Introduction.The study of catastrophic events that affected past marine ecosystems provides us the unique opportunity to establish models which can be applied to ongoing environmental changes and to understand future ...Introduction.The study of catastrophic events that affected past marine ecosystems provides us the unique opportunity to establish models which can be applied to ongoing environmental changes and to understand future evolution of the biotas.The growing interest of the society for the ongoing and potential future environmental changes attests for the value represented by the analysis of past climatic changes.In the case of the Toarcian Oceanic Anoxic Event(T-OAE,Early Jurassic;~182 Ma),a dramatic change of marine ecosystems related to massive extinction has been documented in several areas around the world.The Pliensbachian–Toarcian transition and the T-OAE are two global episodes recording worldwide palaeoenvironmental perturbations(Jenkyns,1988;Jenkyns and Clayton,1997;Hesselbo et al.,2007).The end of the Pliensbachian regression is followed by a transgression occurring in the Early Toarcian(Haq et al.,1987;de Graciansky et al.,1999).This transgression was also coeval with a widespread deposition of black shales(Jenkyns,1988),a global warming(Garcia Joral et al.,2011;Korte and Hesselbo,2011;Suan et al.,2011),and perturbations of the carbon cycle indicated by a negative carbon isotopic excursion(CIE)documented in both marine and terrestrial material(Jenkyns and Clayton,1986;Schouten et al.,2000;Hesselbo et al.,2007;Al-Suwaidi et al.,2010;Caruthers et al.,2011;Izumi et al.,2012;Reolid,2014).展开更多
This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists most...This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists mostly of grey to dark-colored alternating oil shales, marls and mudstones. Ammonite beds are found at the top of the Shuanghu oil shale section, which are principally of early Toarcian age, roughly within the Harplocearas falciferrum Zone. Therefore, the oil shale strata at Shuanghu can be correlated with early Toarcian black shales distributing extensively in the European epicontinental seas that contain the records of an Oceanic Anoxic Event. Sedimentary organic matter of laminated shale anomalously rich in organic carbon across the Shuanghu area is characterized by high organic carbon contents, ranging from 1.8% to 26.1%. The carbon isotope curve displays the δ 13C values of the kerogen (δ 13Ckerogen) fluctuating from –26.22 to –23.53‰ PDB with a positive excursion close to 2.17‰, which, albeit significantly smaller, may also have been associated with other Early Toarcian Oceanic Anoxic Events (OAEs) in Europe. The organic atomic C/N ratios range between 6 and 43, and the curve of C/N ratios is consistent with that of the δ 13Ckerogen values. The biological assemblage, characterized by scarcity of benthic organisms and bloom of calcareous nannofossils (coccoliths), reveals high biological productivity in the surface water and an unfavorable environment for the benthic fauna in the bottom water during the Oceanic Anoxic Event. On the basis of organic geochemistry and characteristics of the biological assemblage, this study suggests that the carbon-isotope excursion is caused by the changes of sea level and productivity, and that the black shale deposition, especially oil shales, is related to the bloom and high productivity of coccoliths.展开更多
The Global Stratotype Section and Point(GSSP)for the base of Toarcian Stage,Lower Jurassic,is placed at the base of micritic limestone bed 15e at Ponta do Trovão(Peniche,Lusitanian Basin,Portugal;coordinates:39&#...The Global Stratotype Section and Point(GSSP)for the base of Toarcian Stage,Lower Jurassic,is placed at the base of micritic limestone bed 15e at Ponta do Trovão(Peniche,Lusitanian Basin,Portugal;coordinates:39°22′15″N,9°23′07″W),80km north of Lisbon,and coincides with the mass occurrence of the ammonite Dactylioceras(Eodactylites).The Pliensbachian/Toarcian boundary(PLB/TOA)is contained in a continuous section forming over 450m of carbonate-rich sediments.Tectonics,syn-sedimentary disturbance,metamorphism or significant diagenesis do not significantly affect this area.At the PLB/TOA,no vertical facies changes,stratigraphical gaps or hiatuses have been recorded.The base of the Toarcian Stage is marked in the bed 15e by the first occurrence of D.(E.)simplex,co-occurring with D.(E.)pseudocommune and D.(E.)polymorphum.The ammonite association of D.(Eodactylites)ssp.and other species e.g.Protogrammoceras(Paltarpites)cf.展开更多
