The trace fossil Zoophycos was enriched in the lower part of the Guadalupian Maokou Formation of Permian in Laibin, Guangxi of South China, and characterized by observable lamellae within its spreiten. Associated with...The trace fossil Zoophycos was enriched in the lower part of the Guadalupian Maokou Formation of Permian in Laibin, Guangxi of South China, and characterized by observable lamellae within its spreiten. Associated with these lamellae are the prolific coccus- and spirillum-shaped microbe fossils. These microbes morphologically identified are 0.4―3.0 μm in diameter or length. Molecular fossils, including normal alkanes (dominated by C18, without an odd-over-even predominance), acyclic isoprenoids (such as pristane (Pr) and phytane (Ph)), extended tricyclic terpanes, pentacyclic triterpanes, steranes, al-kylcyclohexanes, dibenzothiophenes, benzonaphthothiophenes, benzobisbenzothiophenes, were in-strumentally identified in the wackestone characterized by the occurrence of abundant Zoophycos (composite ichnofabric indices are 4) and crowded microbial fossils. The value of the Pr/Ph ratio is less than 1, indicative of a dysoxic condition. The identification of abundant sulfur compounds (the thio-phene series) related to the contribution of reductive sulfur favors the occurrence of sulphate-reducing bacteria. The association of abundant microbial colonies with microbial molecular fossils within the spreiten suggests that trace fossils Zoophycos would be a multifunctional garden carefully constructed by the Zoophycos-producer, where different microbial colonies were orderly and carefully planted and cultured in different minor lamellae within spreiten. Hence, it is proposed that the Zoophycos-producer symbiosed with microbial colonies on the mutual basis of food supply and the redox conditions.展开更多
Early Cretaceous succession of the Oued Fodda Formation in the Ouarsenis Mountains(northwestern Algeria) is mainly composed of marl—limestone alternations, which are subdivided into four informal units(Units 1 to 4),...Early Cretaceous succession of the Oued Fodda Formation in the Ouarsenis Mountains(northwestern Algeria) is mainly composed of marl—limestone alternations, which are subdivided into four informal units(Units 1 to 4), based on distinct lithological, stratonomical, and ichnological features. The ichnological analysis reveals a low diversity of the trace-fossil assemblage, which is exclusively reported from Units 2 and 3.The ichnoassemblage contains six ichnotaxa(Chondrites intricatus, Ophiomorpha isp., Planolites isp., Thalassinoides isp., Zoophycos brianteus, and Zoophycos cauda-galli), among which Zoophycos and Chondrites are the most common elements of the assemblage and occur in distinct mud-rich substrates showing different bioturbation intensities. The development of Zoophycos in the middle part of Unit 2 shows a high degree of bioturbation(bioturbation index(BI) = 4). Zoophycos specimens are of large size, between 45 cm and 75 cm in width, which were interpreted to have formed in a lower offshore environment where the oxygenation amount was optimal, the sedimentation rate was low, and the benthic food was abundant on the seafloor. Toward the upper part of Unit 2, Zoophycos-bearing levels exhibit a less intense degree of bioturbation(BI between 1 and2) in contrast to Planolites-and Chondrites-bearing levels which have a bioturbation index(BI) between 3 and4. At these levels, Zoophycos displays relatively small, coiled to U-shaped spreiten, probably in response to stressful and dysoxic conditions prevailing in the water bottom. With improved oxygenation in a quiet lower offshore to shelf margin environment in Unit 3, the benthic organisms recovered, as represented by medium to large size Zoophycos in association with Ophiomorpha and scarce Chondrites burrows, even if the overall bioturbation intensity is very low. The combination of trace-fossil assemblage and lithofacies of the Oued Fodda Formation indicates relatively stable outer shelf environments below the storm wave base, which corresponds classically to the lower offshore to shelf edge environments, and the prevailing palaeoecological conditions are optimal and stressful for the benthic organisms.展开更多
