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Monday, January 31, 2011

The Flood geology of oil

Oil is an interesting subject in geology for many reasons, not the least of which derives from its modern importance to domestic and foreign policies on energy, environmental safety, climate change, and perhaps even military action (at least in the public perception). In other words, the study of oil directly affects us all in some manner. As I see it, the sociological consequence is twofold: on the one hand, geology gains public reputation as a vital scientific discipline; on the other hand, everyone seems to have a strong opinion—albeit commonly misinformed—on the topic of oil.

But lucky for you, I am not here as a political commentator. For this post, I am more interested in discussing the geological origin of oil and gas resources.

The study of oil’s origin and subsequent migration, accumulation, and recovery falls under the discipline of petroleum geology, which elegantly combines aspects of stratigraphy, sedimentology, paleoclimatology, oceanography, geochemistry, geophysics, structural geology, and even engineering. As such, it is also a complex and in-depth subject, so I would summarize it in this way: 1) organic matter is preserved through its burial in sediments, which undergo pressure and heat at depth (like an oven); 2) oil is buoyant compared to other fluids in the rocks and migrates through pore spaces and fractures in the overlying rocks; 3) if migrating oil meets an impermeable barrier (which can take on many forms), it will be trapped and accumulate until the barrier is compromised. Simple, right? Well, petroleum geologists must also be aware of several guiding principles, which account for the fact that only a tiny percentage of Earth’s past life has produced oil:

1) Organic matter decays in the presence of oxygen (this is intuitive, especially for gardeners that produce their own compost). Thus organic matter must be isolated from an oxic environment before it returns to the atmosphere and ocean (and for reference, more than 99% of organic matter is oxidized and escapes burial in the modern carbon cycle).

2) Organic matter must undergo thermal maturation, but not too much. This is much like understanding the basics of baking a cake: too little heat and/or time and the cake is ruined; too much heat and/or time and the cake is ruined. If organic-rich sediments are not buried deeply enough or for long enough, the result is immature kerogen, while burying the rocks too deeply or for too long results in postmature kerogen. Neither is economically useful to us.

3) Organic matter must be concentrated in the sediments. A “good” source rock is one that contains more than 1% Total Organic Carbon (TOC) by weight. This may not sound like much, but even 1% TOC can turn a rock quite dark in color and produce sufficient quantities of oil. Given that organic matter is readily oxidized in a well-mixed water column, only specific environments allow for the concentration of TOC.

4) Oil must be able to migrate freely, but must also be trapped in order to accumulate. If the oil can not escape its source rock, it is buried further and becomes postmature (like a cake that remains locked in the oven after the timer goes off). On the other hand, oil will continue to migrate toward the surface unless trapped by an impermeable boundary. As a fluid, oil disperses throughout the pore spaces and fluids already present in overlying reservoir rocks. The trap must not only be in place at the time of oil migration, but its geometry must allow for the concentration of oil in the sediments.

5) The trap must not have been compromised since the time of accumulation. Like the foundation of a house, petroleum traps are subject to geological forces (like faulting from tectonic movements, or uplift and erosion). In time, the likelihood that a trap will continue to hold significant quantities of oil can decrease substantially.

In summary, petroleum geology is about understanding a system of elements, in which timing is everything. From environmental factors (e.g. nutrient supply, temperature, salinity, dissolved oxygen and carbon dioxide) during the life cycle of marine organisms to the burial history of rocks to seemingly unrelated, subsequent sedimentary events (like the deposition of an impermeable rock millions of years after the fact), the preservation of petroleum systems is a delicate process. So at this point, I hope I have not bored you with details. Rather, my intention was to communicate the intricate nature of petroleum exploration, by which I am quite fascinated.

And which, by the way, involves more than a bad aim with a rifle or randomly drilling million-dollar holes in the ground.

Flood geology and the occurrence of oil

Until recently, I had not considered the implications of petroleum systems for Flood geology (and I suspect I’m not the only one). My search for a young-Earth response yielded a single full-length article by Dr. Andrew Snelling, entitled The Origin of Oil, which made some reference to an ICR article by David McQueen, entitled The Chemistry of Oil – Explained by Flood Geology. The former provides a basic hypothesis of oil formation as a result of the Flood, while the latter focuses on the presence of porphyrins (an organic molecule) as evidence for catastrophic burial of sedimentary rocks. Both argue that petroleum systems are better explained by the Flood model, and that the conventional understanding of geology cannot explain the range of geochemical data. In conjunction, they form the following line of reasoning:

1) Many oils contain porphyrins, which is a type of organic compound derived from plant and animal matter. It occurs in trace amounts (up to 400 ppm), but its presence can be demonstrated clearly.

2) Organic matter containing porphyrins must rapidly escape degradation (being oxidized), since porphyrins are unstable in the presence of oxygen. Anoxic conditions are not common in the ocean today, so geologists must consider areas of high sedimentation rate (like deltas) to explain porphyrins in the geological record.

3) Deltas bury sediments more rapidly than other environments, but contain abundant oxygen. Therefore, we should not expect to find porphyrins preserved in deltaic sediments.

4) Conventional geology cannot explain the widespread preservation of porphyrins. A catastrophic flood, however, would have rapidly buried massive quantities of organic matter and preserved these delicate molecules.

5) And since Flood geology can better explain the preservation of key biomolecules, we need not comment on the thermal maturation of organic matter (except that heat from burial during the Flood was responsible), or subsequent migration of oil into trapped reservoirs.

I admit, that last point was a bit tongue-in-cheek and results from my disappointment with the authors’ oversimplification of petroleum systems. Nonetheless, their case is in the form of a scientific argument, which can be tested by outstanding evidence. Does the argument hold? Have petroleum geologists ignored a catastrophic origin of oil source rocks in favor of an evolutionary timescale? Let’s take a look.

Distribution of porphyrins in petroleum reservoirs: a case for catastrophism?

Neither young-Earth author is mistaken in noting that porphyrins are commonly found in oil recovered from petroleum systems. In fact, porphyrins were the first biomarkers to be discovered in oil, and have since been used to interpret the source, depositional environment, and maturity of oil (e.g. Sundaraman and Raedeke, 1993). How does this work? Porphyrins found in petroleum systems are derived from chlorophyll in bacteria, algae, and other plant material. The organic molecule is a type of ligand, which means that its geometry and atomic structure allows for a metal cation, like iron, to be bound in the center.

And if that doesn’t make sense, just imagine a donut (ligand) with a ping-pong ball stuck in the center (metal cation).

In petroleum systems, porphyrins are most commonly bound to nickel or vanadium (actually, a vanadyl ion: VO2+), and the relative abundance of each reflects whether the depositional environment was oxidizing or reducing (e.g. Chen and Philp, 1991; Huseby et al., 1996). Vanadyl porphyrins are more stable, for example, in reducing conditions, where nickel preferentially bonds to sulfur and free cations become less abundant (Chen and Philp, 1991). Thus a relatively high ratio of vanadyl porphyrin vs. nickel-bound porphyrin suggests that the source rock was deposited in a low-oxygen marine environment, while the opposite relationship may indicate a deltaic/shelf environment, or a terrestrial source of organic matter (Premovic et al., 1998). As the sediments are buried more deeply, the temperatures increases and both types of porphyrin begin to break down into simpler organic compounds. Again, vanadyl porphyrins are more stable at higher temperature (Huseby et al., 1996), so their enrichment against nickel-bound porphyrins and preferential depletion versus more stable algal lipids can be used as a proxy for thermal maturity (e.g. Sundararaman and Raedeke, 1993). This method is particularly important in source rocks of marine origin, since the most common maturity indicators (Vitrinite Reflectance – Ro, and Thermal Alteration Index – TAI) use terrestrial (land-derived) organic matter.

