A hierarchical sequential Gaussian cosimulation method is applied in this study for modeling the variables with an inequality constraint in the bivariate relationship. An algorithm is improved by embedding an inverse transform sampling technique in the second simulation to reproduce bivariate complexity and accelerate the process of cosimulation. A heterotopic simple cokriging (SCK) is also proposed, which introduces two moving neighborhoods: single and multiple searching strategies in both steps of the hierarchical process. The proposed algorithm is tested over a real case study from an iron deposit where iron and aluminum oxide shows a strong bivariate dependency as well as a sharp inequality constraint. The results showed that the proposed hierarchical cosimulation with a multiple searching strategy provides satisfying results compared to the case when a single searching strategy is employed. Moreover, the proposed algorithm is compared to the conventional hierarchical cosimulation, which does not implement the inverse transform sampling integrated into the second simulation. The proposed methodology successfully reproduces inequality constraint, while conventional hierarchical cosimulation fails in this regard. However, it is demonstrated that the proposed methodology requires further improvement for better reproduction of global statistics (i.e., mean and standard deviation).
{"title":"Assessing heterotopic searching strategy in hierarchical cosimulation for modeling the variables with inequality constraints","authors":"Sultan Abulkhair, N. Madani","doi":"10.5802/CRGEOS.58","DOIUrl":"https://doi.org/10.5802/CRGEOS.58","url":null,"abstract":"A hierarchical sequential Gaussian cosimulation method is applied in this study for modeling the variables with an inequality constraint in the bivariate relationship. An algorithm is improved by embedding an inverse transform sampling technique in the second simulation to reproduce bivariate complexity and accelerate the process of cosimulation. A heterotopic simple cokriging (SCK) is also proposed, which introduces two moving neighborhoods: single and multiple searching strategies in both steps of the hierarchical process. The proposed algorithm is tested over a real case study from an iron deposit where iron and aluminum oxide shows a strong bivariate dependency as well as a sharp inequality constraint. The results showed that the proposed hierarchical cosimulation with a multiple searching strategy provides satisfying results compared to the case when a single searching strategy is employed. Moreover, the proposed algorithm is compared to the conventional hierarchical cosimulation, which does not implement the inverse transform sampling integrated into the second simulation. The proposed methodology successfully reproduces inequality constraint, while conventional hierarchical cosimulation fails in this regard. However, it is demonstrated that the proposed methodology requires further improvement for better reproduction of global statistics (i.e., mean and standard deviation).","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"353 1","pages":"115-134"},"PeriodicalIF":1.4,"publicationDate":"2021-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45247975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Badro, P. Sossi, Zhengbing Deng, S. Borensztajn, N. Wehr, F. Ryerson
We carried out evaporation experiments on a B-type calcium–aluminium-rich inclusion (CAI) melt in a gas-mixing aerodynamic levitation laser furnace, at 1873 K and an oxygen partial pressure of 10−9.1 atm, for durations ranging from 60 to 600 s. Evaporation of SiO2 and MgO follow the same trend as those observed in vacuum furnace experiments at the same temperature and starting composition, showing that their evaporation relative to one another from the melt is independent of pressure, oxygen fugacity, and hydrodynamical regime specific to the furnace. Isotopic ratios of Mg and Si in evaporation residues are used to derive fractionation factors of αMgvap−liq = 0.9906± 0.0004 and αSivap−liq = 0.9943± 0.0003, which are both significantly closer to unity than those found for evaporation in a vacuum, which translates to less isotope fractionation. The residues are also less isotopically fractionated than expected for cases in which transport of the gas species away from the melt is diffusion-controlled at 1-atm. By analysing the flow regimes in our furnace, we find that advection by the levitating gas is the primary mode of mass transport away from the melt surface, as opposed to diffusion-limited transport in a vacuum or 1-atm tube furnace. A modified Hertz– Knudsen–Langmuir formulation accounts for this process, and shows that isotopic fractionation of both Si and Mg reflect a saturation factor (ratio of the pressure of the evaporating species to vapour saturation pressure) equal to 0.75. This is in perfect accord with recent measurements of Cu isotopic fractionation using a similar furnace. The fact that three elements (Mg, Si, Cu) with varying equilibrium vapour pressures, activity coefficients in the liquid, and diffusion coefficients in the gas have the same scaling behaviour to saturation pressure is a strong indication that the mechanism controlling evaporation is driven by the hydrodynamical regime imposed in the furnace. Therefore, this class of experiments can be used to constrain processes in which advection dominates over ∗Corresponding author. ISSN (electronic) : 1778-7025 https://comptes-rendus.academie-sciences.fr/geoscience/ 102 James Badro et al. diffusion, such as (but not limited to) planetary ejecta, tektites, giant impacts, nebular condensation in a turbulent flow, or nuclear fallout material. Finally, the possibility to reach high temperatures (in excess of 3500 K) in this furnace allows it to be used to evaluate the activity coefficients of melt components in extreme conditions relevant to molten planetary interiors (i.e., magma oceans), with a specific focus on refractory elements.
