Mechanical alterations in shale formations due to exposure to water-based fracturing fluids and supercritical carbon dioxide(ScCO_(2))significantly affect the performance of shale gas exploration and CO_(2) geo-seques...Mechanical alterations in shale formations due to exposure to water-based fracturing fluids and supercritical carbon dioxide(ScCO_(2))significantly affect the performance of shale gas exploration and CO_(2) geo-sequestration.In this study,a hydrothermal(HT)reaction system was set up to treat Longmaxi shale samples of varying mineralogies(carbonate-,clay-,and quartz-rich)with different fluids,i.e.deionized(DI)water,2%potassium chloride(KCl)solution,and ScCO_(2) under HT conditions expected in shale formation.Statistical micro-indentation was conducted to characterize the mechanical property alterations caused by the shale-fluid interactions.An in situ morphological and mineralogical identification technique that combines scanning electron microscopy(SEM)and backscattered electron(BSE)imaging with energy-dispersive X-ray spectroscopy(EDS)was used to analyze the microstructural and mineralogical changes of the treated shale samples.Results show no apparent changes in the Young's modulus,E,and hardness,H,after treatment with DI water under room temperature(20℃)and atmospheric pressure for 7 d.In contrast,E and H were decreased by 31.2%and 37.5%at elevated temperature(80℃)and pressure(8 MPa),respectively.The addition of 2%KCl into DI water mitigated degradation of the mechanical properties.Quartz-rich shale specimens are the least sensitive to the water-based fracturing fluids,followed by the clay-rich and carbonate-rich shale formations.Based on in situ morphological and mineralogical identification,the primary factors for the mechanical degradation induced by water-based fluids include carbonate dissolution,clay swelling,and pyrite oxidation.Slight increases in the measured E and H and compression of porous clay aggregates were observed after treatment with ScCO_(2).The major factor contributing to the mechanical changes resulting from the exposure to scCO_(2) appears to be the competition between swelling caused by adsorption and compression of shale matrix.展开更多
Following votes by the Valanginian Working Group,the International Subcommission on Cretaceous Stratigraphy and the International Commission on Stratigraphy,the Executive Committee of the International Union of Geolog...Following votes by the Valanginian Working Group,the International Subcommission on Cretaceous Stratigraphy and the International Commission on Stratigraphy,the Executive Committee of the International Union of Geological Sciences unanimously approved in December 2024 the Global Stratotype Section and Point(GSSP)for the Valanginian Stage(Cretaceous System).展开更多
Deciphering the kinematics of deformation is key to understand the crustal evolution.In the last decades several techniques have been developed to help constraining the timing of deformation.On one side geochronology ...Deciphering the kinematics of deformation is key to understand the crustal evolution.In the last decades several techniques have been developed to help constraining the timing of deformation.On one side geochronology techniques allow the dating of a wider range of minerals with higher spatial resolution.On the other side thermochronology,with the help of numerical simulations(PeCube,QTQt…),help to constrain the rock exhumation history that is often linked to the vertical component of deformation.In both cases the deformation timing can accurately be discussed only together with a serious structural analysis.展开更多
In the recent years,exceptional fossil sites have revealed astonishing details on the anatomy,lifestyles and behaviour of Cambrian animals but surprisingly,very little is known about one of their most vital features,r...In the recent years,exceptional fossil sites have revealed astonishing details on the anatomy,lifestyles and behaviour of Cambrian animals but surprisingly,very little is known about one of their most vital features,reproduction.We describe here in situ eggs(clusters of 3 to 30 oocytes)in the tube-dwelling priapulid worm Paraselkirkia sinica from the Cambrian Stage 3 Xiaoshiba Lagerstätte(ca.514 Ma,South China).These oocytes were accommodated within paired tubular ovaries located in the posterior half of the primary body cavity as in modern meiobenthic priapulid worms,thus indicating that the general organization of female tubular gonads in priapulid worms has remained virtually unchanged for half a billion years.Our findings provide for the first time,key information on the reproductive organs and strategies of early ecdysozoans,a huge animal clade that dominated Cambrian marine ecosystems and accounts for a large part of today’s biodiversity(e.g.arthropods).Moreover,we also emphasize the critical role of ecology on the reproductive strategies and lifestyles of both modern and Cambrian worms.展开更多
Introduction,A better understanding the functioning of Earth System in the context of past climatic upheavals is essential for predictions about the fate of the diversity of life and the future of our society.The Inte...Introduction,A better understanding the functioning of Earth System in the context of past climatic upheavals is essential for predictions about the fate of the diversity of life and the future of our society.The International Geoscience Program(IGCP),a joint initiative of UNESCO and IUGS,serves as a knowledge hub to facilitate international scientific cooperation in the geosciences.One of the strategical themes of the IGCP is Global Change:evidence from the geological record,which perfectly applies to the project IGCP-655,Toarcian Oceanic Anoxic Event:Impact on marine carbon cycle and ecosystems.展开更多