Although the interpretation is not always straightforward (Premovic and Jovanovic, 1997), geologists have long been able to interpret and predict the distribution of oil-related porphyrins according conventional geological timescales. So why Dr. Snelling and Mr. McQueen focus on the preservation of porphyrins as evidence in their favor? Consider the following statement from Dr. Snelling:

“...experiments have shown that plant porphyrin breaks down in as little as three days when exposed to temperatures of only 410°F (210°C) for only 12 hours. Therefore, the petroleum source rocks and the crude oils generated from them can’t have been deeply buried to such temperatures for millions of years.”

On this point, Dr. Snelling’s assessment is spot on: exposure to high temperatures for any significant period of time would deplete any petroleum reservoir of porphyrins. Even vanadyl porphyrins of marine origin are only thermally stable up to ~300°C (Premovic and Jovanovic, 1997), so how do conventional geologists solve the dilemma?

It’s simple: they don’t, because there is no dilemma.

Oil is produced at temperatures between ~60°C–150°C. In the average tectonic setting, this translates to burial between 2.4–6 km below the Earth’s surface. If a source rock is buried much deeper or exposed to higher temperatures (e.g. from magmatic intrusions or hydrothermal fluids), then the rock quickly becomes postmature and will not produce any usable oil. Actually, the argument is easily turned against Dr. Snelling and Mr. McQueen. This range of temperatures is called the oil window, and demonstrates the predictive power of petroleum geology. If one can estimate the time at which the source rock reached the oil window (that is, using the geologic timescale), one can predict when and where the oil migrated. Does the method work? I would suggest that more than 100 billion barrels of burnt oil and the continued profits of Exxon, Chevron, and others clearly demonstrate the method’s validity.

Dr. Snelling also notes that “experiments have produced a concentration of 0.5% porphyrin (of the type found in crude oils) from plant material in just one day.” Since immature kerogen with relatively high concentrations of porphyrins contain at most 400 ppm porphyrin (12.5 times less), Flood geologists must rather explain the rarity of metal-bound porphyrins in petroleum systems, assuming that the organic material was buried catastrophically less than 6,000 years ago and never exceeded 60°C (as indicated by independent maturity and temperature proxies).

Ocean anoxia and the preservation of organic matter

Both Dr. Snelling and Mr. McQueen argue that anoxic conditions are too rare to account for the massive quantities of preserved organic matter. Rather than elucidating whether this is actually true, they engage in a hook, line, and sinker tactic by noting that many authors cite high sedimentation rates as a probable cause for organic-rich sediments. Mr. McQueen writes,

‘If a "high sedimentation rate" will preserve organic material, a catastrophic sedimentation rate, such as we envision for the worldwide Flood, would uproot, kill, and bury organic material so rapidly as to cut the porphyrins off from oxidizing agents which would destroy them in the ocean water.’

Unfortunately, he misunderstands the mechanism behind the original authors’ reasoning. First, dissolved-oxygen content rapidly decreases below the sediment-water interface due to microbial activity (i.e. bacteria eating dead organic matter to produce methane, CO2, and/or H2S), even when the overlying water is oxygenated. Yes, deltaic environments are oxidizing in the water column, but this actually results in poorer quality of oil compared to deeper-water settings, not the absence of oil. Second, catastrophic burial of organic matter in well-mixed ocean water would actually leave sufficient oxidants to chemically degrade most of the organic matter, thus Mr. McQueen’s extrapolation is unwarranted speculation. Third, most organic-rich rocks show geochemical (biomarker) evidence for thorough bacterial “eating” or reworking of the organic matter. If the sediments were buried catastrophically to several kilometers’ depth, how did this process occur?

Fourth, the preservation of organic matter depends on several factors, of which sedimentation rate and dissolved oxygen content are only two: local productivity, nutrient supply, clay fraction of sediments, source of organic matter, and bacterial population also play a major role. Each factor varies in importance for different depositional environments. For example, in a deltaic environment, the input of terrestrial organic matter, amount of clay minerals (which bond to organic molecules), and overall sedimentation rate are most important. In continental shelf and slope settings (further from the coast), primary productivity of marine organisms and the extent of the oxygen minimum zone (OMZ) is most important.

And speaking of the oxygen minimum zone...

Dr. Snelling claims that “[Anoxic] environments are too rare to explain the presence of porphyrins in all the many petroleum deposits found around the world. The only consistent explanation is the catastrophic sedimentation that occurred during the worldwide Genesis Flood.” But how rare are they? Well, to be sure, most of the ocean contains sufficient oxygen to degrade organic matter. Dr. Snelling fails to mention, however, what every introductory geology student already knows about the ocean: that in a small zone between ~200–1,000 m, the water column is anoxic due to the active degradation of organic matter. Anoxia is strongest in areas where upwelling delivers fresh nutrients to heterotrophic marine organisms in this zone (such as the Peruvian or West African coasts) and is less prevalent in areas of downwelling (such as the East Atlantic coast). Therefore, sediments deposited on the western continental shelf (especially near the equatorial zone) can preserve ample organic matter, porphyrins included. As an aside, this means that if petroleum geologists know the paleogeography (ancient position of the continents), they can predict where upwelling was the strongest and better find oil. Along the Peruvian coastline, the anoxic zone extends more than 1,000 km across the shelf.

For reference, a source rock that extends for one thousand kilometers in any direction is spelled with a capital $.

Not only is Dr. Snelling in error about this basic geological feature, he also ignores paleoceanographic conditions during the height of source rock generation (i.e. the chemistry of the ocean when most our oil was deposited as organic-rich sediments). Ocean anoxic events during the Jurassic and Cretaceous periods resulted in widespread deposition of organic-rich sediments, which have produced some of the highest quality oils to date. Of course, Dr. Snelling may reject the geologic timescale and geochemical interpretation of these events, but he cannot make the claim that conventional geology fails to explain the widespread preservation of organic matter in ancient deposits.

Once again, the argument can be turned against the young-Earth authors: how does Flood geology explain the widespread occurrence of Cretaceous black shales, which contain up to 20% TOC sourced from marine organic matter? Catastrophically buried forests may ‘begin’ to explain coal seams, but have nothing to do with geochemically distinct, marine black shales. Furthermore, it is impossible to hydrodynamically concentrate marine organic matter in sediments. On the other hand, the accumulation of organic matter in sediments is readily explained through clay-adsorption at moderately low sedimentation rates (less than a few cm per year) under anoxic conditions.