Many kinds of ichnofossil Zoophycos occur commonly in the carbonate rocks of Pennsylvanian to Cisuralian Taiyuan Formation in North China. In this study, carbonate microbodies types were identified in four differently...Many kinds of ichnofossil Zoophycos occur commonly in the carbonate rocks of Pennsylvanian to Cisuralian Taiyuan Formation in North China. In this study, carbonate microbodies types were identified in four differently-colored fillings of Zoophycos using scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. Based on the morphologic characteristics, these carbonate microbodies can be divided into three groups, i.e., spheroids, framboids and rhabditiforms. According to the structural features of surface and individual or aggregate morphologies, the three groups can be further subdivided into thirteen types： （1） smooth spheroids; （2） spheroids with tiny thorns; （3） spheroids with a finely granulated surface; （4） spheroids with a flocculent surface; （5） spheroids with a vermiform surface; （6） framboid monomers; （7） framboid colonies; （8） linear smooth rhabditiform bodies; （9） smooth rhabditiform bodies with expanding ends; （10） biserial rhabditiform bodies; （11） spiral rhabditiform bodies; （12） thorny rhabditiform bodies; and （13） branched rhabditiform bodies. This paper not only describes the morphology, composition and occurrence of the various carbonate microbodies, but also discusses their possible microbial genesis, as follows： （1） carbonate spherical microbodies most likely were generated after globular bacterial cells had been fully displaced by minerals; （2） framboid monomers and colonies corresponding to the morphology of biogenic strawberry （or raspberry） pyrite, with their appearance and internal structure possibly inheriting the morphology of microbial cells, were indirectly generated by some microenvironmental changes due to microbial activity; （3） the morphological features, size, occurrences and preservation of filamentous and rhabditiform microbodies indicate that they may be biogenic structures, and possibly mineralized microbial fossils; and （4） some kind of symbiotic relationship exists between microbial action and the Zoophycos trace-makers. Besides, the differently-colored fillings of Zoophycos are most likely closely related to differences in the composition of microbial taxa, which in turn reflect different microenvironmental conditions.展开更多
基金the Special Project of Basic Research of China (Grant No. 2005CCA05000)the National Natural Science Foundation of China (Grant Nos. 40472020, 40621002 and 40525008)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 2004000127) other projects (Grant Nos. IRT0546 and G0800-06-ZS-319)
文摘The trace fossil Zoophycos was enriched in the lower part of the Guadalupian Maokou Formation of Permian in Laibin, Guangxi of South China, and characterized by observable lamellae within its spreiten. Associated with these lamellae are the prolific coccus- and spirillum-shaped microbe fossils. These microbes morphologically identified are 0.4―3.0 μm in diameter or length. Molecular fossils, including normal alkanes (dominated by C18, without an odd-over-even predominance), acyclic isoprenoids (such as pristane (Pr) and phytane (Ph)), extended tricyclic terpanes, pentacyclic triterpanes, steranes, al-kylcyclohexanes, dibenzothiophenes, benzonaphthothiophenes, benzobisbenzothiophenes, were in-strumentally identified in the wackestone characterized by the occurrence of abundant Zoophycos (composite ichnofabric indices are 4) and crowded microbial fossils. The value of the Pr/Ph ratio is less than 1, indicative of a dysoxic condition. The identification of abundant sulfur compounds (the thio-phene series) related to the contribution of reductive sulfur favors the occurrence of sulphate-reducing bacteria. The association of abundant microbial colonies with microbial molecular fossils within the spreiten suggests that trace fossils Zoophycos would be a multifunctional garden carefully constructed by the Zoophycos-producer, where different microbial colonies were orderly and carefully planted and cultured in different minor lamellae within spreiten. Hence, it is proposed that the Zoophycos-producer symbiosed with microbial colonies on the mutual basis of food supply and the redox conditions.