{"title":"Experimental investigation of elemental and isotopic evaporation processes by laser heating in an aerodynamic levitation furnace","authors":"J. Badro, P. Sossi, Zhengbing Deng, S. Borensztajn, N. Wehr, F. Ryerson","doi":"10.5802/CRGEOS.56","DOIUrl":"https://doi.org/10.5802/CRGEOS.56","url":null,"abstract":"We carried out evaporation experiments on a B-type calcium–aluminium-rich inclusion (CAI) melt in a gas-mixing aerodynamic levitation laser furnace, at 1873 K and an oxygen partial pressure of 10−9.1 atm, for durations ranging from 60 to 600 s. Evaporation of SiO2 and MgO follow the same trend as those observed in vacuum furnace experiments at the same temperature and starting composition, showing that their evaporation relative to one another from the melt is independent of pressure, oxygen fugacity, and hydrodynamical regime specific to the furnace. Isotopic ratios of Mg and Si in evaporation residues are used to derive fractionation factors of αMgvap−liq = 0.9906± 0.0004 and αSivap−liq = 0.9943± 0.0003, which are both significantly closer to unity than those found for evaporation in a vacuum, which translates to less isotope fractionation. The residues are also less isotopically fractionated than expected for cases in which transport of the gas species away from the melt is diffusion-controlled at 1-atm. By analysing the flow regimes in our furnace, we find that advection by the levitating gas is the primary mode of mass transport away from the melt surface, as opposed to diffusion-limited transport in a vacuum or 1-atm tube furnace. A modified Hertz– Knudsen–Langmuir formulation accounts for this process, and shows that isotopic fractionation of both Si and Mg reflect a saturation factor (ratio of the pressure of the evaporating species to vapour saturation pressure) equal to 0.75. This is in perfect accord with recent measurements of Cu isotopic fractionation using a similar furnace. The fact that three elements (Mg, Si, Cu) with varying equilibrium vapour pressures, activity coefficients in the liquid, and diffusion coefficients in the gas have the same scaling behaviour to saturation pressure is a strong indication that the mechanism controlling evaporation is driven by the hydrodynamical regime imposed in the furnace. Therefore, this class of experiments can be used to constrain processes in which advection dominates over ∗Corresponding author. ISSN (electronic) : 1778-7025 https://comptes-rendus.academie-sciences.fr/geoscience/ 102 James Badro et al. diffusion, such as (but not limited to) planetary ejecta, tektites, giant impacts, nebular condensation in a turbulent flow, or nuclear fallout material. Finally, the possibility to reach high temperatures (in excess of 3500 K) in this furnace allows it to be used to evaluate the activity coefficients of melt components in extreme conditions relevant to molten planetary interiors (i.e., magma oceans), with a specific focus on refractory elements.","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"353 1","pages":"101-114"},"PeriodicalIF":1.4,"publicationDate":"2021-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42662637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Pastre, É. Debard, Catherine Ferrier, M. Fialin, B. Gély, Bertrand Kervazo, Frédéric Maksud, F. Mokadem, S. Nomade, N. Rividi, Ségolène Saulnier-Copard
A cryptotephra belonging to the Upper Pleistocene volcanism of the Bas-Vivarais was identified for the first time in the sedimentary infilling of the entrance area of the Chauvet-Pont d’Arc cave. This slightly reworked tephra fall is characterized by its heavy minerals assemblage, among which magnesian olivine, enstatite, and chromian diopside issued from peridotites and olivine and diopside of basaltic origin. This composition likely refers to a phreatomagmatic eruption of a maar crater. The 14C datings of the cryptotephra beds are contemporaneous with the Aurignacian settlement and paintings, that is, an age slightly older or close to 36 ka. Among the maar craters from the Bas-Vivarais, the Ray-Pic maar have the closest 40Ar/39Ar age (36.2±11.3/32.2±11.1 ka). By contrast, the Vestide du Pal, the biggest maar crater of this country, seems to have a younger age, but the 40Ar/39Ar dating was measured on a basalt which could have occurred later and been the source of the tephra fall, since its tephras contain the same minerals of unknown origin as those found in Chauvet cave. This discovery strengthens the previous hypothesis according to which the humans living in the Chauvet-Pont d’Arc area during the Upper Paleolithic have witnessed eruptions from the Bas-Vivarais volcanic field and