Petroleum systems involve more than oil and gas generation

After employing a number of misleading arguments to convince the reader that one should not expect to find oil reservoirs on the conventional geologic timescale, Dr. Snelling sweeps away the aspects of petroleum geology most challenging to his position in a simple, anecdotal conclusion. He writes:

“All the available evidence points to a recent catastrophic origin for the world’s vast oil deposits...during the global Flood cataclysm...forests were uprooted and swept away. Huge masses of plant debris were rapidly buried in what thus became coal beds, and organic matter generally was dispersed throughout the many catastrophically deposited sedimentary rock layers...[which] became deeply buried as the Flood progressed. As a result, the temperatures in them increased sufficiently to rapidly generate crude oils and natural gas from the organic matter in them. These subsequently migrated until they were trapped in reservoir rocks and structures, thus accumulating to form today’s oil and gas deposits.”

His concluding paragraph is filled with gratuitous assertions and leaves many important questions unanswered. A more detailed explanation is warranted in the future, so I will comment briefly on the major points.

1) As mentioned, catastrophic burial does not explain the occurrence of petroleum reservoirs, where bacterial degradation, partial oxidation, and long timescales played an important part in turning a biomass much larger than the present-day biosphere into high-quality fuel. Nor does it explain the specific geochemistry, which is the direct consequence of these processes. In essence, Dr. Snelling is claiming that since he can use a microwave to fully cook a piece of fresh beef in minutes, you shouldn’t assume that the $50, prime-cut, seasoned and aged prime rib on your plate actually took any longer to prepare. You can taste the difference when it comes to good cooking; so can petroleum geochemists when it comes to oil and gas.

2) Theories about burying floating forests, or uprooting terrestrial forests, only go so far in petroleum geology, since many oil and gas reservoirs were sourced from marine organic matter. Can terrestrial plant material produce Type I and Type II kerogens? And if not, how was marine organic matter concentrated under catastrophic conditions? Much oil and gas (and the highest quality thereof) is produced from marine algae, phytoplankton, and diatoms, all of which thrive in the surface ocean. How does the Flood geologist account for high TOC in certain types of rocks (shales) and not others (adjacent cap carbonates)? Or in certain types of shales but not others, without invoking a valid sorting mechanism for suspended, single-celled organisms?

3) On a similar note, biomarkers (like porphyrins) are vital to the study of petroleum geology, because they tell us about the source of the oil (marine vs. terrestrial; diatom vs. algal; angiosperm vs. gymnosperm). Evolutionary theory and the geologic timescale provide age constraints on certain biomarkers, and allow us to make predictive assessments of petroleum systems. In other words, if one finds biomarkers from angiosperms, the source rock can not be older than Cretaceous, when angiosperms evolved/diversified; if one finds biomarkers from diatoms, the source rock can not be older than Jurassic, when diatoms first evolved/diversified. Porphyrins are derived from chlorophyll, and should be found in organic-rich sediments of all ages (provided the rocks are not postmature). Such predictions are verified when various petroleum geologists use multiple independent methods to link a petroleum reservoir empirically to its source rock. The same goes for thousands of other biomarkers, which testify to the validity of the geologic timescale and evolutionary theory over against a catastrophic explanation.

4) For organic-rich sediments to produce oil, they must reach a temperature within the oil window (~60°C-150°C). If this occurs through slow burial, temperature increases systematically with depth, since the upper mantle provides a conductive heat source for the crust. If a bulk of sedimentary rocks were deposited during the Flood in the last 4,000-6,000 years, what is the heat source? Imagine taking a hot pan and adding a thin layer of pancake batter every hour for a full day. After your stack is several inches tall, there will be a gradient in temperature from the bottom of the stack (which is in contact with the hot plate) to the top (which is cooled by the room-temperature air). There will also be a gradient of “doneness”, from burnt pancake to raw batter. This process resembles the conventional geologic timescale, where there is ample time for equilibration of the temperature gradient and cooking of the “batter”. On the other hand, if you instantly pour 3 inches of pancake batter into an empty pot on the burner and checked it after only 30 seconds, what would the result be? The edges might be burnt, but there will not have been enough time for heat to reach even the middle of the batter. As I see it, Flood geologists are faced with a serious dilemma: if the upper mantle provided heat to buried sediments, then not nearly enough time has passed for the geothermal gradient to equilibrate in the thick crust (especially if the sediments were soft and water-saturated, like in the Flood model); if hydrothermal fluids provided a heat source during burial (this would also be reflected in oxygen/helium isotopes in cements, but it’s not), then why does the oil window accord roughly to the modern thermal gradient and why can immature oils still be found at depth? In other words, the Flood geology model would predict a majority of oil and gas to be severely “underdone” or “overdone”. In the former case, the oven came on during the Flood but is still on preheat; in the latter case, someone tried to reduce the cooking time by tripling the temperature. But neither explanation predicts what is seen in petroleum systems today.

5) Lastly, once oil and gas are generated, they need time to migrate through the rocks and accumulate in traps. Yet Dr. Snelling has not divulged just how long this process takes in rocks under pressure. Secondary porosity (cracks and fissures) speed up the intermediate process, but oil must still travel through and within the low-permeability source rock, then over a great distance (sometimes several kilometers) before accumulating in a higher permeability reservoir rock. This process alone can take many thousands of years or more, even in a pure quartz sandstone (as modeled by modified groundwater equations and observed in oil seeps).


Petroleum geology provides an elegant, multidisciplinary approach to finding one of the world’s most prized resources. Regardless of your opinion of the oil industry, its success is testimony to the validity of the conventional geologic timescale, evolutionary theory, and theories of oil generation, maturation, migration, and accumulation over multi-million-year timescales. This stands over against the proposed catastrophic explanations of petroleum systems offered by Dr. Snelling and Mr. McQueen, who overlooked many basic geological facts to convince their readers that the occurrence of petroleum systems supports Flood geology. As it stands, Flood geology is neither explanatory of outstanding geochemical evidence from oil and gas resources nor predictive of evidence in the field. Notwithstanding a major restructuring of existing theories by Flood geologists, oil and gas resources provide a powerful argument against a young-Earth interpretation of geologic history.

For the record

Petroleum-associated porphyrins might be structurally similar to heme in human hemoglobin, but are chemically distinct. There is no evidence that oil reservoirs contain trace remnants of “ancient, antediluvian human blood,” as Mr. McQueen postulates as an example of the predictive power of Flood geology. He is correct in noting that scientific hypotheses may be generated from the Flood model, but I would argue that they have already been falsified.

References cited:

Berkel, G.J, and Filby, R.H., 1987, Generation of Nickel and Vanadyl porphyrins from kerogen during simulated catagenesis: American Chemical Society Symposium Series, p. 110-134.

Chen, J.H., and Philp, R.P., 1991, Porphyrin distributions in crude oils from the Jianghan and Biyang basins, China: Chemical Geology, v. 91, p. 139-151.

Huseby, B., Barth, T., Ocampo, R., 1996, Porphyrins in Upper Jurassic source rocks and correlations with other source rock descriptors: Organic Geochemistry, v. 25, p. 273-294.

Premovic, P.I., and Jovanovic, L.S., 1997, Are vanadyl porphyrins products of asphaltene/kerogen thermal breakdown?: Fuel, v. 76, p. 267-272.

Sundararaman, P., and Raedeke, L.D., 1993, Vanadyl porphyrins in exploration: maturity indicators for source rocks and oils: Applied Geochemistry, v. 8, p. 245-254.

