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Paratirolites kittli Stoyanow, 1910, lateral and dorsal views of MB.C.25210, Ali Bashi N, ¡ 2.65 m. Scale bar D 5 mm.
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The Changhsingian (Late Permian), 4 to 5 m thick Paratirolites Limestone has yielded diverse ammonoid assemblages composed of the genera Neoaganides, Pseudogastrioceras, Dzhulfites, Paratirolites, Julfotirolites, Alibashites, Abichites, Stoyanowites and Arasella. The succession of ammonoid species allows for a subdivision of the rock unit into eigh...
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... Diagnosis. Fifty-four Paratirolites specimens with a conch (Aras Valley, reaching Ali 190 Bashi mm N, dm. Ali Subadult Bashi 4). stage with rounded trapezoidal, weakly to moderately depressed whorl cross section (ww/wh D Diagnosis. Paratirolites with a conch reaching 190 mm dm. Subadult stage with rounded trapezoidal, weakly to moderately depressed whorl cross section (ww/wh D 1.30 1.60) and rounded venter; 10 12 very coarse ventrolateral nodes per volution. Adult stage with strongly trapezoidal and weakly depressed whorl cross section (ww/wh D 1.00 À 1.30), flattened tectiform venter and subangular ventrolateral shoulder; weak ventrolateral nodes. Prongs of the external lobe usually multiply serrated; altogether 12 À 21 notches of the E, A and L lobes. Description. Specimen MB.C.25210 (Ali Bashi N, ¡ 2.65 m) is a more or less complete specimen with 140 mm conch diameter. Its body chamber is strongly weathered but the last two volutions of the phragmocone are rather well preserved (Fig. 20). The conch is thinly discoidal and subevolute in the last volution (ww/dm D 0.40; uw/dm D 0.42) and shows a weakly depressed trapezoidal whorl cross section (ww/wh D 1.12) with flattened diverging flanks, a subangular ventrolateral shoulder and a broadly rounded venter. A similar whorl cross section can also be seen in the subadult stage at about 60 mm conch diameter. Particularly the penultimate volution (up to 60 mm dm) displays prominent conical ventrolateral nodes (10 per volution); these nodes become weaker and more densely spaced on the last preserved volution. Specimen MB.C.25217 (Ali Bashi N, ¡ 3.35 m) is another rather complete specimen with 132 mm conch diameter; it also has a strongly corroded body chamber. The conch is thinly discoidal and subevolute in the last volution (ww/dm D 0.42; uw/dm D 0.43) and possesses ...
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Citations
... The conodont-based (Kozur, 1980;Taraz et al., 1981;Sweet and Mei, 1999a, b;Gallet et al., 2000;Partoazar, 2002;Kozur, 2004Kozur, , 2005Kozur, , 2007Henderson et al., 2008;Richoz et al., 2010;Shen and Mei, 2010;Ghaderi et al., 2014a;Isaa et al., 2016;Gliwa et al., 2020), the brachiopod-based (Stepanov et al., 1969;Teichert et al., 1973;Taraz et al., 1981;Ghaderi et al., 2014b;Garbelli et al., 2014;Viaretti et al., 2021), the ammonoidbased (Stepanov et al., 1969;Teichert et al., 1973;Taraz et al., 1981;Ghaderi et al., 2014a;Korn et al., 2016) and the foraminifera based (Altiner et al., 1980;Okimura and Ishii, 1981;Kotlyar et al., 1984Kotlyar et al., , 1989Leven, 1975Leven, , 1998Vachard, 2003, 2005;Kobayashi and Ishii, 2003) biostratigraphic dating in Lopingian Julfa and Abadeh sections provided an opportunity to assemble complete and precise biozonations and follow the detailed faunal diversity changes throughout the Lopingian and after the Permian/Triassic boundary (PT-B). Moreover, the well-exposed Permian and Triassic sediments in Iran have been extensively studied in terms of carbon isotope changes with specific focus on the mass extinction (Baud et al., 1989;Korte et al., 2004Korte et al., , 2010Heydari et al., 2000Heydari et al., , 2003Richoz, 2006;Horacek et al., 2007;Richoz et al., 2010;Shen et al., 2013). ...