基金supported by the General Directorate of Scientific Research and Technological Development“DGRSDT”(Algeria) to Imad Bouchemla and Madani Benyoucefthe Fundamental Research Funds for the Universities of Henan Province (NSFRF200340)+1 种基金the Program for Innovative Research Team (in Science and Technology) of Henan Polytechnic University(T2022-5) to Li-Jun Zhang“Male Projekty 2022”(Faculty of Natural Sciences, University of Silesia in Katowice) to Mariusz A. Salamon。
文摘Early Cretaceous succession of the Oued Fodda Formation in the Ouarsenis Mountains(northwestern Algeria) is mainly composed of marl—limestone alternations, which are subdivided into four informal units(Units 1 to 4), based on distinct lithological, stratonomical, and ichnological features. The ichnological analysis reveals a low diversity of the trace-fossil assemblage, which is exclusively reported from Units 2 and 3.The ichnoassemblage contains six ichnotaxa(Chondrites intricatus, Ophiomorpha isp., Planolites isp., Thalassinoides isp., Zoophycos brianteus, and Zoophycos cauda-galli), among which Zoophycos and Chondrites are the most common elements of the assemblage and occur in distinct mud-rich substrates showing different bioturbation intensities. The development of Zoophycos in the middle part of Unit 2 shows a high degree of bioturbation(bioturbation index(BI) = 4). Zoophycos specimens are of large size, between 45 cm and 75 cm in width, which were interpreted to have formed in a lower offshore environment where the oxygenation amount was optimal, the sedimentation rate was low, and the benthic food was abundant on the seafloor. Toward the upper part of Unit 2, Zoophycos-bearing levels exhibit a less intense degree of bioturbation(BI between 1 and2) in contrast to Planolites-and Chondrites-bearing levels which have a bioturbation index(BI) between 3 and4. At these levels, Zoophycos displays relatively small, coiled to U-shaped spreiten, probably in response to stressful and dysoxic conditions prevailing in the water bottom. With improved oxygenation in a quiet lower offshore to shelf margin environment in Unit 3, the benthic organisms recovered, as represented by medium to large size Zoophycos in association with Ophiomorpha and scarce Chondrites burrows, even if the overall bioturbation intensity is very low. The combination of trace-fossil assemblage and lithofacies of the Oued Fodda Formation indicates relatively stable outer shelf environments below the storm wave base, which corresponds classically to the lower offshore to shelf edge environments, and the prevailing palaeoecological conditions are optimal and stressful for the benthic organisms.
基金jointly supported by the National Natural Science Foundation of China(Grant No.41772104)the Basic and Frontiers Research Program of Henan Province(Grant No.162300410256)the Doctor Foundation of Henan Polytechnic University(Grant No.B2013-075)
文摘Many kinds of ichnofossil Zoophycos occur commonly in the carbonate rocks of Pennsylvanian to Cisuralian Taiyuan Formation in North China. In this study, carbonate microbodies types were identified in four differently-colored fillings of Zoophycos using scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. Based on the morphologic characteristics, these carbonate microbodies can be divided into three groups, i.e., spheroids, framboids and rhabditiforms. According to the structural features of surface and individual or aggregate morphologies, the three groups can be further subdivided into thirteen types： （1） smooth spheroids; （2） spheroids with tiny thorns; （3） spheroids with a finely granulated surface; （4） spheroids with a flocculent surface; （5） spheroids with a vermiform surface; （6） framboid monomers; （7） framboid colonies; （8） linear smooth rhabditiform bodies; （9） smooth rhabditiform bodies with expanding ends; （10） biserial rhabditiform bodies; （11） spiral rhabditiform bodies; （12） thorny rhabditiform bodies; and （13） branched rhabditiform bodies. This paper not only describes the morphology, composition and occurrence of the various carbonate microbodies, but also discusses their possible microbial genesis, as follows： （1） carbonate spherical microbodies most likely were generated after globular bacterial cells had been fully displaced by minerals; （2） framboid monomers and colonies corresponding to the morphology of biogenic strawberry （or raspberry） pyrite, with their appearance and internal structure possibly inheriting the morphology of microbial cells, were indirectly generated by some microenvironmental changes due to microbial activity; （3） the morphological features, size, occurrences and preservation of filamentous and rhabditiform microbodies indicate that they may be biogenic structures, and possibly mineralized microbial fossils; and （4） some kind of symbiotic relationship exists between microbial action and the Zoophycos trace-makers. Besides, the differently-colored fillings of Zoophycos are most likely closely related to differences in the composition of microbial taxa, which in turn reflect different microenvironmental conditions.