Sunday, January 30, 2011

Personal reflections as an American in Russia: "Россия – любимая наша страна"

"The illusion which exalts us is dearer to us than ten thousand truths." -A. S. Pushkin

This blog has been quiet for a number of weeks, but not because I have lost interest in the topics. I recently returned from a month-long trip to Russia, where I was able to visit with my new family as well as see many sites within the country. Having settled back in to my home in the U.S., I hope to continue writing here about various geological wonders, but with a new sense of global awareness. Adjusting to the new culture was an exhausting experience, to be sure, but I don’t regret a moment of it. In fact, I look forward to returning to Russia in the future for a more permanent stay—that is, on a sort of “green-card equivalent” status as I develop a research project in paleoclimatology within continental Russia.

Before I arrived to the country, I was well aware of the decaying American image abroad, and thus I was cautious—almost petrified—to speak to anyone I didn’t know, whether in English or in Russian. “How will they treat me if they recognize me as a foreigner, let alone an American?” Months before trip, I had read about nationalism in Russia (Moscow in particular), in which the author advised against speaking English loudly or in public [note: the article was written by a Russian, toward prospective teachers of English abroad]. Hoping to error on the side of caution, I took the advice and accorded my perception of the general public in Russia.

Within a couple days, however, I realized that despite my “research”, the prejudgment was naïve and unfounded.

Whenever a Russian citizen discovered that I was from America, their persona immediately shifted, divulging an amenable eagerness to represent their country with honor and gain my respect. In a nutshell, I was treated as visiting royalty, and the experience was both humbling and encouraging. On the trip to Moscow, my wife and I were seated next to complete strangers from Uzbekistan, Chechnya, and Armenia—all of whom worked in Moscow but were meeting an American for the first time. Even when political topics arose—through which I was assured that the American economy would collapse when we lost our ability to make unlawful war against developing countries with no viable defenses—the outspoken strangers applied no guilt by association and welcomed me as a friend (even sharing their dinner with me). Notwithstanding any truth or error to their political assessments, my point is that they were able to distinguish in practice between America the geopolitical empire and the American individual, who, like themselves, cannot be reduced to caricatures.

For this alone, I discovered more nobility in an economy-class train car to Moscow than in the average American university.

But it didn’t end there. One day, I walked my brother-in-law to school (3rd grade). On the way home, I was alone and attempting to keep to myself. As I passed the bus stop, a man (some 30-years-old, with a lit cigarette in hand) tried to stop me with a question. Not anticipating the context, I was unable to put the sentence together at first—“Добратся... автовус... рублей...”—but later realized he was asking me to help with his bus fare. Taking my mother-in-law’s advice, I responded in English: “I’m sorry, I don’t understand.” Unfortunately, the man didn’t recognize it as English and gave me a confused look. Not wanting to insult him, I responded in Russian: “I’m sorry, I am an American, I didn’t understand what you said. Could you please repeat yourself?” His countenance changed at once, as a warm smile appeared on his face. He dropped the question and said nothing more. Instead, he opened his arms and gave me a hug before proceeding to the bus stop.

What is the lesson? Perhaps I am not qualified to say, so I would encourage you to take my anecdotal reflection as you see fit. In concluding my thoughts, however, I cannot help but to mention how disturbed I was to hear the news of the bombing at Domodedovo, given my positive experience abroad. Though I would not have been directly affected by the explosion, I cannot escape the erie sense that I left the city less than 24 hours before such an unspeakable tragedy took place. I do not wish to engage in political discussion over the reasons behind the attack, or theological discussion over the ability of human arrogance to degrade into such grand delusion (which, in my opinion, is the psychological prerequisite for a suicide-bombing). Rather, I can only express my (seemingly trivial) condolences, while praying that justice would come to those responsible and comfort to those affected. I cannot imagine how America would have reacted to the same event, had it occurred in Dulles or Reagan, but I think it speaks volumes to the strength of the Russian spirit that officials were able to maintain control and order in the airport, which remained in service throughout the day.

Of course, even a brief historical synopsis of challenges to the Russian people (and their response) would sufficiently undermine any reasonable expectation to the contrary. I feel more blessed every day for my connection to this wonderful nation.

P.S. If anyone knows the source/original Russian for the quote I cited at the top, I would greatly appreciate it. Though I’ve enjoyed struggling through some of Pushkin’s work in his own language, I did not come across this one firsthand.

Monday, January 10, 2011

Judgmental Gemstones? A Corundum Conundrum

Colorful gemstones were long a trademark of royalty and stature in ancient cultures. Notwithstanding the shear rarity of precious jewels, the pure, monochromatic radiance of a top-quality gemstone distinguished it from the chaotic and visually unbecoming vulgarity of the ore-body matrix in a way that royalty could truly appreciate.

Modern jewelers and mining efforts have since made rubies, sapphires, emeralds, and other stones available to a more "common" clientelle, but these geologic wonders never lost their sanctifying quality. Owning and being adorned by (or, for that matter, gifting) such a beautiful and unique piece of the Earth is sufficiently special that anyone can feel like royalty in the eyes of their loved ones.

So how do gemstones form? And does knowing the origin of gemstones impact the value we assign to them?

Admittedly, gemstones are not my expertise and I have little experience in the field of mineralogy as a whole. Thus I can only comment at an introductory level on the "geology of jewels" and would direct you elsewhere for more detailed discussion. A basic understanding, however, is all that is necessary for this week's post, which stands in response to an article by Dr. Andrew Snelling entitled "Rubies and Sapphires - Sparkling Reminders of God's Judgment." There, Dr. Snelling argues that gemstones formed under the unique geological conditions concomitant with catastrophic processes during and shortly after the global Flood. In other words, they should remind us of a period in Earth history when God's judgment resulted in cosmic overturn. Noting also that sapphires (among other gemstones) are described as construction materials in the New Jerusalem (i.e. heaven; Rev. 21:19-20), he concludes: "[Rubies and sapphires] are not just pretty reminders of God’s creativity, but they serve as eternal reminders of God’s righteousness, judgment, and mercy." I will return to the theological symbology of gemstones, but first want to consider whether Dr. Snelling has provided a plausible mechanism by which gem-quality minerals should be found in such natural abundance.

Formation and occurrence of Himalayan rubies and sapphires

The translucent crystals commonly known as ruby and sapphire are gem-quality variants of the mineral corundum, which is comprised of aluminum (Al) oxide (the chemical formula is Al2O3, though traces of chromium or iron actually give the gem its color). Aluminum is found in common minerals like feldspar and mica, but only as a minor constituent. Under the right conditions, however, aluminum may concentrate to form Al-bearing minerals like corundum. One example, and the major source of industrial aluminum, can be found in many tropical soils (laterites), where rain and groundwater leach water-soluble metals from rocks and soils near the surface. Water-insoluble oxides, such as aluminum and iron oxide, concentrate as residuals in the hard soil horizon and are later mined, refined, and smelted to make cans of Dr. Pepper--well, among other products, but life has priorities.