... These limestones are mainly composed of bioturbated sponge spicule ostracod wackestone, red burrowed bioclastic wackestone, bioturbated bioclastic intraclastic packstone with abundant ostracods and sponge spicules and some crinoids. Ammonoids are the main and almost unique macrofossils in these limestones but toward the top of the limestones they become rare and have been redescribed recently by Korn et al. (2016) who proposed 8 ammonoid zones. The topmost part of the Paratirolites Limestone is characterized by sponge packstone with sponge fibers as the main constituent. ...
... The co-occurrence of the keratose sponge fabric with thrombolite facies continues from earliest Griesbachian to Dienerian (Luo and Reitner, 2014;Friesenbichler et al., 2018;Heindel et al., 2018;Baud et al., 2021) is a post-extinction feature. On the other hand, the transition of the Paratirolites Limestone to the "Boundary Clay" represents a carbonate factory shutdown and a complete takeover by small-size ostracods, sponges, later crinoids, along with new conodonts and ammonoids (Ghaderi et al., 2014a;Korn et al., 2016Korn et al., , 2021aKorn et al., , 2021b indicative of a major environmental change. The start of this change is confirmed by discontinuous decrease of ammonoid species indicative of extinction at the top of the Paratirolites Limestone (Korn et al., , 2021a(Korn et al., , 2021b and a characteristic ostracod turnover with pandemic species across PTB (Mette, 2008(Mette, , 2010 in Zal section which has been considered as the result of the end-Permian mass extinction. ...
The end-Permian mass extinction, the greatest biotic crisis through the Phanerozoic, caused a severe loss of marine organisms in terms of abundance and diversity. Knowing sea level fluctuations, environmental conditions and the sequence stratigraphic architecture of the Upper Permian deposits will enable us to reconstruct events before the mass extinction and across the Permian/Triassic boundary in a regional and global context. The Upper Permian deposits are examined in well-known sections in Julfa, NW Iran and Abadeh in SW Iran using microfacies analyses, depositional environment interpretation and sequence stratigraphic framework. Detailed petrographic examination and microfacies analyses show third- and fourth-order cycles both in Wuchiapingian and Changhsingian deep-water distally deposited strata of Julfa and Abadeh sections. Considering Iranian tectonics during Permian through Triassic time, there was rifting accompanied by drift and subsequent subsidence. Tectonics was a main factor that influenced the depositional environment and sequence stratigraphic framework in the study areas. According to previous studies, since subsidence increased in a North to SW direction during Middle Permian through Triassic time, this effect is seen in lithologic characteristics of the Wuchiapingian with more mid-ramp settings in Julfa Beds in Julfa area, compared to the more outer-ramp settings of the Unit 6 of the Hambast Formation in Abadeh area. Tectonic subsidence influence was also responsible for creating the fourth-order cycles within third-order cycles despite the absence of common glacial events to create high-frequency cycles in Iran during the Lopingian. The Lopingian successive deepening in Iran caused the faunal changes which is evident in decreasing trend of body size and biodiversity in brachiopods and ammonoids and also marks the beginning of the transgressive system tracts during this time interval.
... According to their results, the Permian-Triassic strata in the area consist of the Gnishik Formation (bedded limestone), the Khachik Formation (bedded limestone with abundant occurrence of chart nodules), the Julfa Formation (limestone and shale), the Ali Bashi Formation (shale with thin intercalations of limestone and Paratirolites limestone in its uppermost part), and the Elikah Formation (limestone, shale, and massive to thick bedded dolostone in its uppermost part) in ascending order. Considering previous age determinations based on ammonoids (Stepanov et al., 1969;Ghaderi, et al., 2014b;Korn et al., 2015), bivalves (Stepanov et al., 1969), brachiopods (Stepanov et al., 1969;Ghaderi, et al., 2014a), conodonts (Sweet and Mei, 1999;Partoazar, 2002;Kozur, 2004Kozur, , 2005Kozur, , 2007Henderson et al., 2008;Shen and Mei, 2010;Ghaderi, et al., 2014b), foraminifers (Stepanov et al., 1969;Altiner et al., 1980;Ghaderi, et al., 2014a), nautiloids and rugose corals (Iljina, 1965;Flügel, 1971;Ezaki, 1991), the most probable ages for each formation are as follows: Gnishik Roadian? to Wordian (lower middle? to middle middle Permian); Khachik Capitanian (upper middle Permian); Julfa Wuchiapingian (lower upper Permian); Ali Bashi Changhsingian (upper upper Permian); Elikah Induan (lower Lower Triassic). Paleogeographically, the Julfa area was situated in a low latitude area during the middle Permian to Early Triassic time (e.g., Muttoni et al., 2009). ...
