The establishment of Global Standard Stratotype-section and Point (GSSP), i.e. the ‘Golden Spike’, forms the cornerstone of Phanerozoic subdivision and correlation of global chronostratigraphy, and compose common scientific language for exploring Earth history and life evolution, which has great scientific significance for the Stratigraphy and Palaeontology. The GSSP for the base of the Carboniferous System was accepted and ratified by IUGS in February 1990, and is defined by the first appearance of the conodont Siphonodella sulcata at La Serre near Cabrie`res, southern France. Two auxiliary stratotype sections, including the Hasselbachtal section in Germany and the Nanbiancun section in South China, were established to better constrain the Devonian-Carboniferous boundary (DCB) around the world. Nevertheless, since the proposal of the GSSP, the choice of La Serre has received criticism due to unfavourable lithofacies and lack of a “true” phylogenetic transition from Si. praesulcata to Si. sulcata. Meanwhile, there are many difficulties in distinguishing the index conodont Si. sulcata from its ancestor, Si. praesulcata, owing to the existence of abundant transitional forms and morphotypes. As a result, the ICS established a task group to redefine the DCB GSSP. In 2016 Montpellier DCB workshop, a new criterion “base of the Protognathodus kockeli Zone, beginning of radiation and top of major regression (top of the Hangenberg Sandstone event) and end of mass extinction” has been proposed by the task group, which need to be tested for global correlation. Drs. Markus Aretz and Corradini, the chair and vice-chair of the GSSP redefinition work group, organized a special issue (entitled as the “Global review of the Devonian-Carboniferous Boundary”) recently in Palaeobiodiversity and Palaeoenvironments, aiming to provide newest overviews of DCB intervals in important regions (e.g. western Europe, North America and South China etc.), and check the suitability of the proposed boundary level all over the world. In this new paper, we not only briefly review the research history, current status and achievement of DCB in China, but also illustrate representative DCB sections in South China, western Junggar and Tibet. Furthermore, we test the “Montpellier criterion” for the Devonian-Carboniferous boundary redefinition. In South China, there exist numerous well-preserved and continuous Devonian-Carboniferous boundary successions that were formed in low-latitude passive margin basin, and this presents a unique opportunity to decipher the strata along a proximal to basinal transect using integrated biostratigraphical, event-stratigraphical, and geochemical approaches. Our geochemical data (δ13Ccarb, δ15Nbulk, δ238U and Mo/U enrichments, I/Ca ratio) indicated local and global C-N cycling perturbations and marine anoxia in the main phase of the Hangenberg Crisis interval (Middle Siphonodella praesulcata Zone), which coincided with a major regression in South China. Stromatoporoid biostromes and most typical Devonian faunas did not survive into the interval, and the deep-water black shales yield only opportunistic survivors, such as ammonoid Postclymenia cf. evoluta and bivalve Guerichina, along with miospores belonging to the LN Zone. The upper Hangenberg Crisis interval (Upper Si. praesulcata Zone, equal to the Protognathodus kockeli Zone) is marked by initial post-glacial transgression, a global δ13Ccarb spike, and opportunistic faunal blooms, coincident with conodont biofacies shift to the polygnathid-protognathodid biofacies. The Protognathodus fauna, nearly absent from platform facies, is often found in the condensed upper crisis interval of the basin, slope, and platform margin facies within the Youjiang Basin, although the abundance is extremely low and the phylogenetic lineage of Pr. meischneri-Pr. collinsoni-Pr. kockeli cannot be recognized in most successions. In South China, the first occurrence of Pr. kockeli seems to correspond to lithofacies changes, recorded in the first level of transgression just above the Hangenberg Sandstone event. Multiple lines of evidence, including great spatial heterogeneity of δ13Ccarb and δ15Nbulk records, extremes of redox proxies, and lack of macrofossils, suggest that marine habitats remained in a critical/turbulent state during the Upper Si. praesulcata Zone, triggering the opportunistic blooms and minor extinctions. Reference: For detailed information about this paper, please check: Qie, W., Sun, Y., Guo, W., Nie, T., Chen, B., Song, J., Liang, K., Yin, B., Han, S., Chang, J., Wang, X., 2021. Devonian-Carboniferous boundary in China. Palaeobiodiversity and Palaeoenvironments 101, 589-611. https://doi.org/10.1007/s12549-021-00494-z (Note: Springer offers free access till of 18th of August, 2021) For detailed information about the updated DCB special issue, please check: Aretz M., Corradini C., 2021. Global review of the Devonian-Carboniferous Boundary. Palaeobiodiversity and Palaeoenvironments, 101 (2).