In the present paper we describe the distribution of brachiopods in the proposed Toarcian GSSP(Global Boundary Stratotype Section and Point)at Peniche.We differentiated four assemblages in the stratigraphic interval f...In the present paper we describe the distribution of brachiopods in the proposed Toarcian GSSP(Global Boundary Stratotype Section and Point)at Peniche.We differentiated four assemblages in the stratigraphic interval from the upper Emaciatum Zone of the Pliensbachian to the Levisoni Zone of the Toarcian.Assemblage 1 clearly presents Northwestern European affinities,with many species that are also present in Southern England.展开更多
The Almonacid de la Cuba section,located in the Iberian Range,in central-eastern Spain,contains an outstanding record of the Pliensbachian-Toarcian boundary(Early Jurassic).Four ammonite assemblages,characterized resp...The Almonacid de la Cuba section,located in the Iberian Range,in central-eastern Spain,contains an outstanding record of the Pliensbachian-Toarcian boundary(Early Jurassic).Four ammonite assemblages,characterized respectively by the presence of Pleuroceras,Canavaria,Dactylioceras(Eodactylites)and Dactylio-ceras(Orthodactylites)have been distinguished.展开更多
The Early Toarcian“Oceanic Anoxic Event”(T-OAE)is recorded by marked disruption to both the climate system and marine ecosystems.Here,we present intergraded high-resolution carbon-isotope data(δ^(13)C),bulk geochem...The Early Toarcian“Oceanic Anoxic Event”(T-OAE)is recorded by marked disruption to both the climate system and marine ecosystems.Here,we present intergraded high-resolution carbon-isotope data(δ^(13)C),bulk geochemistry,mineral characterization from an open-ocean setting in the eastern Tethys.With these data,we(1)construct the high-resolution record of the T-OAE from an open-ocean setting in the eastern Tethys;(2)show that the T-OAE in the Sewa succession was marked by coarser-grained deposits associated with high-energy conditions within the otherwise low-energy claystone deposits that likely linked to a globally increased supply of clastic sediments into marginal and deeper marine basin;(3)propose that the low C_(org):P_(total) ratios,in combination with bioturbated structure and depletion or slight enrichment in redox-sensitive trace elements of V,Mo,and U suggest a long-term oxygenation event throughout the T-OAE interval at the Sewa succession,and hence,anoxia may not play a fundamental role during the Toarcian negative CIE in this setting;(4)exhibit that a warming and more humid climate began at the start of the T-OAE,and many episodic changes in sediment provenance throughout the T-OAE interval occurred at this location;and(5)suggest that accumulation of organic-matter sediments during the T-OAE is generally controlled by global climatic changes,but a regional environmental perturbation also might influence the preservation of organic matter.展开更多
The Toarcian Oceanic Anoxic Event(T-OAE,∼183 Ma)is marked in the sedimentary record by a sharp negative carbon isotope excursion,thought to be causally linked to the emplacement of the Karoo-Ferrar Large Igneous Prov...The Toarcian Oceanic Anoxic Event(T-OAE,∼183 Ma)is marked in the sedimentary record by a sharp negative carbon isotope excursion,thought to be causally linked to the emplacement of the Karoo-Ferrar Large Igneous Province and the associated release of^(12)C-enriched carbon.The T-OAE coincided with global climate and environmental changes,as well as biotic events,indicating substantial modifications in ecosystems.Recent studies have focused on the evidence of geological responses to the T-OAE in Early Jurassic terrestrial basins in China,particularly the Sichuan Basin.Nevertheless,debate remains over the identification of this event,owing to inadequate age-constraints of many sections,and a lack of robust correlations of the carbon isotope records.Moreover,the long-term evolution of the terrestrial carbon isotope record through the Early Jurassic,and its correlation to marine records,is still not firmly established.In this paper,we present new carbon isotope analyses of carbonate(δ^(13)C_(carb))from lacustrine carbonates and terrestrial organic matter(δ^(13)C_(org))from bulk rocks within the Ma’anshan and Da’anzhai members of the Ziliujing Formation from the Dacao‘D’(DCD)section in the eastern Sichuan Basin.Palynological-palynofacies analysis reveals a predominance of Classopollis pollen together with marker taxa such as Ischyosporites variegatus,Contignisporites problematicus,in the palynological assemblage,indicating a Pliensbachian–Toarcian age.A negative carbon isotope excursion(NCIE)is recorded in the organic carbon isotope data at the topmost part of the Pliensbachian Ma’anshan Member,which can be correlated to the Pliensbachian–Toarcian Boundary Event.This is followed,in the Toarcian Da’anzhai Member,by a major NCIE recorded in both organic matter and carbonate carbon isotope data which can be correlated to the T-OAE NCIE.A long-term carbon isotope record spanning the Sinemurian to Toarcian in Sichuan terrestrial sediments is also been reconstructed and its correlation with coeval marine records is proposed.A broader review of δ^(13)C data from Chinese terrestrial basins spanning the Pliensbachian–Toarcian highlights a distinct^(13)C-depleted signature in the Sichuan Basin compared to basins at higher latitudes.Changes in latitudinal gradients and organic matters in the lake sediments were likely important factors influencing the amplitudes of the T-OAE NCIE and the carbon isotope values in terrestrial sedimentary records.展开更多
