The uranium isotope composition of seawater provide insights to how much sediment burial occurs globally in anoxia settings. Therefore, it is desirable to measure uranium isotopes to track the oxygenation state of the oceans through geological time. However, there is currently no geological archive that can reliably record the composition of ancient seawater. Calcitic brachiopods … Read More
Research
Review: Tracing the global ocean oxygenation state with uranium isotopes
May 21, 2020 The stable isotope fractionation of uranium in nature – unrelated to radioactive decay – has led to a profound tool for tracing O2 in the Earth’s oceans from the geological record. Feifei Zhang has gathered many of the leading researchers in the community to provide a summary of how uranium isotopes are … Read More
New paper: The impact of land plant evolution on Earth’s climate and oxygenation state
The colonization of land by plants, fungi and animals has had a profound impact on Earth’s climate and oxygenation state. In a comprehensive review paper, we have summarized the current state of knowledge and compiled available evidence in support that terrestrial life has caused: Atmospheric CO2 decline and climatic cooling (permanent transition) Atmospheric O2 rise … Read More
New GCA paper: Volcanic eruptions triggered repeated marine anoxia and reveal global-scale feedbacks during the Permian-Triassic mass extinction 250 million yeers ago
The largest animal extinction event in recorded history occurred 251 Ma at the Permian-Triassic boundary coinciding with expansive marine anoxia. In a new study, led by postdoc Feifei Zhang, of a greatly expanded dolomite section from the Carnic Alps, Austria, marine anoxia is found to have expanded in two pulses separated by ~100,000 years. Global … Read More
Expansive ocean anoxia during the Late Devonian Hangenberg event
Marine animal extinction events have occurred episodically over the past 550 million years with expansive marine anoxia as the proximate kill mechanism. New evidence from a carbonate section in South China (Long’an) shows that the Late Devonian Hangenberg event should be counted as one such events. Postdoc Feifei Zhang have analyzed uranium isotopes in a … Read More
New study solves 500 million year old animal breathing paradox
Animals breath oxygen, but fossils of some of the earliest animals are found in what appears to be anoxic parts of the oceans. New research, led by Tais W. Dahl in collaboration with researchers from GEUS and Royal Holloway University London, shows that fluctuations in O2 availability at the seafloor allowed benthic animals to invade … Read More
Tais honored as Guest Professor at the China University of Geosciences, Wuhan
On Jan 4, 2019 Vice President Professor Yongsheng Liu of the China University of Geosciences Wuhan (CUG-W) gratulates Tais W. Dahl with the new title. Members of the award ceremony in front of the State Key Laboratory for Geological Processes and Mineral Resources (GPMR). From left: GPMR Secretary Huaqiang Weng, Postdoc Feifei Zhang, Prof. Chao [...]
Research visit from FAU Erlangen Nürnberg
Prof. Axel Munnecke and PhD stud Theresa Nohl are visiting our research group from Nov 12-16. Axel will give an EarthTalk Wednesday Nov 14th at noon.
Nordic Winter Meeting January 2018 – 4 presentations
Our group will give several presentation at the Nordic Winter Meeting at DTU in Lyngby, Denmark Wednesday Jan 10, 2018 10.00-11.00 Student poster presentations Magnus A. R, Harding “Surface analyses of fossil leaves” Julius C. Havsteen “The Silurian Lau event – testing plant weathering as driver for ocean anoxia and animal extinction” Thursday Jan 11, … Read More
New paper in press: Ocean redox conditions between the Neoproterozoic Snowballs
A new paper on the redox conditions in the oceans after the Sturtian and before the Marinoan ‘Snowball’ glaciations is now press in Precambrian Research. Our results suggest that oceans remained largely anoxic after the Sturtian glaciation and that something else triggered oxygenation of the Ediacaran oceans after the Marinoan glaciation. This ‘something’ could be due to the way animals affect the global … Read More
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