Stable Isotope Lab: hands on experience

The stable isotope lab, pictured above, at the University of Cincinnati is a shiny new lab space where a lot of great science is happening. Through a field methods course I am taking under Aaron Diefendorf I am getting some hands on experience with the mass spectrometer and other essential lab tools. Last post I shared some of the adventure of collecting the water samples, and if you follow me on Twitter @OrdovicianDaily you saw I collected some snails too (yay carbonates).

Now that the water and gastropod samples are back at the lab it is time for prep.

Here a couple of us are labeling vials and getting organized to pipette standards and collected bog water samples.

Next we purged the samples so they were ready to be fed to the auto sampler aka life saver. 

While this was all happening we sonicated the collected shells to remove sand and grime. 

Once the shells were clean and dry we crushed them into a fine homogenized powder for carbon and oxygen isotopes. One shell I separated into the different whirls. The remaining shells were bulk samples. I am looking forward to the carbonate results and the techniques I learned are directly applicable to the work I am doing in the Ordovician :)

Back in the lab the samples have been loaded into the auto sampler and will run overnight. Tomorrow we learn how to process raw data from the mass spec!

Bog Water Collection

This past week I stepped outside of the local Ordovician rocks and went to Brown's Lake Bog in North-Eastern Ohio with a group of friends from the geology department. As part of a field methods class we are off to the bog to sample water from a variety of sources.

We had amazing weather. The trees are just starting to bud, but we were still able to collect leaves from the canopy with the help of a slingshot ;)

Here I am using a bailer to clear out the monitoring well so we can be sure to be sampling a fresh recharge.

YES... I said sling shot :) We shot beanbags into the tree to release leaves from the top of the canopy.

Here's my friend Julia collecting water from the bog.

We will be running carbon and oxygen isotopes on each of the sample next week to think about the source of the bog water. These samples are apart of an ongoing research project so I wont be going into details, but I'll have to have some photos of our new mass spectrometer to show you when I am done.

After we were done with the bog we went over to the small lake and used a pump and filter to collect particulate organic matter (POM) at different depths. POM = dijon mustard of the lake

At the end of the day we packed up our gear and drove home, collecting samples from various waypoints along the way.

Next week... science happens :)

What is a "butter shale"?

So there is a good chance that as I post more about the work that I am doing this summer, there may be a lot of references to something called a 'butter shale' or 'trilobite shale'. So here I want to explain those terms a little bit to put things in context.


Butter shales are blue-green, clay rich deposits that we find throughout the Katian strata along the Cincinnati Arch. These deposits tend to be a couple meters thick, show conchoidal fracturing and not much obvious bedding in outcrop.

Image of the Treptoceras duseri butter shale from Indiana

There are two schools of thought as to how these shales derived their names. The first school of thought (and the one I tend to go with) is that they get their names from the fact that when the shales are wet, they turn into soft mud that you could cut with a butter knife. Just last year I was digging through one of Waynesville Fm butter shales and both my feet got stuck in the wet mud. I had to have an undergrad student who was with me at the time, dig me out while perching himself on a limestone float block! The second school of thought is that the name is derived from the buttery yellow coloration some of these shales show when very weathered. Reality it is probably a combination of both, but if any of our readers out there have some insight be sure to leave us a comment below!

(I tried to image this butter knife in shale bit but every time I stuck the knife into the shale that I had soaked in water it slice all the way through....so case in point I suppose!)


Now all these properties are interesting, but why do people care about these shales? Here is where the second name 'trilobite shale' comes into play. These shales heavily sought after because they generally contained well articulated trilobites (Isotelus, Flexicalymene, Amphilichas, etc) along with articulated bivalves, wonderful lingulids and other assorted critters. Now not all the shales that look like butter shales have these fossils in them, and even the ones that do require lots of work to find and properly collect the fossils, but the results are glorious! These fossils are thought to have been preserved through rapid burial of fine grained sediment during storm events, essentially smothering the local fauna. Some of these deposits have been trace over 100km showing that these were widespread events!

Image of a Flexicalymene peaking out from the Treptoceras duseri butter shale in Indiana

Image of a large lingulid brachiopod that are common in the butter shales

Finding the fossils is always an exciting process, but recently I have become interested in what makes these shales different from "normal shales" or shales that don't show these same buttery characteristics. To that end, I have applied for a Clay Mineralogical Society research grant (fingers crossed) to try to really dissect these shales with as many different tools as possible. If this grant comes through then there will be a lot of butter shale work being done this summer!


Recently I published a short paper on a new butter shale from Indiana in the Estonian Journal of Earth Sciences. In this paper we show a block of the butter shale that we cut out of the outcrop and then polished. What was revealed was a complex network of Chondrites, Teichichnus, Lingulichnus, bryozoan colonies, limestone lenses, and other features! It is a quick (and I think interesting) read so I hope you take the time to look it over! I am open to any thoughts you all might have on the subject of these shales.

