Ophiolite,
We should start with the Sloan Deep Earth hydrocarbon lectures.
The problem with defending one hypothesis over the other is the objective unfortunately becomes to win an argument as opposed to compare hypothesis to hypothesis and to attempt to explain what is observed. My comment that mountain formation is not understood for example as there are multi regions such as the Rockies or the Andes Mountains that occur at regions where there is not a collision of continental plates. The deep Earth CH4 hypothesis might explain mountain formation at those regions, as the CH4 from the ocean plates is moved under the continent into the mantel, thereby releasing some of the entrapped CH4. Alternatively the movement of the ocean floor under the continent might provide a passage from the deep Earth for CH4.
I continue back to the process which I fear is akin to a debate as opposed to comparison of hypothesis to hypothesis. I will continue this discussion for a couple of comments because I believe the subject is interesting.
You have not explained how the late veneer hypothesis can explain the observations such as the massive amount of water on the planet or the C12/C13 isotope ratio of carbon dioxide in the atmosphere and the lack of change in the C12/C13 ratio in the carbon that is deposited in geological formations. As Gold notes plants preferentially use C12 for photosynthesis. If the carbon in the atmosphere was thin veneer and recycled the atmosphere would over geological time become enriched with C13. That is not what is observed.
Your defense of the late veneer hypothesis is restricted to quoting papers that state emphatically that the source of natural gas or oil is from biological sources. The papers in question do not address the scores of unexplained observations that the biological source hypothesis appears to be unable to answer, related to natural gas or liquid hydrocarbon. (That observation is why I stated that I have not seen a paper that explains how biological sources could explain the massive super large deposits of natural gas and oil. I accept the the observation that the papers state the source of massive deposits is a biological source. The papers in question do not discuss the observations that appear to dispute that hypothesis.) There appears to be no paper that compares hypothesis to hypothesis and that discusses the observations which the late veneer hypothesis and the biogenic theory cannot explain.
The following is a subset of the issues with the thin late veneer hypothesis and the biological origin for massive hydrocarbon deposits.
The depleted ratio of C13 in “natural” gas for example (the carbon in natural gas is mostly C12) although C12 is significantly dominate, there is a higher range in the ratio of C13/C12 in natural gas than in the atmosphere. The C13/C14 ratio in the carbon in calcium carbonate deposits over time do not change over geological time and closely match that of the atmosphere. (The carbon in the calcium carbonate deposits is from the atmosphere and does not change over geological time. There is one exception which I will start a separate thread for. There is a massive deposit of carbon that is depleted in C13 and that matches natural gas.) Gold explained the C12/C13 ratio variance in natural gas from region to region do to isotopic fractionation that occurs as the molecule with the heavy isotope of carbon moves slower through the pores in the deep earth. The porosity of the mantel and the travel time varies from region to region which explains the variance in the ratio. The CH4 that is released to the atmosphere increases in C13 do to the cosmic rays that create C14 that decays to form the stable C13. The carbon dioxide in the atmosphere is deposited as calcium carbonate and in dead plants. If the CH4 has not added to the atmosphere from deep sources it would have become carbon dioxide would have become depleted over time in the atmosphere.
The massive hydrocarbon deposits in specific locations of the planet. The finding of extremely high amounts of helium at natural gas and oil deposits, for example.
This thread is the comparison of two fundamental hypotheses. The late thin veneer hypothesis and the deep Earth hydrocarbon hypothesis. The deep Earth hydrocarbon hypothesis is a scientific hypothesis. There are scientific papers that advocate that hypothesis.
The origin of CH4, “natural” gas and oil is a secondary and related question.
As Gold notes the deep ocean and the permfrost regions have vast amounts of methane hydrates. The carbon in the methane hydrates and in “natural” gas deposits is significant deficient in the carbon isotope C13. Carbon dioxide in the atmosphere and the carbon that is deposited in geological formations is higher in C13. The ratio of C13/C12 in the atmosphere does not increase in time although plants preferentially use C12 which should over time result in a gradual increase in the ratio of C13/C12 if the origin of hydrocarbons was in accordance to the late veneer hypothesis.
The alternative hypothesis, Gold’s which is an extension to the Soviet abiogenic hypothesis for the origin of oil/natural gas, is the deep Earth hydrocarbon hypothesis. Gold’s hypothesis has been further developed by research that shows the liquid core of the planet contains a significant amount of lighter elements. The deep core hypothesis is as the core solidifies the lighter elements are expelled. The very, very, high pressure liquid that is expelled breaks through the mantel and over time rises up to the surface gradually releasing CH4. Experimental work has confirmed under very high pressures CH4 is converted to long chain hydrocarbon molecules.
Observational evidence to support the deep Earth hypothesis is that radon and xenon gas in the earth’s atmosphere does not match comets. The deep earth’s hypothesis explanation for that observation is the Mars sized object that struck the Earth roughly 50 million year after the formation of the planet. The energy from that collision stripped the early earth’s mantle of its lighter elements including hydrogen (the most abundant element in the solar system/universe) and carbon the fourth most abundant element in the universe. The source of the unoxidized hydrocarbons on the surface of the planet (carbon on surface of the planet is 100 times more concentrated than the mantel. There are massive deposits of carbonates on the continents which supports the assertion that methane gas is released to the atmosphere from a deep Earth source. The methane disassociates in the upper atmosphere forming water and carbon dioxide.
The massive methane hydrate deposits on the ocean floor and in permafrost regions is one observation that supports Gold’s hypothesis. The methane hydrates located on the ocean floor is many times greater than all known coal, oil, and natural gas deposits.
Another is the massive, deposits of unoxidized hydrocarbons that is concentrated in specific regions.
