Contact Again!
[There is still no Internet connection to Lake Joyce. Dawn sent a CD out on a helo with Cindy to give to Lisa in McMurdo to email to me in Kittitas. Here is her next blog. Bill Sumner]
November, 6, 2009
Yesterday’s blog was about a microbialite sample. This is what it looked like:
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The microbial growth is the soft looking part sitting above sand. The stuff that looks like old shag carpet is all bacteria, thread-like (or filamentous) bacteria. I dissected it as described before, and ended up with some nice pieces of calcite, which I talked about categorizing. Here is how I’ve grouped my pieces:
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The large pieces not in a petri dish are special and don’t fit a category. The ones in the dish in the bottom middle have complicated, lace-like structures. The ones toward the right side of the dish are more rod-like but still have lace-like details. The pieces in the dish on the lower right has rods on the left and smoother plates toward the right. The plates toward the bottom have extra little details on their surfaces.
The dishes in the upper row are left grouped by where I found them. The outer coating bits (in the left dish) were on the outside of the structure, but lower down. The dish in the middle has calcite that came from the tip of the microbialite. These calcite pieces probably grew about the same time as the “outer coating” pieces, but they are much bigger and more robust. That might suggest that calcite forms more quickly at the tips of the structures. The dish on the far right has pieces that were mixed in with sand at the base of the microbialite. When I dissected the structure, these bits looked like they were crushed by the sand falling on them. The rest of the microbialite then grew up over them.
Our plan is to take more core samples like this one. We’ll drain the water and rinse them with distilled water to keep more calcite from forming. Then we’ll ship them back to the US. Once there, my student Tyler will work with them. I’d like to use x-ray computed tomography (like a medical CAT scan) to map out the distribution of the calcite before Tyler dissects the structures. That will help us figure out where all the bits come from. Then Tyler will pull the samples apart, looking at the relationships between the calcite, the (dead) bacteria, and the rock flour and sand grains. We’ll look at pieces using a scanning electron microscope (SEM) to see what the individual crystals look like and to look for fossilized bacteria. Finally, we’ll analyze the carbonate chemically to see if we can figure out the chemical environment that causes the crystals to grow. We’ll specifically look at the ratio of 12C and 13C to see if microbial processes affected mineral growth. This is going to be an EXCELLENT project, right Tyler?
November, 6, 2009
Yesterday’s blog was about a microbialite sample. This is what it looked like:
.jpg)
The microbial growth is the soft looking part sitting above sand. The stuff that looks like old shag carpet is all bacteria, thread-like (or filamentous) bacteria. I dissected it as described before, and ended up with some nice pieces of calcite, which I talked about categorizing. Here is how I’ve grouped my pieces:
.jpg)
The large pieces not in a petri dish are special and don’t fit a category. The ones in the dish in the bottom middle have complicated, lace-like structures. The ones toward the right side of the dish are more rod-like but still have lace-like details. The pieces in the dish on the lower right has rods on the left and smoother plates toward the right. The plates toward the bottom have extra little details on their surfaces.
The dishes in the upper row are left grouped by where I found them. The outer coating bits (in the left dish) were on the outside of the structure, but lower down. The dish in the middle has calcite that came from the tip of the microbialite. These calcite pieces probably grew about the same time as the “outer coating” pieces, but they are much bigger and more robust. That might suggest that calcite forms more quickly at the tips of the structures. The dish on the far right has pieces that were mixed in with sand at the base of the microbialite. When I dissected the structure, these bits looked like they were crushed by the sand falling on them. The rest of the microbialite then grew up over them.
Our plan is to take more core samples like this one. We’ll drain the water and rinse them with distilled water to keep more calcite from forming. Then we’ll ship them back to the US. Once there, my student Tyler will work with them. I’d like to use x-ray computed tomography (like a medical CAT scan) to map out the distribution of the calcite before Tyler dissects the structures. That will help us figure out where all the bits come from. Then Tyler will pull the samples apart, looking at the relationships between the calcite, the (dead) bacteria, and the rock flour and sand grains. We’ll look at pieces using a scanning electron microscope (SEM) to see what the individual crystals look like and to look for fossilized bacteria. Finally, we’ll analyze the carbonate chemically to see if we can figure out the chemical environment that causes the crystals to grow. We’ll specifically look at the ratio of 12C and 13C to see if microbial processes affected mineral growth. This is going to be an EXCELLENT project, right Tyler?