Figure from Aucoin et al 2015

There are a number of  other papers on the subject if you find these shales interesting. I will leave the references below!


Lastly before this turns into a book, I will be presenting a sequence stratigraphic interpretation of these butter shales at the North-Central Geological Society of America Conference in Madison, Wisconsin this may so if you are there be sure to stop by! You can read the abstract here!


Relevant Readings:

Aucoin, C. D., Dattilo, B., Brett, C. E., and Cooper, D. L., 2015, Preliminary report on the Oldenburg "butter shale “ in the Upper Ordovician (Katian; Richmondian) Waynesville Formation, USA: Estonian Journal of Earth Sciences, v. 64, no. 1, p. 3-7.

Ferree, R. A., 1994, Taphonomy, Paleoecology and Depositional Environment of a Trilobite Lagerstätten, Mount Orab, Ohio: University of Cincinnati.

Frey, R. C., 1983, The paleontology and paleoecology of the Treptoceras duseri shale unit(Late Ordovician, Richmondian) of southwestern Ohio: Miami University, Dept. of Geology.

-, 1987a, The occurrence of Pelecypods in Early Paleozoic epeiric-sea environments, Late Ordovician of the Cincinnati, Ohio area: PALAIOS, v. 2, no. 1, p. 3-23.

-, 1987b, The paleoecology of a Late Ordovician shale unit from southwest Ohio and southeastern Indiana: Journal of Paleontology, p. 242-267.

-, 1989, Paleoecology of a well-preserved nautiloid assemblage from a Late Ordovician shale unit, southwestern Ohio: Journal of Paleontology, p. 604-620.

Hughes, N. C., and Cooper, D. L., 1999, Paleobiologic and taphonomic aspects of the" granulosa" trilobite cluster, Kope Formation (Upper Ordovician, Cincinnati region): Journal of Paleontology, p. 306-319.

Hunda, B. R., 2006, Trilobite Taphonomy and Temporal Resolution in the Mt. Orab Shale Bed (Upper Ordovician, Ohio, U.S.A.): PALAIOS, v. 21, no. 1, p. 26-45.

Rosenkrantz, K. J., 2009, Compositional variation in Cincinnatian mudstone communities (Upper Ordovician of Ohio, Indiana and Kentucky)| Implications for coordinated stasis: University of Cincinnati.

Schumacher, G. A., and Shrake, D. L., 1997, Paleoecology and comparative taphonomy of an Isotelus (Trilobita) fossil lagerstätten from the Waynesville Formation (Upper Ordovician, Cincinnatian Series) of southwestern Ohio: Paleontological Events. Stratigraphic, Ecological and Evolutionary Implications: Columbia University Press, New York, p. 131-161.

Velbel, D. B., 1984, Ichnologic, Taphonomic, and Sedimentologic Clues to the Deposition of Cincinnatian Shales (Upper Ordovician) Ohio, USA.

BRIDGING THE LIMESTONE TO SHALE TRANSITION: UPPER ORDOVICIAN (KENTUCKY AND OHIO)

The abstract I submitted to the North Central Geological Society of America meeting this coming May was accepted. I hope to see a few of you at the meeting!

Correlation of shallow marine limestones into deeper shale-dominated settings remains an area of great uncertainty in many sedimentary basins impairing the accuracy of depositional models. The Lexington Platform-Sebree Trough transition (Kentucky-Ohio) represents a well preserved Upper Ordovician example of this problem. In this study, outcrops and cores in central Kentucky and new drill cores from Cincinnati, Ohio were logged using litho-, bio-, and chemo-stratigraphy to develop detailed correlation of chrono-stratigraphic packages across a major facies transition from a the carbonate-dominated Lexington Limestone platform succession to the dark, mudrock-dominated deposits at the transition to the Sebree trough. A number of facies-crossing markers provide useful, first-order controls on stratigraphy: these include abrupt facies offsets, K-bentonites, fossil epiboles (e.g. Prasopora bryozoans), and deformed beds, probably representing regional seismites. These correlations are corroborated by gamma ray, carbon isotope curves, and elemental abundance profiles. This research expands the regional correlation of the Lexington Formation and its members into more distal settings and provides strong evidence that depositional sequences, and distinctive faunal epiboles, and chemo-stratigraphic signatures are of regional extent. Thus, despite local abrupt facies variations, associated with far field tectonics, there is strong evidence for allocyclic, probably eustatic control of large and small-scale cycles. However, the degree of environmental change across this gradient varies strongly with stratigraphic levels. Thus, lower units (Curdsville, Logana members) persist across the profile with relatively little change. In contrast, the upper Lexington units display much more abrupt northward change to shaly facies, suggesting increasing rates of subsidence in the Sebree trough through deposition of the Lexington sediments.

