Ben Creisler
Some recent Mesozoic papers that may be of interest:
Free pdf:
Sofie LindstrÃm, Hamed Sanei, Bas van de Schootbrugge, Gunver K. Pedersen, Charles E. Lesher, Christian Tegner, Carmen Heunisch, Karen DybkjÃr and Peter M. Outridge (2019)
Volcanic mercury and mutagenesis in land plants during the end-Triassic mass extinction
Science Advances 5(10): eaaw4018
DOI: 10.1126/sciadv.aaw4018
https://advances.sciencemag.org/content/5/10/eaaw4018During the past 600 million years of Earth history, four of five major extinction events were synchronous with volcanism in large igneous provinces. Despite improved temporal frameworks for these events, the mechanisms causing extinctions remain unclear. Volcanic emissions of greenhouse gases, SO2, and halocarbons are generally considered as major factors in the biotic crises, resulting in global warming, acid deposition, and ozone layer depletion. Here, we show that pulsed elevated concentrations of mercury in marine and terrestrial sediments across the Triassic-Jurassic boundary in southern Scandinavia and northern Germany correlate with intense volcanic activity in the Central Atlantic Magmatic Province. The increased levels of mercury--the most genotoxic element on Earth--also correlate with high occurrences of abnormal fern spores, indicating severe environmental stress and genetic disturbance in the parent plants. We conclude that this offers compelling evidence that emissions of toxic volcanogenic substances contributed to the end-Triassic biotic crisis.
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Free pdf:
Judith Totman Parrish, E. Troy Rasbury, Marjorie A. Chan & Stephen T. Hasiotis (2019)
Earliest Jurassic U-Pb ages from carbonate deposits in the Navajo Sandstone, southeastern Utah, USA.
Geology 47(11): 1015-1019.
doi:
https://doi.org/10.1130/G46338.1Free pdf:
https://pubs.geoscienceworld.org/geology/article-pdf/47/11/1015/4852055/1015.pdfNew uranium-lead (U-Pb) analyses of carbonate deposits in the Navajo Sandstone in southeastern Utah (USA) yielded dates of 200.5 Â 1.5 Ma (earliest Jurassic, Hettangian Age) and 195.0 Â 7.7 Ma (Early Jurassic, Sinemurian Age). These radioisotopic agesâthe first reported from the Navajo erg and the oldest ages reported for this formationâare critical for understanding Colorado Plateau stratigraphy because they demonstrate that initial Navajo Sandstone deposition began just after the Triassic and that the base of the unit is strongly time-transgressive by at least 5.5 m.y.
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Pay-walled papers:
The Jehol Biota represents an important phase in the history of biological evolution on Earth. Two sites with Aptian Jehol Biota, located in western Liaoning Province and in northern Hebei Province, northeastern China, have generated a major debate about the relationships between their fossil-bearing layers, resulting in confusions about their stratigraphic correlation and biogenetic sequence. We have applied carbon isotope analysis of total organic carbon to provide new data relevant to this debate and have re-examined the connection between volcanism and carbon cycle perturbations, with consideration of the paleoenvironmental conditions. The rare earth element data show that the provenances of the Jehol Group in western Liaoning and northern Hebei were similar and derived mainly from the underlying andesite. Constrained by the radiometric age, the Î13Corg curve suggests that the Dadianzi Formation in northern Hebei is comparable to the three lacustrine layers of the Yixian Formation (ranging from the Jianshangou Bed to the Jingangshan Bed) in western Liaoning. These layers are highly correlated with the early Aptian marine sequence in Oceanic Anoxic Event 1a (OAE 1a), implying that a possible teleconnection (possibly related to a large igneous province) existed between oceanic and terrestrial realms. We also propose that the Xiguayuan Formation above the Dadianzi Formation in northern Hebei is equivalent to the Huanghuashan Breccia Bed at the top of the Yixian Formation in western Liaoning. Moreover, the Î13Corg and element geochemical data suggest that the carbon cycle perturbation and the paleolimnological environments were distinctly influenced by the effects of volcanic CO2 during the early Aptian.
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R. M. Joeckel, G. A. Ludvigson, A. MÃller, C. L. Hotton, M. B. Suarez, C. A. Suarez, ÂB. Sames, ÂJ. I. Kirkland and B. Hendrix (2019)
Chronostratigraphy and Terrestrial Palaeoclimatology of BerriasianâHauterivian Strata of the Cedar Mountain Formation, Utah, USA.
Geological Society Special Publications 498: Cretaceous Climate Events and Short-Term Sea-Level Changes (accepted article)
doi:
https://doi.org/10.1144/SP498-2018-133https://sp.lyellcollection.org/content/early/2019/10/16/SP498-2018-133This paper presents breakthroughs in the chronostratigraphy of the heretofore poorly-constrained Yellow Cat Member of the Cedar Mountain Formation, which is an important record of terrestrial environments, ecosystems, and global change in the ancient North American Cordilleran foreland. Zircon populations from ten stratigraphic horizons in the Yellow Cat Member yield youngest single grain ages ranging from 142.5Â2.7 Ma to 133.7Â2.7 Ma (Berriasian-late Valanginian); those from one mudstone palaeosol yield a robust Concordia Age of 136.3Â1.3 (Valanginian). Additionally, a new palynoflora--one of a few to be published from the Cedar Mountain Formation--is assigned to the middle Berriasian to early Hauterivian stages, based on the presence of Foraminisporis wonthaggiensis and Trilobosporites sp. cf. T. canadensis, and the absence of F. asymmetricus, Appendicisporites spp. and angiosperms. Furthermore, these chronostratigraphic data allow us to interpret part of the so-called âWeissert Eventâ C-isotope excursion (Valanginian) in a new C-isotope profile through a palaeosol-bearing alluvial succession in the Yellow Cat Member. This research extends a firm understanding of the formation further back into the Early Cretaceous than was the case previously and sets the stage for future advancements.
Supplementary material at
https://doi.org/10.6084/m9.figshare.c.4697138