One could sift through megatons of lateritic soil, however, and never find a corundum gemstone. The formation of ruby and sapphire not only requires the concentration of oxidized aluminum in a fluid phase, but other unique physical conditions--namely, high temperatures and pressures not found in surficial soils. So rubies and sapphires are formed deep beneath the surface of the Earth, under the tremendous weight of overlying sediments, and typically during regional metamorphism in transcompressional tectonic settings (i.e. where mountain chains are forming as tectonic plates collide). Several factors made the Himalayan orogeny an ideal setting for the formation of Al-rich gemstones: 1) it was a broad scale event, resulting from the collision of India with the rest of Asia, in which very high temperatures and pressures dominated; 2) the rocks being metamorphosed were comprised largely of limestone/dolostone, which was deposited on a shallow carbonate platform (like the Bahama Bank), and thus were rich in aluminum but poor in silica--a factor that promoted the localized formation of corundum over aluminosilicates like kyanite and sillimanite; and 3) granitic magma bodies intruded the metamorphosed sediments in several stages, which added heat and pressure to the system while mobilizing aluminum and other ions in the rock. Though I have simplified the "recipe", one can begin to envision the process by which natural gemstones are cooked in Earth's kitchen. But at this point, the recipe I described is missing one vital element, which Dr. Snelling neglected to discuss.

Better set your clocks; this recipe calls for a lot of time.

Deposition of carbonate and evaporitic sediments

Before the collision of the tectonic plates now hosting southeast Asia, the surface of each plate was covered with several miles thickness of sedimentary rock layers. Modern Himalayan mountain peaks are the carbonate, shale, and sandstone remnants of a long and dynamic depositional history, which has been interpreted to reflect environments ranging from carbonate platform and lagoon (coastal) to deep-sea turbidite and flysch (continental slope) settings. While the rate of deposition varied significantly over geologic time, numerous sedimentary layers show evidence of very slow deposition. In particular, organic-rich shales need time to trap organic matter in the water column, which first needs time to grow. The minerals in some Precambrian shale layers also contain geochemical proxies for euxinic conditions, meaning they were deposited in an ocean chemically distinct from that of today. Euxinia refers to a water column that is poor in oxygen but rich in sulfur (like the modern Black Sea), implying that these shales were deposited in deep, stagnant water, which could not have supported complex modern or fossil marine life in the years leading up to the flood (and no, the massive addition of hydrothermal fluids during the Flood would not create such conditions; besides, most Precambrian rocks are interpreted as pre-Flood sediments). Although mudstone can be deposited rapidly under the right conditions, the Precambrian shales of the Himalayas were certainly not.

Another evidence for slow deposition is the shear mass and composition of carbonate rocks in the Himalayas. Dr. Snelling and others may try to argue that carbonate minerals precipitated rapidly from a bicarbonate-saturated slurry under catastrophic conditions, but rapid crystallization always results in the formation of aragonite--not calcite and dolomite, regardless of the magnesium concentration. Diagenetic alteration of aragonite to calcite and dolomite also takes time, which is not available in the Flood model. It is simply unreasonable to think that advancing flood waters deposited alternating layers of specific carbonate lithologies at a rate no less than 50 meters per day, while preserving fossil and geochemical patterns that could be correlated across the entire globe.

Since the purpose of this article was to discuss gemstones, I should note that salts from sedimentary evaporites (like gypsum) played a major part in mobilizing metals (like aluminum) to allow the growth of ruby and sapphire crystals. Young-Earth researchers have elsewhere attempted to explain the unlikely occurence of sedimentary evaporites in a Flood geology model using isolated (and hypothetical) cases-in-point, but the challenge becomes even greater in the context of the Himalayan sequence. In other words, it is hard enough to explain how thick layers of salt can form in under a year; postulating the accumulation of thick layers of salt during catastrophic deposition of 5 miles of sediment in under a year borders on desperation. Even granting the impossible, however, the Himalayan mountain range did not exist before the Flood. So where did it come from?

Himalayan orogeny

Biostratigraphic and radiometric age constraints suggest that sedimentary deposition occured between ~1 billion and 55 million years ago, after which continental collision initiated metamorphism, uplift, and erosion of the sediments. Dr. Snelling rejects this timeline, but it's worth noting that multiple independent methods have been used to detail the structural history of the Himalayas. If uplift began ~55 million years ago, then syntectonic deposits (sedimentary rocks that form in response to the erosion of adjacent mountain ranges) should not yield dates older than 55 Ma (they don't). Radiometric dates of minerals and intrusive magma bodies formed during metamorphism should not be greater than 55 Ma (they aren't), and should get younger away from the center (they do). A reduction in atmospheric carbon dioxide and global temperatures during the later Cenozoic, which is recorded in rocks around the world, has been partially attributed to the induced carbonate weathering of the massive Himalayan range. Oxygen isotopes from fossilized mammal teeth on the Tibetan plateau record a dramatic shift in plant life due to higher elevation, and thus correlate to the inferred multi-million-year uplift history of the range. Numerous, falsifiable predictions originate from the conventional understanding of the Himalayan orogeny, and can be tested by field observations. Can the same be said for the Flood geology model? Dr. Snelling writes:

"Pre-Flood and early Flood sedimentary and igneous rocks were buckled, squeezed, and heated, transforming them into the metamorphic gneisses and granulites that host the ruby and sapphire deposits of eastern Africa, Madagascar, India, and Sri Lanka. Then, according to the biblical model of earth history, when rapid crustal plate movements were quickly slowing down at the end of the Flood, the Indian plate collided with the Eurasian plate to form today’s Himalaya mountains. Limestones that had been deposited early in the Flood were then metamorphosed into the ruby-containing marbles of Myanmar, Vietnam, Nepal, Pakistan, and Afghanistan."

What distinguishes the statement above from a gratuitous assertion? Dr. Snelling is eager to present a simple geological story for his readers--I understand the article is written on a popular level--but employs the technique of "so-so" story telling. In other words, despite his use of scientific terminology, Dr. Snelling's description lacks scientific reasoning--saying it was so does not make it so, and no positive evidence is given for the young-Earth version of the story. Alternatively, abundant evidence against the Flood geology model for the formation of Himalayan gemstones should motivate us to consign Dr. Snelling's summary to the realm of science fiction. To be clear, I am not trying to belittle Dr. Snelling or the scenario he proposes. Rather, I am simply trying to make a categorical distinction between a scientific approach to the problem and simple storytelling. Many conventional geologists have faced similar criticism from their peers, and it's only fair to hold Dr. Snelling equally accountable. Should Dr. Snelling provide falsifiable predictions that stem from the Flood geology model, and then test those predictions with existing geological data, I will gladly retract my criticism.

On a quick side note, I am troubled by the phrase "according to the biblical model of earth history, when rapid crustal plate movements were quickly slowing down..." (emphasis added), particularly since I am unable to find a description of plate tectonic rates in the biblical text. The model of catastrophic plate tectonics offered by young-Earth geologists is not rooted in scripture so much as an admission that the preponderance of geological evidence warrants a belief that the continents have moved thousands of miles over geological history. An a priori reduction of geological history to <10,000 years forces young-Earth geologists to squeeze plate tectonic movements into a year-long catastrophe, however, despite the fact that doing so undermines the evidence for plate tectonic theory. The result is an extravagant geological tale, which has attained the status of dogma among young-Earth researchers and thus can neither be criticized effectively from without nor from within. In the meantime, we'll just have to pretend that it works (though if you're interested, Greg Neyman offers a helpful discussion here that highlights a few problems with catastrophic plate tectonics).

