Duration and Intensity of End-Permian Marine Anoxia

Pimentel-Galvan, Michael
Lau, Kimberly V.
Maher, Katharine
Mukerji, Tapan
Lehrmann, Daniel J.
Altıner, Demir
Payne, Jonathan L.
Ocean anoxia was an important kill mechanism in the end-Permian mass extinction and uranium isotope data are among the most powerful tools for quantifying the global extent and duration of ocean deoxygenation due to the dependence of uranium isotope fractionation on bottom-water redox conditions. Although coherent stratigraphic variation in uranium isotope ratios (delta U-238) and uranium concentrations ([U]) indicative of prolonged deoxygenation beginning coincident with the extinction is well established, the precise extent of anoxia and associated uncertainty have yet to be quantified. Uncertainty arises from both noise in the data and imprecise knowledge of key parameters within the uranium cycle. In this study, we use the Monte Carlo method to explore a range of scenarios and their implications for the uranium cycle across the Permian-Triassic boundary and through the first 1.7 million years of the Triassic. We then compare model predictions against measured data using principal component analysis to identify model runs and associated parameter values most compatible with trends in the observed data. The best-fitting models indicate a pronounced increase in the extent of seafloor anoxia across the Permian/Triassic transition, reaching 18% of the seafloor (95% CI: [11%, 47%]), lasting anywhere from 20 kyr to 1.2 Myr. There is an inverse relationship between the extent and duration of anoxia in the set of best-fitting models. This initial pulse of pronounced anoxia is followed by a prolonged aftermath, which continues through the remainder of the study interval, of less extensive, yet still expanded, anoxia covering 7.8% of the seafloor (95% CI: [1.6%, 48.9%]). Both expanded and protracted anoxia are required to fit existing data, with no indication of full re-oxygenation during the study interval.


HOROWITZ, CJ; YILMAZ, O (1994-06-01)
The parity violating (PV) nucleon self-energy in nuclear matter is calculated in a relativistic Hartree-Fock approximation. Omega meson contributions are enhanced 63% by relativistic effects. However, the total PV self-energy is dominated by pi and rho contributions, which are relatively insensitive to relativistic effects. These results are used to estimate the 2dr5/2 to 2f5/2 PV matrix element in Pb-207.
Environmental isotopes and noble gases in the deep aquifer system of Kazan Trona Ore Field, Ankara, central Turkey and links to paleoclimate
ARSLAN, Sebnem; Yazıcıgil, Hasan; Stute, Martin; Schlosser, Peter (2013-03-01)
Environmental isotopes and noble gases in groundwater samples from the Kazan Trona Ore Field are studied to establish the temperature change between the Holocene and the late Pleistocene. Noble gas temperatures (NGTs) presented in this study add an important facet to the global paleotemperature map in the region between Europe and North Africa. The groundwater system under investigation consists of three different aquifers named shallow, middle and deep in which delta O-18 and delta H-2 vary from -8.10 part...
Inorganic antimony speciation using tungsten coil atom trap and hydride generation atomic absorption spectrometry
Akay, Pınar; Ataman, Osman Yavuz; Department of Chemistry (2010)
Antimony is a toxic element which is mostly found in two oxidation states (III and V) in environmental, biological and geological samples. Antimony may form various inorganic and organic compounds that exhibit differences in analytical behavior, toxicity and mobility; inorganic compounds of antimony are more toxic than organic forms and toxicity of Sb(III) has been shown to be 10 times higher than that of Sb(V). Therefore selective determination of Sb(III) and Sb(V) is required in environmental and biologic...
Nanoalumina-supported rhodium(0) nanoparticles as catalyst in hydrogen generation from the methanolysis of ammonia borane
Ozhava, Derya; Özkar, Saim (2017-10-01)
Rhodium(0) nanoparticles were in situ formed from the reduction of rhodium(II) octanoate and supported on the surface of nanoalumina yielding Rh(0)/nanoAl(2)O(3) which is highly active catalyst in hydrogen generation from the methanolysis of ammonia borane at room temperature. The kinetics of nanoparticle formation can be followed just by monitoring the volume of hydrogen gas evolved from the methanolysis of ammonia borane. The evaluation of the kinetic data gives valuable insights to the slow, continuous n...
BUYUKMUMCU, Z; ERTEN, HN; ARAS, NK (Springer Science and Business Media LLC, 1994-06-01)
Extensive experimental and evaluated yield data are now available for the fragments in low energy nuclear fission. Using these data we re-examined the influence of even nuclear numbers and closed shells on the mass and charge distribution in low energy fission. We used WAHL's Zp model and Ap model. We also examined the effects of Z = 50, N = 82 and possibly N = 88 shells. A new method was developed based on two Gaussian curves for the even and odd products. The EOZ and EON values calculated are based on the...
Citation Formats
M. Pimentel-Galvan et al., “Duration and Intensity of End-Permian Marine Anoxia,” GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, vol. 23, no. 1, pp. 0–0, 2022, Accessed: 00, 2022. [Online]. Available: https://hdl.handle.net/11511/95973.