The Times about time: Geochronology themed article in the NY Times

No real analysis here, but I'd like to draw your attention to this recent article by Kenneth Chang in the New York Times about recent work that might shed light on the very early earth. I am highlighting the article both because it deals with geochronology (U-Pb zircon geochronology to be exact), and because it is a rare article dealing explicitly with geology; not modern climate change or some geoscience themed hazard, but straight up geology. The article also has some good quotes from some of the grand high mucky mucks of geology including Mark Harrison, John Valley, and Norm Sleep. I've seen a talk version of some of this data before, and when I get into my office tomorrow I'll check out the Nature paper as well and try to comment, although in all honesty I seriously doubt I'd come up with much more insightful than Professors Harrison, Valley, Sleep, and Mojzsis.

In consideration of self promotion, if you'd like some background on geochronology to help with the NY Times article, check out this earlier post of mine, or any of the background geology posts I have listed on my sidebar.

President Elect Barack Obama!

Apparent Dip is thrilled and profoundly happy to announce that my endorsement of Barack Obama for president appears to have worked, tipping the balance in crucial states, and leading to an overwhelming victory for Barack Obama.

I am unfortunately listening to television pundits try to sound profound right now. John McCain gave a fantastic concession speech, I am glad he did not speak like that during the campaign, I feel the contest would have been much closer.

Time to watch his acceptance speech!

Thermochronologists for Obama

The wait is over. All across the country, undecided voters have been waiting by their televisions, constantly checking email, listening non-stop to NPR, just to learn which presidential candidate has earned the Apparent Dip seal of approval. I know how much sway my choice has, believe me, as the author of the world's leading thermochronology themed blog...well, let's just say the responsibility has weighed heavily on my (figurative) shoulders.

Apparent Dip is officially endorsing the Obama/Biden ticket. No big surprise perhaps. As someone who reads books, did well in school, and grew up in California, I obviously don't belong to the "real America" I've heard so much about at GOP rallies. I grew up in a decent sized city, which means I lack "small town values" and therefore hate my neighbors, can't stand families, am allergic to hard work, do nothing worthwhile, am a communist, cavort with terrorists, and of course, want America to fail. I am also an elitist because I think issues are complicated and can't always be summed up as one-liners, oh, and I also enjoy reading and non-motorized outdoor activities, which means I am a whiny liberal tree-hugger. Oh, and I don't believe that the term "mothers health" should be put in air quotes or muttered in a snide tone. I care a great deal about my mother's health, and don't consider that an extreme position.

On the issues, well, this seems to be a no brainer. I can't think of a single thing that has gone well in the Bush administration, and McCain agreed with Bush 90% of the time. Right now, the university I work at has a football team that has had a rough few years. Really rough, no bowl games, no winning seasons, no big crowds, embarrassing losses, you know what I mean. Much of the blame is laid at the feet of the coach. Would a fan of this team want to replace the coach with someone who thought he did 90% of everything right? Of course not.

Add to this the fact that for the first time in my life, I have been inspired by a politician. Now, I don't agree with everything Obama is proposing, and I understand the realities of politics, I know many of his plans will be difficult to enact. They always are. What gives me hope though, is that Obama recognizes and acknowledges that issues are complicated. Obama has even spoken about what a huge problem anti-intellectualism is in America today. Seriously, a politician who isn't pretending to be a doofus. A politician who thinks it is important to be more than a guy "you can have a beer with." You know what guys who you can have a beer with are good for? Having a beer with.

On a serious thermochronology note, McCain and Palin have both made offensively ignorant and anti-scientific statements recently. They both love to rail against government spending on research, even when it is obvious that they have no idea what the research is really for. Remember Palin's rant about fruit fly funding? I'm no geneticist, but anyone who has stayed awake through a college biology course knows the importance of fruit flies in genetics research. And guess what, the research Palin was slamming actually is involved with treating children's autism. In one of the debates, McCain brought up DNA research on grizzly bears as a waste of money. Turns out that is the most effective way to understand their population and therefore enforce the endangered species act. But hey, who cares? This also came up a few years ago, when I heard McCain ranting about funding to study "cow farts." The research was actually about methane, a potent greenhouse gas, much of which happens to come from cows. But hey, as long as you can reduce serious science down to a funny one-liner, it must be a waste of money. Not a good use of funds like the Iraq war. To be fair, I don't expect McCain and Palin to know all the science. I do, however, expect them to consult with scientists on scientific issues, which from their statements they apparently do not. And to boot, Palin is a proponent of teaching creationism (excuse me, I mean incompetent design) in public schools, a sure fire way to undermine science. If someone wanted to destroy America's ability to compete scientifically in the future I believe they'd favor the same programs.

