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![Estimated atmospheric carbon dioxide levels during the Permian, shown as parts per million by volume ( μ L · L − 1 ) and relative to pre-industrial levels (PIL: 280 μ L · L − 1 ), against a background of low (blue) and warm (red) global temperatures. Adapted from Montañez et al. [36] for the Cisuralian, and from Royer [41] for the later Permian. Note that there are considerable uncertainties in these estimates, which are based on modelling and proxy data, but they indicate a general warming, caused by increasing atmospheric CO 2 levels, throughout much of the Permian.](profile/Marc-Reichow/publication/225378751/figure/fig5/AS:302801654697991@1449204948997/Estimated-atmospheric-carbon-dioxide-levels-during-the-Permian-shown-as-parts-per.png)
Estimated atmospheric carbon dioxide levels during the Permian, shown as parts per million by volume ( μ L · L − 1 ) and relative to pre-industrial levels (PIL: 280 μ L · L − 1 ), against a background of low (blue) and warm (red) global temperatures. Adapted from Montañez et al. [36] for the Cisuralian, and from Royer [41] for the later Permian. Note that there are considerable uncertainties in these estimates, which are based on modelling and proxy data, but they indicate a general warming, caused by increasing atmospheric CO 2 levels, throughout much of the Permian.
Source publication
The association between the Siberian Traps, the largest continental flood basalt province, and the largest-known mass extinction
event at the end of the Permian period, has been strengthened by recently- published high-precision 40Ar/39Ar dates from widespread localities across the Siberian province[1]. We argue that the impact of the volcanism was...
Contexts in source publication
Context 1
... the 50 million years of the Permian Period, the Earth's climate had progressively warmed, albeit with evidence for strong global climate oscillations on at least Ma time scales [36] . The Period began with ice-house conditions, similar in extent to the Quaternary glaciations, followed by general warming interrupted by periods of abrupt cooling ( Figure 6). Overall, the Permian period appears to have been char- acterised by increasing global temperatures, almost cer- tainly as a result of build-up of atmospheric CO 2 . ...
Context 2
... the Permian period appears to have been char- acterised by increasing global temperatures, almost cer- tainly as a result of build-up of atmospheric CO 2 . Proxy determinations (for example from compositions of pa- laeosols and leaf stomatal densities) and modelling sug- gest that atmospheric pCO 2 varied from concentrations similar to pre-industrial levels (PIL; 280 μL·L −1 by volume) in the Early Permian, to as much as 10×PIL during the late Permian [36][37][38][39][40][41] (Figure 6). These data should be used with caution, because the applied tech- niques have inherently large error bars. ...
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Citations
... The Siberian eruptions are closely linked with the extinction in time (Renne et al., 1995;Kamo et al., 2003;Burgess et al., 2014;Burgess and Bowring, 2015;Burgess et al., 2017). Input of erosols, CO 2 , CH 4 , and possibly SO 2 to the atmosphere from the Siberian eruptions (Ganino and Arndt, 2009;Saunders and Reichow, 2009;Svensen et al., 2009;Brand et al., 2012;Payne and Clapham, 2012) is proposed to have initiated a "volcanic winter" (Rampino et al., 1988;Saunders and Reichow, 2009) that manifested itself in a range of subsidiary mechanisms. Volcanic aerosol input to the atmosphere may be linked with lethally hot atmospheric temperatures (Sun et al., 2012), with increasing seawater temperature , with marine anoxia (Wignall and Twitchett, 1996;Meyer and Kump, 2008;Jenkyns, 2010), and with acidification of seawater (Hinojosa et al., 2012;Clarkson et al., 2015), all of which could contribute to extinction in the oceans. ...
