Can Rapid Magnetic Reversals Cause a Mass Extinction?
A study by Dr. Joseph Meert — Professor in the Department of Geological Sciences — and his colleagues suggests an unstable magnetic field may provide an explanation for major evolutionary changes at the end of the Ediacaran Period (542Ma). Read more about their study in a recent article featured in Science Magazine, “Hyperactive magnetic field may have led to one of Earth’s major mass extinctions.” The original research article is currently in press in Gondwana Research — “Organisms with the ability to escape UV radiation would be favored in such an environment.”
Meert, J.G., Bazhenov, M.L., Levashova, N.M., Landing E., Rapid changes in magnetic field polarity during the Late Ediacaran: Linking the Cambrian Evolutionary Radiation and increased UV-B radiation, Gondwana Research, doi://10.1016/j.gr.01.001
Those with UF Gatorlink access can read the in press article here.
Paul Mueller honored at Geological Society of America Meeting
Paul Mueller honored with a special session at the Geological Society of America Meeting in Seattle.
A special session in celebrating of the career contributions of Professor Paul Mueller was a feature of the Geological Society of America Annual Meeting in Seattle in October. The session included talks and posters centered on the topic of the origin and evolution of the continental crust.
Paul A. Mueller has made career-long contributions to the study of the genesis and evolution of continental crust. Paul is highly regarded by his peers and the international geochemical research community in general and has remained at the forefront of geochemical and isotopic research through his field and laboratory investigations as well as his continued development of advanced analytical methods and instrumentation for Earth sciences. He is one of the leading experts on the use of Multi-Collector Inductively Coupled Plasma Mass Spectrometers (MC-ICP-MS) for measuring radiogenic isotopes. His research has focused on the use of major and trace element geochemistry, and the radiometric systems of U-Pb, Rb-Sr, Hf-Lu, and Sm-Nd in order to improve our understanding of the tectonic and geochemical evolution of the continents. He has been a principal player in identifying some of the oldest rock units in North America and striving to document their origins and significance in terms of the formation Earth’s early crust and the onset of plate tectonics. His research has addressed Archean geology of the Wyoming Province, remobilization of this crust in the Paleoproterozoic Great Falls Tectonic Zone, detrital zircon geochronology of the Mesoproterozoic Belt and Uinta Basins, and Phanerozoic history of the assembly of the Appalachian Orogen. Paul has been a generous scientific collaborator, offering his experience, insights, and use of his laboratory and analytical facilities to colleagues and students for over 40 years.
Yucatan Field Course
It was a busy first week for students attending the UF in Merida (Yucatan, Mexico) Program. After arriving in Merida on the evening of June 17, students met on Monday (June 19) at the Centro Institucional de Lenguas, where they study Spanish.
On Wednesday, they headed for the town of Izamal, where they visited a technical university, interacted with local students, reaped the benefits of the culinary arts program, and encountered some of the gaily decorated horses and carriages in the main square (Photos 3-5).
On Friday, it was off to the organic farm of Dr. Juan Jimenez, where students learned about cultivating dragon fruit, a native climbing cactus that blooms for one night only. It is know locally by its Maya name, pitaya. The UF students also instructed a couple of students from the University of Yucatan on details of the “Gator Chomp”.
Then it was on to the town of Dzitya, where local artisans work with tropical hardwoods and local limestone. Although they use power tools today, they used to rely on more traditional tools to work wood, like the foot-operated lathe.
Next, it was off to the archaeological site of Dzibilchaltun, where the group visited the “Temple of the Seven Dolls” and saw some of the local fauna, such as the ubiquitous “black iguana.” Much as today, the ancient Maya “mined” the local rock to create their infrastructure, such as buildings and roads. As you look around Williamson Hall, note that so much of what you see ultimately came from the Earth (walls, windows, desks, light fixtures, tiles, bathroom sinks and toilets, etc.). Everyone was pleased to have the opportunity to take a dip in Cenote Xlakah, a sinkhole where the underlying aquifer is exposed.
The next day, it was off to the west coast, and the town of Celestun. Students toured the long coastal lagoon via boat, stopping at the “ruins” of an old village previously involved in salt production. Heavy rains made it necessary to wade along parts of the inundated old road. The lagoon is bounded by a barrier peninsula and rimmed by mangroves (4 species). The very productive coastal lagoon system is a source of aquatic resources (e.g. crabs) , and is home to a large population of flamingoes.
At Valdiocera Spring, which discharges into the lagoon, we had the good fortune to see a young tiger heron.
Using Noise to Monitor Permafrost
UF Geological Sciences PhD student Stephanie James has been advancing new methods to use seismic noise to monitor seasonal changes in depth to ice in Alaskan sediments. With co-authors from Sandia National Laboratory and UF, she recently published a paper “Improved moving window cross-spectral analysis for resolving large temporal seismic velocity changes in permafrost” in Geophysical Research Letters. This paper was selected as a recent “Editor’s Highlight”.
Stephanie James completed her PhD in May and received a National Science Foundation Postdoctoral Fellowship to continue her research in this field. She will be collaborating with researchers at the US Geological Survey in Colorado.
GrAINFluxes – Greenland Atmospheric Isotopic and Nutrient Fluxes
A study aimed at developing a holistic understanding of weathering across forelands of retreating ice sheets.
Following the last glacial maximum about 20,000 yrs ago, ice sheets retreated from much of North America and Eurasia, leaving the Greenland Ice Sheet (GrIS) as the largest ice sheet in the northern hemisphere. Chemical weathering of finely ground sediments exposed during the retreat of the ice sheets alters atmospheric CO2concentrations as well as nutrient and isotopic fluxes to the ocean. The nutrient fluxes are likely to stimulate ocean productivity, further impacting atmospheric CO2, while the isotopic fluxes may produce a history of ice sheet dynamics that is preserved in marine sediments.
Most previous studies of weathering in the vicinity of the GrIS have focused on proglacialwatersheds that receive dilute but high volumes of glacial meltwater from the top and underneath the ice sheet. In contrast, deglacialwatersheds that are no longer physically connected to the ice sheet and instead are sourced only by annual precipitation and permafrost melt have received little attention. Yet, preliminary work from our group and others suggests deglacial watersheds may be equally or more important than proglacial watersheds for oceanic and atmospheric fluxes.
The Greenland Research Project at UF addresses the question of how mineral weathering reactions impact atmospheric CO2 and oceanic nutrient and isotope fluxes across proglacial and deglacial watersheds of western Greenland. Results of the project have the potential to change our understanding of global CO2, nutrient, and isotope cycling in response to ice sheet collapse. This understanding should inform predictions of future responses to global warming and ice sheet retreat and provide a context to interpret past high latitude ice sheet retreat and climate change based on marine isotope records.