������̳

• Mary Rose Gilliland
• Emily Lazo
• Mishelley Low
• Leila N'Diaye

Mary Rose Gilliland

Advisor: Pedro Marenco

Exploring the Role of Microbialites During the Early Ordovician Period

Our field team investigated and collected samples from mud mounds and adjacent sediment in the Fillmore Formation near Ibex, Utah. Mud mounds are carbonate fossil reefs with enigmatic origins; however, they have been hypothesized to have been built by microbes. These reefs were built during the early Ordovician period (~480 million years ago), a time of transition for reefs as reef-building animals were beginning to evolve. During this period, reefs were built by sponges and microbialites (rocks formed from microbial activity) and existed prior to the evolution of modern coral reefs. Modern reef environments are currently undergoing a comparative transition period as they are experiencing a negative influence from human activity causing them to be replaced by sponges and algae. It is valuable to study these past reefs from the Ordovician Period in order to understand and predict the future of reef systems and their effect on biodiversity.

In order to study and collect data on Ordovician fossil reefs, we are analyzing and comparing known microbial samples from the mud mounds and known fill sections. Through comparing the stable isotopes of carbon present and the elemental composition in the known microbialite sample, we plan to develop a geochemical fingerprint to test for a microbial origin of mud mounds.

Emily Lazo

Advisor: Pedro Marenco

Investigating the geochemistry of microbialites in Lower Ordovician reefs

The Ordovician (about 480 million years ago) was a crucial transition period for reefs, where reefs went from microbial- to animal-dominated. The microbial reefs in question were structures called stromatolites and thrombolites (collectively called microbialites), which are thought to have been built by microbial communities. The rock record shows other types of structures that also seem to have functioned as reefs, however we are not sure how these reefs were built. These structures are known as “mud mounds” because they are made primarily of calcium carbonate mud in a domal shape. This shape could not have been maintained without some sort of binding activity of organisms. It has been hypothesised that these mud mounds were made by microbial activity. Today’s reefs are in crisis, as corals are being replaced by microbes and sponges. Because Ordovician reefs were also built by microbes and sponges, it is useful to look at these past reef systems, in a similar transitional phase, to see what happened, and to help us make predictions about what will happen to modern reef environments.

We are working with rock samples from the Fillmore Formation, from our field work in Utah, which we will use to make thin sections to look for microscopic evidence of microbialites. We are using 1) samples taken from rocks that we know are microbialites, 2) samples that we know don’t have microbialites, and 3) samples that we think might have microbialites (mud mounds). Some modern microbial communities tend to concentrate certain elements. We are hoping to find similar patterns in the microbialites to use as a geochemical fingerprint, and in turn use that to determine whether the mud mounds are microbial. Microbialites are generally assumed to use photosynthesis to form. Since photosynthesis can alter the isotopic composition of carbon, we are hoping to find differences in the carbon isotopes between the microbial and non-microbial rocks.

Mishelley Low

Advisor: Selby Hearth

Investigating pigment production of acid mine drainage in Pennsylvania’s anthracite coal belt

Acid Mine Drainage (AMD) occurs when water and oxygen come into contact with reactive minerals that are exposed due to mining activity. The oxidation of these minerals produces metals and acids, which pollute downstream environments and transform streams into a rusty yellow-orange color. This causes devastating environmental aftermath not only for animals and plants living in the area but for public health as drinking water can easily be contaminated. AMD can have an effect that lasts for thousands of years. It is a worldwide issue but is especially relevant in Pennsylvania as it contains coal mines with AMD more than any other state in the country. In this project, I will work with Selby Hearth to do a combination of fieldwork in the Anthracite Coal Belt in Pottstown as well as laboratory work to investigate the mineral properties of precipitates that are produced in AMD environments. We will investigate if it is possible to transform AMD into pigment that can be used for production. In this method, bodies of water would be actively treated and the profit made from pigment could possibly be used to offset money to remediate AMD. In our research, we try to answer if this process can be done widespread or in just site specific areas.

Leila N'Diaye

Advisor: Katherine Marenco

Investigating The Structure and Composition of Ordovician Reefs in Western Utah: Microbes and Sponges as Reef-Builders

Modern coral reefs are bustling ecosystems supported by coral and algae frameworks that provide shelter for a variety of species. Similar structures are found in rocks from the Ordovician Period, ~480 million years ago, yet no coral fossils are present. In the absence of coral, sponges and communities of microbes constructed several varieties of reef structures, referred to as mounds, that supported populations of other organisms. Microbial structures have variable complexities, ranging from enigmatic “mud mounds” to laminated or branching structures. My work will involve studying the Fillmore, Juab, and Wah-Wah rock formations in western Utah to further understand the relationships among these organisms. Analysis will primarily focus on the spatial relationships among reef components, especially the changes in relative abundance and areal coverage through time. 

My research aims to quantify the percentage of rock that each reef component occupies through analysis of a combination of grid data and rock samples, and to create visualizations that illustrate the spatial relationships present in the reef mounds. In the field, a 25cm x 25cm grid was used to create focus areas in rock surfaces from which we recorded the presence of sponges, other fossils, and reef cavities, noting size and proximity to other reef components. Larger samples were collected to be studied in the lab using acetate peels. Initial field observations suggest that the average size of sponges and other fossils increased from the Early to the Middle Ordovician. This may indicate an increased importance of sponges as reef scaffolders over time. Middle Ordovician mounds also display higher relative abundance and diversity of fossils than earlier mounds in the succession. This work will allow me to better understand the evolutionary history of early reefs, and the ecological role that certain reef components played in the construction and maintenance of these reefs. Microbes continue to play an important role in reef-building today, so learning more about ancient microbe-supported reefs can provide information about how these reefs responded to environmental change that may inform our study of climate change in relation to modern coral reefs.