I could go on, and it would become more rantish. Long story short, the world's leading thermochronology blog is officially endorsing the Obama/Biden ticket for the 2008 presidential election. I care too much about the future of the country, despite my status as a fake american elitist. Don't forget to vote!

Events

On Saturday night a close friend and colleague was hit and killed while riding his bicycle in a park near campus. Alec Waggoner was a 23 year old masters student working in our group, a Kansas native with a bright and promising future. I could go on for pages about Al's scientific and academic ability, but it is his friendship and entirely genuine and unique take on life that I will miss the most. Alec was good at life, and was someone who I admired immensely. His passing can only be described as a monumental tragedy. Many of us have lost a great and true friend, and the earth science community has lost a bright and motivated young talent.

I do not have any experience writing about young friends in the past tense. I will probably write more about Alec later, but not now. My heart and thoughts go out to Al's family.

A few years ago, I read Antoine de Saint Exupéry's autobiographical book Wind, Sand, and Stars. I initially read it because it was listed inthe National Geographic list of the 100 greatest adventure books of all time. When I started reading the book I was initially kind of disappointed. Truth is there isn't a great deal of adventure in the book, especially in the beginning. It is much more philosophical than I was expecting. By the end though, I was really into it, and I ended up re-reading it many times. I often find myself thinking about certain passages, especially during difficult times. This is the one that has been in my head ever since I heard about Alec.

Bit by bit, nevertheless, it comes over us that we shall never again hear the laughter of our friend, that this one garden is forever locked against us. And at that moment begins our true mourning, which, though it may not be rending, is yet a little bitter. For nothing, in truth, can replace that companion. Old friends cannot be created out of hand. Nothing can match the treasure of common memories, of trials endured together, of quarrels and reconciliations and generous emotions. It is idle, having planted an acorn in the morning, to expect that afternoon to sit in the shade of the oak.
So life goes on. For years we plant the seed, we feel ourselves rich; and then come other years when time does its work and our plantation is made sparse and thin. One by one, our comrades slip away, deprive us of their shade.

FT2008 - Alaska chapter 4 and a big thanks

Before I write any more about FT2008, the International Conference on Thermochronometry, I need to take care of one blog related item. Last week I was named a "blog of note" on blogger.com, and have since seen a drastic increase in my readership. Above is a bar graph of my daily page loads from 10/10/2008 until today. Take the statistics challenge, see if you can tell what day I was named a blog of note. I removed the actual numbers, well, mainly because I have been shamed into realizing I was letting my blog suffer tremendously and therefore are unwilling to admit my average readership. But, thanks to the recognition, my page loads really spiked, that first day they were 2 orders of magnitude higher than average, and although they have settled down, are still 20 times what I am used to. Now, based on the comments, many people want to attribute this to my pretty pictures from Alaska, but that is probably only because they are embarrassed to admit how addictive thermochronology can be. I understand gentle readers, but don't be ashamed, it is OK to admit that you are fascinated by thermochronology, that you now want to quit your career and pursue this new passion, that you now try to work in the phrase "thermally activated volume diffusion" into everyday conversations, and you are constantly frustrated when reviewing papers that compare apparently phase-independent "⁴⁰Ar/³⁹ ages" to U-Pb zircon ages like they are the same thing.

Seriously though, thank you to whoever named me a blog of note, and to all of the people who've had so many nice things to say about the blog and my pictures. I appreciate the kind words.

So back to FT2008, the International Conference on Thermochronmetry. In a previous post, I discussed some of the methodoligical advancements I was most interested in. Today I just wanted to highlight a few of the case studies I found most intriguing. Again, if you are interested in these topics, make sure to check out the free and downloadable extended abstracts from the meeting, available from the Union College FT2008 website. Of course, these will be interspersed with random pictures from the field trips, in no particular order.