To provide basic information on the End-Permian Extinction of tabulate corals, we examined their taxonomic characters and stratigraphic distributions using the material from the Permian-Tri-assic boundary section at Kuh-e-Ali Bashi of the Julfa area, Northwest Iran. The results are as follows: pyrgiid auloporid Cladochonus sp. indet. from the Roadian? to Wordian (lower middle? to middle middle Permian) Gnishik and the Capitanian (upper middle Permian) Khachik formations; favositid Suther-landia khachikensis sp. nov. and micheliniid Protomichelinia favositoides from the Khachik Formation; micheliniid Julfamichelinia allata from the Wuchiapingian (lower upper Permian) Julfa Formation; and micheliniid Michelinia vesiculosa from the Changhsingian (upper upper Permian) Ali Bashi Formation. Julfamichelinia is a new genus proposed herein. In this stratigraphic section, auloporid and favositid corals disappeared near the Capitanian/Wuchiapingian transition. The latest appearance of the only surviving micheliniid is approximately 4 m below the Permian-Triassic boundary.
... Klug et al., 2005;Riedel, 1916;Urlichs, 2006). This does not only apply to Triassic species; already late Permian representatives of the order Ceratitida show septal crowding, together with simultaneous attenuation of sculpture, as a rather reliable mature modification (Korn et al., 2016c). Only the combination of several mature modifications permits to identify maturity in incomplete specimens and the calculation of the maximum conch size (Kiessling et al., 2018). ...
... The representatives of the Tornoceratina are suitable objects for investigating possible correlations between chamber length and the course of the suture line for the following reasons: many representatives of the suborder possess a very similar discoidal conch with a closed umbilicus. In the course of their evolutionary history, many forms retained the conservative conch morphology, while the suture line acquired greater complexity with increasing numbers of lobes and saddles (Korn et al., 2016a(Korn et al., , 2016b(Korn et al., , 2016c. However, there is no clear trend in the morphological evolution from tornoceratids with simple suture lines (Gundolficeras) to those with more complex suture lines (e.g. ...
Septal crowding is widely known as a sign of maturity in conchs of ammonoids and nautiloids. However, reduced septal spacing may also occur as a consequence of adverse ecological conditions. Here, we address the question how septal spacing varied through ontogeny in representatives of some of the major clades of Devonian and Carboniferous ammonoids. We found that the degree of ontogenetic variation is similar between clades and that variation is only weakly linked with conch form. The results show that septal crowding alone is insufficient to identify adulthood in ammonoids; intermediate septal crowding is a common phenomenon and occurs in various growth stages. Changes in septal distances during ontogeny were, in addition to adulthood of the individuals, a passive reaction likely caused by fluctuating environmental conditions.
... Intensive investigations, however, are often hampered by the low number of regions in which fossil-rich sedimentary successions are exposed, both in the marine and the terrestrial realm. Sections that represent the deeper shelf and contain ammonoid assemblages, for instance, are known from only few regions worldwide, such as the Transcaucasus/NW Iranian region (e.g., Stoyanow 1910;Shevyrev 1965Shevyrev , 1968Stepanov et al. 1969;Teichert et al. 1973;Kotlyar et al. 1983;Zakharov 1992;Ghaderi et al. 2014;Korn et al. 2016Korn et al. , 2019Korn & Ghaderi 2019) and South China (e.g., Zhao et al. 1978;Zheng 1981;Liang 1983;Yang 1987;Yang & Yang 1992). For this reason, any new occurrence of latest Permian ammonoids bears the potential for a signifi cant contribution to the knowledge of this fossil group. ...