... The Siberian eruptions are closely linked with the extinction in time (Renne et al., 1995;Kamo et al., 2003;Burgess et al., 2014;Burgess and Bowring, 2015;Burgess et al., 2017). Input of erosols, CO 2 , CH 4 , and possibly SO 2 to the atmosphere from the Siberian eruptions (Ganino and Arndt, 2009;Saunders and Reichow, 2009;Svensen et al., 2009;Brand et al., 2012;Payne and Clapham, 2012) is proposed to have initiated a "volcanic winter" (Rampino et al., 1988;Saunders and Reichow, 2009) that manifested itself in a range of subsidiary mechanisms. Volcanic aerosol input to the atmosphere may be linked with lethally hot atmospheric temperatures (Sun et al., 2012), with increasing seawater temperature , with marine anoxia (Wignall and Twitchett, 1996;Meyer and Kump, 2008;Jenkyns, 2010), and with acidification of seawater (Hinojosa et al., 2012;Clarkson et al., 2015), all of which could contribute to extinction in the oceans. ...
We report extensive major and trace element data for the Permian-Triassic boundary (PTB) at Meishan, China. Analyses of 64 samples from a 2.5 m section span the last 75 kyr of the Permian and the first 335 kyr of the Triassic, from beds 24 to 34. We also report data for 20 acetic acid extracts that characterize the carbonate fraction. Whole rock major element data reflect the change of lithology from carbonate in the Permian to mudstone and marl in the Triassic, indicate an increase of siliciclastic input and MgO in and above the extinction interval (beds 24f-28), and silica diagenesis in carbonates below the extinction horizon. Above bed 27, enrichment factors calculated with respect to Al and Post-Archean Australian Shale (PAAS) are ∼1 for most trace elements, confirming that siliciclastic input dominates trace element distributions in the Triassic. Within the extinction interval, beds 24f and 26 show increases in As, Mo, U and some transition metals. V, Cr, Co, Ni, Cu, Zn, Pb, and Ba are variably enriched, particularly in bed 26. Below the extinction interval, the top of bed 24d shows enrichment of V, Cr, Co, Ni, Cu, Zn, Pb, and Ba in a zone of diagenetic silicification. Trace elements thus reflect siliciclastic input, diagenetic redistribution, and responses to redox conditions. Trace element patterns suggest either a change in provenance of the detrital component, or a change in the proportion of mechanical to chemical weathering that is coincident with the beginning of the extinction in bed 24f. Ba, Zr, and Zn behave anomalously. Ba shows little variation, despite changes in biological activity and redox conditions. The enrichment factor for Zr is variable in the carbonates below bed 24f, suggesting diagenetic Zr mobility. Zn shows a sharp drop in the extinction horizon, suggesting that its distribution was related to phytoplankton productivity. Rare earth element content is controlled by the siliciclastic fraction, and carbonate extracts show middle rare earth enrichment due to diagenesis. Ce and Eu anomalies are not reliable indicators of the redox environment at Meishan.
... The presence of Glossopteris leaves in assemblages dominated by gangamopterid leaf patterns in the final deglaciation interval at 307.7 AE 3.1 Ma (Kasimovian-Moscovian) as well as at the beginning of the first coal-prone interval in the southern Paraná Basin at ca. 298 Ma could be linked, besides to the paleogeography and paleoclimate, to the change in the composition of atmospheric gases in the Gzhelian-Asselian during a stage of lower atmospheric CO 2 content (Saunders and Reichow 2009). ...
... The acme of glossopterids in the southern Paraná Basin occurred during the second coal-prone interval (Faxinal Coalfield) at ca. 285 Ma, currently corresponding to the Artinskian (Cohen et al. 2013(Cohen et al. , updated 2019. The expressive size and abundance of the leaves occurred in a time interval characterized by the sudden and significant decrease in atmospheric CO 2 content (Saunders and Reichow 2009), ratifying the hypothesis of Schwendemann (2018). The adaptation to consistently cold, humid mire habitat under cold temperate, strongly seasonal climates has been considered as the main driver of the glossopterid expansion throughout the Gondwana (Bomfleur et al. 2018). ...
