Home Original page

Platinum-group elements link the end-Triassic mass extinction and the Central Atlantic Magmatic Province - PubMed

Platinum-group elements link the end-Triassic mass extinction and the Central Atlantic Magmatic Province

Christian Tegner et al. Sci Rep. .

Abstract

Elevated concentrations of iridium (Ir) and other platinum-group elements (PGE) have been reported in both terrestrial and marine sediments associated with the end-Triassic mass extinction (ETE) c. 201.5 million years ago. The source of the PGEs has been attributed to condensed vapor and melt from an extraterrestrial impactor or to volcanism. Here we report new PGE data for volcanic rocks of the Central Atlantic Magmatic Province (CAMP) in Morocco and show that their Pd/Ir, Pt/Ir and Pt/Rh ratios are similar to marine and terrestrial sediments at the ETE, and very different from potential impactors. Hence, we propose the PGEs provide a new temporal correlation of CAMP volcanism to the ETE, corroborating the view that mass extinctions may be caused by volcanism.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1

Late Triassic paleogeographic map showing the distribution of land (Pangaea supercontinent) and sea c. 200 million years ago. Also shown are: (i) the original extent of c. 201 million year old lava flows and intrusions of the Central Atlantic Magmatic Province (CAMP); (ii) the locations of a marine (Kurusu, Japan) and a continental (Fundy and Newark basins, USA) sedimentary succession of the end-Triassic mass extinction (ETE) with reported iridium (Ir) or full platinum-group element (PGE) concentrations (white stars); (iii) the location of the CAMP volcanics studied for PGEs in Morocco (grey star). The paleogeographic map is modified from ref. with location of CAMP from ref. and the locations of ETE sections with Ir and/or PGE anomalies from refs. ,,,,,.

Figure 2
Figure 2

Correlation of Ir, Pt, and negative δ13Corg carbon isotope excursions (CIE) in continental sediments and CAMP lavas in the Fundy Basin and Morocco, and in marine sediments from Japan and Austria. Data from refs. ,,,,,,,,,,. There is also a report of Ir concentrations in the Newark basin (not shown) that is very similar to Ir variations in the Fundy basin. The end-Triassic extinction interval (ETE) is located between the uppermost occurence of ammonoid Choristoceras marshi (marked a) and the lowermost occurence of ammonoid Psiloceras spelae tirolicum (marked b) and giving name to the CIE’s. The thicknesses of the measured sections are shown with vertical arrows.

Figure 3
Figure 3

Pd/Ir vs Pt/Ir (a) and Pd/Ir vs Pt/Rh (b) for volcanic rocks of of this study for the Central Atlantic Magmatic Province (CAMP) in Morocco (see Methods). Also shown are compositions of: (i) sediments that coincide with the end-Triassic mass extinction (ETE) in the continental section of the Fundy basin (Passaic formation); a deep-marine section from Kurusu, Japan; (ii) CI and ordinary chondrite,; (iii) a field for sediments from the impact layer at the Cretaceous-Paleogene boundary (K/Pg) (field encompassing 106 analyses covering world-wide locations); (iv) a field for published compositions of the basalts of the Deccan Traps– and (v) fields for iron meteorite impactors–. The published data for the CAMP basalts and ETE sediments are listed in supplementary dataset 2. We have filtered the dataset by Goderis et al. to avoid two sections very close to the Chicxulub impact crater, two sections with anomalous Pt values, and three samples where replicate analyses of Ir deviated by more than 100%.

References

    1. Blackburn T, et al. Zircon U-Pb Geochronology Links the End-Triassic Extinction with the Central Atlantic Magmatic Province. Sci. 2013;340(941):945. - PubMed
    1. Lindström S. Palynofloral patterns of terrestrial ecosystem change during the end-Triassic event – a review. Geol. Mag. 2016;153(1):29.
    1. Mcghee GR, Jr, Clapham ME, Sheehan PM, Bottjer DJ, Droser ML. A new ecological-severity ranking of major Phanerozoic biodiversity crises. Palaeogeogr. Palaeoclim. Palaeoecol. 2013;370:260–270. doi: 10.1016/j.palaeo.2012.12.019. - DOI
    1. Stanley SM. An Analysis of the History of Marine Animal Diversity. Paleobiology. 2007;33:1–55.
    1. Davies JH, et al. End-Triassic mass extinction started by intrusive CAMP activity. Nat. Commun. 2017;8(15596):8. - PMC - PubMed

Publication types