... N, 52.44305° E; Fig. 8): the section is located 50 m southsoutheast of the C section on the eastern side of the same gorge. The conspicuous discrepancy in the putative ammonoid succession between the Hambast Range and other regions such as NW Iran (e.g., Ghaderi et al. 2014;Korn et al. 2016Korn et al. , 2019Kiessling et al. 2018) and Baghuk Mountain (this paper) is surprising. According to current knowledge, all Late Permian sections between Shahreza and the Hambast Range are very similar in their lithology; signifi cant changes in thickness and lithology are not known. ...
... All of the sections at Baghuk Mountain show a very similar lithological succession (Fig. 3), and hence correlation between them can easily be done with laterally continuous beds. The interval studied here comprises of the upper part of the Hambast Formation, of which the top four metres are an equivalent of the Paratirolites Limestone of Transcaucasia and NW Iran (e.g., Ghaderi et al. 2014;Leda et al. 2014;Korn et al. 2016;Kiessling et al. 2018). In contrast to the NW Iranian sections, the Late Permian succession at Baghuk Mountain is almost entirely composed of carbonates; a shale equivalent of the Zal Member is missing in Central Iran. ...
The Changhsingian (Late Permian) Hambast Formation of sections at Baghuk Mountain
(Central Iran) has yielded diverse ammonoid assemblages composed of the genera Pseudogastrioceras, Shevyrevites, Arasella, Dzhulfi tes, Paratirolites, Clivotirolites gen. nov., Esfahanites gen. nov., Alibashites, Lutites gen. nov., Abichites and Stoyanowites. The succession of ammonoid species allows for a subdivision of the rock unit into biozones, which largely correlate with the occurrences in northwestern Iran. Three new genera, Clivotirolites Korn & Hairapetian gen. nov., Esfahanites Korn & Hairapetian gen. nov. and Lutites Korn & Hairapetian gen. nov., as well as 19 new species are described: Shevyrevites corrugatus Korn & Hairapetian sp. nov., Arasella falcata Korn & Hairapetian sp. nov., Dzhulfi tes brevisellatus Korn & Hairapetian sp. nov., Paratirolites rubens Korn & Hairapetian sp. nov., Paratirolites lanceolobatus Korn & Hairapetian sp. nov., Paratirolites robustus Korn & Hairapetian sp. nov., Paratirolites baghukensis Korn & Hairapetian sp. nov., Paratirolites aduncus Korn & Hairapetian sp. nov., Clivotirolites decoratus Korn & Hairapetian gen. et sp. nov., Clivotirolites petilus Korn & Hairapetian gen. et sp. nov., Esfahanites armatus Korn & Hairapetian gen. et sp. nov., Lutites paucis Korn & Hairapetian gen. et sp. nov., Lutites lyriformis Korn & Hairapetian gen. et sp. nov., Lutites profundus Korn & Hairapetian gen. et sp. nov., Lutites alius Korn & Hairapetian gen. et sp. nov., Lutites plicatus Korn & Hairapetian gen. et sp. nov., Abichites ovalis Korn & Hairapetian sp. nov., Abichites infi rmus Korn & Hairapetian sp. nov. and Stoyanowites parallelus Korn & Hairapetian sp. nov. The material described here is, together with the material from NW Iran, the most diverse assemblage known from the interval before the end-Permian mass extinction.
... It is obvious that the ammonoid succession at Baghuk Mountain closely resembles the succession in Transcaucasia and NW Iran (Ruzhencev and Shevyrev, 1965;Shevyrev, 1965;Ghaderi et al., 2014;Korn et al., 2016. In ascending order, seven major assemblages can be separated, of which the first six are of Late Permian age: ...
Permian–Triassic boundary sections at Baghuk Mountain (Central
Iran) are investigated with respect to their lithological succession,
biostratigraphy (particularly conodonts, nautiloids and ammonoids) as well
as chemostratigraphy (carbon isotopes). The rock successions consist of the
Late Permian Hambast Formation, the youngest Permian Baghuk Member (new name
for the “Boundary Clay”) and the Early Triassic Claraia beds. Correlation of the
data allows the establishment of a high-resolution stratigraphy based on
conodonts with seven Changhsingian zones. Abundant ammonoids enable the
separation of ammonoid assemblages with the successive Wuchiapingian genera
Prototoceras, Pseudotoceras and Vedioceras, as well as the Changhsingian genera Shevyrevites, Paratirolites, Alibashites, Abichites and Arasella. Griesbachian and
Dienerian ammonoids are usually poorly preserved. Nautiloids occur
predominantly in the Wuchiapingian part of the section with two successive
assemblages dominated by the Liroceratidae and Tainoceratidae, respectively.
Numerous Early Triassic strata contain microbialites of various outer
morphology and microstructure. The carbon isotope curve (δ13Ccarb) shows a continuous late Changhsingian negative excursion
continuing across the Baghuk Member with the lightest values at the base of
the Triassic.
... A total of 8864 original occurrences (one species or higher taxonomic rank occurring at one place) were checked. The taxonomy was revised based on previously published classifications (Zhao et al. 1978;Tozer 1994;Leonova 2002;Bucher 2008, Brühwiler et al. 2012c;Korn et al. 2016;Ware et al. 2018b). The Middle Triassic data were published by Brayard et al. (2015) and used directly in this work without modifications. ...
... Patterns of ammonoid biogeographic distributions were totally different between the late Permian and the Griesbachian, with a dramatic BC increase and a shift from a very simple to a complex DIN. However, the biogeographic distribution of the late Permian ammonoids could be influenced by sampling biases, because most of the late Permian ammonoid assemblages are limited to only two regions, that is, south China and Transcaucasian-northwest Iran (Zhao et al. 1978;Korn et al. 2016). The Griesbachian is a time interval with marked cosmopolitanism of ammonoid assemblages. ...
... Survivors did not show a higher BC than the overall value of the Changhsingian, but they displayed a significant increase in BC during the Griesbachian, thus supporting model 2 for this event. Changhsingian ammonoid assemblages are known from only a few locations, of which only two regions (i.e., south China and Transcaucasian-northwest Iran region) show diverse ammonoid assemblages (Zhao et al. 1978;Korn et al. 2016). However, the ammonoid composition of the two regions is significantly distinct, with only two shared genera (i.e., Pseudogastrioceras and Neoaganides). ...
Cosmopolitanism occurred recurrently during the geologic past, especially after mass extinctions, but the underlying mechanisms remain poorly known. Three theoretical models, not mutually exclusive, can lead to cosmopolitanism: (1) selective extinction in endemic taxa, (2) endemic taxa becoming cosmopolitan after the extinction and (3) an increase in the number of newly originated cosmopolitan taxa after extinction. We analyzed an updated occurrence dataset including 831 middle Permian to Middle Triassic ammonoid genera and used two network methods to distinguish major episodes of ammonoid cosmopolitanism during this time interval. Then, we tested the three proposed models in these case studies. Our results confirm that at least two remarkable cosmopolitanism events occurred after the Permian–Triassic and late Smithian (Early Triassic) extinctions, respectively. Partitioned analyses of survivors and newcomers revealed that the immediate cosmopolitanism event (Griesbachian) after the Permian–Triassic event can be attributed to endemic genera becoming cosmopolitan (model 2) and an increase in the number of newly originated cosmopolitan genera after the extinction (model 3). Late Smithian cosmopolitanism is caused by selective extinction in endemic taxa (model 1) and an increase in the number of newly originated cosmopolitan genera (model 3). We found that the survivors of the Permian–Triassic mass extinction did not show a wider geographic range, suggesting that this mass extinction is nonselective among the biogeographic ranges, while late Smithian survivors exhibit a wide geographic range, indicating selective survivorship among cosmopolitan genera. These successive cosmopolitanism events during severe extinctions are associated with marked environmental upheavals such as rapid climate changes and oceanic anoxic events, suggesting that environmental fluctuations play a significant role in cosmopolitanism.
... Unit 7 (-15.5 to -1.5 m) of the Hambast Formation is mainly composed of reddish thin-bedded nodular limestone containing abundant ammonoids and conodonts. The topmost ~4 m of this unit contains abundant Paratirolites and therefore is usually referred as the "Paratirolites Bed" (Taraz et al., 1981;Ghaderi et al., 2014b;Leda et al., 2014;Korn et al., 2016). The Hambast Formation is overlain by the Elikah Formation, which is easily distinguished from the underlying reddish limestone by its overall dark color, very-thin-bedded coarse limestone (Fig. 2C). ...
