1 Introduction The end-Triassic mass extinction event is one of the five global mass extinctions,and destroyed both the marine and terrestrial biological worlds.Though years the marine endTriassic mass extinction(ETE)...1 Introduction The end-Triassic mass extinction event is one of the five global mass extinctions,and destroyed both the marine and terrestrial biological worlds.Though years the marine endTriassic mass extinction(ETE)event has been widely studied and discussed,and the standard marine Triassic/Jurassic boundary(TJB)(base-Jurassic)has also been determined.However.展开更多
The end-Triassic （also Triassic-Jurassic） mass extinction severely affected life on planet Earth 200 million years ago. Paleoclimate change triggered by the volcanic eruptions of the Central Atlantic Magmatic Provin...The end-Triassic （also Triassic-Jurassic） mass extinction severely affected life on planet Earth 200 million years ago. Paleoclimate change triggered by the volcanic eruptions of the Central Atlantic Magmatic Province （CAMP） caused a great loss of marine biodiversity, among which 96% coral genera were get lost. However, there is precious little detail on the paleoecology and growth forms lost between the latest Triassic extinction and the Early Jurassic recovery. Here a new pilot study was conducted by analyzing corallite integration levels among corals from the latest Triassic and Early Jurassic times. Integration levels in corals from the Late Triassic and Early Jurassic were determined through both the Paleobiology Database as well as from a comprehensive museum collection of fossil corals. Results suggest that in addition to a major loss of diversity following the end-Triassic mass extinction, there also was a significant loss of highly integrated corals as clearly evidenced by the coral data from the Early Jurassic. This confirms our hypothesis of paleoecological selectivity for corals following the end-Triassic mass extinction. This study highlights the importance of assigning sim- ple to advanced paleoecological characters with integration levels, which opens a useful approach to understanding of mass extinction and the dynamics of the recovery.展开更多
Storm deposits or tempestites are event sequences formed by storms,requiring at least a water temperature of 26.5℃.While inland lakes are unlikely to form storm deposits because of their limited width and water tempe...Storm deposits or tempestites are event sequences formed by storms,requiring at least a water temperature of 26.5℃.While inland lakes are unlikely to form storm deposits because of their limited width and water temperature.The Upper Triassic Xujiahe Formation in the Sichuan Basin is a set of coal-bearing,clastic sequences with dominant sedimentary facies varying from braided river delta to lacustrine settings,with storm deposits widely reported.In the Zilanba of Guanyuan area,in situ tree trunks on a palaeosol surface in Member Vof the Xujiahe Formation provide new evidence of a storm event.Six fallen-down directions of nine in situ tree trunks were predominant in the NW direction,contrary to the palaeocurrent direction of the underlying strata,suggesting that the southeasterlies prevailed during the end-Triassic in the northern Sichuan Basin.Massive mud clasts were frequently recorded in sandstones of the Xujiahe Formation,as well as in the Xindianzi section.These mud clasts showed a rip-up or a plastic deformation with upside-down V-shapes,were capped on an erosional surface,showed no transport traces and were therefore interpreted as a storm lag deposit.The megamonsoonal climate prevailed during the Late Triassic,although the megamonsoons themselves could not generate a storm deposition in the Xujiahe Formation due to its low maximum surface wind speed.The driving mechanism for generating storm deposits in the Xujiahe Formation is suggested to be tropical cyclones over the Tethys Ocean moving eastward,further landfalling on the western margin of the Sichuan Basin.Statistics of storm events in the circum-Tethys region show a widespread storm surge in low latitudes during the end-Triassic.The storm deposits at the top of the Xujiahe Formation represent a sedimentary response to the end-Triassic hyperthermal event.展开更多
