Tuesday, September 26, 2006

A zircon that predates the universe

I have on my desk a rather curious geochronology result. It is a SHRIMP analysis that I ran a month or two ago on a zircon- a very routine analysis. However, the result is somewhat surprising.

According to this summary sheet, the 206Pb/238U age of the zircon is 160 million years. Jurassic. No big deal.

The 207Pb/206Pb age, however, is a bit older- 3362 million years, or early Archean. That is a bit odd, but not completely implausible. A severe Pb-loss event caused by metamictization could, in theory, create such extreme discordance. The real problem is the thorium age.

The 208Pb/232Th age for this sample came out at 15,223 million years. 15.2 billion. That’s really old. It is more than three times the accepted age of the Earth and solar system (4.56 Ga), and considerably older than the best estimate that astronomers give us for the age of the universe: 13.7 Ga. Such an age is a bit counter-intuitive for a zircon from a Phanerozoic orogeny.

When trying to interpret such a result, the extreme value gives us only two possibilities:

1. The arcane disciplines of cosmochemistry, geochronology, isotopic analysis, and astronomy are all conspiratorial hoaxes perpetrated by godless, soul-destroying, ivory tower elitists, whose evil scheme is to avenge their social ostracism by polluting our precious bodily fluids.

2. I fucked up the analysis.

Obviously, choice one is more appealing to my sense of self-worth. It allows me to stroke my ego to sleep at night with the belief that I have single-handedly exposed the academic fraudsters. It fills me with the warm glow of knowing that humanity owes me for bringing justice, light, and honesty into the realm of physical science. It excites me that this selfless discovery will undoubtedly arouse the thousands of nubile young damsels who found zirconology fan clubs and fantasize about thorium decay.

Unfortunately, there is one small problem. There is a conceit among scientists- an unspoken rule of the laboratory code. It says that science should have predictive value. In order for my ground-breaking pre-universal zircon to overturn science, destroy the paradigm, and score me some hot chicks, I need to put it in a meaningful context. I can do this by either developing a new theorem, that will explain my data while reinterpreting the last 40 years of research in a new light, or I need to show that all the previous studies were flawed. Before I can do either, I need to understand the body of knowledge which I wish to overturn. This will require attending a library.

Thing is, I’m not real fond of libraries. The stacks smell musty, the babes give me dirty looks, and there is nothing to do other than sit and read. So instead of reviewing all the crusty old theories that my new data will disprove, I will procrastinate by testing hypothesis two, the outlandish possibility that the analysis is not completely perfect.

To be continued...

p.s. Note to the ANU students who read blogs instead of working on their mid-terms: Please don’t give the punch line away.

No comments: