The extensive Late Mesozoic–Early Cenozoic sedimentary succession exposed within the James Ross Basin,Antarctica has huge potential to enhance paleobiological investigations into both the marine and terrestrial fossi...The extensive Late Mesozoic–Early Cenozoic sedimentary succession exposed within the James Ross Basin,Antarctica has huge potential to enhance paleobiological investigations into both the marine and terrestrial fossil records.In excess of 7 km in total thickness and spanning the Early Cretaceous(Aptian)–Late Eocene in age,it represents an invaluable high-latitude(~65°S)site for comparison with lower latitude,tropical ones in an essentially greenhouse world.The Early Cretaceous(Aptian–Albian)sequence is deep-water but there are indications of shallowing to inner shelf depths in both the Turonian and Coniacian stages.The first prolific shallow-water marine fauna occurs in the Santonian–Campanian Santa Marta Formation and this is followed by repeated occurrences through the later Campanian,Maastrichtian,Danian and Middle Eocene(Lutetian).In this study an attempt has been made to compare these Antarctic faunas directly with the well-known ones of the same age from the US Gulf Coast.Detailed comparisons made for three time slices,Late Maastrichtian,Danian and Middle Eocene,indicate that the Antarctic is characterised by both low taxonomic diversity and high levels of endemism.The James Ross Basin is providing important evidence to indicate that the highest southern latitudes have always been characterised by a distinctive temperate biota,even on a pre-glacial Earth.The roots of at least some elements of the modern Southern Ocean biota can be traced back to a Late Mesozoic–Early Cenozoic austral realm.展开更多
An osteosynthesis of the mandible should be called stable when this type of treatment does not need to be supported by intermaxillary fixation,without disturbing the healing process.In that intention,many techniques o...An osteosynthesis of the mandible should be called stable when this type of treatment does not need to be supported by intermaxillary fixation,without disturbing the healing process.In that intention,many techniques of osteosynthesis based on different concepts were proposed during the last century.A classification of these concepts was formulated.The adaptive osteosynthesis which is pragmatically i.e.empirical,wherein the goal is immobilizing the fracture by bringing the fragments together and fixing them with rigid screwed plates.The rigid compressive osteosynthesis which is an extrapolation of the ideas of Lane proposed in 1912.The stable dynamic elastic osteosynthesis whose principles,equipment and technique as their applications were developed exclusively through biomechanical studies.The basic principle was the recovery of mobility by neutralization of detrimental distraction stresses,and reestablishment of favorable compressive stresses providing dynamic physiological stimulations.The biomechanical characteristics of the plates and the screws made possible the use of the fixation of all types of fractures or orthognathic procedures in mandibular surgery.With the application of mini or microplates in other facial bones and the skull,the art of fracture treatment and of reconstructive surgery of the craniomaxillofacial skeleton,including orthognathic and reconstructive surgery with or without bone grafting,has profoundly changed.At the present time,metal plates are sometimes superseded by resorbable plates and screws.Nevertheless,the fundamental biomechanical principles of osteosynthesis and bone healing remain unchanged.展开更多
The Hejiazhuang pluton is located in the South Qinling Tectonic Belt （SQTB） in the north side of the MianxianLueyang Su ture Zone, and consists dominantly of granodiorites. LAICPMS zircon UPb dating and LuHf isotopi...The Hejiazhuang pluton is located in the South Qinling Tectonic Belt （SQTB） in the north side of the MianxianLueyang Su ture Zone, and consists dominantly of granodiorites. LAICPMS zircon UPb dating and LuHf isotopic analyses reveal that these granodiorites of the Hejiazhaung pluton emplaced at 248 Ma, and show a large variation in zircon eHt（t） values from 4.8 to 8.8. These granodiorite samples are attributed to highK to midK calcalkaline series, and characterized by high SiO2 （66.6±70.0%）, A1203 （15.04±16.10%） and Na20 （3.74±4.33%） concentrations, with high Mg# （54.2±61.7）. All samples have high Sr （627±751 ppm）, Cr （553±73 ppm） and Ni （17.2182 ppm）, but low Y （5.42-8.41 ppm） and Yb （0.59-0.74 ppm） concentrations with high Sr/Y ratios （84.90±120.66）. They also display highly fractionated REE patterns with （La/Yb）N ratios of 18.93-4.0 and positive Eu anomalies （0＂Eu=1.102.22） in the chondritenormalized REE patterns. In the primitive mantle normalized spidergrams, these samples exhibit enrichment in LILEs but depletion in Nb, Ta, P and Ti. These geochemical fea tures indicate that the granodioritic magma of the Hejiazhuang pluton was derived from the partial melting of hybrid sources comprising the subducted oceanic slab and sediments, and the melts were polluted by the mantle wedge materials during their ascent. The emplacement ages and petrogenesis of the Hejiazhuang pluton prove that the initial subduction of the Mianlue oceanic crust occurred at 248 Ma ago, and the SQTB was still under subduction tectonic setting in the Early Triassic.展开更多
