So it has been quite a while since I posted anything on here, but I have a story to tell that I hope will get me jump started back into posting a little more often.
I spent a good part of last week traveling to and attending the Geological Society of America conference in Denver CO. The GSA annual meeting is a great place to network in the geology community, since it is the one place most of the who's who of geology end up every year. GSA is also a great place to see work other people are doing on every aspect of geology. Throughout the conference there are talks and poster presentations for much of the current research in the community, so it allows a geologist to see the most current work done in a particular area.
On the third day of the conference, the chair of Geosciences Dept. at BSU told me that there was someone with a poster relating to the Albion-Grouse Creek-Raft River core complex where I had originally planned to do my Master's thesis, and still plan to do some dating and geochemistry work; so I had to go check it out. So I tracked the poster down, and sure enough this person had just completed some dating of the basement rocks in this area (something I wanted to do) as part of a larger project that involved a different primary focus than dating of the basement rocks.
After looking her poster over, I thought I might ask her a few questions about her work. So I told her that I had been interested in dating the basement in this location, and that I was actually already in the process mineral separation, and that I believed the basement might be younger than what she had found, which was in agreement with the general consensus of the scientific community. Upon telling her this, she assured me that they were of archean age, and that her work proved it, and basically treated me like I was some kind of drooling idiot. So needless to say this got my hackles up, and I proceeded to tell her that I didn't appreciate being talked down too, and that I was even more committed to proceeding with my research after our little encounter. At which point she decided to walk away to talk with someone else.
With that, I decided it was time to take a close look at the work that she had done, to see just how sound it was. This person happened to be from Standford, and works on a piece of equipment called the SHRIMP (super high resolution ion microprobe), of which there are only two in the United States, because they are very expensive, and typically very accurate. SHRIMP folk tend to think their shit doesn't stink, and this case was no exception. Not to diminish SHRIMP, if used properly it should be the perfect tool for dating very complex zircons, which may have several age domains (sections of different ages), like the ones her researched focused on down in the the Grouse Creek range. Basically a SHRIMP can zap a very small location on a zircon grain with a laser, and date it very accurately, which is great for complex grains.
So when I told her I was going to date these rocks using TIMS (thermal ionization mass spectrometer) she told me I was crazy, that the grains were just too complex. And if I were trying to date grains like the ones that she was dealing with, she is probably right, they might very well be too complex for the TIMS process. The reason for this, is that with TIMS we actually have to dissolve and entire grain, or at least a whole piece of material (this could be a bit of a grain that we have snapped off). So if you have something that is very complex, it is nearly impossible to separate the different age domains from one another, making TIMS a poor too for such a problem. BUT, what she was not taking into account was that the location she collected these grains was from a place where they were much more likely to have been modified (and made more complex) than the location I collected my grains. I collected my grains directly from the basement rock, as opposed to her samples which was from what she assumed was melted basement rock, or highly deformed basement rocks.
These things mentioned above are big clues into the big problem with her work, which was that she didn't have a single date, from a single grain, that was 2.5 Ga (2.5 billion years), which is what she was claiming the age was. All of her grains dated differently, 1.7 Ga, 1.4 Ga, 1.1 Ga, and she used a specific analytical technique to say that these grains had undergone mixing of young and old domains, and had extrapolated and age of 2.5 Ga, which, with SHRIMP should not be a problem, because you should be able to find a zone large enough that you can sample, that should give you a date for that specific zone, and not a mixing of two.
This range of ages could be due to a couple of different problems. They could be related to loss of lead from the zircon, which would make the grains look younger than they were, or it would be that the dates are right, and that the cores of these zircons were 1.7, 1.4, and 1.1 Ga, which would mean that these were probably detrital grains (like grains of sand that came from another source) and which would mean that the rock she collected them from was not sampling the basement at all, that it was sampling sediments. Either way, her story seems more and more bogus the more I think about.
I really hesitate to call anyone out in a situation like this, especially since a lot of my questions were not answered to my satisfaction. But the very way I was treated, and the sort of smugness that went along with her reactions to me questions has really emboldened me to pursue this issue. My luck, I will do all of the work just in time to find out that her dates are more legitimate than I think they are, and that it was time wasted, but at this point in my career, I can't help but think it will be time well spent either way. So (raises a glass), here's to my first professional feud, may it be equally infuriating as it is enlightening.
