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Comments 101 to 101 out of 101:

101. chris at 21:29 PM on 10 June, 2010
     Berényi Péter at 16:41 PM on 10 June, 2010

     The root mystery, not explained in those books is twofold. 1. How biological debris is transformed to kerogen in the first place? (chemical pathways instead of handwaving please) 2. How does it get into carbonaceous chondrites?

     On #1. The sedimentation and transformation of biological debris into kerogen is understood in some detail including the nature of the reductive processes and chemical transformations. A good starting point is the mind-numbingly detailed and extensive review published by Vandenbroucke and Largeau a couple of years ago: M. Vandenbroucke, C. Largeau (2007) Kerogen origin, evolution and structure Organic Geochemistry 38, 719-833. On #2. This isn't very difficult to source either Peter. A very good starting point is a study published earlier this year on the characterization and origins of organic material in the Murchison meteorite [*]. P. Schmitt-Kopplin et al. (2010) High molecular diversity of extraterrestrial organic matter in Murchison meteorite revealed 40 years after its fall Proc. Natl. Acad. Sci. USA 107, 2763-2768. ----------------------------------------------------- [*] The section of this paper entitled Links toward the origin of Murchison organic matter gives considerable insight into the origins of organic material in the Murchison meteorite. It’s worth remembering that many of the simple molecules identified spectroscopically in protoplanetary discs (e.g. CO, CN, CS, H3COH) and with some of the more reactive molecules like H2CO and HCN, the possibilities for extensive series of molecules based on generic CHO, CHN, and CHNO series are very well characterized. Aromatic nitrogen heterocycles and other hydrogen-deficient molecules characteristic of kerogen-like precursors, are known to be produced under very low temperature conditions and high irradiation regimes in reducing atmospheres (CH4, NH3) characteristic of likely primordial nebulae chemistry.
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102. chris at 00:01 AM on 11 June, 2010
     Berényi Péter at 20:24 PM on 10 June, 2010 "Any widely held public misperception has its own marketing value…." There's no question that's true [*]. "One would like to think truth prevails in the long run, but that may be a misperception on its own right." Yes, I suspect truth does, Peter. Historic precedent lends us to that conclusion. Ultimately the weight of evidence combined with access to knowledge (education) is the key. And of course this pertains to small scale efforts at promoting misperceptions too. One could look at just this thread and notice that a single person has attempted to promote a series of misperceptions (that might be taken to constitute a “mini-conspiracy theory”) including: (i) An extraordinarily detailed attempt to insinuate that a poorly drawn graph in a report constitutes an attempt at fraud. (ii) An attempt to insinuate that the pattern of 20th century warming is inconsistent with scientific understanding of enhanced greenhouse contributions to Earth surface temperature. (iii) An attempt to pursue the rather astonishing deceit that oil cannot have a biogenic origin. (iv) An attempt to pursue the deceit that there is little scientific understanding of (a) the formation of kerogen from denuded biological material, and (b) the origin of organic material in meteorites. On these scientific issues and on this very small scale (a single blog thread!) “truth does prevail in the end”. This requires an effort from those that have a degree of relevant expertise and a willingness to counter misconceptions with the basic level of investigation that those “seeding” misconceptions prefer not to do. Science and its evidence base is a terribly powerful means towards proximal truths. In many cases these proximal truths (lead residues from petrol and paints can induce neurological damage; aspirin-taking in children can causes Reyes syndrome; ciggie smoking greatly increases the risk of lung cancer and circulatory and respiratory disease; man-made chlorofluorocarbons cause catalytic destruction of stratospheric ozone; enhanced greenhouse gas concentrations causes global warming etc. etc. etc.) have negative implications for powerful economic and corporate interests, and so it’s not surprising that considerable efforts are made in generating misconceptions on issues of science [*]. It’s more difficult (but also very interesting) to understand why individuals engage in this on a much smaller scale! [*] see for example : D. Michaels and C. Monforton (2005) Manufacturing Uncertainty: Contested Science and the Protection of the Public’s Health and Environment American Journal of Public Health Supplement 1, 2005, Vol 95, S39-S48.
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103. Berényi Péter at 00:52 AM on 11 June, 2010
     Chris, you could still explain how spontaneous transformation is possible from low chemical potential biological detritus to high chemical potential hydrocarbons with no external free energy source and/or carefully controlled coupling between entropy increasing/decreasing processes.
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104. chris at 01:42 AM on 11 June, 2010
     Berényi Péter at 00:52 AM on 11 June, 2010 Peter, much of the biological detritus is at a high chemical potential (highly electron rich hydrocarbon content in biological membrane lipids, triacylglycerols and to a lesser extent carbohydrate) [***]. These molecules, molecules derived from these during the processes of sedimentation, and other molecules like phenols can spontaneously polymerize further under rather straightforward chemical reactions. A major part of the process by which kerogen converts to oils and shales involves the high temperature breakdown of longer polymers into shorter ones. These can involve both straightforward reductive elimination of oxygen (as H2O or CO2), and radical forming/mediated C-C bond cleavage. There's a similarity with industrial "cracking" I believe, whereby the highish temperatures result it dominant entropic contributions to the overall free energy. So these processes occur spontaneously. The review by Vandenbroucke and Largeau cited in my post just above, is likely a very good source of information on this. [***] If you have ever walked through very peaty areas like the Western Highlands of Scotland, you can obtain a rather vivid insight into the high chemical potential of vegetable matter that has transformed even during very short (100's to few 1000's of years) into a highly combustible fuel. All that is required (in Scotland anyhow) is an acidic and partly anaerobic conditions. In fact you often see a rather oily sheen on the surface of ponds and puddles as you squelch through a peaty landscape... You can dig peat up, dry it and use it as a rather smelly fuel. Underground peat fires can last for months and years. It's very easy to imagine how peat might undergo further transformation by heat and pressure to form lignite which isn't very far from coal, compositionally-speaking. I don't really see any problems in considering related scenarios in marine and lake sediments to yield oils, tars and shales.
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105. Doug Bostrom at 03:08 AM on 11 June, 2010
     BP while the helium problem is somewhat complicated it is significantly due to an ideological fixation with "the market" causing the U.S. government to tamper with a long-term policy that considered helium to be a strategically important element and thus maintained a policy of reserving it for applications more important that inflating childrens' balloons. The U.S. has subsequently sold most of its helium reserve for relatively little money though of course downstream marketers have done well with profits on the gas. You can look it up, or just check this article for a synopsis: Helium shortage hampers research and industry I don't think it's axiomatic that we absolutely must burn enormous quantities of natural gas in order to extract helium, there are undoubtedly more optimum arrangements that could be engineered.
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106. Ned at 03:38 AM on 11 June, 2010
     doug_bostrom writes: I don't think it's axiomatic that we absolutely must burn enormous quantities of natural gas in order to extract helium, there are undoubtedly more optimum arrangements that could be engineered. Besides burning it, natural gas is fairly important in fertilizer production.
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107. scaddenp at 07:07 AM on 11 June, 2010
     BP - this sounds like rehash of long-resolved questions from the 1970s. The reactions require of course require energy - supplied by geothermal heat. For this reason, basin modelling concentrates so hard on the thermal evolution of a basin. The theory gets tested every time someone drills a well where we have a prediction for thermal regime and hydrocarbon chemical history. (Though by the way, coaly source rocks are generally poor oil sources - producers of gas instead. Favoured source rocks are marine black shales.)
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108. scaddenp at 11:39 AM on 11 June, 2010
     BP, this is so offtopic, but if you want to continue offline, I am Phil Scadden at GNS Science. Feel free to email.
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109. gallopingcamel at 14:40 PM on 11 June, 2010
     BP & Co: Very entertaining! I was hoping to make some kind of contribution but when you guys get going my ghast gets flabbered.
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110. Berényi Péter at 20:24 PM on 11 June, 2010
     #108 scaddenp at 11:39 AM on 11 June, 2010 this is so offtopic It is. We should wait for a thread on peak oil or something I guess. If that happens, I'll backlink here. Feel free to email Thanks, I will. However, it's so much more useful to discuss things like this in public.
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