of the area produces nine tenths of the amount, then in the gas-prone areas one meter STP methane would come up every 300 years. If natural gas fields are filled from outgassing methane, such a supply rate would be much more than adequate in the timespans available to create all the known fields.

If the supply of carbon from below ceased, the present rate of laying down carbon would deplete the atmosphere-ocean reservoir in something on the order of 500,000 years, a very short fraction of geologic time. Outgassing of carbon in some form must have been a continuous process; it is not likely that humans evolved just in the last period, just before the death of all plant life. We must therefore inquire what quantities of carbon would have been available at deep levels, in what form this was, and in what manner this resupply of the atmospheric-oceanic CO2 reservoir could have taken place. It is also clear that one cannot discuss the man-made additions to the atmospheric carbon gases without regard to the large and surely variable natural carbon emission that has taken place throughout geologic time.

The resupply of carbon must be from juvenile sources. Recycling of sediments cannot account for it, both for reasons of the quantities involved and for reasons of the isotopic composition. If the repeated subduction of carbonate rocks occurred on the necessary massive scale, it would seem that old carbonates should have disappeared almost completely. This is not the case. The isotopic information, to which we shall return later, also would say that in a process of continuous recycling the proportion of13C would continuously increase in the atmosphere, and hence the younger carbonates should be isotopically heavier than the old ones; this also is not the case. Marine carbonates of all ages back to the Archaean show the same narrow range of the carbon isotopic ratio (Schidlowski and others, 1975, see also Figure 4).
How much carbonaceous chondrite material would have been required to provide the supply of the surface carbon? Let us make a simple calculation for this. Suppose that in the depth range between 100 and 300 kilometers we have a patchwork in which the carbonaceous chondrite material comprises 20 percent on an average. In this material, carbon amounts to 5 percent. This means, on an average, each square centimeter column through the 200 kilometer layer would contain 1 percent of carbon (5% of 20%), which would translate into 660 kilograms per square centimeter. If one-thirtieth of this had been mobilized and reached the outer crust, it would suffice to account for all the carbon of the carbonate sediments and the sediments of unoxidized carbon. Of course the proportion of carbonaceous chondrite type of material may have been very much larger, and the producing layer much thicker. The fraction that needs to have been mobilized would then be much smaller. All one can really say at this stage is that there is no quantitative problem. Volatile-rich material of sufficient quantity to have supplied the water of the oceans, as discussed by Levin (1958), could quite easily have supplied the quantity of hydrocarbons for all the surface carbon.

As we have seen, the primary source material in the Earth that would send up a carbon-bearing fluid is likely to be a hydrocarbon mix, not a substance that would produce CO2 in the first place. On the way up, however, some unknown fraction would come on pathways held open by magma, where these fluids would largely be oxidized to CO2 and water. On other pathways, created by pressure fracturing in solid rock, the direct oxidation will be minimal and these fluids may arrive at the surface as methane and other hydrocarbon gases or liquids. However, even in the solid rock a substantial proportion is frequently oxidized at shallow levels, as is indicated by the common presence in oil and gas-rich regions, of carbonate cements. These cements derive from metal oxides initially present in the rocks, and CO2 derived apparently from the oxidation of methane with some oxygen supplied from the rocks; the carbon isotope ratio of these pore-filling cements is not compatible with a derivation from atmospheric CO2, and their distribution fills the pores in a vertical column, suggesting an origin from ascending fluids. This oxidation is probably due to the action of microorganisms that obtain oxygen from components of the rock, and it is then limited to the outer levels of the crust where the temperature is in the range in which microbial activity can take place. It can be presumed quite reasonably that only a fraction of the CO2 so produced will in fact remain in the ground as carbonate, and a substantial fraction, quite possibly the major amount, will escape into the atmosphere.

A supply of hydrocarbons at depth may thus provide CO2 into the atmospheric-oceanic reservoir in three different ways. One is through volcanic pathways and oxidation with oxygen supplied by the magma; another is by ascent of hydrocarbons through solid rocks and oxidation at shallow levels, most likely by bacterial action, with subsequent escape of CO2 to the atmosphere; a third process will be the escape of methane and other hydrocarbons into the atmosphere, where, in the presence of atmospheric oxygen, they would reside on average 10 years before oxidation to CO2. What fraction of carbon resupply comes by each of these pathways is still not known directly, but some limits can be placed by considerations of the

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