The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting ...The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting subject to geologists. The evidences for this event come obviously from bivalves, brachiopods, ammonites, corals, radiolaria, ostracods and foraminifera of marine habitats, and plants and tetrapods of terrestrial realm. By contrast, for some of other groups, such as marine gastropods and marine vertebrates, no mass extinction has been recog-nized yet. The extinction event is strongly marked at specific level but shown a complicated situa-tion at generic and family levels. Dramatic changing of the environment, such as the temperature raise due to the greenhouse effect, the marine anoxic habitats caused by a sudden transgression after the regression at the end of Triassic, has been claimed to be the main cause of the extinction. Many hypotheses have been suggested to demonstrate the mechanisms of the environment changing, among which two popular ones are the bolide impact and volcanic eruption. The Triassic-Jurassic (Tr-J) boundary mass extinction event is still poorly understood because no enough data have been obtained from the Tr-J boundary successional sections of both marine and terrestrial sediments, and most of these studies were regionally restricted. The basic aspects of the event and its associated environmental conditions remain poorly characterized and the causal mechanism or mechanisms are equivocal. Some authors even doubt its occurrence. China has many successionally developed terrestrial and marine Tr-J sections. Detailed studies of these sections may be important and significant for well understanding of the event.展开更多
This paper reassesses published interpretation that beef and cone-in-cone （B-CIC） fibrous calcite cements were precipitated contemporaneously just below the sea floor in uncon- solidated sediment, in limestones asso...This paper reassesses published interpretation that beef and cone-in-cone （B-CIC） fibrous calcite cements were precipitated contemporaneously just below the sea floor in uncon- solidated sediment, in limestones associated with the end-Permian （P/T） and end-Triassic （T/J） mass extinctions. That interpretation introduced the concept of a sub-seafloor car- bonate factory associated with ocean acidification by raised carbon dioxide driven by volcanic eruption, coinciding with mass extinction. However, our new fieldwork and petrographic analysis, with literature comparison, reveals several problems with this concept. Two key points based on evidence in the T/J transition of the UK are： （I） that B-CIC calcite deposits form thin scattered layers and lenses at several horizons, not a distinct deposit associated with volcanic activity; and （2） B-CIC calcite is more common in Early Jurassic sediments after the extinction and after the end of the Central Atlantic Magmatic Province volcanism proposed to have supplied the carbon dioxide required. Our samples from Late Triassic, Early Jurassic and Early Cretaceous limestones in southern UK show that B-CIC calcite occurs in both marine and non-marine sediments, therefore ocean processes are not mandatory for its formation. There is no proof that fibrous calcite was formed before lithification, but our Early Jurassic samples do prove fibrous calcite formed after compaction, thus interpretation of crystal growth in uncon- solidated sediment is problematic. Furthermore, B-CIC crystals mostly grew both upwards and downwards equally, contradicting the interpretation of the novel carbonate factory that they grew preferentially upwards in soft sediment. Finally, Early Jurassic and Early Cretaceous examples are not associated with mass extinction. Three further key points derived from the literature include： （I） B-CIC calcite is wide- spread geographically and stratigraphically, not clustered around mass extinctions or the Paleocene-Eocene Thermal Maximum （PETM） event; （2） isotope signatures suggest B-CIC calcite formed under high pressure in burial at 70-120℃, incompatible with interpretation of formation of B-CIC calcite at the redox boundary below the ocean floor; and （3） B-CIC calcite reported in P/T boundary microbialites in one site in Iran is the only occurrence known despite extensive published studies of similar shallow marine settings, demon- strating its formation is localized to the Iran site. Based on the above evidence, our opinion is that B-CIC calcite is best explained as a later diagenetic feature unrelated to rapid Earth-surface environmental change associated with mass extinctions; thus a novel carbonate factory is highly unlikely.展开更多
