Broad range of research presented to Geological Society of America

A robust geoscience program will draw thousands of curious minds to the Colorado Convention Center in Denver for the 122nd Annual Meeting & Exposition of the Geological Society of America, Oct. 31 to Nov. 3. More than 3,700 technical presentations will illuminate geological and integrative science research of international, national and regional interest. Among the papers presented by University of Cincinnati faculty and students at the Geological Society of America annual meeting are:

Our understanding of global climate changes during the extinction at the end of the Permian period is based on geologic data collected around the world. UC geologist Thomas J. Algeo and colleagues describe an analysis of the carbon content of marine sediments at 33 widespread locations. The samples, in general, show similar patterns, except for rocks now preserved in southern China. While most rocks deposited during the Permian extinction show increased concentrations of total organic carbon and higher organic carbon accumulation rates, the Chinese samples show the opposite effect. It is probable that this indicates an explosive regional volcanic eruption. Sediments in the area are sterilized. The data may show that the combined effects of local volcanism and global climate change were especially lethal.

Presenter: Thomas J. Algeo, University of Cincinnati

Co-Authors: Richard V. Tyson, GE Tech
Jinnan Tong, China University of Geosciences at Wuhan
Qinglai Feng, China University of Geosciences at Wuhan
Hongfu Yin, China University of Geosciences at Wuhan
Charles Henderson, University of Calgary

UC geologist Thomas J. Algeo will present new research on the conditions leading to oxygen depletion in the oceans during the late Permian. Warm global climates certainly played a part in oceanic oxygen depletion as uniformly hot conditions stifled turnover by ocean currents. However, Algeo has found evidence that chemical weathering by acid rain and similar processes also contributed. When late-Permian erosion seven times the normal rate sent large flows of nutrients into the ocean, it created conditions much like the over-fertilization we see today near the outlets of large rivers. As it does today, this condition led to a microbial feeding frenzy and the removal of oxygen – and life – from the late Permian ocean.

Presenter: Thomas J. Algeo, University of Cincinnati

Nitrogen is cycled through ocean environments by bacteria. The amount of nitrogen indicates available nutrients. During relatively recent geologic time – the most recent two million years or so – the process by which bacteria reduce marine nitrates to atmospheric nitrogen has acted to amplify global climate change. UC geologist Thomas J. Algeo and colleagues have examined evidence for nitrogen cycling over the previous 540 million years. Over this multi-million-year timescale, nitrogen cycles appear to act as a brake on climate change. While it is possible that the older variations reflect only changes caused by continental drift, it is more likely that these variations reveal an important negative feedback mechanism affecting long-term climate change.

Presenter: Thomas J. Algeo, University of Cincinnati

Co-Authors: Philip A. Meyers, University of Michigan
Harry Rowe, University of Texas at Arlington

Through isotopic analysis of Devonian and Carboniferous fossil plants, UC graduate student Zhenzhu Wan explores the relationship among environmental factors, water-use efficiency and isotopic composition of ancient plants. Modern plants show different ratios of carbon isotopes based on how efficiently the plants use water to grow. Wan studied eight fossil plant types and found variations that can be attributed to water-use efficiency. Some of the plants are preserved in the same locations, which will allow research within the same environment. Some of the plant types have a long history in the fossil record, which may provide ecological information from different habitats.

Presenter: Zhenzhu Wan, University of Cincinnati

A type of brachiopod known as Ambocoelia is relatively common in North American rocks dating from the Devonian period (416 million to 359 million years ago). James Zambito and a colleague have conducted the first scientific review of these fossils in more than a century. They discovered that a century of haphazard classification had confused our understanding of these ancient animals. Their new classification furthers our understanding of the evolution, paleoecology and biogeography of Ambocoelia.

Presenter: James J. Zambito IV, University of Cincinnati

Co-Author: Mena Schemm-Gregory, University of Coimbra

The Ordovician rocks underneath Cincinnati are divided by scientists into a variety of layers based on the types of rock and fossils they contain. Geologists have been frustrated by one such layer, known as the Maysvillian. This layer, named for an exposure near Maysville, Ky, seems to be a jumble of local features with no widespread regional patterns. UC graduate student Thomas J. Schramm, working with colleagues has used evidence of ancient earthquakes, bacterial remains and cycles of sediment to identify fine-scale stratigraphic patterns for a large section of Maysvillian rocks. The work reveals previously unrecorded widespread features.