Figure 1. A) Palaeogeography locations of Chinese plates during the Late Devonian, paleogeographic maps are from Ron Blakey (www2.nau.edu/rcb7) and B) Tectonic-stratigraphic regions of the Devonian and well-known Devonian-Carboniferous boundary sections in China Figure 2. The international auxiliary stratotype section of the Devonian-Carboniferous boundary at Nanbiancun, Guilin, China. Figure 3. The Muhua II DCB section at Muhua, Changshun, Guizhou. Figure 4. Important shallow-water conodont elements from the DCB intervals in South China characterized by the polygnathid-clydagnathids biofacies of the upper Hangenberg Crisis interval and the endemic siphonodellids biofacies of lower Tournaisian. Figure 5. Stratigraphically important deep-water conodont elements from the DCB intervals in Youjiang Basin, South China characterized by the polygnathid-protognathodid biofacies of the upper Hangenberg Crisis interval and the siphonodellids biofacies of lower Tournaisian Figure 6. Composite geochemical profiles of Devonian-Carboniferous boundary successions in South China.
The mid-Proterozoic (1.85-0.85 Ga) is a critical time for early evolution of eukaryotic organisms. However, this interval has often been referred as the “Boring Billion”, new fossil records will provide some new ideas and basis for the dilemma about the Boring Billion. The mid-Proterozoic (1.85-0.85 Ga) is a critical time for early evolution of eukaryotic organisms. However, this interval has often been referred as the "Boring Billion", new fossil records will provide some new ideas and basis for the dilemma about the Boring Billion. In North China, the Yanshan area represents one of the few geological sites in the world having mid-Proterozoic sedimentary successions with preservation of excellent fossil records, e.g. the oldest eukaryotic fossils recovered from the lower Changcheng Group (ca.1.67~1.63 Ga) (Miao et al., 2019, Precambrian Research), multicellular eukaryotic macrofossils from the Gaoyuzhuang Formation (ca.1.56 Ga) (Zhu et al., 2016, Nature Communications). Recently, an international research group led by Prof. ZHU Maoyan from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) reports a diverse organic-walled microfossil (OWM) assemblage from the shale-dominated Mesoproterozoic Xiamaling Formation (ca. 1.4-1.35 Ga) in the Yanshan area. The study has been recently published on the international academic journal Precambrian Research. The well-preserved OWMs in the assemblage are classified into 36 form species belonging to 28 genera, including 1 new species and 5 unnamed taxa, consisting of various individual vesicles, filamentous microfossils and cellular aggregates (or colonial microfossils). Prof. ZHU says, "most of these taxa are reported for the first time in the Xiamaling Formation". Among them, the researchers inferred 12 taxa with eukaryotic affinity on the basis of the combined characteristics of complex morphology and large cell size. These eukaryotic fossils are predominately spheroidal vesicles with micron-scale surface ornamentations or sculptures (e.g. tubular process, reticulate sculpture, concentric striations, verrucae, outer membrane, equatorial flange), and spheroidal to ellipsoidal vesicles with complex wall structure (e.g. tessellated wall, double-wall construction), and one large tubular taxon Jixiania lineata with longitudinal equidistant striations. According to the researchers, the fossil assemblage shows a moderate eukaryotic diversity which is similar to other contemporaneous OWMs worldwide, demonstrating that the prokaryotes may have still dominated the Mesoproterozoic ecosystems, but eukaryotic life had shown a certain degree of diversification during the Earth's middle age. In addition, Jixiania lineata represents the only taxon in the Xiamaling assemblage with relatively short stratigraphic range, and has been reported from several early Mesoproterozoic successions in Australia, Siberia and Laurentia. The recognition of Jixiania lineata in North China expands its geographic distribution and further enhances its potential as index fossil for early Mesoproterozoic strata. This work was supported by the National Natural Science Foundation of China and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences. Reference: Miao, L., Moczydlowska, M., Zhu, M., 2021. A diverse organic-walled microfossil assemblage from the Mesoproterozoic Xiamaling Formation, North China. Precambrian Research 360, 106235. https://doi.org/10.1016/j.precamres.2021.106235 Fig 1. Taxonomic compositions of the Xiamaling assemblage from the lowermost Xiamaling Formation. Fig2. Simple vesicles of uncertain biological affinity from the Xiamaling assemblage. Fig 3. Various cellular aggregates from the Xiamaling assemblage. Fig 4. A broad stratigraphic range of organic-walled microfossils in the mid-Proterozoic.Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Volcanic activity drove an increase in the intensity of wildfire events, which in turn disturbed and affected terrestrial ecosystem. Volcanic activity drove an increase in the intensity of wildfire events, which in turn disturbed and affected terrestrial ecosystem. Wildfire is an important part of terrestrial ecosystem. It plays a significant role in many environmental and evolutionary innovations in geological history. The End-Permian mass extinction is the biggest extinction event in Earth's history, and the response of terrestrial vegetation systems to this event has been highly concerned in recent years. Nowadays more and more records of wildfire are reported from the Late Paleozoic, the investigations focusing on wildfire are of great significance to learn the collapse of terrestrial ecosystem and the vegetation changeover during the Permian-Triassic transition. Recently, the Late Paleozoic research group from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), Nanjing University and Yunnan University, carried out a systematic studies focused on charcoals and δ13Corg from the upper Permian of the Dalongkou section in Xinjiang Uygur Autonomous Region and of the Lengqinggou section in Guizhou, Southwest China. The results were published on Earth-Science Reviews and Frontiers in Earth Science. In Dalongkou section, charcoals from several stratigraphic horizons in the lower-middle Guodikeng Formation evidenced the frequency of palaeo-wildfires during the late Permian. The reflectance values of the charcoals indicate that surface fires were dominant throughout the sequence, with fire regime changing in the upper of the Guodikeng Formation from higher reflectance to extremely low reflectance. It probably hints at a vegetational impoverishment and the lack of fuel during that time. The distribution of all categories of the charcoals, the difference of cuticles and the evidence of spore-pollen also support the deforestation stage. In addition, the coupling of the Hg/TOC peaks and the organic carbon isotope (δ13Corg) values and the abundance of the charcoals in the sequence indicates that volcanic activities could be the deep-seated drivers for wildfires and the δ13Corg change. The work of Lengqinggou section shows that charcoals from the Xuanwei Formation occurred more frequently, with higher reflectance and diversity, while that from the Kayitou Formation exhibit low reflectance and diversity. This phenomenon supports the point that the vegetation had changeover from rainforest to herb land between the two formations. Meanwhile, the fire regime also changed from high temperature crown fire to the ground fire with lower temperature. Furthermore, an ash bed in the uppermost coal in the Xuanwei Formation was concerned. Detailed sampling shows that an abrupt excursion of δ13Corg and reduction of charcoal abundance occurred immediately above the volcanic ash. It suggests that the intensive wildfire associated with volcanism culminated at that time, leading to the eventual vegetation changeover of the terrestrial ecosystems in Southwest China during the Permian-Triassic transition. The works were supported by the Strategic Priority Research Programs (B) of the Chinese Academy of Sciences and the National Natural Science Foundation of China and CAS. Related Article: Cai, Y.F., Zhang, H. *, Cao C.Q., Zheng, Q.F., Jin, C.F., Shen, S.Z., 2021. Wildfires and deforestation during the Permian–Triassic transition in the southern Junggar Basin, Northwest China. Earth-Science Reviews 218 (7): 103670. DOI: 10.1016/j.earscirev.2021.103670 Cai, Y.F., Zhang, H. *, Feng, Z., Shen, S.Z., 2021. Intensive wildfire associated with volcanism promoted the vegetation changeover in Southwest China during the Permian-Triassic transition. Frontiers in Earth Science. 9:615841. https://doi.org/10.3389/feart.2021.615841 SEM images of charcoal from the Dalongkou section in Xinjiang Uygur Autonomous Region, Northwest China Co-variation diagrams for the δ13Corg values, Hg/TOC values, charcoal abundance, reflectance and types of fossil charcoal in the Dalongkou section SEM images of charcoal from the Lengqinggou section in Guizhou Province, Southwest China Stratigraphic column and δ13Corg, charcoal abundance and types of fossil charcoals in the Lengqinggou section, Guizhou Province, Southwest China Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Recently, Associate Professor MNEG Fanwei and Senior Engineer FANG Yan, from Nanjing Institute of Geology and paleontology, Chinese Academy of Sciences translated the lost creations of the earth: mass extinction in the history of life by American science writer Jon Erickson into Chinese, and published it in Science Press. The long history of geology has been marked by the appearance of many glorious creatures that have either appeared briefly in the history of life or have flourished to this day. These surviving creatures make up the natural world as we know it today. The order in which these fossilized organisms appeared can be identified by the age of the rocks deposited in the past. The book systematically introduces the origin of life, as well as pictures of the main types of fossils that appear in each geological era, and is quite professional and detailed. The Chinese translation is accompanied by explanations of various geological terms and English cross-references, which can be used as a reference manual for undergraduate students and practitioners of stratigraphy and paleontology and other geology-related majors, or as an advanced science book for young enthusiasts. The book is supported by the China-Israel Cooperation Program of the Natural Science Foundation of China and the Basic Frontier Science Research Program of the Chinese Academy of Sciences. Book information: Jon Erickson, USA, translated by Meng Fanwei and Fang Yan, April 2021, "life lost on the earth: mass extinction in the history of life" (in Chinese), Science Press, ISBN: 978-7-03-063998-1