Growth of gemstone-quality minerals: pressure, temperature, and time

Many Himalayan rubies are now hosted in various types of marble. Marble is a metamorphic rock, which formed from carbonate rocks during the mountain-building process. Petrologists can estimate the pressure and temperature at which minerals grew as a result of metamorphism, using various chemical proxies. Rubies in the Himalayan marble formed at temperatures between 620°C and 650°C and pressures between 2.6 kbar and 2.9 kbar (between 2,600 and 2,900 times atmospheric pressure at sea level). Intrusion of granitic plutons during the mid-late Cenozoic influenced the mobilization of aluminum and other metals in hot metamorphic brines (very salty water), which promoted the growth of large, euhedral crystals of corundum.

Dr. Snelling describes the same process and applies it to the year-long Flood scenario without qualification. Several problems exist, however, with regard to the timeline:

1) Rapid crystal growth is possible, but tends to result in lots of tiny, poorly developed crystals (at least outside of a laboratory setting). The abundance of large, well developed gemstones in nature (albeit rare from an economic standpoint) is testimony to a long metamorphic history of the Himalayan mountain range, wherein crystals grew very slowly for hundreds or even millions of years.

2) Mineral growth is limited by the dissolution and transport of key elements to the site of nucleation. Despite high temperatures in the metamorphic system, the diffusion (movement through solid rock) of elements like Al, Cr, Fe, and others is extremely slow in rocks under pressure. By way of comparison, near-surface groundwater in highly permeable aquifers commonly moves only tens of meters per year! The rate of crystal growth also depends on the concentration of elements in the fluid. Given that the necessary components of gemstones exist as trace elements in the host rock/fluid, it is unreasonable to posit the formation of large rubies and sapphires in a matter of days, months, or even a few thousand years.

3) Since aluminum oxides are rather water-insoluble, the volume of metamorphic fluids necessary to promote the growth of gemstones is many times that of the host rock. This process takes far more time (and water, ironically) than is allowed in the Flood scenario.

4) Rubies and sapphires are mined at the surface of the Earth, but are formed many kilometers below your feet. So how do they get from point A to point B? Dr. Snelling proposes that gemstones were carried to the surface by rapidly ascending basaltic magma shortly after the flood. I am unsure, though, how he makes the connection (or why). Rubies can be found in situ within marble now exposed in the mountain peaks. Not only does this make the "basalt express elevator" an unnecessary explanation for the evidence, it also means that several kilometers of sediment have been removed since the formation of these rubies. How long does it take to remove such vast quantities of sediment? The steep slopes of Himalayan peaks suggests that it was far longer than ~4,000 years (i.e. slow removal of hard rock through snow, ice, and gravity; not rapidly from receding flood waters over soft-sediments).

Judgmental gemstones: the theological connection

Previously, I cited Dr. Snelling's description of rubies and sapphires as a reminder of God's moral attributes, since he classifies them as geological products of the Flood. I think that most people (religious or not) can appreciate Dr. Snelling's desire to attribute moral significance to natural wonders. He does not intend to give us a childhood lesson, however, but scientific grounds for using gemstones "as a witnessing tool and as a personal reminder of God’s transforming power on our behalf." Despite his seemingly pure intentions, I wonder how effective a misinformed story of the gem's origin could be. Either the recipient recognizes that the story is contrary to the facts, and assigns a false story to God's message, or the recipient is won over by a bad argument and consequently stands on shaky ground.

But what is wrong with telling the real story? Is God's magnificent masked by a process that is actually far more intricate and complex than the Flood geological scenario? If you can recall the full process by which Himalayan rubies and sapphires were made, consider the range of variables involved: life cycles of marine planktonic organisms, which concentrated organic matter and trace metals in carbonate sands--all of which controlled the metamoprhic fluid chemistry that promoted the growth of gemstones; the ancient sun evaporating excess water in just the right place to precipitate salts necessary to mobilize the elements; precise and timely emplacement of magmatic bodies of the proper composition and viscosity; the plate tectonic movement of massive continents along a 70-million year collision coarse, which made contact at the precise moment in time, and compressed sediments and uplifted mountains at the precise rate. All of these sensitive, geological factors worked in perfect accord to make some of the world's most spectactular minerals, and to make them accessible to human cultures. In the words of N.T. Wright, "Dust we are, and to dust we shall return. But God can do new things with dust." There were, perhaps, a million divine reasons behind the formation of rubies and sapphires, but I propose that we can know at least one: that we might truly understand majesty, and ask rhetorically, "What is man, that you should be mindful of him?"

Foundational gemstones: a heavenly vision

For those not familiar with the vision described in Revelation 21:19-20, sapphires (among other gemstones) are mentioned as construction materials in the New Jerusalem. The broader context of this chapter is responsible for our vision of heaven as a large city with streets of gold, and my impression is that Dr. Snelling (like others at AiG) believes that precious metals and gemstones will actually comprise the base of a structure with dimensions equal to that recorded in John's unveiling. Many years ago, I read arguments by Henry Morris and others that insisted on a consistent "literalist" hermeneutic between Genesis and Revelation--in other words, if we accept Creation/Flood account of Genesis as historical and scientifically descriptive, then we must accept John's vision in the same terms and expect heaven to be made of such Earthly materials in the exact dimensions listed. Granted, the chapters are exegetically linked (the Book of Revelation contains more powerful and obvious intertextual imagery than any other book of the NT), but I now perceive that 'missing the point' in Genesis has led some to 'miss the point' in Revelation.

How so?

If your heavenly vision includes streets of gold and walls lined with precious gems, then I exhort you to open your eyes just a little wider. Take note that John only describes the material nature of the most basic features (walls, streets, etc.), but uses the most beautiful and valuable descriptors to do so. The take home message is that even the simplest, most common features of heaven are worth far more than the most valuable and beautiful features of the world you now know. Let your hermeneutic be as deep as time itself, albeit still faithful to the Word, and you will be rewarded with the majesty of a God that can hardly be captured by words.

Tuesday, January 4, 2011

Has Answers in Genesis debunked K-Ar dating?

Radiometric dating is not a simple topic. Chances are, you learned a simplified version of the technique at one point—if you remember your chemistry teacher discussing isotopes, half-lives, hourglasses, well, that was it—but have since removed the lesson to a box labeled "High School Amnesia" in some dark corner of your brain. If you're reading this now, however, you might be curious to reopen that box in an effort to follow my argument as I answer the title of this post (or, if nothing else, to avoid admitting that chemistry was "not really your thing"). But whatever your passion for decaying metals and your level of chemical comprehension is now, I want to share my confidence that you can follow along just fine. Anyone can learn technical jargon (queue Wikipedia page for Potassium Argon Dating); reading this post only requires a knack for scientific reasoning.

Before I begin, there is one set of terms you should be able to distinguish: radiometric dating is a method of estimating the age of geological events using radioactive isotopes in minerals; radioactive dating occurs in the storage room at the nuclear power plant and has very little to do with geology. Confusion of these terms is a sure sign of geological ignorance. So now that you are better prepared, let's continue!

