Siberian Trap volcanism, global warming and the Permian Triassic mass extinction: New insights from Armenian Permian-Triassic sections: Reply

M.M. Joachimski1,†, A.S. Alekseev2,3, A. Grigoryan4, and Yu. A. Gatovsky2 1GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Schlossgarten 5, 91054 Erlangen, Germany 2Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russian Federation 3Borissiak Paleontological Institute, Russian Academy of Sciences, 123 Profsoyuznaya Street, 117647 Moscow, Russian Federation 4Institute of Geological Sciences, National Academy of Sciences of Armenia, 24a Baghramian Avenue, Yerevan 0019, Armenia

Horacek et al. (2021) commented on our was published by Kozur (1996), and before this, shown lower in sample Z 3, ∼1 m above the top publication arguing that we used an incorrect all forms with a relatively high cusp were as- of the “Boundary Clay.” In the “Boundary clay” biochronology to define the Permian-Triassic signed to H. parvus. H. praeparvus was initially and up to the level of sample Z 3, H. praeparvus (PT) boundary and that this inaccurate defini- established as a subspecies of H. latidentatus, occurs. H. parvus was also illustrated from the tion resulted in an erroneous interpretation of the though in our opinion H. praeparvus has very Kuh-e-Hambast (Abadeh) section (Kozur, 2004, oxygen isotope record in the studied Chanakhchi little in common with this latter species. It dif- plate 1, fig. 5). This specimen comes from sam- (former Sovestashen) section. Their comment fers from H. parvus by a relatively shorter and ple VI 68c, a microbial limestone ∼1.1 m above gives us the opportunity to discuss in depth the wider cusp. The holotype of H. parvus (Kozur, the “Boundary Clay” (Kozur, 2005, Fig. 3), and identification of the PT boundary and to address 1975, plate 1, fig. 22; Kozur et al., 1975, plate 7, represents the lowest occurrence of H. parvus some of the flawed arguments of Horacek et al. fig. 7; Kozur, 1996, plate 2, fig. 7) shows a cusp in the section. Instead, Richoz et al. (2010; p. Horacek et al. argue that Joachimski et al. ∼3 times higher than the next denticle, which 241) claim that the first occurrence of H. parvus (2020) “base their stratigraphy on the conodont is greatly reduced in size. Instead, the cusp of is from “….silty marl containing limestone con- investigation of the Chanakhchi section by the holotype of H. praeparvus (Kozur, 1996, cretions and thin limey beds” (sample 94/264). Grigoryan (1990)….” This statement is incor- plate 2, fig. 2) is only 1.5 time higher than the However, the illustrated specimen of H. parvus rect since conodont biostratigraphy in Joachim- next denticle that is not small. H. Kozur did not (sample 94/264; Richoz et al., 2010, plate 2, fig. ski et al. (2020) is based on a new taxonomic indicate how the height of the denticles should 6) is a fragmentary element with broken tips of study of a total of 90 conodont samples (see be measured, thus, the correct identification of denticles and also a broken and strongly curved “Conodont Biostratigraphy” section and fig. these two very close morphotypes is difficult. cusp, which to our evaluation can neither be at- 6 in Joachimski et al., 2020) with the highest As a consequence, Kozur (2004, p. 56) distin- tributed to H. praeparvus nor to H. parvus. In sampling density of all studies performed so guished some advanced forms of H. praeparvus summary, the first occurrences of H. parvus in far in Chanakhchi. According to this new study, as “transitional to H. parvus.” limestones overlying the “Boundary Clay” in Hindeodus parvus first occurs two meters above Horacek et al. justify their criticism by ar- Iranian sections are consistent with what we ob- the base of the microbial limestones and not at guing that the taxonomic determinations of serve in the Chanakhchi section. the base of the microbial limestones as suggested A. Grigoryan were revised by H. Kozur (in Horacek et al. (2021) argue that the wrong 13 by Horacek et al. (2021). Zakharov et al., 2005). However, Kozur never placement of the PTB is mirrored in the δ Ccarb Horacek et al. claim that Grigoryan (1990) visited Yerevan (Armenia) and thus never stud- record with the minimum in δ13C expected the identified “the firstHindeodus parvus on top ied Grigoryan’s conodont collection. Zakharov upper H. parvus and I. isarcica Zone. The δ13C the basal microbialites.” Again, this statement et al. (2005, p. 141) mention that “we were minimum in the Chanakhchi is registered at is false, since Grigoryan (1990) reported the able to copy some parts of his thesis.” In our the PT boundary and in the H. parvus Zone, in first occurrence of H. parvus from the upper- opinion, it is inadequate to revise taxonomic agreement with Korte and Kozur (2010). How- most reddish marls (“Boundary Clay”) below determinations based on a few specimens of ever, we acknowledge that Horacek et al. might 13 the basal microbialites (see as well figure 1 in the genus Hindeodus illustrated in a photo- have been irritated by the low δ Ccarb values Zhakarov et al., 2005). The apparent discrep- copied thesis. measured in the H. praeparvus Zone. These low ancy between the taxonomic determinations of In most sections studied in Iran, Nakhichevan, values are interpreted as a diagenetic artifact A. Grigoryan (base of the H. parvus Zone in the and Armenia, the typical elements of H. parvus which is underlined by the unusual large scatter 13 topmost “Boundary Clay”) and our determina- occur at various levels in the limestones over- in δ Ccarb of neighboring samples. tions (base of H. parvus Zone 2 m above the base lying the “Boundary Clay” (e.g., Kozur 2004, We agree with Horacek et al. that the PT of the microbial limestones) is explained by the 2005, 2007). For example, Kozur (2004) illus- boundary should be positioned as precisely as fact that in 1990, when Grigoryan’s thesis was trated three rather typical H. parvus specimens possible. However, in our opinion, the avail- completed, Hindeodus praeparvus was not yet (Kozur, 2004, plate 1, figs. 6–8) from sample able biostratigraphic data from the Chanakhchi identified. The first description ofH. praeparvus Z 1 in the Zal 1 section, taken ∼2.3 m above as well as Iranian sections argue for a position the “Boundary clay,” in the upper part of the of the boundary within the overlying microbial H. parvus Zone (Kozur, 2005, fig. 9). The first limestones. Most important, our publication is †[email protected]. ­occurrence of H. parvus (Kozur, 2005, table 5) is focusing on the temperature evolution across