... The abrupt change in the pattern of the Glossopteris leaves at ca. 279 Ma (Kungurian after Cohen et al. 2013Cohen et al. , updated 2019 from restrict lacustrine environments could be attributed to the general warm climatic conditions during the Permian (Saunders and Reichow 2009). This assemblage could represent differentiated stocks adapted to warm Mediterranean-like climates under high CO 2 atmospheric levels. ...
We summarize here the glossopterid record for the late Paleozoic of southernmost Paraná Basin from the Kazimovian–Gzhelian through the Roadian, a time interval spanning ca. 30 Ma. Isolated and clustered leaves are the dominant fossils; reproductive organs, conductive tissues (Agathoxylon-type wood), and Vertebraria roots were less frequently described. The material is mostly preserved as impressions, very rarely as petrifactions or compressions. The oldest leaf patterns within the studied interval show the dominance of the Gangamopteris over Glossopteris during the final stages of deglaciation (307.7 + - 3.1 Ma) and the increasing dominance of Glossopteris during the early Permian peat-deposition cold temperate interval (295.8 + - 3.1 – 304.0 + - 5.6 to 285.42 + 1.2/ - 2.1 Ma), when the glossopterids reached their acme under low CO2 paleoatmospheric levels. The conservative morphography of the leaves in almost all the studied intervals contrasts with distinct patterns of ovuliferous structures related to the genera Arberia, Ottokaria, and Plumsteadia. The persistence of Glossopteris as a component of floristic associations in the Kungurian and Roadian after the disappearance of environmental and climatic conditions favorable to the development of extensive peatlands during the Asselian–Artinskian interval attests to the remarkable adaptative capacity of these plants.
... Because a substantial portion of the Siberian Traps is covered by thick sedimentary sequences or was removed by erosion, an accurate extent and volume is difficult to estimate. A conservative "working estimate" Saunders & Reichow, 2009) suggested 5 × 10 6 km 2 and 3 × 10 6 km 3 for the size and volume, respectively, whereas Ivanov (2007) estimated these numbers to be higher as around 7 × 10 6 km 2 and 4 × 10 6 km 3 . Stratigraphic subdivisions of the Siberian Traps volcanic sequence were summarized in Ivanov et al. (2013), which correlated four main regions with different stratigraphic units: Putorana, Noril'sk, Maymecha-Kotuy, and Nizhnyaya Tunguska. ...
... One hypothesis is that massive and short-lived basaltic volcanism of the Siberian Traps outgassed vast amounts of water, carbon dioxide, sulphur dioxide, hydrogen sulphide, together with particulates enriched in nickel and other metals into the atmosphere (Saunders and Reichow, 2009), and caused contact metamorphism of organic carbon-rich sediments to further inject these and other materials, like Ni and Hg, into the atmosphere and ultimately oceans (Retallack ...
The Bálvány North Permian-Triassic boundary sediments were deposited on a carbonate platform in the tropical part of the western PaleoTethys ocean. The overall elemental geochemistry of the detailed two-metre-thick section across the boundary that we studied shows that the clastic content of the sediments came from dominantly silica-rich continental sources though with some more silica-poor inputs in the uppermost Permian and lowest Triassic limestones as shown by Ni/Al and Nb/Ta ratios. These inputs bracket, but do not coincide with, the main extinctions and associated C, O and S changes. Increased aridity at the Permian-Triassic boundary with increased wind abrasion of suitable Ti-bearing heavy minerals accounts for both the high Ti/Al and Ti/Zr ratios. Various geochemical redox proxies suggest mainly oxic depositional conditions, with episodes of anoxia, but with little systematic variation across the Permian–Triassic extinction boundary. The lack of consistent element geochemical changes across the Permian-Triassic boundary occur not only in adjacent shallower-water marine sections, and in other marine sections along the SW Tethys margin such as the Salt Range sections in Pakistan, but also in deeper shelf and oceanic sections, and in non- marine African and European continental sediments. In the absence of significant changes in physical environments, chemical changes in the atmosphere and oceans, reflected in various isotopic changes, drove the Permian–Triassic extinctions.