Long-term geological processes are usually described with curves reflecting continuous changes in the characteristic parameters through the geological history, and such curves can be employed directly for recognition ...Long-term geological processes are usually described with curves reflecting continuous changes in the characteristic parameters through the geological history, and such curves can be employed directly for recognition of episodic(relatively long-term) events linked to these changes. The episodic events can be classified into several categories according to their scale(ordinary and anomalous events), "shape"(positive, negative, and neutral events), and relation to long-term trend change(successive, interruptive,facilitative, stabilizing, transformative, increasing, and decreasing). Many types of these events can be defined depending on the combination of the above-mentioned patterns. Of course, spatial rank,duration, and origin can be also considered in description of these events. The proposed classification can be applied to events in some real long-term geological processes, which include global sea-level changes,biodiversity dynamics, lithospheric plate number changes, and palaeoclimate changes. Several case examples prove the usefulness of the classification. It is established that the Early Valanginian(Early Cretaceous) eustatic lowstand(the lowest position of the sea level in the entire Cretaceous) was negative,but ordinary and only interruptive event. In the other case, it becomes clear that the only end-Ordovician and the Permian/Triassic mass extinctions transformed the trends of the biodiversity dynamics(from increase to decrease and from decrease to increase respectively), and the only Cretaceous/Paleogene mass extinction was really anomalous event on the Phanerozoic biodiversity curve. The new palaeontological data are employed to reconstruct the diversity dynamics of brachiopods in Germany(without the Alps) and the Swiss Jura Mountains. The further interpretation of the both diversity curves implies that the Early Toarcian mass extinction affected the regional brachiopod faunas strongly, but this event was only decreasing(biotic radiation continued after it, although "restarted" from the lower point)similarly to the end-Triassic and Cretaceous/Paleogene mass extinctions. The number of lithospheric plates decreased in the Early Cretaceous; however, the previous trend to increase in this number reestablished after the noted event. The Oi-1 glaciation in the very beginning of the Oligocene was anomalous event, but it only stabilized the earlier trend of temperature decline and did not transform it.Further development of the comprehensive classification of geological events is necessary. For instance,it has become clear that the Silurian environmental perturbations and the Cretaceous oceanic anoxic events should be classified as discrete events that differ essentially from episodic events, the latter of which are relevant to continuous changes in geological processes.展开更多
Numerous new records of Ferganiella, Podozamites, and Schidolepium, including a new species, Ferganiella ivantsovii sp. nov., are described from the Early Jurassic(Toarcian) Middle Subformation of the Prisayan Formati...Numerous new records of Ferganiella, Podozamites, and Schidolepium, including a new species, Ferganiella ivantsovii sp. nov., are described from the Early Jurassic(Toarcian) Middle Subformation of the Prisayan Formation from the Euro-Sinian paleofloristic region in the Irkutsk Basin, Eastern Siberia, Russia. An analysis of the paleogeographic distribution of Ferganiella and Podozamites shows that both genera were the most diverse and numerous in the East Asian province of the Euro-Sinian region and in the Northern Chinese province of the Siberian region during the Early and Middle Jurassic. These phytochoria were located in the subtropical and temperate subtropical climate zones, which allows us to consider Ferganiella and Podozamites as thermophilic plants, which are important indicators of the Early Toarcian climatic optimum. Their abundance in the Irkutsk Basin thus may indicate Early Toarcian warming;further abundant Schidolepium cones, which produced Araucariacites pollen, typical for Euro-Sinian flora complement the scenario. Thus, the new finds are the first macrofloristic indicators of the Toarcian climatic optimum in the Irkutsk Basin.展开更多
基金This is a contribution of the IGCP-655 project of the IUGS and UNESCO.