Cambrian in South China is mainly composed of sedimentary clastic rocks of slope facies, and trilobites are mostly globose fossils distributed globally, which is convenient for global comparison. A new Cambrian stratigraphic framework has been established in South China, and the framework of geological times for the global Cambrian stratigraphic division has also been formed. However, the Cambrian System in North China is mainly composed of carbonate rocks of shallow platform facies, and trilobites are mainly local molecules (regional fossils). It is the lack of preserved or identified biostratigraphic marker fauna, coupled with the two plates belong to different sedimentary environments, which leads to the difficulty of accurate stratigraphic division and correlation between the two different facies areas for a long time. Carbon isotope stratigraphy can accurately compare the carbonate facies with the global stratigraphic correlation. Therefore, through the carbon isotope stratigraphy of carbonate rocks and the biostratigraphy of shallow platform facies, the accurate division and multiple correlation of biostratigraphy / chronological strata in two different facies areas can be carried out. In order to solve this problem, with the support of the Opening Foundation of the State Key Laboratory of Palaeobiology and Stratigraphy, Dr MENG Fanwei (corresponding author), Professor YUAN jinliang of Nanjing Institute of Geological and Palaeontology, Chinese Academy of Sciences (NIGPAS), and Professor schiffbauer J D (co-corresponding author) of the University of Missouri, USA, cooperated with Professor REN Guangying (specially hired) of Linyi University, China, conducted a geological investigation on more than ten sections of late Cambrian in Shandong Province, North China, and a large number of fossils and rock samples were collected. Based on the comprehensive research of biostratigraphy, petrostratigraphy, chronological stratigraphy and geochemistry, the high-resolution carbon isotope stratigraphy was studied, The SPICE (steptoean positive carbon isotope exception) event between the Miaolingian and Furongian series boundaries is identified in North China. The research results have been published online in the well-known international Paleontological journal Lethia. The study found that, the positive drift of carbon isotopes is better than previous data of δ 13C drift profile is more complete, which reflects the regional changes of paleoenvironment / sea level in the region and the similarities and differences with global changes. It explains that the Jiulongshan section, Gushan and Chaomidian Formation belong to the shallow platform paleoenvironment, but the sea water of the Paleoenvironment represented by this profile is deeper than that of other areas of Shandong Province, North China. In addition, Fenghuangella laevis Park and Choi, 2011, an iconic species, was found on the boundary layer of Jiulongshan section. It was found for the first time in China. This discovery of the fossil provides a strong evidence for the division and comparison of the boundary between the Miaolingian and Furongian series, Cambrian. At the same time, the first appearance datum (FAD) of "species" was established for the first time in the Kushan Formation of North China platform; The problem of the contrast between the platform facies of North China and the boundary of Miaolingian and Furongian Series in the South China slope facies is solved. This research is supported by the Opening Foundation of the State Key Laboratory of Palaeobiology and Stratigraphy. Reference: Ren, G., Meng, F., Pulsipher, M. A., Schiffbauer, J. D., Yuan, J., Zhao, Y., Guo, Y., Gao,J., & Chang, C., 2021. A contiguous record of the SPICE event, sea level change and the first appearance of Fenghuangella laevis in Shandong Province, North China. Lethaia, https://doi.org/10.1111/let.12425. Fig. 1. Stratigraphical column, biostratigraphical ranges and geochemical data of the measured portion of the Jiulongshan section, Shandong Province, North China Fig. 2. Photographs of example Fenghuangella laevis specimens recovered from the Jiulongshan section Fig. 3. Comparative δ13C profiles of the Jiulongshan section versus other SPICE sections in Shandong and Liaoning Provinces, North China Fig. 4. Comparative δ13C profiles of the Jiulongshan section versus other glauconite‐bearing SPICE sections from Laurentia