Introduction to the controversy

Over the years, Answers in Genesis has committed to undermining the credibility of radiometric dating techniques. Their motivation is obvious: all techniques consistently yield age estimates far older than the purported <10,000-year-old Earth. Despite technological improvements to various methods that resulted in "adjusted" age estimates and the discovery of some invalid assumptions, scientists have long been confident in ascribing a 4.5-billion-year age to our planet. Believing the Earth was young in the 20th century meant casting serious doubt on scientists, whose age estimate must have been wrong by a factor of more than 10,000. About ten years ago, the Radioisotopes and the Age of The Earth (RATE) team was formed to combat the traditional interpretations of geochronologists (people who develop/practice radiometric dating methods), and reopen a case that seemed already to be closed. To their credit, they have remained prolific, and optimistic about their findings, despite widespread ridicule from academia and the general public. Unfortunately, I don't feel their optimism is warranted and believe the sheer volume of their publications works to mask the invalidity of their interpretations from a majority of readers that would look to them for answers.

So where to start? I imagine that I will return to this topic some time in the future, as AiG has published a number of articles and books that discuss radiometric dating methods (and the Potassium-Argon method in particular). For now, I wanted to consider an older article, only a page long, entitled "How do you date a New Zealand volcano?" Although the article was not published by any member of the RATE team, it provides a simple example of AiG's critical approach: 1) remind readers that several assumptions are inherent to radiometric dating methods; 2) provide a case-in-point where at least one of those assumptions was falsified; 3) extrapolate the proven uncertainty to the rest of geochronology without qualification; 4) (optional) advise readers that anyone defending radiometric dating methods is trying to undermine God's clear teaching of a young Earth and, consequently, the gospel itself. Regardless of the article's technical level, AiG authors will make all 3 (or 4) points in their publications, so I decided this jargon-free, "short enough to read on your smoke break" commentary on New Zealand volcanoes was a great place to start.

And in case you don't actually have "smoke breaks", then keep in mind that simply reading about natural wonders that smoke is a valid substitute.

First, a simple overview of the K-Ar, or Potassium-Argon radiometric dating method

Many minerals, such Feldspar and Mica, contain significant quantities of potassium (K). Less than 1% of this potassium occurs as 40K, which is the radioactive isotope. For any given element, an isotope refers to the forms with different numbers of neutrons, while the number in front of the element (in this case, 40) refers to the total atomic mass of that particular isotope. Since neutrons have no charge, they don't affect the chemical behavior of an element (besides its mass). Therefore, any mineral that contains potassium (K) will contain a mixture of all its isotopes (39, 40, and 41).

When 40K decays radioactively, it produces both 40Ar (argon) and 40Ca (calcium), with a half-life of 1.25 billion years. For example, imagine you crsytallize a rock with 1 gram of 40K (and no 40Ar). If you came back after 1.25 billion years, and assuming nobody has heated the rock or altered it chemically, you would find 1/2 grams of 40K and 1/2 grams of 40Ar/40Ca. After another 1.25 billion years, you should find 1/4 grams of 40K and 3/4 grams of 40Ar/40Ca. Therefore, one can use the measured ratio of potassium to argon in a given mineral to infer the time at which the mineral crystallized and began to accumulate argon (note: 40Ca is not considered in the equation, because it is a common isotope that is already abundant in the rock). Typically, one assumes that no argon (or negligible amounts thereof) was initially present, because argon is a noble gas and can easily diffuse out of minerals that are still hot. If any excess argon becomes trapped in the mineral during crystallization, the mineral will appear older than it actually is; if any argon is lost after the mineral crystallizes, the mineral will appear younger. As you can imagine, the chaos of Earth systems can produce both scenarios, so geochronologists have developed techniques to verify (test) each assumption.

Before moving on, I must clarify one thing. Most people (geologists included) think of radiometric dating methods as a means to assign absolute ages to rocks/minerals. This definition can be misleading, however, without some qualification. First, all radiometric dating methods are scientific models used to estimate the age of geologic events, provided a number of physical assumptions regarding the rock's history are met. In this sense, it is much like estimating the origin of a cannonball in flight, using a set of physical observations and the laws of gravity. Secondly, radiometric dating methods (K-Ar in particular) do not estimate the age of a rock, but the time at which a mineral in that rock was last near a given temperature (called the closing temperature). For any given rock, each kind of mineral will yield a different age, depending on how quickly the rock cooled. If the rock was reheated at any point, the method no longer provides a straightforward interpretation of the cooling age (hence all dates are termed "apparent ages"). While such geological complexities pose additional challenges to geochronologists, even "bad" dates can be very useful. My hope is to convince you this is the case through the following example, and that AiG had prematurely discredited the K-Ar dating method.

How do you date a New Zealand volcano?

Robert Doolan of Answers in Genesis concluded that the K-Ar method is not a valid option in response to the above question. His argument goes like this:

1) We can use the distribution of vegetation, tree rings, carbon-dating from wood samples buried in ash, and even historical reports to date a number of recent volcanoes in New Zealand.
2) Therefore, even by "evolutionist" standards, we know from multiple lines of evidence that the volcanic eruptions occured between 50,000 and 300 years ago (i.e. they are recent in either paradigm).
3) However, radiometric dates, using the K-Ar (potassium-argon) method, yield ages of 145,000 to 465,000 years for the youngest volcano!
4) Since we know these are false ages due to excess argon being trapped in the cooling lava flows, we should not trust the K-Ar method to date volcanic rocks.

At first glance, Mr. Doolan provides a convincing case against the credibility of K-Ar dating. I remember reading similar reports years ago, which cited numerous cases of historical lava flows (note: historical meaning humans witnessed it) that were dated radiometrically to be a few hundred thousand to millions of years old. I was originally quite convinced by the discrepancy that radiometric dating methods were fundamentally flawed: "If radiometric dating methods are so wrong when the age is known, how can we trust them when the age is unknown?" Now, my concern is that to the non-scientist (or even to the experienced scientist that doesn't regularly work with geochronology) this reasoning may seem plausible and end the debate without warrant. But if the failure of the K-Ar dating method is so obvious, why do scientists still spend so much money on running samples? Is there a grand conspiracy to hide the flaws, which are so simple to point out?

As you might expect, it is never that simple. So here is my analysis:

1) The author is either ignorant of his source or is being intentionally deceptive

Mr. Doolan first explains that the largest volcano is the youngest. This is true, but he does so in a way that would make you think scientists either doubted that young age, or figured they could use K-Ar dating to come up with a "final answer." (If you did not get this impression from the first paragraph, then my point here is invalid, but I'll continue nonetheless) First, Mr. Doolan says: "In the late 1960s, scientists from the Australian National University in Canberra dated numerous volcanoes in Auckland using the potassium-argon method...Results seemed to show that Rangitoto was not a few hundred years old as it appeared to be." Then he notes that "In every case the potassium-argon dates were clearly wrong to a huge extent," so "If the real dates were not fairly well established by other means, who could have proved that the potassium-argon dates were so wrong?" Unfortunately, it appears that he expected his readers to assume that since he quoted a reputable journal source, he must have done his homework. Anyone with access to a university library system can check whether this is true, but most AiG readers (and I don't blame them) wouldn't care to take the time to find a 40-year old journal article. Since I always have a search engine open for journal articles, I was able to find it rather quickly. One only need to read the abstract to get my point here, where McDougall writes: "Because of the good age control, this area was chosen for a detailed study to test whether the K-Ar dating method could be used for dating such young basaltic rocks."

In other words, the original study was not by any means carried out to determine the age of volcanoes, but rather to test to the model assumption that no argon would be present in newly crystallized rocks. As you can see, they found this assumption to be false—all samples contained between 1 and 5E-13 moles/g of argon. So did the original authors warn others to reject the K-Ar method and that it could never give us insight to the true age of rocks? Of course not.

