Well its been a slow start to the blog as this is the first of my entry and it is almost into my third week of research. But as the old adage goes, better late than never.
Week One
So the first week the daily meeting with Dr. Boyer and John helped me get onto the metaphorical boat with research. I'll try to sum it up as briefly as possible.
Throughout the geological history of the earth—some 4.57 billion years—there has be five major extinction events, one of these such events is the Late Devonian extinction. This event took place in the geological period of the Devonian (416-359 Ma) around 374 million years ago at a boundary that marks the beginning of the last stage of the Devonian, the Frasian-Famennian boundary. It has been said by many this is perhaps the least understood of the extinction, and indeed it is shrouded in a veil of mystery, with ranges for this extinction taking between 500,000 to 25,000,000 years or whether this event was one or several distinct catastrophic pulses. Along the same lines the processes that caused this event are equally unknown. The most prevalent among these theories is a global oceanic anoxia event, simply meaning that the ocean’s water column had little too no oxygen. This is the theory that I wish to test in my research project. Previously collected black shales, typical indicators of anoxic or even euxinic events, were the center of my project. Within all black shales is authigenic pyrite or “fool’s gold” ranging in mineral habit from euhedral crystals to rounded “lumps” of pyrite. The one variety of pyrite I am using is characterized as type-1 pyrite framboids, as described in Wignall and Newton (1998). Type 1 framboids are raspberry-like, densely-packed, spherical aggregates of equigranular, microcrystals of pyrite (see images blah blah). Although framboidal pyrite can form in a number of conditions the most common environment is in organic rich sediment butting an anoxic water column. The main aspect of my research is to determine if framboid diameter, and to a lesser extent, size distribution and pyrite type can be a useful tool in the determination of anoxia in these past environments—mainly the Devonian. A range of samples were acquired from the black shales, and the particular layers I was using had the ichnofabric index determined along with geochemical data, both are other proxies for anoxia. My samples where taken from a variety of indexes, from non-bioturbated to bioturbated (1 being nonturbated and 5, you guessed it, turbated). These are to be compared with the framboid diameter to see if there is any correlation between the ichnofabric index, and in turn the relative state of anoxia in the water.
As you can see a lot to take in after being on summer vacation for two and a half months! But in conclusion the first week was full of discussions, deciding what black shales to run the SEM on, and just getting all around organized. Oh also I went out in the field with John to aid in his own research.
Week Two
The second week was all prep. work. After all 14 samples were decided on, most had geochemical data to go along with it (and ichnofabric index data also) that was researched by an alumni of SUNY Oswego, Ellen Wilcox, who is off to graduate school now.
All of the shale samples were previously collected by Dr. Boyer and her colleagues in 2010. Most were wrapped in duct tape to thwart the fissile nature of shale in order to preserve the meticulous stratigraphic measurements taken upon the sampling. So as I said before the samples were decided based on the presence of geochemical data and variety (i.e. ichnofabric index). With each duct-taped-wrapped sample there are individual layers that had been geochemically analyzed. I then had to hammer, chisel, and cut pieces of the said layer out, being very careful to maintain the layer and orientation I needed. I would take a decent sized chunk out approx. 3x3 cm which would then have to polished with first a 400 grit sand and then 800 grit sand on a LAP machine, essentially a potters wheel. That is when I cut these chunks of often irregularly shaped layers into 1x1 cm squares using the small rock saw in our Geology Student Research Lab (see the pictures).
So that is where I'm at right now. On Monday, if I'm not mistaken I will travel down to to the SUNY ESF scanning electron microscope (SEM) facility in Syracuse, maybe with John, to get a rundown of the SEM. And over the next week will be taking shots of the polished black shales looking for the infamous little pyrite framboids so that I may measure them at a latter date. But more information about that to come!
Here's some pictures. Going from the top and from left to right: The rock saw I used; the LAP I used to polish the samples; an incomplete organizer box with semi-prepared samples; a typical shale sample I need to prepare, WC-the location, 7-15 (cm)-the stratigraphic range of the same from some base point, and the circle with a dot meaning the "up" direction; and another view of the previous sample, not the layers of shale within the sample.