Flowering plants (angiosperms) dominate most terrestrial ecosystems, provide the bulk of the food consumed by people, and contribute many other services that are critically important for life on our planet, but their origin has been a mystery since the earliest days of evolutionary thought. Angiosperm flowers are hugely diverse, but central to clarifying the origin of flowers and how angiosperms might be related to other kinds of plants, is understanding the evolution of the parts of the flower, especially angiosperm seeds and the fruits in which the seeds develop. Flowering plants (angiosperms) dominate most terrestrial ecosystems, provide the bulk of the food consumed by people, and contribute many other services that are critically important for life on our planet, but their origin has been a mystery since the earliest days of evolutionary thought. Angiosperm flowers are hugely diverse, but central to clarifying the origin of flowers and how angiosperms might be related to other kinds of plants, is understanding the evolution of the parts of the flower, especially angiosperm seeds and the fruits in which the seeds develop. Fossil seed-bearing structures preserved in a newly discovered Early Cretaceous silicified peat in Inner Mongolia, China, which dates from about 126 million years ago, provide a partial answer and support an earlier idea that the distinctive outer covering of developing seeds of flowering plants – the so-called second integument – is fundamentally comparable to structures that occur in certain extinct non-angiosperm seed plants from the ‘Age of Dinosaurs’. The seeds of cycads, ginkgo and conifers are enclosed and protected by a single integument, which is believed to correspond to the inner integument in flowering plants. However, the outer (second) integument is a unique structure. Its development is linked to its curious recurved form and is controlled by different genes than those responsible for the development of the inner integument. The new fossils, which are exceptionally well preserved and abundant in the silicified peat from China, have two seeds enclosed inside a specialized recurved structure – the cupule. Similar cupules occur in several groups of extinct plants from the Mesozoic that are known only from fossils, and while it has been suggested some of these cupules may be precursors of the second integument of flowering plants, discussions have been hampered by inadequate information. The new material from China, along with the reexamination of previously described fossils, suggests that the recurved cupules found in several groups of extinct seed plants from the Mesozoic are all fundamentally similar and are the likely the precursors of the second integument of flowering plants. The recurved structure seen in the young seeds of flowering plants is therefore a hold-over from an earlier pre-angiosperm phase of evolution. Variation among extinct Mesozoic seed plants in the number of seeds per cupule and other features likely reflect differences relating to pollination, as well as seed output, protection and dispersal. Recognition of extinct seed plants with a structure comparable to a key feature of living angiosperms provides a partial answer to the question of flowering plant origins, helps focus future work on understanding how living and fossil groups of seed plants are interrelated, and has important implications for ideas on the origin of another diagnostic feature of flowering plants that evidently came later – the carpel – the structure that forms the fruit wall in which the seeds develop. This research was supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2017359), the US National Science Foundation grant DEB-1748286, the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB26000000), the National Natural Science Foundation of China (41790454) and the Oak Spring Garden Foundation. Figure 1. The fossil chert locality at the Zhahanaoer open-cast coal mine, Jarud Banner, eastern Inner Mongolia, China. Figure 2. Fossil cupules and associated leaf and stem from the Early Cretaceous Zhahanaoer chert locality Figure 3. Fossil cupules and seed from the Early Cretaceous Zhahanaoer chert locality Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Until now, most radiolarian investigations have been undertaken in the eastern and central segments. Less radiolarian studies have been done in the western segment, especially those involving any systematic research on the biostratigraphy and paleobiogeography of the radiolarians. The Yarlung Tsangpo suture zone (YTSZ) marks the collision boundary between the Eurasian Plate and the Indian Plate and remains geological records of the disappeared Neo-Tethyan ocean, which is a hotspot on the study about the Neo-Tethyan ocean evolution and the Qinghai-Tibet Plateau uplift. The YTSZ consists of eastern (Qushui–Motuo), central (Angren–Renbu) and western (Saga to the boundary of India–China) three segments. Until now, most radiolarian investigations have been undertaken in the eastern and central segments. Less radiolarian studies have been done in the western segment, especially those involving any systematic research on the biostratigraphy and paleobiogeography of the radiolarians. In recent years, well-preserved Jurassic-Cretaceous