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
Recent studies demonstrate that many avialan features evolved incrementally prior to the origin of the group,but the presence of some of these features,such as bird-like brooding behaviours,remains contentious in non-...Recent studies demonstrate that many avialan features evolved incrementally prior to the origin of the group,but the presence of some of these features,such as bird-like brooding behaviours,remains contentious in non-avialan dinosaurs.Here we report the first non-avialan dinosaur fossil known to preserve an adult skeleton atop an egg clutch that contains embryonic remains.The preserved positional relationship of the adult to the clutch,coupled with the advanced growth stages of the embryos and their high estimated incubation temperatures,provides strong support for the brooding hypothesis.Furthermore,embryos in the clutch are at different developmental stages,suggesting the presence of asynchronous hatching—a derived feature even among crown-group birds—in non-avialan theropods.These findings demonstrate that the evolution of reproductive biology along bird-line archosaurs was a complex rather than a linear and incremental process,and suggest that some aspects of non-avialan theropod reproduction were unique to these dinosaurs.展开更多
The shoot apical meristem （SAM）, which produces all the aerial parts of the plant, plays a major role in the establish- ment of plant architecture. In many higher plants, the SAM has a stereotypic organization in zo...The shoot apical meristem （SAM）, which produces all the aerial parts of the plant, plays a major role in the establish- ment of plant architecture. In many higher plants, the SAM has a stereotypic organization in zones with different func- tions. At the summit of the dome-shaped meristem is a popu- lation of stem cells （called the central zone）, required for meristem maintenance. Part of the cells produced by the central zone will enter a differentiation pathway and their descendants will serve as founders for the stems and lateral organs at the meristem periphery （or peripheral zone）. During the last decades, much of the research on the SAM has focused on three major signaling cascades required for its function：展开更多
基金funded by the Open Research Fund Programof State Key Laboratory of Hydroscience and Engineering(Project Number:sklhse-2023-D-04)the National Natural Science Foundation of China(Grant Nos.51979144,51661165015,and 51323014).
文摘Mechanical alterations in shale formations due to exposure to water-based fracturing fluids and supercritical carbon dioxide(ScCO_(2))significantly affect the performance of shale gas exploration and CO_(2) geo-sequestration.In this study,a hydrothermal(HT)reaction system was set up to treat Longmaxi shale samples of varying mineralogies(carbonate-,clay-,and quartz-rich)with different fluids,i.e.deionized(DI)water,2%potassium chloride(KCl)solution,and ScCO_(2) under HT conditions expected in shale formation.Statistical micro-indentation was conducted to characterize the mechanical property alterations caused by the shale-fluid interactions.An in situ morphological and mineralogical identification technique that combines scanning electron microscopy(SEM)and backscattered electron(BSE)imaging with energy-dispersive X-ray spectroscopy(EDS)was used to analyze the microstructural and mineralogical changes of the treated shale samples.Results show no apparent changes in the Young's modulus,E,and hardness,H,after treatment with DI water under room temperature(20℃)and atmospheric pressure for 7 d.In contrast,E and H were decreased by 31.2%and 37.5%at elevated temperature(80℃)and pressure(8 MPa),respectively.The addition of 2%KCl into DI water mitigated degradation of the mechanical properties.Quartz-rich shale specimens are the least sensitive to the water-based fracturing fluids,followed by the clay-rich and carbonate-rich shale formations.Based on in situ morphological and mineralogical identification,the primary factors for the mechanical degradation induced by water-based fluids include carbonate dissolution,clay swelling,and pyrite oxidation.Slight increases in the measured E and H and compression of porous clay aggregates were observed after treatment with ScCO_(2).The major factor contributing to the mechanical changes resulting from the exposure to scCO_(2) appears to be the competition between swelling caused by adsorption and compression of shale matrix.
基金support of a project(2021-2023)funded by the Polish and French Ministries of foreign affairs(Partenariat Hubert Curien,cf.the current palaeomagnetic study that also includes the contribution of Chmielewski Andrezj,Iwanczuk Jolanta and Ploch Izabela from the Polish Geological Institute of Warsaw,colleagues who are hereby thanked)the CNRS SYSTER program(WOAW SYSTER French project,with the contribution of two students Lea Baubant and Durel Franchevel who are acknowledged),Project APVV-20-0079(Slovakian National Grant Agency,thanks to Diana Olveczka)and various grants from the Laboratoire de Geologie de Lyon.