Presenter: Thomas J. Schramm, University of Cincinnati

Co-Authors: Carlton E. Brett, University of Cincinnati
Benjamin F. Dattilo, Indiana University Purdue University Fort Wayne

As we use more water, it's critical to know how water is exchanged between rivers and creeks and the underlying aquifers. Such aquifers are the sole source of drinking water for 1.6 million people in southwest Ohio. A better understanding of this exchange helps us understand the impact of surface water quality on the quality of groundwater pumped from public water supply wells. UC graduate student Matthew Nemecek has measured variations in surface-water and groundwater flows for Paint Creek in South-central Ohio. His method can track the path and velocity of water traveling through the streambed with great accuracy, and will generate data when other methods cannot, for instance, during flooding.

Presenter: Matthew Nemecek, University of Cincinnati

Co-Author: David Nash, University of Cincinnati

The color of fossil shells can tell a lot about how these animals became fossils, according to UC graduate student Sarah Kolbe. She examined more than 1,000 specimens of fossilized brachiopods and – after accounting for multiple characteristics – found that shell color is strongly related to shell condition. Dark gray and black shells were more degraded, a sign that they had spent more time exposed on the sea floor before ultimate burial.

Presenter: Sarah E. Kolbe, University of Cincinnati

Co-Authors: James J. Zambito IV, University of Cincinnati
Julia Linnaea Wise, University of Cincinnati
Carlton E. Brett, University of Cincinnati
Ryan D. Wilson, Indiana University

Many of the fossils on prominent museum display were found in Lagerstätten – deposits of exceptional preservation. In Paleozoic rocks, such Lagerstätten are often associated with strata that exhibit alternating dark gray shales and limestones with many concretions – spherical or ovoid mineralized deposits. UC geologist Carlton E. Brett, working with colleagues suggests that these concretionary limestones are only partially explained by local events like mudflows. The nature of preservation suggests that larger factors, such as a general rise or fall in sea level or widespread erosion, plays a role. These larger cycles may even be tied to global environmental changes.

Presenter: Carlton E. Brett, University of Cincinnati

Co-Authors: Brenda R. Hunda, Cincinnati Museum Center
Patrick McLaughlin, Wisconsin Geological & Natural History Survey
Donald D. Wilson, Paleontological Research Institution

The rate at which different types of crystals form in volcanic rocks can tell a lot about these igneous minerals. UC undergraduate student Adam Leu, working with UC geologist Attila Kilinc has tested a new way to measure the growth rate of clinopyroxene crystals in basalts formed from the Kilauea volcano. Tracking the distribution of crystal sizes, Leu found a growth rate slightly higher than previously published data.

Presenter: Adam R. Leu, University of Cincinnati

Co-Author: Attila Kilinc, University of Cincinnati

Perched nearly 20 feet above modern sea level, an ancient coral reef on Curaçao provides evidence about the environment of 125,000 years ago. This reef formed during the last period between worldwide glaciation, and UC graduate student Tanya Del Valle has studied it extensively. Despite popular perceptions that corals cannot prosper when sea surface temperatures warm, the Curaçao reef flourished throughout a time marked by warm seas, oceanic acidification, and rising sea levels.

Presenter: Tanya Del Valle, University of Cincinnati

Co-Author: David L. Meyer, University of Cincinnati

When volcanoes erupt, they project more than lava. Liquid streams of mud and ash flow down the volcano. These flows harden into masses of sediment called lahars. In an annual field trip, the UC geology department sampled lahars associated with three volcanoes in the Cascade Range and determined that the chemical composition of a lahar can pinpoint the volcano from which it flowed. This is helpful when a valley surrounded by several volcanoes contains multiple lahars. Jones' reports on the department's work and his study of individual magnetite grains, both of which demonstrate that Mt. Rainier has a very different chemical "fingerprint" than Mt. St. Helens or Mt. Hood.

Presenter: Matthew L. Jones, University of Cincinnati

Co-Authors: Julia Linnea Wise, University of Cincinnati
Gianna L. Evans, University of Cincinnati
Nadeesha Koralegedara, University of Cincinnati
Mike E. Lees, University of Cincinnati
Adam R. Leu, University of Cincinnati
Brian J. Vonderhaar, University of Cincinnati
Barry J. Maynard, University of Cincinnati
Warren D. Huff, University of Cincinnati

The bedrock of northeastern Spain and southern France reveals a geologic jigsaw puzzle created out of ancient turmoil as continents fragmented, collided, and reformed. UC geologist Craig Dietsch and colleagues have helped illuminate a chapter of this complex tale by dating single crystals contained in the reworked igneous rocks of this region. These refined dates, ranging between about 490 and 450 million years ago, provide new insights into ancient mountain building, even in areas where melted source rocks do not appear at the surface.

Presenter: Craig Dietsch, University of Cincinnati

Co-Authors: F.J. Martinez, Universitat Autonoma de Barcelona
A. Iriondo, Universidad Nacional Autonoma de Mexico
J.N. Aleinikoff, U.S. Geological Survey
J.-J. Peucat, Universite de Rennes 1
J. Cires, Institut Geologic de Catalunya