radiolarian fossils have been collected within the western YTSZ by the research group of Prof. LUO Hui from the Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences (NIGPAS). Ph.D. candidate CUI Xiaohui and others from this group, cooperating with Prof. Jonathan C. Aitchison from the University of Queensland in Australia, make a detailed analysis of Early Cretaceous (Hauterivian to late Barremian) radiolarians from Jiangyema section in the west segment of the YTSZ. The results have been published in the international geological research journal Cretaceous Research. Two radiolarian zones and two subzones are recognized and respectively named as the Cecrops septemporatus zone, Aurisaturnalis carinatus zone, Aurisaturnalis carinatus carinatus subzone and Aurisaturnalis carinatus perforatus subzone. They can be correlated well with coeval radiolarian biozones between western Tethys and/or Japan, which provide a better biostratigraphical framework and reliable age constraints for parts of the Neo-Tethyan Ocean floor that were subducted beneath supra-subduction zone (SSZ) ophiolites in the western part of the YTSZ. Comparison of geochemical characteristics on discriminant graphs suggests that the bedded cherts were deposited in a deep oceanic basin near a continental margin. These results and integration of available radiolarian studies along the YTSZ suggest that the Neo-Tethys was a deep ocean between the Indian and Eurasian continents in which pelagic sedimentation was on-going until at least late Barremian time. This research was supported by the National Natural Science Foundation of China, the Strategic Priority Research Program of Chinese Academy of Sciences and the Second Tibetan Plateau Scientific Expedition and Research. Reference: Cui, X.H., Luo, H., Jonathan C.A., Li, X. Fang, P.Y., 2021. Early Cretaceous radiolarians and chert geochemistry from western Yarlung Tsangpo suture zone in Jiangyema section, Purang county, SW Tibet. Cretaceous Research, 125 104840. https://doi.org/10.1016/j.cretres.2021.104840. Simplified geological map of the Purang ophiolitic melange showing the location of studied section (modified after Liu et al., 2011) Comparison of Early Cretaceous radiolarian zones (modified after Gorican et al., 2018; Li et al., 2017) Scanning electron micrographs of selected radiolarians from siliceous samples in the Jiangyema section (1) Scanning electron micrographs of selected radiolarians from siliceous samples in the Jiangyema section (2)
In recent years, a particular pattern of marl tuffs has attracted increasing attention from geological colleagues and has become one of the major international hot topics. Think of a pattern consisting of two components, in biogenic limestones of deep-time: a) dark-colored ellipsoidal areas of various sizes and shapes, and b) curved light-colored areas filling the space between the ellipses. Is the pattern made of: 1) dark ellipsoidal objects with lightcoloured intervening spaces, or 2) a light-coloured complex curved framework with a dark infilling? This conundrum lies at the heart of the problem of distinguishing clotted micrite from sponges in micritic limestones. In recent years, a particular pattern of marl tuffs has attracted increasing attention from geological colleagues and has become one of the major international hot topics. Think of a pattern consisting of two components, in biogenic limestones of deep-time: a) dark-colored ellipsoidal areas of various sizes and shapes, and b) curved light-colored areas filling the space between the ellipses. Is the pattern made of: 1) dark ellipsoidal objects with lightcoloured intervening spaces, or 2) a light-coloured complex curved framework with a dark infilling? This conundrum lies at the heart of the problem of distinguishing clotted micrite from sponges in micritic limestones. Some curved structures resemble published images of interpreted sponges, raising the question of their nature, relevant to many carbonate studies including reefs and mud mounds throughout the Phanerozoic. A conundrum lies at the heart of the problem of distinguishing clotted micrite from sponges in micritic limestones. Understanding this issue is relevant for many carbonate studies in the Phanerozoic rock record, which include the widespread occurrence of reefs and mud mounds; the interpretations of presence of sponges are not necessarily always justified, affecting assessment of faunal assemblages, sedimentary processes and diagenesis. Recently, Prof. Yue Li and Dr. Qi-jian Li from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) and his collaborators from Brunel University try to demonstrate the issue mentioned above by using material from Early Silurian patch reefs rich in such complex fabrics. The results have been published online in the Sedimentary Record, an open access journal hosted by the International Society for Sedimentary Geology (SEPM). The study describes Early Silurian carbonate reef facies in the Ningqiang Formation containing amalgamated micritic masses, commonly layered, interpreted to have formed by bacterial processes creating clotted