Climate warming, probably as a result of massive degassing of greenhouse gases from the Siberian Traps magmatism, has often been acclaimed as a major cause of the end-Permian mass extinction. Indeed, several studies have documented a sudden rise in seawater temperatures during the latest Permian-earliest Triassic, as evidenced by oxygen isotopic records measured on conodont apatite. However, whether such a rapid increase in seawater temperatures occurred before, during, or after the mass extinction remains controversial. Moreover, the pattern of this rise in seawater temperatures and its timing relative to the latest Permian-earliest Triassic carbon cycle disruption, mass extinction, as well as the Siberian Traps magmatism still need to be rigorously examined in various regions. In this study, we present high-resolution oxygen isotopic records of conodont apatite (δ¹⁸Oapatite) from the Upper Permian-lowermost Triassic interval at the Abadeh section, central Iran that are analyzed with in situ secondary ion mass spectrometry (SIMS) method. The δ¹⁸Oapatite results from Abadeh demonstrate a clear pattern consisting of three phases: (1) From the lower Wuchiapingian Clarkina dukouensis Zone to the end-Permian mass extinction horizon, δ¹⁸Oapatite values are relatively stable, fluctuating in the range of 18.28-20.15‰ with an average of 19.44‰. (2) δ¹⁸Oapatite value remains high as 19.26‰ at the mass extinction horizon. Above this horizon, a sudden decrease occurs in the Clarkina hauschkei Zone and reaches a low value of 17.05‰ close to the Permian-Triassic boundary. (3) In the lowermost Triassic, δ¹⁸Oapatite values maintain a low baseline in the range of 16.92-17.39‰ with an average of 17.11‰. Overall, the most dramatic change in δ¹⁸Oapatite values (i.e., a decrease of ~2‰), converting into an abrupt warming of ~10 °C, occurred above the mass extinction horizon and below the Permian-Triassic boundary at Abadeh. The Abadeh δ¹⁸Oapatite record is consistent with previous results documented in South China, Iran, and Armenia in terms of the timing and magnitude of a substantial warming, and therefore represents a global signature. If applying the high-precision temporal framework established in the well-dated Meishan GSSP section to Abadeh, the abrupt warming of ~10 °C took only a maximum duration of ~37 kyr (thousand years). By projecting the carbon cycle change, temperature rise, mass extinction at the Abadeh and Meishan sections, and the temporal evolution of the Siberian Traps magmatism onto a unified timescale, the temporal correlation strongly suggests that the switch from dominantly extrusive eruptions to widespread sill intrusions is probably the most annihilating phase of the Siberian Traps magmatism, and is temporally consistent with the end-Permian mass extinction.
... d -EDX spectrum of a celestine crystal in c. Kozur (2005Kozur ( , 2007, Shen and Mei (2010) and Ghaderi et al. (2014) with the ammonoid stratigraphy by Shevyrev (1965) and Korn et al. (2016). Triassic (Tr.), Griesbachian (Gr.),Wuchiapingian (Wu.). ...
... Biostratigraphic data (e.g., Kozur 2004Kozur , 2005Kozur , 2007Mette and Mohtat-Aghai 2004;Richoz et al. 2010;Shen and Mei 2010) and chemostratigraphic characteristics (Holser and Magaritz 1987;Baud et al. 1989;Korte et al. 2004a;Korte and Kozur 2005a;Kakuwa and Matsumoto 2006;Richoz 2006;Horacek et al. 2007;Richoz et al. 2010) were published in the last 25 years for the Ali Bashi sections and led to a significantly increased knowledge about these sections. Recently, a revision of brachiopod, conodont and ammonoid stratigraphy from the section near Julfa was done by Ghaderi et al. (2014aGhaderi et al. ( , 2014b and Korn et al. (2016). Schobben et al. (2014Schobben et al. ( , 2015Schobben et al. ( , 2016Schobben et al. ( , 2017 presented the systematics with respect to bulk carbonate carbon, bulk carbonate oxygen, carbonate associated sulphate (CAS), chromium-reducible sulphide (CRS), oxygen isotopes from diagenetically resistant conodont apatite, and oxygen isotopes from low Mg-calcite of well-preserved brachiopods for the Kuh-e-Ali Bashi 1 and Zal sections (both NW Iran) that led to considerable improvement of the geochemical knowledge about these sections. ...