三叠纪—侏罗纪之交(Triassic-Jurassic boundary,TJB)发生了三叠纪末的生物大灭绝(end-Triassic mass extinction,ETE),海洋和陆地生态系统都发生了不同程度的崩溃。而在陆地生态系统中,植物群首当其冲,但是该时段的植物群变化的详细...三叠纪—侏罗纪之交(Triassic-Jurassic boundary,TJB)发生了三叠纪末的生物大灭绝(end-Triassic mass extinction,ETE),海洋和陆地生态系统都发生了不同程度的崩溃。而在陆地生态系统中,植物群首当其冲,但是该时段的植物群变化的详细数据还相对缺乏。本文在新疆准噶尔盆地南缘郝家沟剖面TJB地层系统采样研究,来揭示该过程的植物群响应。根据孢粉属种组成及含量变化划分了3个孢粉组合,对古气候进行了重建。结果表明,准噶尔盆地南缘TJB的气候演变经历了湿热—湿冷—干热的转换过程。同时对ETE和TJB两个重要界线及灭绝发生的期次关系进行了讨论,由孢粉数据结合前人植物大化石、有机碳同位素地层曲线、生物标志化合物和Hg/TOC全球对比的结果,指示ETE和TJB可能分别位于郝家沟组43层底附近和八道湾组49层底附近;并推测三叠纪末陆地植被的灭绝在高纬度的准噶尔盆地记录到3个期次。在ETE与TJB之间地层中发现了与全球多处记录到的孢子含量激增一致的现象,推测该时期陆地生态系统的波动具有全球性。展开更多
The calimicrobialites of Chongyang （崇阳）, Hubei （湖北） Province, occur above the mass extinction line in the Late Permian reef facies. Below the boundary are the sponge reef limestone, crinoid limestone and algae...The calimicrobialites of Chongyang （崇阳）, Hubei （湖北） Province, occur above the mass extinction line in the Late Permian reef facies. Below the boundary are the sponge reef limestone, crinoid limestone and algae-foraminifer bioclastic limestone of the Changxing （长兴） Formation. The calimicrobialites are generally composed of mid-coarse grains and microlite calcite with a structure of ＂graniphylc fabric＂ and stromatolite. The fossils discovered in the calimicrobialites include globular cyanobacteria, ostracods, micro-gastropods, bivalves, fish teeth and some micro-problematical fossils. Conodont fossils of Hindeodus parvus, H. typicalis and H. latidentatus were also found in the calimicrobialites. According to the conodonts, the calimicrobialites spanned the latest Permian and earliest Triassic in the Chongyang Section. The upper part above the first occurrence of Hindeodus parvus should be attributed to the earliest Triassic, and the lower part to the Changhsingian. The sedimentary structure, fossil composition and conodont zonation of the Chongyang calimicrobialites can be well correlated with the calimicrobialites found in other areas of South China.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.41730317)Special Basic Program of Ministry of Science and Technology of China(Grant No.2015FY310100)+1 种基金Bureau of Geological Survey of China and National Committee ofStratigraphy of China(Grant No.DD20160120-04)UNESCO-IUGS IGCP project 632.
文摘1 Introduction The end-Triassic mass extinction event is one of the five global mass extinctions,and destroyed both the marine and terrestrial biological worlds.Though years the marine endTriassic mass extinction(ETE)event has been widely studied and discussed,and the standard marine Triassic/Jurassic boundary(TJB)(base-Jurassic)has also been determined.However.
文摘The end-Triassic （also Triassic-Jurassic） mass extinction severely affected life on planet Earth 200 million years ago. Paleoclimate change triggered by the volcanic eruptions of the Central Atlantic Magmatic Province （CAMP） caused a great loss of marine biodiversity, among which 96% coral genera were get lost. However, there is precious little detail on the paleoecology and growth forms lost between the latest Triassic extinction and the Early Jurassic recovery. Here a new pilot study was conducted by analyzing corallite integration levels among corals from the latest Triassic and Early Jurassic times. Integration levels in corals from the Late Triassic and Early Jurassic were determined through both the Paleobiology Database as well as from a comprehensive museum collection of fossil corals. Results suggest that in addition to a major loss of diversity following the end-Triassic mass extinction, there also was a significant loss of highly integrated corals as clearly evidenced by the coral data from the Early Jurassic. This confirms our hypothesis of paleoecological selectivity for corals following the end-Triassic mass extinction. This study highlights the importance of assigning sim- ple to advanced paleoecological characters with integration levels, which opens a useful approach to understanding of mass extinction and the dynamics of the recovery.