But why not? The first reason is that the amount of initial Argon, while detectable, is very very small. I realize that to most people an error of 400,000 years seems substantial, but if the volcano you are dating is actually 500 million years old then it makes no difference that the "clock" started at 400,000. The second reason is more profound, but before I elucidate, I would conclude that Mr. Doolan has clearly misused the source he cited: McDougall et al. (1969) did not attempt to date the volcanoes by the K-Ar method but rather used well-dated volcanoes to improve the use of the K-Ar method on volcanic rocks.

2) Despite an attempt to discredit the K-Ar method, the author cited a source that actually proved the effectiveness and reliability of the K-Ar method, even when model assumptions are invalid

Now the more important question becomes "Why is there argon trapped in cooling lava and why doesn't that invalidate the model?" The first answer is simple: while argon can easily diffuse from minerals when temperatures are high, the partial pressure of argon in the atmosphere often causes trace amounts to remain trapped in the crystal structure (or in fluid inclusions, which are pieces of melt that get trapped inside of crystals—think of an air bubble being trapped in a piece of ice). This process is obviously more important in rocks that solidify at the surface (i.e. lava flows), but may be true for minerals that crystallized deep in the Earth as well. In order to get to the surface, magma must make its way through thick portions of country rock, which is much older and may contain a significant amount of radiogenic argon. While the magma rises to the surface, it heats up the surrounding rock and argon is transferred to the melt. This argon is potentially captured in the crystal structure of forming minerals, which would give it an anomalously old date.

Geologists have known about this problem since the K-Ar method was first put forth, and McDougall et al. (1969) is a prime example. Therein, the authors explain contamination processes and consider the isochron method to solve the problem (I won't describe that process in detail here; their results are given on p. 1507 (Figures 5-8) in the article for those interested). The isochrons plot well, and form statistically significant lines (i.e. they are internally consistent). Each isochron yields "apparent ages" from ~70,000 to 534,000 years (anomalously old). While they disagree on the "age", all isochron lines point consistently to a high initial 40/36 argon ratio. In other words, there was more initial argon than might be expected from a purely atmospheric source.

McDougall et al. (1969) continued to investigate the source of excess radiogenic argon by analyzing the mineralogy of the samples. Scattered fluid inclusions in olivine/pyroxene could be found throughout the sample. Xenolithic quartz was also found, indicating that the melt had incorporated foreign material during its assent. While 87/86Sr ratios and whole rock chemistry indicate that enrichment from the surrounding sedimentary rocks was very small, it would have been sufficient to provide the excess radiogenic argon that resulted in dates that were obviously too high. Thus McDougall et al. (1969) concluded that one may not rely solely on the K-Ar method when dealing with "young" volcanic basalts, even when the isochrons are internally consistent. This method should always be combined with thorough petrographic analyses to constrain the degree of contamination from the atmosphere and wall rock, as well as other radiometric dating methods like C-14 and Uranium partitioning.

While the resultant isochron ages were obviously "false", they did produce internally consistent isochron ages. This means that if one came back in 100 million years and dated the same volcanic rock, it would produce an age that is 70-535,000 years too old, or 100.07-100.535 million years, as opposed to 100 million years. In other words, this study confirms the use of K-Ar isochrons in older volcanic rocks (since the true age would be within the uncertainty range of your model age). To summarize thus far:

a) The purpose of McDougall et al.'s study was to test the reliability of the K-Ar method in basaltic rocks that are known to be very young. The authors found the method to be unreliable in isolation, but readily explained the discordant ages using thorough petrographic and geochemical analyses.
b) While it may sound comforting to AiG readers that the ages appeared much older than they actually were (half a million years vs. 300 years), it should not. As documented in the McDougall paper, the excess radiogenic argon had to come partly from sedimentary rocks surrounding the magma chamber. This means radiogenic argon had been accumulating in those rocks for hundreds of thousands, if not millions of years before it was incorporated into the erupting basalts. Even if all K-Ar ages are invalid, one must still deal with the physical reason they are invalid.
c) Lastly, the article cited was published in 1969. Radiometric dating techniques were rudimentary, in that they required large samples and a steady hand. McDougall et al. predicted that fluid inclusions in olivine/pyroxene could have been largely responsible for the excess argon, but had no way to test this, since fluid inclusions were far too small to be analyzed individually. So wouldn't it be nice if someone used more recent technology to test such predictions? That brings me to my next point.

3) AiG needs to update their article database

Cassata et al. (2008) published a paper in Earth and Planetary Science Letters in 2008, entitled "Laschamp and Mono Lake geomagnetic excursions recorded in New Zealand". It is fairly concise, but in depth. The most important statement relative to our discussion is this:

"Most experiments yielded concordant or weakly discordant age spectra that revealed little evidence of excess or inherited argon, indicating sample preparation procedures sufficiently removed potential sources of extraneous argon. To confirm this, experiments were conducted on lava that erupted during historical time at Rangitoto, which had previously resulted in discordant K–Ar ages ranging from 146±12 to 465±11 ka (McDougall et al., 1969). The purified groundmass from this lava resulted in an age spectrum in which all but the highest temperature steps yielded a zero age owing to negligible quantities of radiogenic argon. Similarly, the highest temperature steps for all samples occasionally yielded apparent ages significantly older than the plateau age and distinct from the isochron array, most likely a result of excess argon in melt inclusions within fragments of incompletely removed olivine and pyroxene (McDougall et al., 1969; Esser et al., 1997). These steps were imprecise and were not consistently reproduced in successive experiments on additional subsamples, indicative of incomplete removal of phenocrysts and hence a small degree of sample heterogeneity." (p. 82, emphasis added)

In short, Cassata et al. (2008) used the same method to analyze rocks from the same volcano, but with newer technology. They determined that according to the K-Ar method, the age of the volcano was indistinguishable from zero (i.e. consistent with the historical record), except when the minerals were analyzed at the highest temperature. Release of excess argon at high temperatures suggests the presence of contaminants within the mineral, and explains the anomalously old ages obtained by earlier studies.

Fortunately, we are now able to obtain elemental and isotopic ratios from much smaller samples with far better precision than 40 years ago. Contamination can often be accounted for, along with the loss of argon. Now, instead of dating a whole sample of rock/mineral, one can obtain a number of "apparent ages" from various locations within a single crystal, quantifying the diffusive loss of argon in the sample and accounting for microvariations in potassium content from zoning. Such technology has been used in recent years to confirm early suspicions of geologists that tried to interpret discordant dates.

Concluding remarks

In this particular article, I think it is clear that Mr. Doolan has employed argumentation that is misleading, if not deceptive (though I will grant the benefit of the doubt, and assume he is not intending to deceive anyone). Granted, I picked an article that was rather short and old, so I will aim to verify whether newer publications by the RATE team have added anything qualitatively to the debate. On the other hand, while I disagree with the scientific conclusions of Mr. Doolan and others at AiG, I am not hesitant to point out where they have raised valid points (in this case, for example, the presence of excess radiogenic argon is a valid problem when using the K-Ar dating method, and warrants objection to its accuracy in some studies). Overall, I only wish to encourage consistency in scientific arguments, especially when those arguments are aimed at more pertinent matters than historical geology.