YOUNG, Allison L., Geology, University of Cincinnati, 500 GeoPhys, Cincinnati, OH 45221, younga9@mail.uc.edu, BRETT, C.E., Department of Geology, University of Cincinnati, 500 Geology/Physics Building, Cincinnati, OH 45221-0013, and MCLAUGHLIN, Patrick I., Wisconsin Geological Survey, University of Wisconsin - Extension, 3817 Mineral Point Rd, Madison, WI 53705

Ordovician Atlas

You have probably noticed that in past posts about the local paleontology, I have often linked specific fossil genera to an 'Ordovician Atlas' page. I thought I would share a little bit about this resource because I think it is a wonderful way to learn about the paleontology of the Cincinnati Arch.

This Ordovician Atlas is part of a collaborative NSF-funded initiative to produce digital atlases for multiple intervals of Earth history.

The Ordovician Atlas website is a series of interactive pages which allow you to search different fossil taxa that can be found in the strata along the Cincinnati Arch. Whether it be arthropods, brachiopods, echinoderms, cnidaria, mollusks or bryozoans, the Ordovician Atlas is a great resource for identifying taxa, identifying that strata you might find them in, ecological niches, descriptions or publication relevant to the taxa in question.


I know personally when dealing with fossils genera that I may be unfamiliar with, I always check the Ordovician Atlas to see if they have a listing. Below I have posted a few screenshots from the website to show some of the features present for individual genera, in this case Isotelus.

Example of the Isotelus page showing the Linnaean classification, geologic range and location map. 

Some of the pages shows these nice paleoecological diagrams depicting the range of habitats and organism may have lived. This image is for Isotelus maximus

These two images show the stratigraphic distribution of the general in question (Isotelus maximus) along with basic fossil descriptions.

Lastly, many of these pages will have a list of references and descriptions from those references, of the fossil in question.

The site contains more than just information about the various Cincinnatian genera. There is a page about the local geologic setting, the Richmondian Invasion (a person interest of mine) and various educational resources for the teachers among you. For those of you who like to go collecting, they have a page dedicated to listing good sites for doing just that!

I want to thank Dr. Alycia Stigall and the students in her lab for the great work they have put in and continue to put into this great resource.


I also would like to point you to this recent publication which discusses the program further.

Stigall, Alycia L., Jennifer E. Bauer, and Hannah-Maria R. Brame. "The Digital Atlas of Ordovician Life: digitizing and mobilizing data for paleontologists and the public." Estonian Journal of Earth Sciences 63.4 (2014): 312œ316.

Keep checking back for more additions to the Ordovician Atlas. If you are Twitter savvy, @PaleoDigAtlas is one source for updates to not just the Ordovician Atlas but the entirety of the 'Digital Atlas of Ancient Life' project.

Modern Sedimentary Structures (Great Salt Lake)

This past summer I embarked on the "Utah Trip" lead by the extraordinary geologist Carl Brett. We saw many things over the 15 day whirl wind, but one thing I keep going back to is our trip to the shores of the Great Salt Lake. I was blown away by the similarity of these structures to those so often seen in our local sedimentary rocks. The last photo is of some Cambrian age ripples we came across later that day for comparison of preservation in the rock record.

Ohio Geological Survey Visit

Yesterday I returned from the Ohio Geological Survey (OGS) after 2 days of drilling samples and photographing a few of the sections. I had a great time and collected a lot of information that will help answer some questions we are working on in my research group for my thesis.

OGS has a whole facility dedicated to storage and analysis of core at their office just north of Columbus, OH the Horace R. Collins Laboratory.

If you have questions about the local geology when traveling to a new state or even exploring your local rocks the state geological survey is a great place to start for information. Surveys are very different state-to-state but one thing they all have in common is a group of people who know their local rocks. In addition to the informed and helpful staff they hold a wealth of information, including records that go further back then you would think. Most of the records are becoming available on their websites including maps, publications, and well logs.

Core is very expensive to drill so we rely on core available to us at geologic surveys to collect data on these packages of rock not exposed at the surface. The advantages of core is it provides access to a large continuous section of rock while being easy to sample. Thin beds that may be unrecognizable in outcrop are easily seen in core. Additionally, its size allows for instantaneous comparison of multiple sections side by side and within a single day.

While you are restricted to the diameter of the core, often a few inches or less, when analyzing bedding planes fossils are still found and can be crucial to constraining intervals with the help of biostratigraphy.

Graptolites

Trilobites! ( Triarthrus?)

Triarthrus cephalon

Fossil finds are not restricted to the bedding planes. It is very common to see cross sections of
many fossils such as the possible bryozoan pictured here. 

Big shout out to OGS especially facility coordinator Aaron Evelsizor for all of their help!