... The end-Permian extinction (EPE), ~252 Ma (Burgess et al., 2014;Baresel et al., 2017), was the largest biological crisis in Earth's history, with the extinction of more than 90% of marine species (e.g., Raup, 1979;Erwin, 1994;Alroy et al., 2008;Stanley, 2016). The emission of the Siberian continental flood basalts is currently considered as the main trigger for the crisis, and the associated release of aerosols and/or CO 2 and their feedbacks on oceanic and terrestrial systems may have intensified its environmental and ecological stresses (e.g., Campbell et al., 1992;Renne et al., 1995;Reichow et al., 2009;Saunders and Reichow, 2009). The Triassic was one of the most significant intervals of time in the history of biodiversity with the stepwise restoration of land and sea ecosystems after the EPE, the rise of the 'modern' fauna and the emergence of modern-type ecosystems (e.g., Sepkoski Jr, 1984;Brusatte et al., 2010;Chen and Benton, 2012;Benton et al., 2013). ...
The Triassic was a turning in the history of biodiversity: bracketed by two major biotic crises, characterised by major biotic, climatic and tectonic events, it saw the transition from the Palaeozoic to the Modern evolutionary faunas. Herein, we propose the first synthetic analysis of the diversity of marine and brackish-water ostracods over the entire Triassic, in the light of palaeoecological, palaeoenvironmental and palaeogeographical contexts. Although general diversity trends witnessed poor ostracod communities during most of the Early Triassic after the end-Permian crisis, the roots of their Triassic taxonomic rediversification were visible as early as the Di- enerian. The explosive diversification of the Spathian and Anisian was followed by a high-diversity plateau up to the brink of the end-Triassic extinction. A “morphological phylogeny” proposes that all Permian and Triassic ornate Bairdiidae derived from Petasobairdia in the Kungurian, with the emergence of the Ceratobairdia-lineage and Abrobairdia-lineage. While they are generally the “poor cousin” of trophic chain analyses, traces of typical Mesozoic drilling predation on Late Triassic ostracods unexpectedly document the increase in the efficiency of predators drilling abilities through the Triassic. Finally, the palaeogeographical distribution of ostracods was very dynamic during this interval, with distinct peri-palaeo-tethyan and peri-neotethyan biotas in the Early Triassic, followed by a dispersal and thus a relative homogenisation from the Anisian onwards.
... The most important being perhaps the Earth's crust cracking giving the start to the so called Continental Drift. The best explanation up to this moment is that a broad phenomenon took place in a very large area in Siberia with a big lava flow, today known as "Siberian Traps" (BENTON et al, 2003;SAUNDERS, 2009). Together with this lava flow a huge release of noxious gases took place causing this big extinction. ...
... This event would also have expelled such tremendous amounts of noxious gases into the atmosphere, with consequences in the oceans, practically making life almost impossible in the whole planet. Only some forms of life were capable of surviving the resulting harsh conditions (SAUNDERS et al, 2009). ...
... On the contrary, the evidence suggests some kind of phenomena from within the planet. In particular, this is probably by all the facts presented the cause of the Permian extinction (SIMONELLI, 2006;SHEN et al, 2011;BENTON et al, 2003;SAUNDERS, 2009 years). Such regularity suggests some kind of "Nature clock". ...
It is well known that about 250 million years ago a huge catastrophe took place in our planet, with effects so big that about 95 % of the species disappeared in the process including sea animals. This event is called “the Permian extinction”. Other effects are also apparently connected to this event. This kind of event would require an extremely huge amount of energy. Since there is no evidence for an asteroid impact, the energy source should be searched inside the planet. Most importantly, it should show an energy source capable of producing such huge phenomenon. The aim of this paper is to propose a model to explain this extinction event and to show that there is evidence that this is a phenomenon that apparently happened several times not only in our planet but also in other Solar System bodies.