在Chauvet-Pont d’arc岩洞入口的沉积充填中，首次发现了下维瓦莱地区上更新世火山活动的隐层。这片经过轻微改造的毛毡落具有重矿物组合的特点，其中镁质橄榄石、顽辉石、铬质透辉石来自橄榄岩，而橄榄石和透辉石则来自玄武岩。这种成分可能是指一个maar火山口的呼吸岩浆喷发。隐毯层的14C测年与奥里尼亚纪的聚落和绘画是同时期的，即年龄稍早或接近36ka。其中，Ray-Pic陨石坑具有最接近的40Ar/39Ar年龄(36.2±11.3/32.2±11.1 ka)。相比之下，这个国家最大的马尔陨石坑Vestide du Pal似乎有一个更年轻的年龄，但40Ar/39Ar的年代测定是在玄武岩上进行的，该玄武岩可能是后来发生的，并且是tephra坠落的来源，因为它的tephras含有与Chauvet洞穴中发现的相同的未知来源的矿物质。这一发现加强了先前的假设，即旧石器时代晚期生活在肖韦-阿克桥地区的人类目睹了下维瓦莱火山场和火山喷发
{"title":"A cryptotephra from the Upper Pleistocene volcanism of the Bas-Vivarais in the sedimentary infilling of the Chauvet-Pont d’Arc cave (Ardèche, France)","authors":"J. Pastre, É. Debard, Catherine Ferrier, M. Fialin, B. Gély, Bertrand Kervazo, Frédéric Maksud, F. Mokadem, S. Nomade, N. Rividi, Ségolène Saulnier-Copard","doi":"10.5802/CRGEOS.52","DOIUrl":"https://doi.org/10.5802/CRGEOS.52","url":null,"abstract":"A cryptotephra belonging to the Upper Pleistocene volcanism of the Bas-Vivarais was identified for the first time in the sedimentary infilling of the entrance area of the Chauvet-Pont d’Arc cave. This slightly reworked tephra fall is characterized by its heavy minerals assemblage, among which magnesian olivine, enstatite, and chromian diopside issued from peridotites and olivine and diopside of basaltic origin. This composition likely refers to a phreatomagmatic eruption of a maar crater. The 14C datings of the cryptotephra beds are contemporaneous with the Aurignacian settlement and paintings, that is, an age slightly older or close to 36 ka. Among the maar craters from the Bas-Vivarais, the Ray-Pic maar have the closest 40Ar/39Ar age (36.2±11.3/32.2±11.1 ka). By contrast, the Vestide du Pal, the biggest maar crater of this country, seems to have a younger age, but the 40Ar/39Ar dating was measured on a basalt which could have occurred later and been the source of the tephra fall, since its tephras contain the same minerals of unknown origin as those found in Chauvet cave. This discovery strengthens the previous hypothesis according to which the humans living in the Chauvet-Pont d’Arc area during the Upper Paleolithic have witnessed eruptions from the Bas-Vivarais volcanic field and","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"353 1","pages":"67-79"},"PeriodicalIF":1.4,"publicationDate":"2021-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46319380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This manuscript presents the largest review of lead (Pb) content in bony fish collected worldwide. Lead analyses are assigned to specific species and localized using the Food and Agricultural Organization geographical fishing zones. The data set is expanded according to the number of analyses in each cohort leading to a record of 22190 and 5954 Pb concentrations for muscle and liver, respectively. Descriptive and comparative statistics demonstrate the usefulness of this chronicle to examine Pb content differences in bony fish from the Atlantic, Indian, Pacific oceans, and basins of the Mediterranean Sea. Investigation of distinct tissues are indicative of contaminated habitat imprints on metabolic Pb accumulation at global and regional scales. Muscle and liver Pb content from all mixed species are significantly correlated above 0.1 ppm (wet weight) suggesting a threshold above which liver metabolism may not efficiently balance uptake and excretion of Pb that accumulates more readily in both tissues. This review constitutes a prerequisite to monitor the effect of environmental policies on fish bioindicators, and to examine interand intraspecies responses to environmental Pb insult according to various habitats and biological factors.