fabrics. In most cases, cavity infills comprise fabrics we interpret to be clotted micrite masses, and the layering presumably represents multiple events of infilling of open cavities (Fig. 1), perhaps as microbial micrites. Comparative images of modern lithistid desmas and keratose fibres and show that the size of lithistid desmas is comparable to the curved sparitic features in the Ningqiang Formation sediments, although keratose fibres are much smaller (Fig. 2). The implication of this work is that studies reporting lithistid and keratose sponges in limestones in the Phanerozoic records may warrant careful consideration of the interpretation of presence of sponges, that may have an impact on discussions of sedimentology and diagenesis, and of sponge palaeobiology and evolution. The attempt to identify keratose sponges, using 3D reconstruction that involved destructive grinding, is difficult to achieve, but may be necessary for confirmation. The arguments presented in this study have potential wider implications for the analysis of other carbonate structures, such as mud mounds in Devonian that include fabrics interpreted as sponges. This study was jointly supported by the Youth Innovation Promotion Association of CAS, grants from the Strategic Priority Research Program (B) of CAS and the National Natural Science Foundation of China. Reference: Stephen Kershaw, Qijian Li & Yue Li. 2021. Addressing a Phanerozoic carbonate facies conundrum—sponges or clotted micrite? Evidence from Early Silurian reefs, South China Block. Sedimentary Record, DOI: 10.2110/sedred.2021.1.03. Figure 1．(A) Plane-polarised light (PPL) view of bioturbated wackestone reef fill, with margin of irregular cavity (bottom and left). Large white areas are spar-filled cavities lacking sediment. (B and C) Cross-polarised light (XPL) views of enlargements of the two boxes in (A) showing details of cavity margin and contrast between wackestone reef matrix and amalgamated micritic cavity fills, that are layered. Yellow arrows in (A) and (B) mark the cavity edge. Middle Huashitou reef, Xuanhe, Sichuan Province. Figure 2. (A) View of amalgamated micrite with a second-generation cavity (lower centre) also filled with amalgamated micrite that is partly layered; a smaller round cavity, partly-filled, is shown centre-right. (B) Details of yellow box in (A) emphasising the round mass of sparite that might be a sponge. (C) Modern lithistid sponge desmas in transmitted light; note the difference in scale. (D) Modern keratose sponge fibres, at the same scale as the main picture, from an unidentified sponge, Bahamas.
A recent study on spectacular fossil plants preserved in a volcanic ash fall deposit—known as China’s "vegetational Pompeii,” in Inner Mongolia, China—has resolved a mystery that puzzled palaeontology for over a century: What are Noeggerathiales? A recent study on spectacular fossil plants preserved in a volcanic ash fall deposit—known as China's "vegetational Pompeii," in Inner Mongolia, China—has resolved a mystery that puzzled palaeontology for over a century: What are Noeggerathiales? The study, published in PNAS on March 8, was led by Prof. WANG Jun from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences and by Prof. David Dilcher from Indiana University (USA). Researchers from the UK, Czech Republic and Austria were also involved. The researchers confirmed that Noeggerathiales had the spore propagation mode of ferns and the vascular tissue of seed plants. They belonged to a sister group of seed plants, the former gymnosperm. Noeggerathiales were important peat-forming plants that lived approximately 325-251 million years ago. Although they were first recognized as a distinct plant group in the 1930s, scientists have long argued over their relationships with other plant groups. As a result, they were considered an evolutionary dead end. The researchers studied complete plants preserved in a 66-cm-thick bed of volcanic ash that fell 298 million years ago and smothered all the plants growing in a swamp. The ash prevented the fossils from being consumed by other organisms or decaying and thus preserved many complete individuals. From these complete plants, the scientists reconstructed a new species of Noeggerathiales named Paratingia wuhaia that finally allowed the groups affinity and evolutionary importance to be determined. These results show for the first time that Noeggerathiales were advanced members of the evolutionary lineage from which seed plants evolved. This is important as it shows Noeggerathiales are more closely related to seed plants than they are to other fern groups, and Noeggerathiales can no longer be considered an evolutionary dead end. The study also shows that the ancestral lineage from which seed plants evolved diversified alongside the earliest seed plant radiation during the Devonian, Carboniferous and Permian periods and did not rapidly die out as previously thought. Noeggerathiales are now recognized as an advanced group of –spore plant that evolved complex cone-like structures from modified leaves. Despite their reproductive