基金co-sponsored by the National Natural Science Foundation of China(Grant Nos.41972120,42172129)the State Key Laboratory of Palaeobiology and Stratigraphy(Grant No.173131)。
文摘Storm deposits or tempestites are event sequences formed by storms,requiring at least a water temperature of 26.5℃.While inland lakes are unlikely to form storm deposits because of their limited width and water temperature.The Upper Triassic Xujiahe Formation in the Sichuan Basin is a set of coal-bearing,clastic sequences with dominant sedimentary facies varying from braided river delta to lacustrine settings,with storm deposits widely reported.In the Zilanba of Guanyuan area,in situ tree trunks on a palaeosol surface in Member Vof the Xujiahe Formation provide new evidence of a storm event.Six fallen-down directions of nine in situ tree trunks were predominant in the NW direction,contrary to the palaeocurrent direction of the underlying strata,suggesting that the southeasterlies prevailed during the end-Triassic in the northern Sichuan Basin.Massive mud clasts were frequently recorded in sandstones of the Xujiahe Formation,as well as in the Xindianzi section.These mud clasts showed a rip-up or a plastic deformation with upside-down V-shapes,were capped on an erosional surface,showed no transport traces and were therefore interpreted as a storm lag deposit.The megamonsoonal climate prevailed during the Late Triassic,although the megamonsoons themselves could not generate a storm deposition in the Xujiahe Formation due to its low maximum surface wind speed.The driving mechanism for generating storm deposits in the Xujiahe Formation is suggested to be tropical cyclones over the Tethys Ocean moving eastward,further landfalling on the western margin of the Sichuan Basin.Statistics of storm events in the circum-Tethys region show a widespread storm surge in low latitudes during the end-Triassic.The storm deposits at the top of the Xujiahe Formation represent a sedimentary response to the end-Triassic hyperthermal event.
基金This work was supported by the National Natural Science Foundation of China(Grant No.40372021)IGCP(458)the Special Fund of Research Institute of Petroleum Exploration and Development,PetroChina.
文摘The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting subject to geologists. The evidences for this event come obviously from bivalves, brachiopods, ammonites, corals, radiolaria, ostracods and foraminifera of marine habitats, and plants and tetrapods of terrestrial realm. By contrast, for some of other groups, such as marine gastropods and marine vertebrates, no mass extinction has been recog-nized yet. The extinction event is strongly marked at specific level but shown a complicated situa-tion at generic and family levels. Dramatic changing of the environment, such as the temperature raise due to the greenhouse effect, the marine anoxic habitats caused by a sudden transgression after the regression at the end of Triassic, has been claimed to be the main cause of the extinction. Many hypotheses have been suggested to demonstrate the mechanisms of the environment changing, among which two popular ones are the bolide impact and volcanic eruption. The Triassic-Jurassic (Tr-J) boundary mass extinction event is still poorly understood because no enough data have been obtained from the Tr-J boundary successional sections of both marine and terrestrial sediments, and most of these studies were regionally restricted. The basic aspects of the event and its associated environmental conditions remain poorly characterized and the causal mechanism or mechanisms are equivocal. Some authors even doubt its occurrence. China has many successionally developed terrestrial and marine Tr-J sections. Detailed studies of these sections may be important and significant for well understanding of the event.
文摘This paper reassesses published interpretation that beef and cone-in-cone （B-CIC） fibrous calcite cements were precipitated contemporaneously just below the sea floor in uncon- solidated sediment, in limestones associated with the end-Permian （P/T） and end-Triassic （T/J） mass extinctions. That interpretation introduced the concept of a sub-seafloor car- bonate factory associated with ocean acidification by raised carbon dioxide driven by volcanic eruption, coinciding with mass extinction. However, our new fieldwork and petrographic analysis, with literature comparison, reveals several problems with this concept. Two key points based on evidence in the T/J transition of the UK are： （I） that B-CIC calcite deposits form thin scattered layers and lenses at several horizons, not a distinct deposit associated with volcanic activity; and （2） B-CIC calcite is more common in Early Jurassic sediments after the extinction and after the end of the Central Atlantic Magmatic Province volcanism proposed to have supplied the carbon dioxide required. Our samples from Late Triassic, Early Jurassic and Early Cretaceous limestones in southern UK show that B-CIC calcite occurs in both marine and non-marine sediments, therefore ocean processes are not mandatory for its formation. There is no proof that fibrous calcite was formed before lithification, but our Early Jurassic samples do prove fibrous calcite formed after compaction, thus interpretation of crystal growth in uncon- solidated sediment is problematic. Furthermore, B-CIC crystals mostly grew both upwards and downwards equally, contradicting the interpretation of the novel carbonate factory that they grew preferentially upwards in soft sediment. Finally, Early Jurassic and Early Cretaceous examples are not associated with mass extinction. Three further key points derived from the literature include： （I） B-CIC calcite is wide- spread geographically and stratigraphically, not clustered around mass extinctions or the Paleocene-Eocene Thermal Maximum （PETM） event; （2） isotope signatures suggest B-CIC calcite formed under high pressure in burial at 70-120℃, incompatible with interpretation of formation of B-CIC calcite at the redox boundary below the ocean floor; and （3） B-CIC calcite reported in P/T boundary microbialites in one site in Iran is the only occurrence known despite extensive published studies of similar shallow marine settings, demon- strating its formation is localized to the Iran site. Based on the above evidence, our opinion is that B-CIC calcite is best explained as a later diagenetic feature unrelated to rapid Earth-surface environmental change associated with mass extinctions; thus a novel carbonate factory is highly unlikely.