{"title":"Lead abundances in bony fish from the world oceans: significance for contaminated marine habitats and environmental policies","authors":"A. Véron, Isabelle Bernier, B. Hamelin","doi":"10.5802/CRGEOS.49","DOIUrl":"https://doi.org/10.5802/CRGEOS.49","url":null,"abstract":"This manuscript presents the largest review of lead (Pb) content in bony fish collected worldwide. Lead analyses are assigned to specific species and localized using the Food and Agricultural Organization geographical fishing zones. The data set is expanded according to the number of analyses in each cohort leading to a record of 22190 and 5954 Pb concentrations for muscle and liver, respectively. Descriptive and comparative statistics demonstrate the usefulness of this chronicle to examine Pb content differences in bony fish from the Atlantic, Indian, Pacific oceans, and basins of the Mediterranean Sea. Investigation of distinct tissues are indicative of contaminated habitat imprints on metabolic Pb accumulation at global and regional scales. Muscle and liver Pb content from all mixed species are significantly correlated above 0.1 ppm (wet weight) suggesting a threshold above which liver metabolism may not efficiently balance uptake and excretion of Pb that accumulates more readily in both tissues. This review constitutes a prerequisite to monitor the effect of environmental policies on fish bioindicators, and to examine interand intraspecies responses to environmental Pb insult according to various habitats and biological factors.","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"353 1","pages":"37-54"},"PeriodicalIF":1.4,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45978763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Moynier, D. Fike, Gabrielle Menard, W. Fischer, J. Grotzinger, A. Agranier
The Ediacaran age (ca. 570 Ma) Shuram excursion, a ca. 12h depletion in δCcarb, may record a dramatic oxidation of marine sediments associated with a reorganization of Earth’s carbon cycle closely preceding the rise of large metazoans. However, several geochemical indicators suggest it may instead record secondary processes affecting the sediments such as post-depositional alteration. The stable isotopic composition of iron incorporated within carbonates (δFecarb) reveals an anomalous 56Fe-depletion (down to −1.05h) in strata containing the Shuram excursion, while the underlying and overlying strata have crustal δFecarb values. These depleted δ Fecarb data during the Shuram excursion reflect incomplete reduction of iron oxides, limited by low ambient organic carbon contents. This elevated pulse of sedimentary iron oxides would consume the majority of the limited pool of organic carbon and therefore would give rise to very low net organic carbon burial during a time of enhanced detrital delivery of oxidized iron to the sediments. These results imply a syndepositional origin for the Shuram excursion, which represents a shift in the redox composition of Earth’s sedimentary shell toward more oxidizing conditions, perhaps removing a long-lived buffer on atmospheric
{"title":"Iron isotopes and the redox evolution of Ediacaran sediments","authors":"F. Moynier, D. Fike, Gabrielle Menard, W. Fischer, J. Grotzinger, A. Agranier","doi":"10.5802/CRGEOS.44","DOIUrl":"https://doi.org/10.5802/CRGEOS.44","url":null,"abstract":"The Ediacaran age (ca. 570 Ma) Shuram excursion, a ca. 12h depletion in δCcarb, may record a dramatic oxidation of marine sediments associated with a reorganization of Earth’s carbon cycle closely preceding the rise of large metazoans. However, several geochemical indicators suggest it may instead record secondary processes affecting the sediments such as post-depositional alteration. The stable isotopic composition of iron incorporated within carbonates (δFecarb) reveals an anomalous 56Fe-depletion (down to −1.05h) in strata containing the Shuram excursion, while the underlying and overlying strata have crustal δFecarb values. These depleted δ Fecarb data during the Shuram excursion reflect incomplete reduction of iron oxides, limited by low ambient organic carbon contents. This elevated pulse of sedimentary iron oxides would consume the majority of the limited pool of organic carbon and therefore would give rise to very low net organic carbon burial during a time of enhanced detrital delivery of oxidized iron to the sediments. These results imply a