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the PT boundary with the interpretation not Korte, C., and Kozur, H.W., 2010, Carbon-isotope stratigra- Kozur, H., Mostler, H., and Rahimi-Yazd, A., 1975, Be- phy across the Permian-Triassic boundary: a review: iträge zur Mikrofauna permotriadischer Schichtfolgen. ­depending on whether the boundary is placed Journal of Asian Earth Sciences, v. 39, p. 215–235, Teil II: Neue Conodonten aus dem Oberperm und der 2 m higher or lower in the section. https://doi.org/10.1016/j.jseaes.2010.01.005. basalen Trias von Nord- und Zentraliran: Geologisch-­ Kozur, H.W., 1975, Beiträge zur Conodontenfauna des Paläontologische Mitteilungen Innsbruck, v. 5, p. 1–23. Perms: Geologisch-Paläontologische Mitteilungen Richoz, S., Krystyn, L., Baud, A., Brandner, R., Horacek, M., REFERENCES CITED Innsbruck, v. 5, p. 1–44. and Mohtat-Aghai, P., 2010, Permian–Triassic bound- Kozur, H.W., 1996, The conodonts Hindeodus, Isarcicella, and ary interval in Middle East (Iran and N. Oman): pro- Grigoryan, A., 1990, The Conodonts of the Permian-Triassic Sweetohindeodus in the uppermost Permian and lower- gressive environmental change from detailed carbonate boundary in Armenian SSR [unpublished Ph.D. the- most Triassic: Geologia Croatica, v. 49, p. 81–115. carbon isotope marine curve and sedimentary evolution: sis]: Lomonosov Moscow State University, 209 p. (in Kozur, H.W., 2004, Pelagic uppermost Permian and the Journal of Asian Earth Sciences, v. 39, no. 4, p. 236– ­Russian). Permian–Triassic boundary conodonts of Iran, part I: 253, https://doi.org/10.1016/j.jseaes.2009.12.014. Horacek, M., Krystyn, L., and Baud, A., 2021, Siberian Trap taxonomy: Hallesches Jahrbuch für Geowissenschaften Zakharov, Y.D., Biakov, A.S., Baud, A., and Kozur, H., 2005, volcanism, global warming and the Permian-Triassic B, v. 18, Beiheft, p. 39–68. Significance of Caucasian sections for working out mass extinction: New insights from Armenian Perm- Kozur, H.W., 2005, Pelagic uppermost Permian and the carbon-isotope standard for Upper Permian and Lower ian-Triassic sections: Comment: Geological Society Permian–Triassic boundary conodonts of Iran, Part II: Triassic (Induan) and their correlation with the Perm- of America Bulletin, v. 133, https://doi.org/10.1130/ investigated sections and evaluation of the conodont ian of north-eastern Russia: Journal China University of B36099.1. faunas: Hallesches Jahrbuch für Geowissenschaften B, Geosciences, v. 16, p. 141–151. Joachimski, M.M., Alekseev, A.S., Grigoryan, A., and Ga- v. 19, Beiheft, p. 49–86. tovsky, Y.A., 2020, Siberian Trap volcanism, global Kozur, H.W., 2007, Biostratigraphy and event stratigraphy Science Editor: Brad S. Singer in Iran around the Permian-Triassic Boundary (PTB): warming and the Permian-Triassic mass extinction: Manuscript Received 8 June 2021 New insights from Armenian Permian-Triassic sec- implications for the causes of the PTB biotic crisis: Manuscript Accepted 29 June 2021 tions: Geological Society of America Bulletin, v. 132, Global and Planetary Change, v. 55, p. 155–176, https:// p. 427–443, https://doi.org/10.1130/B35108.1. doi​.org/10.1016/j.gloplacha.2006.06.011. Printed in the USA

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