文摘Following votes by the Valanginian Working Group,the International Subcommission on Cretaceous Stratigraphy and the International Commission on Stratigraphy,the Executive Committee of the International Union of Geological Sciences unanimously approved in December 2024 the Global Stratotype Section and Point(GSSP)for the Valanginian Stage(Cretaceous System).
文摘Deciphering the kinematics of deformation is key to understand the crustal evolution.In the last decades several techniques have been developed to help constraining the timing of deformation.On one side geochronology techniques allow the dating of a wider range of minerals with higher spatial resolution.On the other side thermochronology,with the help of numerical simulations(PeCube,QTQt…),help to constrain the rock exhumation history that is often linked to the vertical component of deformation.In both cases the deformation timing can accurately be discussed only together with a serious structural analysis.
基金This study was supported by the National Natural Science Foundation of China(Grant No.41730318)to X.G.Z.and J.Y.the Innovative Research Fund for Graduate Students of Yunnan University(Grant No.2019228)to X.Y.Y.+1 种基金the ASSEMBLE,PRC(CNRS,France and NSFC,China)PAI(Univ.Lyon 1,Région Auvergne Rhône Alpes)grants to J.V.
文摘In the recent years,exceptional fossil sites have revealed astonishing details on the anatomy,lifestyles and behaviour of Cambrian animals but surprisingly,very little is known about one of their most vital features,reproduction.We describe here in situ eggs(clusters of 3 to 30 oocytes)in the tube-dwelling priapulid worm Paraselkirkia sinica from the Cambrian Stage 3 Xiaoshiba Lagerstätte(ca.514 Ma,South China).These oocytes were accommodated within paired tubular ovaries located in the posterior half of the primary body cavity as in modern meiobenthic priapulid worms,thus indicating that the general organization of female tubular gonads in priapulid worms has remained virtually unchanged for half a billion years.Our findings provide for the first time,key information on the reproductive organs and strategies of early ecdysozoans,a huge animal clade that dominated Cambrian marine ecosystems and accounts for a large part of today’s biodiversity(e.g.arthropods).Moreover,we also emphasize the critical role of ecology on the reproductive strategies and lifestyles of both modern and Cambrian worms.
文摘Introduction,A better understanding the functioning of Earth System in the context of past climatic upheavals is essential for predictions about the fate of the diversity of life and the future of our society.The International Geoscience Program(IGCP),a joint initiative of UNESCO and IUGS,serves as a knowledge hub to facilitate international scientific cooperation in the geosciences.One of the strategical themes of the IGCP is Global Change:evidence from the geological record,which perfectly applies to the project IGCP-655,Toarcian Oceanic Anoxic Event:Impact on marine carbon cycle and ecosystems.
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).
基金supported by the Double First-Class Joint Program of Yunnan Science and Technology Department and Yunnan University (2018FY001-005)the China-Myanmar Joint Laboratory for Ecological and Environmental Conservation+2 种基金the University of Hong Kong Faculty of Science RAE Improvement Fundsupported by the CNRS Program INSU INTERRVIEthe National Natural Science Foundation of China(41688103)。
文摘Recent studies demonstrate that many avialan features evolved incrementally prior to the origin of the group,but the presence of some of these features,such as bird-like brooding behaviours,remains contentious in non-avialan dinosaurs.Here we report the first non-avialan dinosaur fossil known to preserve an adult skeleton atop an egg clutch that contains embryonic remains.The preserved positional relationship of the adult to the clutch,coupled with the advanced growth stages of the embryos and their high estimated incubation temperatures,provides strong support for the brooding hypothesis.Furthermore,embryos in the clutch are at different developmental stages,suggesting the presence of asynchronous hatching—a derived feature even among crown-group birds—in non-avialan theropods.These findings demonstrate that the evolution of reproductive biology along bird-line archosaurs was a complex rather than a linear and incremental process,and suggest that some aspects of non-avialan theropod reproduction were unique to these dinosaurs.
文摘The shoot apical meristem （SAM）, which produces all the aerial parts of the plant, plays a major role in the establish- ment of plant architecture. In many higher plants, the SAM has a stereotypic organization in zones with different func- tions. At the summit of the dome-shaped meristem is a popu- lation of stem cells （called the central zone）, required for meristem maintenance. Part of the cells produced by the central zone will enter a differentiation pathway and their descendants will serve as founders for the stems and lateral organs at the meristem periphery （or peripheral zone）. During the last decades, much of the research on the SAM has focused on three major signaling cascades required for its function：