sophistication, however, they were victims of profound environmental and climate changes during the Permian-Triassic mass extinction approximately 251 million years ago that destroyed swamp ecosystems globally. The "vegetational Pompeii" is certainly a fossil Lagerstatte, preserving a large number of materials that have huge potential for resolving mysteries in the area of palaeobotany. "The whole-plant Paratingia wuhaia reconstructed here represents a tip of the iceberg. The ongoing research based on the fossils from the 'vegetational Pompeii' may bring about more and more reconstruction of ancient plants," said Prof. WANG. The fossil collection from the "vegetational Pompeii" represents the largest number of plant fossils describing a coal-forming forest. Meanwhile, the research group has conducted the largest actual reconstruction of an ancient peat-forming swamp in the world. Reference: Jun Wang, Jason Hilton, Hermann W. Pfefferkorn, Shijun Wang, Yi Zhang, Jiri Bek, Josef Psenicka, Leyla J. Seyfullah, David Dilcher, 2021, Ancient noeggerathialean reveals the seed plant sister group diversified alongside the primary seed plant radiation, PNAS. https://doi.org/10.1073/pnas2013442118. Fig. 1 The type of specimen the new plant is based on, preserving the crown of the tree with leaves and its fertile organs attached to the stem (Image by NIGPAS) Fig. 2 Reconstruction of the peat-forming plant community in which the new species Paratingia wuhaia (yellow arrows) grew (Image by NIGPAS) Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Reconstructions of ancient sulfur cycling and redox conditions commonly rely on sulfur isotope measurements of sedimentary rocks and minerals. Ediacaran strata (635–541 Ma) record a large range of values in bulk sulfur isotope difference (Δ34S) between carbonate-associated sulfate (δ34SCAS) and sedimentary pyrite (δ34Spy), which has been interpreted as evidence of marine sulfate reservoir size change in space and time. However, bulk δ34Spy measurements could be misleading because pyrite forms under syngenetic, diagenetic, and metamorphic conditions, which differentially affect its isotope signature. Fortunately, these processes also impart recognizable changes in pyrite morphology. Reconstructions of ancient sulfur cycling and redox conditions commonly rely on sulfur isotope measurements of sedimentary rocks and minerals. Ediacaran strata (635–541 Ma) record a large range of values in bulk sulfur isotope difference (Δ34S) between carbonate-associated sulfate (δ34SCAS) and sedimentary pyrite (δ34Spy), which has been interpreted as evidence of marine sulfate reservoir size change in space and time. However, bulk δ34Spy measurements could be misleading because pyrite forms under syngenetic, diagenetic, and metamorphic conditions, which differentially affect its isotope signature. Fortunately, these processes also impart recognizable changes in pyrite morphology. To tease apart the complexity of Ediacaran bulk δ34Spy measurements, Dr. WANG Wei, Dr. GUAN Chengguo and Prof. ZHOU Chuanming from the Nanjing Institute of Geology and Paleaontology, Chinese Academy of Sciences (NIGPAS), with other researchers from the Institute of Geology and Geophysics, CAS (IGGCAS) used scanning electron microscopy and nanoscale secondary ion mass spectrometry to probe the morphology and geochemistry of sedimentary pyrite in an Ediacaran drill core of the South China block. The relevant results were published online in the internationally renowned journal Geology. Pyrite occurs as both framboidal and euhedral to subhedral crystals, which show largely distinct negative and positive δ34Spy values, respectively. Bulk δ34Spy measurements, therefore, reflect mixed signals derived from a combination of syndepositional and diagenetic processes. Whereas euhedral to subhedral crystals originated during diagenesis, the framboids likely formed in a euxinic seawater column or in shallow marine sediment. Although none of the forms of pyrite precisely record seawater chemistry, in situ framboid measurements may provide a more faithful record of the maximum isotope fractionation from seawater sulfate. This study exemplifies the fundamental problem with using bulk analyses of sulfur isotopes for paleoenvironmental reconstruction. Given that sulfate concentration is the main controlling factor for sulfur isotope fractionation, the consistently negative δ34S values in framboidal pyrite are suggestive of a larger Ediacaran sulfate reservoir than previously thought. The study was supported by the National Key Research and Development Program of China, the Chinese Academy of Sciences (CAS), and the National Natural Science Foundation of China. Reference: Wei Wang*, Yongliang Hu, A. Drew Muscente, Huan Cui, Chengguo Guan, Jialong Hao, Chuanming Zhou*, 2021, Revisiting Ediacaran sulfur isotope chemostratigraphy with in situ nanoSIMS analysis of sedimentary pyrite. Geology, v. 49, https://doi.org/10.1130/G48262.1 Fig.1 Profiles of sedimentary pyrite δ34S values in Lantian Formation drill core Fig.2 Dominant pyrite morphologies and in situ nanoSIMS sedimentary pyrite δ34S