文摘Introduction.The study of catastrophic events that affected past marine ecosystems provides us the unique opportunity to establish models which can be applied to ongoing environmental changes and to understand future evolution of the biotas.The growing interest of the society for the ongoing and potential future environmental changes attests for the value represented by the analysis of past climatic changes.In the case of the Toarcian Oceanic Anoxic Event(T-OAE,Early Jurassic;~182 Ma),a dramatic change of marine ecosystems related to massive extinction has been documented in several areas around the world.The Pliensbachian–Toarcian transition and the T-OAE are two global episodes recording worldwide palaeoenvironmental perturbations(Jenkyns,1988;Jenkyns and Clayton,1997;Hesselbo et al.,2007).The end of the Pliensbachian regression is followed by a transgression occurring in the Early Toarcian(Haq et al.,1987;de Graciansky et al.,1999).This transgression was also coeval with a widespread deposition of black shales(Jenkyns,1988),a global warming(Garcia Joral et al.,2011;Korte and Hesselbo,2011;Suan et al.,2011),and perturbations of the carbon cycle indicated by a negative carbon isotopic excursion(CIE)documented in both marine and terrestrial material(Jenkyns and Clayton,1986;Schouten et al.,2000;Hesselbo et al.,2007;Al-Suwaidi et al.,2010;Caruthers et al.,2011;Izumi et al.,2012;Reolid,2014).
文摘This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists mostly of grey to dark-colored alternating oil shales, marls and mudstones. Ammonite beds are found at the top of the Shuanghu oil shale section, which are principally of early Toarcian age, roughly within the Harplocearas falciferrum Zone. Therefore, the oil shale strata at Shuanghu can be correlated with early Toarcian black shales distributing extensively in the European epicontinental seas that contain the records of an Oceanic Anoxic Event. Sedimentary organic matter of laminated shale anomalously rich in organic carbon across the Shuanghu area is characterized by high organic carbon contents, ranging from 1.8% to 26.1%. The carbon isotope curve displays the δ 13C values of the kerogen (δ 13Ckerogen) fluctuating from –26.22 to –23.53‰ PDB with a positive excursion close to 2.17‰, which, albeit significantly smaller, may also have been associated with other Early Toarcian Oceanic Anoxic Events (OAEs) in Europe. The organic atomic C/N ratios range between 6 and 43, and the curve of C/N ratios is consistent with that of the δ 13Ckerogen values. The biological assemblage, characterized by scarcity of benthic organisms and bloom of calcareous nannofossils (coccoliths), reveals high biological productivity in the surface water and an unfavorable environment for the benthic fauna in the bottom water during the Oceanic Anoxic Event. On the basis of organic geochemistry and characteristics of the biological assemblage, this study suggests that the carbon-isotope excursion is caused by the changes of sea level and productivity, and that the black shale deposition, especially oil shales, is related to the bloom and high productivity of coccoliths.
基金supported by the BIOSCALES Project(POCTI/36438/PAL/2000)coordinated by the Universidade NOVA de Lisboa+1 种基金R.B.Rocha thanks the support of A.F.Soares,J.C.Kullberg,P.S.Caetano and P.H.VerdialFinancial support was provided to L.V.Duarte,S.Pinto and M.C.Cabral by Projects PDCTE/CTA/44907/2002 and PTDC/CTE-GIX/098968/2008.
文摘The Global Stratotype Section and Point(GSSP)for the base of Toarcian Stage,Lower Jurassic,is placed at the base of micritic limestone bed 15e at Ponta do Trovão(Peniche,Lusitanian Basin,Portugal;coordinates:39°22′15″N,9°23′07″W),80km north of Lisbon,and coincides with the mass occurrence of the ammonite Dactylioceras(Eodactylites).The Pliensbachian/Toarcian boundary(PLB/TOA)is contained in a continuous section forming over 450m of carbonate-rich sediments.Tectonics,syn-sedimentary disturbance,metamorphism or significant diagenesis do not significantly affect this area.At the PLB/TOA,no vertical facies changes,stratigraphical gaps or hiatuses have been recorded.The base of the Toarcian Stage is marked in the bed 15e by the first occurrence of D.(E.)simplex,co-occurring with D.(E.)pseudocommune and D.(E.)polymorphum.The ammonite association of D.(Eodactylites)ssp.and other species e.g.Protogrammoceras(Paltarpites)cf.