• There was one talk and a few posters that dealt with apatite fission-track and (U-Th)/He ages from tunnels in the alps. The talk was by Reinecker, and I apologize for not remembering his first name, and the posters were by Glotzbach and Spiegel. All of these papers were in the Alpine Orogen session on the Thursday of the talk. So why tunnels? Well, these tunnels go straight through significant topographic peaks. Isotherms, or surfaces of equal temperature in the earth, tend to mimic topography, especially at relatively shallow levels. In some ways this is a problem in thermochronology. We often would like to know how fast things came to the surface, but that depends on the depth of the closure temperature isotherm, which in turn depends on toppgraphy (and many other things), which we don't necessarily know. Isotherms are deflected up under large topographic peaks, meaning that if you drill sideways through a mountain, you will experience hotter and hotter temperatures towards the core of the mountain. So I mentioned that the deflection of isotherms is a problem for us brave thermochronologists, but used correctly, it could also be a relatively powerful tool. If topography can affect isotherms, then topography should also be recorded in thermochronometers. The tunnel studies should see evidence for the topography being recorded in the low-temperature thermochronometers. Turns out it isn't so obvious, but I'll leave the abstracts for you to read.

A Blue Grouse (I think, correct me if I am wrong)

• In the last few years there have been a number of studies investigating the link between climate and tectonics. Specifically, which drives which? My own personal belief is that it just isn't an either or, but the idea that climate (namely erosion) could drive crustal processes is kind of hard to swallow for many geologists. Some of the evidence for this involves correlations between erosion rates, rainfall, and uplift rates in active mountain belts. This isn't supposed to work everywhere, there are plenty of places that get tons of rain but where nothing is being uplifted (like the Amazon basin), but many people think of it as a major driver in mountainous regions. Frank Lisker presented a paper on some of his results from Sri Lanka, and what struck me is that the southern part of the island has a rather large mountain (2000+ meters) and gets buckets of rain, but has i n c r e d i b a l l y s l o w uplift rates, slow enough they are reported in meters per million years (typically we report uplift rates in kilometers per million years).
  

More massive piles of Late Miocene - Pliocene conglomerates

So I think that is all I'm going to write on this. It gets difficult to decide what talks to highlight and what talks not to highlight. If you have found any of the things I've discussed intriguing, download and enjoy the abstract volume.

More pillow basalts from the Kenai Peninsula. Seriously, they actually look like pillows!

And my last Alaskan fall picture

FT2008 - Alaska chapter 3 - Alaskan Wildlife

So no geology this post, but instead I thought I'd post some of the wildlife pictures I took on the Denali and Kenai Peninsula field trips. First from the Kenai peninsula fjords cruise, some Stellar Sea Lions, hanging out on pillow basalts. I guess I lied, I said no geology, and here I am tossing around the term pillow basalts. This species is endangered, and if you look at the guy in the center, you can see he has a numbered brand. The decline in sea lion population is a little confusing, allegedly, and the tatoos help track them throughout their range. The pillow basalts, while not endangered, are still fantastic. This cruise actually included some of the best pillow basalt exposures I've ever seen firsthand.

Next up, a black bear! To attempt to head off any scolding comments or emails, I did not approach this bear. I was walking down a path when I came on a student who had stopped. She had been there for a few seconds. She had walked around a corner, and a youngish black bear had seen her and ran into a tree. I had my camera out, snapped this picture, and quietly walked away, trying not to attract anyone else down the walkway.

What would Alaska be without a moose? What this picture doesn't show is the other 50 people on the side of the road snapping pictures of this moose.

I took this last picture for my Mom, just to say that we did not see any of the famous Alaskan "chikens" on the trip.


Enjoy!

FT2008 - Alaska chapter 2

As I mentioned in my last post, the scientific program at FT2008 (The International Conference on Thermochronometry in Anchorage) was overall pretty impressive. I thought I'd highlight a few of the presentations that I found most interesting. As a side note, the extended abstracts for this meeting can be downloaded for free from the official meeting website here. The abstracts vary in length, but most are true extended abstracts with color figures. My discussion is by no means exhaustive, and who knows, I might augment it later. Here are some of my highlights, interspersed with random pictures of mine from the field trips. I am primarily sticking to methodological highlights today, I'll save the others for later posts.