基金Financial support from the UK Natural Environment Research Council is gratefully acknowledged, and in particular: NE/I005803/1
文摘The extensive Late Mesozoic–Early Cenozoic sedimentary succession exposed within the James Ross Basin,Antarctica has huge potential to enhance paleobiological investigations into both the marine and terrestrial fossil records.In excess of 7 km in total thickness and spanning the Early Cretaceous(Aptian)–Late Eocene in age,it represents an invaluable high-latitude(~65°S)site for comparison with lower latitude,tropical ones in an essentially greenhouse world.The Early Cretaceous(Aptian–Albian)sequence is deep-water but there are indications of shallowing to inner shelf depths in both the Turonian and Coniacian stages.The first prolific shallow-water marine fauna occurs in the Santonian–Campanian Santa Marta Formation and this is followed by repeated occurrences through the later Campanian,Maastrichtian,Danian and Middle Eocene(Lutetian).In this study an attempt has been made to compare these Antarctic faunas directly with the well-known ones of the same age from the US Gulf Coast.Detailed comparisons made for three time slices,Late Maastrichtian,Danian and Middle Eocene,indicate that the Antarctic is characterised by both low taxonomic diversity and high levels of endemism.The James Ross Basin is providing important evidence to indicate that the highest southern latitudes have always been characterised by a distinctive temperate biota,even on a pre-glacial Earth.The roots of at least some elements of the modern Southern Ocean biota can be traced back to a Late Mesozoic–Early Cenozoic austral realm.
文摘An osteosynthesis of the mandible should be called stable when this type of treatment does not need to be supported by intermaxillary fixation,without disturbing the healing process.In that intention,many techniques of osteosynthesis based on different concepts were proposed during the last century.A classification of these concepts was formulated.The adaptive osteosynthesis which is pragmatically i.e.empirical,wherein the goal is immobilizing the fracture by bringing the fragments together and fixing them with rigid screwed plates.The rigid compressive osteosynthesis which is an extrapolation of the ideas of Lane proposed in 1912.The stable dynamic elastic osteosynthesis whose principles,equipment and technique as their applications were developed exclusively through biomechanical studies.The basic principle was the recovery of mobility by neutralization of detrimental distraction stresses,and reestablishment of favorable compressive stresses providing dynamic physiological stimulations.The biomechanical characteristics of the plates and the screws made possible the use of the fixation of all types of fractures or orthognathic procedures in mandibular surgery.With the application of mini or microplates in other facial bones and the skull,the art of fracture treatment and of reconstructive surgery of the craniomaxillofacial skeleton,including orthognathic and reconstructive surgery with or without bone grafting,has profoundly changed.At the present time,metal plates are sometimes superseded by resorbable plates and screws.Nevertheless,the fundamental biomechanical principles of osteosynthesis and bone healing remain unchanged.
基金supported by National Key Technology R&D Program(Grant Nos.2011BAB04B05,2006BAB01A11)National Natural Science Foundation of China(Grant Nos.41072143,41072169)
文摘The Hejiazhuang pluton is located in the South Qinling Tectonic Belt （SQTB） in the north side of the MianxianLueyang Su ture Zone, and consists dominantly of granodiorites. LAICPMS zircon UPb dating and LuHf isotopic analyses reveal that these granodiorites of the Hejiazhaung pluton emplaced at 248 Ma, and show a large variation in zircon eHt（t） values from 4.8 to 8.8. These granodiorite samples are attributed to highK to midK calcalkaline series, and characterized by high SiO2 （66.6±70.0%）, A1203 （15.04±16.10%） and Na20 （3.74±4.33%） concentrations, with high Mg# （54.2±61.7）. All samples have high Sr （627±751 ppm）, Cr （553±73 ppm） and Ni （17.2182 ppm）, but low Y （5.42-8.41 ppm） and Yb （0.59-0.74 ppm） concentrations with high Sr/Y ratios （84.90±120.66）. They also display highly fractionated REE patterns with （La/Yb）N ratios of 18.93-4.0 and positive Eu anomalies （0＂Eu=1.102.22） in the chondritenormalized REE patterns. In the primitive mantle normalized spidergrams, these samples exhibit enrichment in LILEs but depletion in Nb, Ta, P and Ti. These geochemical fea tures indicate that the granodioritic magma of the Hejiazhuang pluton was derived from the partial melting of hybrid sources comprising the subducted oceanic slab and sediments, and the melts were polluted by the mantle wedge materials during their ascent. The emplacement ages and petrogenesis of the Hejiazhuang pluton prove that the initial subduction of the Mianlue oceanic crust occurred at 248 Ma ago, and the SQTB was still under subduction tectonic setting in the Early Triassic.