基金funded by project PTDC/CTE-GIX/098968/2008(FCT-Portugal and COMPETE-FEDER)CGL2011-25894,CGL2011-23947(Ministry of Science and Innovation,Government of Spain).
文摘In the present paper we describe the distribution of brachiopods in the proposed Toarcian GSSP(Global Boundary Stratotype Section and Point)at Peniche.We differentiated four assemblages in the stratigraphic interval from the upper Emaciatum Zone of the Pliensbachian to the Levisoni Zone of the Toarcian.Assemblage 1 clearly presents Northwestern European affinities,with many species that are also present in Southern England.
基金financed by projects CGL2008-01273,CGL2008-02203 and CGL2008-03112/BTE of the Spanish Ministerio de Educación.
文摘The Almonacid de la Cuba section,located in the Iberian Range,in central-eastern Spain,contains an outstanding record of the Pliensbachian-Toarcian boundary(Early Jurassic).Four ammonite assemblages,characterized respectively by the presence of Pleuroceras,Canavaria,Dactylioceras(Eodactylites)and Dactylio-ceras(Orthodactylites)have been distinguished.
基金This work was supported by the National Natural Science Foundation of China(Grant No.91955204)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK080301).
文摘The Early Toarcian“Oceanic Anoxic Event”(T-OAE)is recorded by marked disruption to both the climate system and marine ecosystems.Here,we present intergraded high-resolution carbon-isotope data(δ^(13)C),bulk geochemistry,mineral characterization from an open-ocean setting in the eastern Tethys.With these data,we(1)construct the high-resolution record of the T-OAE from an open-ocean setting in the eastern Tethys;(2)show that the T-OAE in the Sewa succession was marked by coarser-grained deposits associated with high-energy conditions within the otherwise low-energy claystone deposits that likely linked to a globally increased supply of clastic sediments into marginal and deeper marine basin;(3)propose that the low C_(org):P_(total) ratios,in combination with bioturbated structure and depletion or slight enrichment in redox-sensitive trace elements of V,Mo,and U suggest a long-term oxygenation event throughout the T-OAE interval at the Sewa succession,and hence,anoxia may not play a fundamental role during the Toarcian negative CIE in this setting;(4)exhibit that a warming and more humid climate began at the start of the T-OAE,and many episodic changes in sediment provenance throughout the T-OAE interval occurred at this location;and(5)suggest that accumulation of organic-matter sediments during the T-OAE is generally controlled by global climatic changes,but a regional environmental perturbation also might influence the preservation of organic matter.
基金The research of VB is conducted in the scope of the internal research project“WEGETA”at the Croatian Geological Survey,funded by the National Recovery and Resilience Plan 2021-2026 of the European Union-NextGenerationEU,and monitored by the Ministry of Science,Education and Youth of the Republic of Croatia.
文摘The Toarcian Oceanic Anoxic Event(T-OAE,∼183 Ma)is marked in the sedimentary record by a sharp negative carbon isotope excursion,thought to be causally linked to the emplacement of the Karoo-Ferrar Large Igneous Province and the associated release of^(12)C-enriched carbon.The T-OAE coincided with global climate and environmental changes,as well as biotic events,indicating substantial modifications in ecosystems.Recent studies have focused on the evidence of geological responses to the T-OAE in Early Jurassic terrestrial basins in China,particularly the Sichuan Basin.Nevertheless,debate remains over the identification of this event,owing to inadequate age-constraints of many sections,and a lack of robust correlations of the carbon isotope records.Moreover,the long-term evolution of the terrestrial carbon isotope record through the Early Jurassic,and its correlation to marine records,is still not firmly established.In this paper,we present new carbon isotope analyses of carbonate(δ^(13)C_(carb))from lacustrine carbonates and terrestrial organic matter(δ^(13)C_(org))from bulk rocks within the Ma’anshan and Da’anzhai members of the Ziliujing Formation from the Dacao‘D’(DCD)section in the eastern Sichuan Basin.Palynological-palynofacies analysis reveals a predominance of Classopollis pollen together with marker taxa such as Ischyosporites variegatus,Contignisporites problematicus,in the palynological assemblage,indicating a Pliensbachian–Toarcian age.A negative carbon isotope excursion(NCIE)is recorded in the organic carbon isotope data at the topmost part of the Pliensbachian Ma’anshan Member,which can be correlated to the Pliensbachian–Toarcian Boundary Event.This is followed,in the Toarcian Da’anzhai Member,by a major NCIE recorded in both organic matter and carbonate carbon isotope data which can be correlated to the T-OAE NCIE.A long-term carbon isotope record spanning the Sinemurian to Toarcian in Sichuan terrestrial sediments is also been reconstructed and its correlation with coeval marine records is proposed.A broader review of δ^(13)C data from Chinese terrestrial basins spanning the Pliensbachian–Toarcian highlights a distinct^(13)C-depleted signature in the Sichuan Basin compared to basins at higher latitudes.Changes in latitudinal gradients and organic matters in the lake sediments were likely important factors influencing the amplitudes of the T-OAE NCIE and the carbon isotope values in terrestrial sedimentary records.