syndepositional origin for the Shuram excursion, which represents a shift in the redox composition of Earth’s sedimentary shell toward more oxidizing conditions, perhaps removing a long-lived buffer on atmospheric","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"352 1","pages":"579-588"},"PeriodicalIF":1.4,"publicationDate":"2021-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43895174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sedimentological analysis has shown that during the syn-rift phase (Upper Triassic) the Mohammedia–Benslimane–ElGara–Berrechid basin (MBEB) is characterized by detrital and evaporite sediment filling. A gradual decrease of palaeoslope over time led to the evolution of paleoenvironments of proximal alluvial fans system to braided rivers and then to an anastomosing system. These environments evolve finally to an alluvial plain associated with a coastal plain where playa lakes, mudflats and lagoons had developed. We have identified fourteen genetic sequences which are included in four progradationalretrogradational minor cycles that are themselves grouped in one major cycle. These cycles are related to the variations of the base level. The dominance of the retrogradation phases giving an asymmetrical appearance to the cycles is related to the predominance of the base level rise. These variations are probably of allocyclic origin: tectonic and probably climatic, in relation with the Tethys and the Atlantic Ocean being opened.
{"title":"Sedimentological and sequence stratigraphy analyses of the syn-rift Triassic series of the Mohammedia–Benslimane–ElGara–Berrechid basin (Moroccan Meseta)","authors":"Abdelkrim Afenzar, R. Essamoud","doi":"10.5802/crgeos.36","DOIUrl":"https://doi.org/10.5802/crgeos.36","url":null,"abstract":"Sedimentological analysis has shown that during the syn-rift phase (Upper Triassic) the Mohammedia–Benslimane–ElGara–Berrechid basin (MBEB) is characterized by detrital and evaporite sediment filling. A gradual decrease of palaeoslope over time led to the evolution of paleoenvironments of proximal alluvial fans system to braided rivers and then to an anastomosing system. These environments evolve finally to an alluvial plain associated with a coastal plain where playa lakes, mudflats and lagoons had developed. We have identified fourteen genetic sequences which are included in four progradationalretrogradational minor cycles that are themselves grouped in one major cycle. These cycles are related to the variations of the base level. The dominance of the retrogradation phases giving an asymmetrical appearance to the cycles is related to the predominance of the base level rise. These variations are probably of allocyclic origin: tectonic and probably climatic, in relation with the Tethys and the Atlantic Ocean being opened.","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"352 1","pages":"417-441"},"PeriodicalIF":1.4,"publicationDate":"2021-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42462608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
U. Villanueva-Amadoz, Marycruz Gerwert Navarro, M. Juncal, J. Díez
This study addresses some of the stratigraphical problems of the Matzitzi Formation of Puebla and Oaxaca States in Mexico. The age assignment for this unit is controversial although most researchers today accept a Leonardian age (Kungurian, 279.3–272.3 Ma) based on the presence of the gigantopterid Lonesomia mexicana Weber. However, after re-examination of the holotype and two paratypes, the absence of diagnostic taxonomic characters prevents the assignment of this fossil type species to the gigantopterid group. Excluding the presence of gigantopterids in this formation, the macroflora seems to be Permian in age. Samples were collected for palynological analysis to determine the age of the formation. Studied palynological assemblages seem to be reworked and are represented by 18 fossil taxa assigned to the following genera: Calamospora, Deltoidospora, Densosporites, Granulatisporites, Laevigatosporites, Latipulvinites, Lophotriletes, Platysaccus, Punctatosporites, Raistrickia, Schopfipollenites, Thymospora, Triquitrites, Verrucosisporites, and Vesicaspora. Described palynomorphs are likely Late Pennsylvanian according to the presence of Latipulvinites kosankii and Thymospora thiessenii. The biostratigraphic and geochronologic age disparities should be solved in the future.