• There were many discussions and presentations by one of the meeting sponsors, Autoscan. Autoscan is an Australian company that has been working to develop an automated fission-track counting system. I am still in the early stages of learning to count tracks, but I've observed the process and know most of the basics. Counting fission tracks is exactly what it sounds like, fission-tracks are etched in acid, and then using a microscope you count the number of tracks in your grain (gross oversimplification, I know, but to make a point). So counting tracks can be tedious, you need to count hundreds of them from dozens of grains to beef up your statistics. Anyways, as nice as it would be to have an automated counting system, the mechanics and potential complications of the process make me wary of trusting an algorithm. That being said, the Autoscan demonstrations are pretty convincing. You can download the demonstration and demo images from the Autoscan website here. Andy Gleadow gave the presentations on Autoscan and led the discussions. He went into detail about how the software deals with some of the more specific problems, comparing reflected and transmitted light images, evaluating overlapping tracks, distinguishing tracks from scratches and dust, etc. By the end I was sold. Again, I am not a certified fission track counter [yet], and therefore am undoubtably missing some important caveats, but Autoscan impresses me.
• Speaking of fission-tracks, there were another set of talks and posters by the group from Union College/SUNY Albany (John Garver and his student Matt Montario) about their recent work using a scanning electron microscope to date high track density zircon samples. The problem is this: Fission-track dating works because with time, tracks form in U-bearing minerals due to the spontaneous fission of ²³⁸U. Old and/or U-rich samples can accumulate so many tracks that they become impossible to count; they overlap and obscure each other too much. The Union/Albany group has developed techniques that allow them to count very high density samples. They do this by using a modified etchant (super secret recipe, well, until they get it published that is) and a scanning electron microscope. Typically, fission-tracks are etched with acid so they become large enough to see with an optical microscope. But, if you have a lot of tracks, this is a problem. So by using a less aggressive etchant, and more powerful microscope, they are able to effectively count samples that would otherwise be useless. I am assuming this will all be published soon, so I'll keep you updated.
• Barry Kohn presented some work he has been doing attempting to reduce single-grain apatite (U-Th)/He age spread in quickly cooled samples. Apatite (U-Th)/He thermochronology has been in widespread use for a little over a decade now, and as more and more data sets are collected, we are starting to identify and grapple with recurring problems. Perhaps the most significant issue are irreproducible single-grain ages. These are samples that appear well-suited for analysis, and have easily measurable quantities of U, Th, Sm, and He. Despite this, it is not uncommon for grains from the same hand sample to show significant scatter, well beyond what you'd expect from simple analytical uncertainty. There are many reasons why you'd actually expect significant single-grain scatter in slowly cooled samples. I won't go into it, but instead refer you to Fitzgerald et al., (2006) for a review. For quickly cooled samples, however, there shouldn't be as many complicating factors. Kohn presented results from his experiments where grains are abraded prior to analysis. Air-abrasion removes the outer rind of the crystals, leaving just a rounded core. Air-abrasion has the potential to deal with the "bad neighbor" problem in apatite (U-Th)/He thermochronology. "Bad neighbors" are U, Th, and/or Sm bearing phases that are close to or in contact with the apatite crystal in the rock. Because the He atoms move about 20 microns or so when they are expelled from their parent atom, He produced in neighboring phases can be implanted into the apatite. You end up with "parentless" He, which gives you artificially old ages. So, the idea is that if you abrade off the rind, you remove the region that could have had "parentless" He implanted into it. Kohn isn't trying to say that this is the only answer or that it always works, but in some of the samples he analyzed it certainly had the desired effect. Namely, abraded grains showed less scatter and were more consistent with fission-track ages and/or other constraints. Obviously still a lot of work to be done, but again, very intriguing.
  

So those are some of the presentations I have thought about the most since I got back from Alaska. I'll have more highlights in later posts. I'll also have more pictures, including a special Alaskan wildlife post, and a brief discussion of our stop at the Wasilla town hall. Yes, we stopped in Wasilla. But before I leave, here is a picture I took of the Exit Glacier, I tried to get the glacial striae in the foreground with the big looming wall o' ice in the background. Unfortunately I couldn't Photoshop out the guard rope and warning sign.

Fitzgerald, P. G., S. L. Baldwin, L. E. Webb, and P. B. O'Sullivan (2006), Interpretation of (U-Th)/He single grain ages from slowly cooled crustal terranes: A case study from the Transantarctic Mountains of southern Victoria Land, Chemical Geology, 225, 91-120.