Detrital minerals done right

This afternoon, I got to go listen to a talk by Andy Morton. As anyone who hangs around the geochronology scene for any length of time knows, detrital provenance studies are done often, with a wide variety of quality and rigour. The basic idea is that you can learn about the source region of a sand by looking at the individual grains. How much you learn, and what sort of study is most informative, is something that isn’t always clear, as this is a field of study where the wheel is reinvented often and badly. The basic idea is so simple that people don’t often spend oodles of library time looking at how the field has evolved over the decades. So it was really cool to listen to the guy who has been at the forefront of doing detrital studies well for the last 30 years.
Like much great science, the talk was deceptively simple. He started out explaining the various sedimentary processes that give rise to sample bias, specifically diagenesis, transport, and weathering. He then went through the heavy mineral ratios, and the chemistry of each one- what the garnet chemistry tells you, what the tourmaline chemistry means, etc., through the entire mineral suite. Only after that did he get into geochronology. And each piece of the puzzle fell together- the tourmalines identified the granite types, the rutiles identified the high grade metamorphic conditions, the garnets identified the medium grade metapelites and deep crustal rocks, the zircons gave the ages. Occasionally spinels would make mafic igneous cameos. As it came together, the picture of the source would suddenly congeal- Of course that combination of X metamorphism and Y plutonism at time Z was from source region W- once all the pieces are assembled, it’s perfectly clear.
And once the provenance is determined, the alteration overprint on the source assemblage in various sands of similar derivation can be used to determine burial temperature, source weathering, flood plain behavior, and a host of other paleoprocesses that most detrital mineral amateurs don’t even begin to consider. It was awesome.

Goldschmidt paleoblogging- the science

As a commercial exhibitor, I spent most of my time in the booth, fixing the internet and talking to potential customers. And when I did go to sessions, they were generally directly related to ion probery. I was disappointed that more SHRIMP labs were not present in the technical development sessions, but many of the talks there were “These are the challenges, anyone got bright ideas what to do about it” type talks, so I didn’t feel that we were being excluded in any way.

I did manage to sneak into some speciation talks, a bit of early earth stuff, and a sulfur session, but I missed the planetary talks I wanted to hear due to customer demand. Notable talks included the use of an ion probe to find Japanese eel breeding grounds in the Pacific. This was great because the Japanese speaker managed to express how incredibly exciting the result was without informing any of the (mostly) western audience *why* anyone cares about eels. There’s nothing like good science combined with complete cultural ignorance.

Because the booth was busy during the poster session, I did not get to attend the posters while the authors were present, and I only manned my own poster for a few 20 minute stints. However, the feedback I got while there was great, both from gurus in the planetary composition field and crazy postdocs who have some of the absurd reduced phases I talked about from a theoretical standpoint around carbon stars in natural terrestrial rock.

Goldschmidt paleoblogging- the business

The reason that we go to conferences is to sell mass spectrometers. I will not go into the confidential nature of sales, but the overall exhibit setup and utility is relevant, so deserves a mention.

Firstly, I dropped the ball a little bit on the booth organization. We should have had more chairs, more stuffed rocks, and a stand for projecting. We generally get an internet link back to a SHRIMP from the booth, and let people either watch the instrument take data automatically, or pause the autoanalysis to have a manual play. This worked to an extent, but the setup in the booth space could have been better.

The exhibition was downstairs with the posters and the lunch room. However, there were no oral sessions on the ground level, and there was no reason for people to transit through the area. In addition, the number of exhibitioners was fairly small, and they were all fairly hard core: instrument manufacturers like us, some (but not all) of the major publishers, and the organizations that sponsored the event. Traffic through the exhibition was slow in the morning and while talks were on, but we were the thoroughfare for the in-house lunch, and were we not far from the beer during the poster sessions, so lunchtime and evening were pretty busy.

The internet connection was very unreliable, and tended to drop out five minutes before an important customer walked up to the booth, but overall it was a much more positive meeting than GSA last year.