文摘在江西修水四都镇东岭村发现了一个连续的、出露完好的二叠纪-三叠纪界线地层剖面。在剖面中有一段厚约2.1m 的地层具有指示海平面下降的岩石组构。这段地层的底部为红色的碳酸盐颗粒岩。红色是颗粒表面的红色铁染,成分为褐铁矿,是出露地表风化形成的。这层红色颗粒岩之上有约2.0 m 的去白云石化灰岩,其中保留了原来粉晶白云石的晶形。去白云石化作用是白云岩受淡水影响而发生的,指示海平面下降事件。这段地层之上是厚1m 的颗粒岩和灰泥岩,代表浅水潮下环境。其上是二叠系-三叠系的界线。这段地层之下的地层中生物丰富多样,并且有复(蜒)、钙藻等大绝灭前的生物。这段地层及其以上的地层中生物种类很少,(蜓)、钙藻等已经消失,表明集群绝灭事件开始于这段地层之下,生物大绝灭的发生与海平面下降事件的发生是基本同时的。由此认为,可能是海平面下降有关的环境剧变事件引发了二叠纪末的集群绝灭事件。
文摘三叠纪—侏罗纪之交(Triassic-Jurassic boundary,TJB)发生了三叠纪末的生物大灭绝(end-Triassic mass extinction,ETE),海洋和陆地生态系统都发生了不同程度的崩溃。而在陆地生态系统中,植物群首当其冲,但是该时段的植物群变化的详细数据还相对缺乏。本文在新疆准噶尔盆地南缘郝家沟剖面TJB地层系统采样研究,来揭示该过程的植物群响应。根据孢粉属种组成及含量变化划分了3个孢粉组合,对古气候进行了重建。结果表明,准噶尔盆地南缘TJB的气候演变经历了湿热—湿冷—干热的转换过程。同时对ETE和TJB两个重要界线及灭绝发生的期次关系进行了讨论,由孢粉数据结合前人植物大化石、有机碳同位素地层曲线、生物标志化合物和Hg/TOC全球对比的结果,指示ETE和TJB可能分别位于郝家沟组43层底附近和八道湾组49层底附近;并推测三叠纪末陆地植被的灭绝在高纬度的准噶尔盆地记录到3个期次。在ETE与TJB之间地层中发现了与全球多处记录到的孢子含量激增一致的现象,推测该时期陆地生态系统的波动具有全球性。
基金This paper is supported by the National Natural Science Foundation ofChina ( Nos .40232025 ,40572002)the National Science Fund forDistinguished Young Scholars (No .40325004) .
文摘The calimicrobialites of Chongyang （崇阳）, Hubei （湖北） Province, occur above the mass extinction line in the Late Permian reef facies. Below the boundary are the sponge reef limestone, crinoid limestone and algae-foraminifer bioclastic limestone of the Changxing （长兴） Formation. The calimicrobialites are generally composed of mid-coarse grains and microlite calcite with a structure of ＂graniphylc fabric＂ and stromatolite. The fossils discovered in the calimicrobialites include globular cyanobacteria, ostracods, micro-gastropods, bivalves, fish teeth and some micro-problematical fossils. Conodont fossils of Hindeodus parvus, H. typicalis and H. latidentatus were also found in the calimicrobialites. According to the conodonts, the calimicrobialites spanned the latest Permian and earliest Triassic in the Chongyang Section. The upper part above the first occurrence of Hindeodus parvus should be attributed to the earliest Triassic, and the lower part to the Changhsingian. The sedimentary structure, fossil composition and conodont zonation of the Chongyang calimicrobialites can be well correlated with the calimicrobialites found in other areas of South China.