文摘Long-term geological processes are usually described with curves reflecting continuous changes in the characteristic parameters through the geological history, and such curves can be employed directly for recognition of episodic(relatively long-term) events linked to these changes. The episodic events can be classified into several categories according to their scale(ordinary and anomalous events), "shape"(positive, negative, and neutral events), and relation to long-term trend change(successive, interruptive,facilitative, stabilizing, transformative, increasing, and decreasing). Many types of these events can be defined depending on the combination of the above-mentioned patterns. Of course, spatial rank,duration, and origin can be also considered in description of these events. The proposed classification can be applied to events in some real long-term geological processes, which include global sea-level changes,biodiversity dynamics, lithospheric plate number changes, and palaeoclimate changes. Several case examples prove the usefulness of the classification. It is established that the Early Valanginian(Early Cretaceous) eustatic lowstand(the lowest position of the sea level in the entire Cretaceous) was negative,but ordinary and only interruptive event. In the other case, it becomes clear that the only end-Ordovician and the Permian/Triassic mass extinctions transformed the trends of the biodiversity dynamics(from increase to decrease and from decrease to increase respectively), and the only Cretaceous/Paleogene mass extinction was really anomalous event on the Phanerozoic biodiversity curve. The new palaeontological data are employed to reconstruct the diversity dynamics of brachiopods in Germany(without the Alps) and the Swiss Jura Mountains. The further interpretation of the both diversity curves implies that the Early Toarcian mass extinction affected the regional brachiopod faunas strongly, but this event was only decreasing(biotic radiation continued after it, although "restarted" from the lower point)similarly to the end-Triassic and Cretaceous/Paleogene mass extinctions. The number of lithospheric plates decreased in the Early Cretaceous; however, the previous trend to increase in this number reestablished after the noted event. The Oi-1 glaciation in the very beginning of the Oligocene was anomalous event, but it only stabilized the earlier trend of temperature decline and did not transform it.Further development of the comprehensive classification of geological events is necessary. For instance,it has become clear that the Silurian environmental perturbations and the Cretaceous oceanic anoxic events should be classified as discrete events that differ essentially from episodic events, the latter of which are relevant to continuous changes in geological processes.
文摘Numerous new records of Ferganiella, Podozamites, and Schidolepium, including a new species, Ferganiella ivantsovii sp. nov., are described from the Early Jurassic(Toarcian) Middle Subformation of the Prisayan Formation from the Euro-Sinian paleofloristic region in the Irkutsk Basin, Eastern Siberia, Russia. An analysis of the paleogeographic distribution of Ferganiella and Podozamites shows that both genera were the most diverse and numerous in the East Asian province of the Euro-Sinian region and in the Northern Chinese province of the Siberian region during the Early and Middle Jurassic. These phytochoria were located in the subtropical and temperate subtropical climate zones, which allows us to consider Ferganiella and Podozamites as thermophilic plants, which are important indicators of the Early Toarcian climatic optimum. Their abundance in the Irkutsk Basin thus may indicate Early Toarcian warming;further abundant Schidolepium cones, which produced Araucariacites pollen, typical for Euro-Sinian flora complement the scenario. Thus, the new finds are the first macrofloristic indicators of the Toarcian climatic optimum in the Irkutsk Basin.