... Over the last three decades several hypotheses have been proposed to explain the PTME, including the eruption of the Siberian Traps and Emeishan Traps (Campbell et al., 1992;Renne et al., 1995;Bowring et al., 1998;Chung et al., 1998;Courtillot, 1999;Jin et al., 2000;Wignall, 2001;Lo et al., 2002;Kamo et al., 2003;Racki and Wignall, 2005;Reichow et al., 2009;Saunders and Reichow, 2009;Grasby et al., 2011;Konstantinov et al., 2014;Shen et al., 2019), and a bolide impact (Kaiho et al., 2001;Becker et al., 2001Becker et al., , 2004Basu et al., 2003). However, the evidence for a bolid impact has been criticized (Isozaki, 2001;Erwin, 2003;Koeberl et al., 2002Koeberl et al., , 2004Farley et al., 2005;Xie et al., 2007) and considered both unnecessary and inadequate to explain the biotic crisis Tohver et al., 2012Tohver et al., , 2013Tohver et al., , 2018. ...
The Permian-Triassic mass extinction (PTME, ca. 252 Mya) was one of the most severe biotic crises of the Phanerozoic, eliminating > 90% of marine and terrestrial species. This was followed by a long period of recovery in the Early and Middle Triassic which revolutionised the structure of both marine and terrestrial ecosystems, triggering the new ecosystem structure of the Mesozoic and Cenozoic. Entire new clades emerged after the mass extinction, including decapods and marine reptiles in the oceans and new tetrapods on land. In both marine and terrestrial ecosystems, the recovery is interpreted as stepwise and slow, from a combination of continuing environmental perturbations and complex multilevel interaction between species in the new environments as ecosystems reconstructed themselves. Here, we present a review of Early Triassic terrestrial tetrapod faunas, geological formations and outcrops around the world, and provide a semi-quantitative analysis of a data set of Early Triassic terrestrial tetrapods. We identify a marked regionalisation of Early Triassic terrestrial tetrapods, with faunas varying in both taxonomic composition and relative abundance according to palaeolatitudinal belt. We reject the alleged uniformity of faunas around Pangaea suggested in the literature as a result of the hothouse climate. In addition, we can restrict the-tetrapod gap‖ of terrestrial life in the Early Triassic to palaeolatitudes between 15°N and about 31°S, in contrast to the earlier suggestion of total absence of tetrapod taxa between 30°N and 40°S. There was fairly strong provincialism following the PTME, according to cluster analysis of a taxon presence matrix, entirely consistent with Early Triassic palaeobiogeography. Unexpectedly, the overall pattern for Early Triassic terrestrial tetrapod faunas largely reflects that of the Late Permian, suggesting that the recovery faunas in the Early Triassic retained some kind of imprint of tetrapod distributions according to palaeogeography and palaeoclimate, despite the near-total extinction of life through the PTME.
... The broad temporal correlation between large igneous provinces (LIPs) and mass extinctions (e.g., Rampino and Stothers, 1988;Wignall, 2001;Courtillot and Renne, 2003;Ganino and Arndt, 2009;Bond and Wignall, 2014;Bond and Grasby, 2017;Ernst and Youbi, 2017) has often been invoked to explain catastrophic biodiversity decline in Earth history, most notably as in the associated events of the Siberian Traps magmatism and the end-Permian mass extinction (EPME) (Renne and Basu, 1991;Renne et al., 1995;Reichow et al., 2009;Saunders and Reichow, 2009;Svensen et al., 2009;Algeo et al., 2011;Svensen et al., 2018;Shen et al., 2019a;Wang et al., 2019). However, significant improvements in high-precision U-Pb geochronology from the Meishan GSSP (Global Stratotype Section and Point) section suggested that the maximum duration of abrupt biodiversity decline around the Permian-Triassic boundary (PTB) (Beds 25-28; i.e., maximum extinction interval) was only 61 ± 48 kyr (thousand years) (Burgess et al., 2014). ...