Source Article in Discovery of same name that describes the researcher's findings.
Their Game Is Mud
Last summer Jerry Dickens and his fellow geologists were hauling mud-filled pipes up from the seafloor onto the deck of the research vessel Resolution when one of the mud-core samples exploded. Just as we were pulling it up, it blew, and mud shot 100 feet like a cannon, says Dickens. The geologists weren’t entirely surprised. They had lugged up the mud--It looks like green Play-Doh, says Dickens--in sampling tubes after drilling about 1,400 feet into ocean sediments. Each 30-foot-long tube has a one- inch hole where a little extra sediment sometimes squeezes out if the material is under high pressure. Some of their earlier sample tubes had come up empty, leading the crew to wonder if an entire 30-foot-long mud sample could have blown out through the quarter-size hole. We thought, ‘That’s crazy,’ says Dickens. And then we had one blow up on deck. Fortunately, no one was hurt.
Dickens was surprised not only by the abundance of the methane but by the form it took. As much was floating free in bubbles as was caged in hydrates. (It was this free methane that created the mud cannon.) No one is sure how the bubbles got there, but Dickens suggests that as new sediment piles onto the ocean floor, the zone where hydrates can form rises. The hydrates left behind melt and release their methane, but the overlying seal of hydrates traps the bubbles.
Look, says Dickens, there’s no way to explain this with the conventional carbon cycle. It’s impossible; it doesn’t make sense. There must be one form of carbon that can be released rapidly in the oceans. And we do have a reservoir like that. That reservoir could be contained in places like Blake Ridge, says Dickens. Because no two hydrate deposits are alike, it’s hard to extrapolate from the 850-foot-thick hydrate layer at Blake Ridge. But it is conceivable that methane hydrates worldwide contain twice the organic carbon contained in all the known deposits of coal, oil, and natural gas.
Source: Paper of same name.
Methane hydrate — A major reservoir of carbon in the shallow geosphere?
Methane hydrates are solids composed of rigid cages of water molecules that enclose methane. Sediment containing methane hydrates is found within specific pressure-temperature conditions that occur in regions of permafrost and beneath the sea in outer continental margins. Because methane hydrates are globally widespread and concentrate methane within the gas-hydrate structure, the potential amount of methane present in the shallow geosphere at subsurface depths of < ∼2000 m is very large. However, estimates of the amount are speculative and range over about three orders of magnitude, from 2 • 103 to 4 • 106 Gt (gigatons = 1015 g) of carbon, depending on the assumptions made. The estimate I favor is ∼ 1 • 104 Gt of carbon.
The estimated amount of organic carbon in the methane-hydrate reservoir greatly exceeds that in many other reservoirs of the global carbon cycle — for example, the atmosphere (3.6 Gt); terrestrial biota (830 Gt); terrestrial soil, detritus and peat (1960 Gt); marine biota (3 Gt); and marine dissolved materials (980 Gt). In fact, the amount of carbon may exceed that in all fossil fuel deposits (5 • 103 Gt). Because methane hydrates contain so much methane and occur in the shallow geosphere, they are of interest as a potential resource of natural gas and as a possible source of atmospheric methane released by global warming. As a potential resource, methane hydrates pose both engineering and production problems. As a contributor to a changing global climate, destabilized methane hydrates, particularly those in shallow, nearshore regions of the Arctic Ocean, may have some effect, but this effect will probably be minimal, at least during the next 100 years.
Source: Wikipedia
Athabasca oil sands
Together, these oil sand deposits lie under 141,000 square kilometres (54,000 sq mi) of sparsely populated boreal forest and muskeg (peat bogs) and contain about 1.7 trillion barrels (270×109 m3) of bitumen in-place, comparable in magnitude to the world's total proven reserves of conventional petroleum. Although the former CEO of Shell Canada, Clive Mather, estimated Canada's reserves to be 2 trillion barrels (320 km3) or more, the International Energy Agency (IEA) lists Canada's reserves as being 178 billion barrels (2.83×1010 m3).[5]
With modern unconventional oil production technology, at least 10% of these deposits, or about 170 billion barrels (27×109 m3) were considered to be economically recoverable at 2006 prices, making Canada's total proven reserves the second largest in the world, after Saudi Arabia's.[6] The Athabasca deposit is the only large oil sands reservoir in the world which is suitable for large-scale surface mining, although most of it can only be produced using more recently developed in-situ technology.[6]
Natural gas
Venezuela has the ninth largest gas reserves in the world and the biggest reserves in South America. Proved recoverable reserves were estimated at 4,179 billion cubic meter (bcm)[11] at the end of 2005 and increased to 4,838 bcm at the end of 2007. However, inadequate transportation and distribution infrastructure has prevented it from making the most of its resources. More than 70% of domestic gas production is consumed by the petroleum industry.[1] Nearly 35% of gross natural gas output are re-injected in order to boost or maintain reservoir pressures, while smaller amounts (5%) are vented or flared. About 10% of production volumes are subject to shrinkage as a result of the extraction of NGLs.[11] The 2010 estimate is 176 trillion cubic feet (5,000 km3), and the nation reportedly produced about 848 billion cubic feet (2.40×1010 m3) in 2008.[12]
Tar sands and heavy oils
Venezuela has non-conventional oil deposits (extra-heavy crude oil, bitumen and tar sands) at 1,200 billion barrels (1.9×1011 m3) approximately equal to the world's reserves of conventional oil. About 267 billion barrels (4.24×1010 m3) of this may be producible at current prices using current technology.[2] The main deposits are located in the Orinoco Belt in central Venezuela (Orinoco tar sands), some deposits are also found in the Maracaibo Basin and Lake Guanoco, near the Caribbean coast.[11]