... Miniaturization, often termed Lilliput Effect, has frequently been proposed for various organisms deposited at the PTB (e.g., Metcalfe et al. 2011;Twitchett 2007), and the size reduction was usually observed in the post-extinction interval. Studies by Korn et al. (2016) yielded a different picture, as the reduction of size occurs already below the extinction horizon. For ammonoids, two extinction pulses may exist at Julfa (1.4 and 2.5 m below the Aras Member), whereas only one pulse is evident at Baghuk (2.4 m below the 'Boundary Clay') (Kiessling et al. 2018). ...
Perm/Trias-Grenzprofile in den Regionen von Julfa (NW-Iran) und Abadeh (Zentral-Iran) zeigen eine Abfolge von drei charakteristischen Gesteinseinheiten, (1) den Paratirolites Limestone mit dem end-permischen Massensterbehorizont an seiner Oberkante, (2) den Boundary Clay und (3) die untertriassische Elikah-Formation mit der mit Conodonten definierten Perm/Trias-Grenze an seiner Basis. Die Karbonatmikrofazies zeigt eine Veränderung in den Profilen bei Julfa; innerhalb des Paratirolites Limestone ist eine zunehmende Anzahl von Intraklasten, Fe-Mn-Krusten und biogenen Verkrustungen erkennbar. Die Karbonatproduktion des späten Perms wurde mit der Ablagerung von mikrobiellen Karbonaten an der Basis der Elikah-Formation in Julfa erneuert. Die in den Profilen von Baghuk (Abadeh-Region) vorkommenden Mikrobialite sind vielfältig; es gibt groß-und kleinskalige, arboreszierendende Mikrobialit-Ansammlungen mit auffälliger Morphologie und innerer Struktur. In den Regionen von Julfa (NW-Iran) und Abadeh (Zentral-Iran) deutet eine deutliche und weltweit nachvollziehbare negative Kohlenstoffisotopenexkursion hin. Die rasche Exkursion der Kohlenstoffisotopenexkursion unterhalb des Aussterbehorizonts im obersten Bereich des Paratirolites Limestone wird durch eine stratigraphische Kondensation, die ein Defizit der Karbonatproduktion/Akkumulation und/oder eine schnelle geochemische Veränderung in Richtung Karbonatuntersättigung spiegelt, verstärkt. Dies deutet darauf hin, dass ein länger andauernder Mechanismus, wie die thermische Metamorphose von an organischem Material reicher Sedimente, und/oder verstärkte Verwitterung auf den Kontinenten, die negative Perm/Trias- Kohlenstoffisotopenexkursion verursacht haben könnte. Die Stickstoffisotopenwerte zeigen keinen Trend unterhalb des Aussterbehorizonts, was auf eine Kombination verschiedener Prozesse (Stickstofffixierung und ein Gleichgewichtszustand zwischen Nitratassimilation, Stickstoff-Fixierung und Denitrifikation) hinweist.
... Many studies have been conducted on the significance of isotopic excursions and fossil content in the PTB strata from different localities in Iran, including Shahreza (Korte et al., 2004a(Korte et al., , 2004bKozur, 2007;Heydari et al., 2008;Richoz et al., 2010), Abadeh (Heydari et al., 2000;Korte et al., 2004a;Horacek et al., 2007;Kozur, 2007;Liu et al., 2013), Alborz Mountains (Gaetani et al., 2009;Angiolini et al., 2010;Garbelli et al., 2016), and Julfa (Baud et al., 1989;Korte et al., 2004c;Kakuwa and Matsumoto, 2006;Horacek et al., 2007;Richoz et al., 2010;Ghaderi et al., 2014;Schobben et al., 2015;Korn et al., 2016;Schobben et al., 2016;Kiessling et al., 2018). Several similar studies have been carried out in the Zagros Mountains and the Persian Gulf (Insalaco et al., 2006;Gaillot and Vachard, 2007;Rahimpour-Bonab et al., 2009;Tavakoli et al., 2011;Rafiee et al., 2015;Mazaheri-Johari and Ghasemi-Nejad, 2017). ...
