Horsetails arose in the Late Devonian,evolved a greater diversity and forming fast growing bamboo-like thickets in the Carboniferous lowland swamp forest ecosystems.However,the diversity of this group drastically decl...Horsetails arose in the Late Devonian,evolved a greater diversity and forming fast growing bamboo-like thickets in the Carboniferous lowland swamp forest ecosystems.However,the diversity of this group drastically declined during the Permian while the climate became more dynamic and arid.Today only a single surviving genus exists,the herbaceous Equisetum.Here we report an exceptional large horsetail tree from the Early Permian Petrified Forest of Chemnitz.This fossil horsetail tree is assigned to Arthropitys bistriata (Cotta) Goeppert.It is 15 m high and over 25 cm in diameter,with thick wood and at least 3 orders of woody branching system formed a big canopy,and is morphologically very comparable with the living woody higher plants.This suggests that the plasticity mechanism of Permian calamitaleans enabled novel growth strategies when they competed with the rising gymnosperms during the environmental changes.展开更多
There are various faults in northern and southern margins of Torbat-e-Jam-Fariman plain which show the probability of enormous earthquake in the future.In present study the geomorphic indices contain Asymmetry Functio...There are various faults in northern and southern margins of Torbat-e-Jam-Fariman plain which show the probability of enormous earthquake in the future.In present study the geomorphic indices contain Asymmetry Function(Af),Sinuosity of mountain front(Smf),Valley floor index(Vf),Hypsometric index(Hi),Mean Axial slope of channel index(MASC)and Drainage Basin Shape(Bs),have been utilized to determine the relative tectonic activity index(IAT)to recognize,eventually,the geo-structural model of the study area.Faults and folds control the geo-structural activities of the study area,and the geomorphic indices are being affected in consequence of their activities.The intensity of these activities is different throughout the plain.There are many geomorphic evidences,related to active transform fault which are detectable all over the study area such as deviated rivers,quaternary sediments transformation,fault traces.Therefore,recognition of geo-structural model of the study area is extremely vital.Field study,then,approved the results of geomorphic indices calculation in determining the geo-structural model of the study area.Results depicted that the geostructural model of the study area is a kind of Horsetail splay form which is in accordance to the relative tectonic activity of the study area.Based on the above mentioned results it can be predicted that the splays are the trail of Neyshabour fault.展开更多
基金partially founded by the Volkswagen Foundation(Az.:I/84638)the National Natural Science Foundation of China(40902006and41172009)the Specialized Research Fund for the Doctoral Program of Higher Education(20095301120003)
文摘Horsetails arose in the Late Devonian,evolved a greater diversity and forming fast growing bamboo-like thickets in the Carboniferous lowland swamp forest ecosystems.However,the diversity of this group drastically declined during the Permian while the climate became more dynamic and arid.Today only a single surviving genus exists,the herbaceous Equisetum.Here we report an exceptional large horsetail tree from the Early Permian Petrified Forest of Chemnitz.This fossil horsetail tree is assigned to Arthropitys bistriata (Cotta) Goeppert.It is 15 m high and over 25 cm in diameter,with thick wood and at least 3 orders of woody branching system formed a big canopy,and is morphologically very comparable with the living woody higher plants.This suggests that the plasticity mechanism of Permian calamitaleans enabled novel growth strategies when they competed with the rising gymnosperms during the environmental changes.
文摘There are various faults in northern and southern margins of Torbat-e-Jam-Fariman plain which show the probability of enormous earthquake in the future.In present study the geomorphic indices contain Asymmetry Function(Af),Sinuosity of mountain front(Smf),Valley floor index(Vf),Hypsometric index(Hi),Mean Axial slope of channel index(MASC)and Drainage Basin Shape(Bs),have been utilized to determine the relative tectonic activity index(IAT)to recognize,eventually,the geo-structural model of the study area.Faults and folds control the geo-structural activities of the study area,and the geomorphic indices are being affected in consequence of their activities.The intensity of these activities is different throughout the plain.There are many geomorphic evidences,related to active transform fault which are detectable all over the study area such as deviated rivers,quaternary sediments transformation,fault traces.Therefore,recognition of geo-structural model of the study area is extremely vital.Field study,then,approved the results of geomorphic indices calculation in determining the geo-structural model of the study area.Results depicted that the geostructural model of the study area is a kind of Horsetail splay form which is in accordance to the relative tectonic activity of the study area.Based on the above mentioned results it can be predicted that the splays are the trail of Neyshabour fault.