Goldschmidt paleoblogging

I had been planning on live blogging the Goldschmidt conference. It was up there on my to-do list with world peace, ending hunger, and saving the whales. And then I started a war over whale burgers, everything blurred, and here I am on the plane home. So forget live blogging- we’re geologists! Here is a paleoblog instead, to be unearthed over the next few days…

The A380

On the flight from Australia to America, I experienced life on the new European super jumbo, the A380.

We were flying QANTAS, so until I fly the same plane on other carriers, I can’t distinguish between the effects of the plane and the carrier’s use of it.

The A380 experience began in the Sydney international terminal, where we were informed of a two hour delay due to the necessity of replacing some parts. Presumably this sort of experience will occur with all new planes, but after the first two years of operation, it seems clear that this superjumbo still harbors several bugs. I’m told that the plane is nicknamed the A180, because it has a habit of taxiing out, doing a 180, and coming back to the gate for repairs. Luckily, we were still in the terminal when they chose to fix the plane, so we didn’t spend the time on the tarmac. Two and a half hours later we were in the air, and despite their promise to make up the time, we got to LA three hours late. The plane was noticeably slower than a 747: I think that the in-air time between LA and Sydney was scheduled to be 20-30 minutes longer than the old planes, and we actually lost time in the air despite trying to catch up.

Our late arrival meant that we had missed the last flight east for the day, so we had to wait around LAX until the redeye left that evening. Luckily, QANTAS provided us with a hotel room, so we could at least get a few hours of sleep in the afternoon before connecting to Knoxville via Charlotte on normal-sized aircraft.

On the plane itself, the seats had the least legroom of any of the planes we took on the journey, with the possible exception of the turboprops that service Canberra and Sydney. To make matters worse, the new seat design means that having the person in front of you lean back reduces kneecap room that is not regained by reclining one’s own seat. I am taller than most (193 cm, or 6’4”), but I had to turn sideways or spill out into the aisle to fit in the A380 seat. They are stacked 10 abreast, but the plane may be slightly wider than the 747.

Friends of mine on the plane complained that the meal service was dreadfully slow, but I was not perturbed by any such lack of service. The food was airplane food. Nothing more, nothing less.

The experience was not all negative, however. The entertainment system was excellent, though I can’t help but wonder if I missed something by watching Avatar on the back of a seat. Even if I did, I can’t blame that on the air plane. However, I think that this was the only area in which the plane excelled.

So in summation, the big new French planes are just as shoddy as their big new mass spectrometers.

Ten reasons why nuking the oil vent is a bad idea

1. Some rock types common to Gulf oil deposits, like salt, don’t fuse into rock when heated- they just melt, become radioactive, and then redissolve into groundwater.

2. In big depositional piles like the Mississippi delta, the sediment is over ten kilometers thick. As it thickens, the pressure and heat created by burial squeeze the water out of the lower sediments. This water can then dissolve the radioactive bomb material and leak it up to the surface.

3. Outside the immediate blast zone, you are likely to create lots of fractures by breaking the rock.

4. The 2 billion year old natural nuclear reactors in Gabon show evidence of hydrocarbon migration. So it’s been tried before.


5. At the pressures found below the sea bed in a mile of water, (over a hundred atmospheres, depending how far below the sea floor you are), the cavity formed by the detonation is likely to collapse, so you don’t actually seal anything.

6. Do we really want oil-producing countries like Iran, Venezuela, and Lybia to think that if they just spill enough oil, they will have a justification for building a bomb?

7. Radioactive Cajun shrimp.

8. When’s the last time a solution for fixing a geological problem devised without consultation with Earth scientists actually worked? Hint, the correct answer is not the tube wells of Bangladesh.

9. Got a 6 inch nuclear weapon? That line may work on the ladies, but here in the real world if your bomb is bigger than the pipe, you’ll need to drill a relief well to get it down there.

10. If these guys can’t even drill a hole in the ground without blowing up their rig, do you really want to trust them with a nuclear weapon?