... The Siberian Traps magmatism represents one of the most voluminous continental flood basalt (CFB) events in the Phanerozoic Ernst, 2014;Ernst and Youbi, 2017). A conservative estimate Saunders and Reichow, 2009) suggested 5 × 10 6 km 2 and 3 × 10 6 km 3 for the size and volume, respectively, whereas Ivanov (2007) estimated these two criteria could be higher as about 7 × 10 6 km 2 and 4 × 10 6 km 3 . In either case, the Siberian Traps can be classified as major LIP (i.e., with a size in the range of 1-10 × 10 6 km 3 ), among the ranks of CAMP (Central Atlantic Magmatic Province) and Karoo-Ferrar LIPs (Ernst, 2014). ...
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.
... Earth system processes such as those reflected by the Phanerozoic marine fossil record, as well as ocean 87 Sr/ 86 Sr and δ 34 S sulfate records have been recognized to display ~62 Myr and/or ~140 Myr cyclicities (Rhode & Muller, 2005;Prokoph et al, 2004aProkoph et al, ,b, 2008. The temporal coincidence between LIPs, ocean chemistry, biodiversity, climate, and major extinctions has been recognized by many workers (Caldeira & Rampino, 1993, Wignall, 2001Courtillot & Renne, 2003;Vaughan, 2007;Isozaki, 2009;Saunders & Reichow, 2009, Melott et al, 2012Sobolev et al, 2011), although much work remains before clear cause-effect relationships are understood. A recent timeseries study by Prokoph et al. (2012) demonstrated correlations between LIPs and ocean chemistry showing a shift from a 64.5 Myr to a weaker ~28-35 Myr LIP cyclicity during the Jurassic with decreased ocean anoxia and increased marine biodiversity during the last ~135 Myr. ...
This chapter summarizes geochronologic and other data for major Phanerozoic Large Igneous Provinces (LIPs), Oceanic Anoxic Events (OAEs) and organic-rich petroleum source rocks. It also evaluates the models that support or refute genetic links between the three groups. The evidence appears to favor genetic links between the three groups, however, additional high precision age and geochemical data are needed to validate several events. Furthermore, the chapter provides insights into the importance of LIPs in hydrocarbon exploration.
Plain Language Summary
During the last five hundred million years the Earth has experienced over a dozen periods each lasting about one million years when extremely massive eruptions of basalt magma erupted on the continents and in ocean basins; these are called Large Igneous Provinces (LIPs). Nearly every one of these LIP events coincided with and contributed to Earth System processes that caused periods when ocean waters experienced extremely low oxygen levels allowing preservation of organic-rich sediments on the seafloor with anomalous stable Carbon isotope ratios; the organic matter would have decomposed under higher oxygen levels. Organic-rich sediments are a key element that eventually results in the formation of buried oil and gas deposits, so understanding when they were deposited in the rock record and where they are most concentrated around the world increase the success of those exploring for oil and gas resources.
... Several scenarios have been proposed as possible causes for the most dramatic demise of life, including extensive Siberian Trap volcanism (e.g., Saunders and Reichow 2009;Svensen et al. 2009) acting as a trigger mechanism for many cascading, devastating environmental events such as rapid temperature changes (Joachimski et al. 2012;Schobben et al. 2014), marine anoxia (e.g., Algeo et al 2011a,b;Brennecka et al. 2011), photic zone euxinia with poisonous H 2 S (e.g., Kump et al. 2005;Riccardi et al. 2006Riccardi et al. , 2007Grice et al. 2007, Meyer et al. 2008, strong terrestrial weathering (Algeo and Twitchet 2010;, and enhanced carbon dioxide concentration (hypercapnia) together with related ocean acidification (e.g., Knoll et al. 1996Knoll et al. , 2007Fraiser and Bottjer 2007) and abrupt blooms of methane-producing microbes (Renne et al. 1995;Berner 2002;Rothman et al. 2014). The synergistic effects of global warming (enhanced ocean uptake of CO 2 with climate driven enhanced vertical water column stratification and subsequent seawater deoxygenation) are referred to as the 'deadly trio' (Bijma et al. 2013). ...
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.