Permian–Triassic boundary (PTB) foraminifers are studied from the upper part of the Dalan Formation and the base of the Kangan Formation in four wells (A, B, E, F) on and near the Qatar Arc, Persian Gulf, Iran. Isotope studies including δ13C and δ18O values from wells B and E and 87Sr/86Sr ratios in wells (B, E, and F) have also been carried out to possibly provide a high-resolution extinction pattern of foraminifers in the PTB interval. The latter has been thoroughly investigated in Iran, Turkey, South China, Vietnam, Slovenia, Carnic Alps and Bükk Mountains, Kashmir, Greenland, and Serbia. The distribution of the last appearance of foraminiferal genera from the PTB interval in all of the wells is very similar featuring a stepwise extinction from 3 to 2 m before the boundary and compares to that observed in some of the sections from elsewhere, i.e., South China, Vietnam, Slovenia, and Serbia. The δ13C value in wells B and E shows a negative shift at the base of a thrombolite unit immediately after the considered PTB, and another negative shift at about 11 m below it in well E. The thrombolite unit is assumed as earliest Triassic, but questionable with no supportive conodonts. The δ18O isotope values in wells B and E demonstrate the same negative upward trend due to dysoxic or anoxic conditions in the end-Permian oceans. The uniform reduction without any sharp incline in the δ18O profile suggests concurrent global warming. The highest 87Sr/86Sr ratio fluctuations in wells B, E, and F coincide with the appearance of thrombolites. Changes in the profiles of carbon, oxygen, and strontium isotopes close to the PTB in wells B, E, and F seem to correspond to lithofacies variations from limestone to dolostone and a reduction in foraminiferal diversity. These changes substantiate a clear perturbation in the marine environmental and global geochemistry elements through the PTB interval. The δ13C, δ18O and 87Sr/86Sr values obtained from the studied wells are comparable to those in other PTB stratigraphic sections in the Paleo-Tethyan region.
... This general scheme of ammonoid stratigraphy can also be applied in the Aras Valley section, but as Ghaderi et al. (2014b) and Korn et al. (2016) have shown, the ammonoids of the Paratirolites Limestone do not represent only one single zone (Paratirolites kittli zone) but a succession of clearly separable units. By contrast, Leonova (2016), in her review on the Permian ammonoid stratigraphy, proposed a much less detailed zonation for the late Permian ammonoid succession. ...
... (1) It neglects the rapid turnover rates of the ammonoid genera and species, as demonstrated by empirical data from the Julfa region (e.g. Kotlyar et al., 1983;Ghaderi et al., 2014b;Korn et al., 2016Korn et al., , 2019a. (2) It accepts the previous assumption by Zhao et al. (1978) that the Transcaucasian genus Paratirolites is stratigraphically older than the south Chinese genera Pleuronodoceras and Rotodiscoceras. ...
... (2) It accepts the previous assumption by Zhao et al. (1978) that the Transcaucasian genus Paratirolites is stratigraphically older than the south Chinese genera Pleuronodoceras and Rotodiscoceras. As Korn et al. (2016) pointed out, such an assumption was probably based on misidentification of specimens from south China as belonging to Paratirolites by Zhao et al. (1978). ...
The Permian–Triassic boundary section in the Aras Valley in NW
Iran is investigated with respect to carbonate microfacies, biostratigraphy
(particularly conodonts, nautiloids, and ammonoids), chemostratigraphy
(carbon isotopes), and environmental setting. Correlation of the data allows
the establishment of a high-resolution stratigraphy based on conodonts (with
four Wuchiapingian, 10 Changhsingian, and three Griesbachian zones),
ammonoids (with nine Changhsingian zones), and carbon isotopes; it forms
the base for the reconstruction of the environmental changes before and
after the end-Permian extinction event at the studied locality. In the Aras
Valley section, there is no evidence for the development of anoxic
conditions, associated with the end-Permian mass extinction.