{"title":"Paleobotanical and palynological evidence for the age of the Matzitzi Formation, Mexico","authors":"U. Villanueva-Amadoz, Marycruz Gerwert Navarro, M. Juncal, J. Díez","doi":"10.5802/CRGEOS.33","DOIUrl":"https://doi.org/10.5802/CRGEOS.33","url":null,"abstract":"This study addresses some of the stratigraphical problems of the Matzitzi Formation of Puebla and Oaxaca States in Mexico. The age assignment for this unit is controversial although most researchers today accept a Leonardian age (Kungurian, 279.3–272.3 Ma) based on the presence of the gigantopterid Lonesomia mexicana Weber. However, after re-examination of the holotype and two paratypes, the absence of diagnostic taxonomic characters prevents the assignment of this fossil type species to the gigantopterid group. Excluding the presence of gigantopterids in this formation, the macroflora seems to be Permian in age. Samples were collected for palynological analysis to determine the age of the formation. Studied palynological assemblages seem to be reworked and are represented by 18 fossil taxa assigned to the following genera: Calamospora, Deltoidospora, Densosporites, Granulatisporites, Laevigatosporites, Latipulvinites, Lophotriletes, Platysaccus, Punctatosporites, Raistrickia, Schopfipollenites, Thymospora, Triquitrites, Verrucosisporites, and Vesicaspora. Described palynomorphs are likely Late Pennsylvanian according to the presence of Latipulvinites kosankii and Thymospora thiessenii. The biostratigraphic and geochronologic age disparities should be solved in the future.","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"352 1","pages":"515-538"},"PeriodicalIF":1.4,"publicationDate":"2021-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45921963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Anticiper l’évolution des territoires","authors":"H. L. Treut","doi":"10.5802/CRGEOS.32","DOIUrl":"https://doi.org/10.5802/CRGEOS.32","url":null,"abstract":"","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"352 1","pages":"329-337"},"PeriodicalIF":1.4,"publicationDate":"2021-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44790054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aucun État ne peut désormais relever à lui seul les défis globaux : terrorisme et corruption sans frontière, crises financières et sociales, sanitaires et écologiques, désastre humanitaire des migrations, changement climatique... Ce dernier n’est qu’un exemple parmi d’autres, mais c’est le phénomène qui a déclenché le plus de transformations dans le champ de la gouvernance mondiale. S’il devait entraîner le sursaut nécessaire, en ces temps de repli sur l’État nation, le changement climatique pourrait être une chance pour que l’humanité prenne conscience de son destin commun et s’adapte à la mondialisation. Les procès climatiques engagés sont déjà une sorte de laboratoire pour observer les dynamiques à l’œuvre.
{"title":"Le changement climatique, une chance pour l’humanité ?","authors":"M. Delmas-Marty","doi":"10.5802/CRGEOS.28","DOIUrl":"https://doi.org/10.5802/CRGEOS.28","url":null,"abstract":"Aucun État ne peut désormais relever à lui seul les défis globaux : terrorisme et corruption sans frontière, crises financières et sociales, sanitaires et écologiques, désastre humanitaire des migrations, changement climatique... Ce dernier n’est qu’un exemple parmi d’autres, mais c’est le phénomène qui a déclenché le plus de transformations dans le champ de la gouvernance mondiale. S’il devait entraîner le sursaut nécessaire, en ces temps de repli sur l’État nation, le changement climatique pourrait être une chance pour que l’humanité prenne conscience de son destin commun et s’adapte à la mondialisation. Les procès climatiques engagés sont déjà une sorte de laboratoire pour observer les dynamiques à l’œuvre.","PeriodicalId":50651,"journal":{"name":"Comptes Rendus Geoscience","volume":"352 1","pages":"279-283"},"PeriodicalIF":1.4,"publicationDate":"2021-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43146550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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