Rocks of the late Neoproterozoic Askaoun pluton (558 ± 2 Ma) located in the Ouzellarh-Sirwa promontory (Anti-Atlas) include magmatic microgranular enclaves (MMEs) ranging from rounded to ovoid in shape, dark and ...Rocks of the late Neoproterozoic Askaoun pluton (558 ± 2 Ma) located in the Ouzellarh-Sirwa promontory (Anti-Atlas) include magmatic microgranular enclaves (MMEs) ranging from rounded to ovoid in shape, dark and fine grained and generally 5 to 10 cm in size, some reaching a size of 50 cm. They are composed of microdiorite, quartz microdiorite and micromonzodiorite, whereas the felsic host rocks comprise mainly quartz-diorite and amphibole-biotite granodiorite based on mineralogical compositions. The mineral assemblage is similar to those described in their hosting granitoids but with different proportions. In this study composition of minerals is used to describe the nature of the magma and estimate the pressure, temperature and oxygen fugacity at which Askaoun pluton is emplaced. Based on chemistry of biotite Askaoun pluton formed from calc-alkaline magma. Compositions of plagioclase (An5 - An29);hornblende (Mg ≠= 0.59 - 0.65) and biotite (Mg ≠= 0.49 - 0.55) of MMEs are slightly distinct or similar to those of host rocks (An7-40;hbl Mg ≠= 0.64 - 0.69;Bi Mg ≠= 0.49 - 0.50) which suggest partial to complete equilibration during mafic-felsic magma interaction. The coexisting hornblende and plagioclase (hornblende-plagioclase thermometry), Al content in hornblende (aluminum-in-hornblende barometry) and the assemblage titanite-magnetite-quartz were used to constrain the P, T and fO2 during the crystallization of the parent magmas. The Askaoun pluton was emplaced at temperature ca. 504°C - 633°C and at pressure ca. 0.9 - 4.66 ± 0.6 Kbars (average depth = 6.5 km) from a highly oxidized magma (log fO2 = ?24.8 to ?19.2).展开更多
The tympanic （Jacobson’s） nerve is a useful anatomi-cal structure in the middle ear with both practical and physiological functions extending beyond its origin. The paper reviews its clinical anatomy in adults and ...The tympanic （Jacobson’s） nerve is a useful anatomi-cal structure in the middle ear with both practical and physiological functions extending beyond its origin. The paper reviews its clinical anatomy in adults and its surgical signifcance. English language articles from 5 major databases and Google scholar search engine were used to identify papers outlining the anatomy of the tympanic nerve, associated pathology and surgical relevance. In the majority of cases the tympanic nerve arises from the inferior ganglion of the glossopharyn-geal nerve traversing through the tympanic canaliculus into the middle ear. On the promontory it coalesces with sympathetic fbres from the carotid chain forming the tympanic plexus which has individual variability. Functionally, as well as giving off parasympathetic fbres to the parotid gland via the lesser petrosal nerve, it is a useful anatomical landmark for cochlear implantation. The surgical importance of the tympanic nerve is not only restricted to middle ear surgery; it also extends to salivary gland disorders. The tympanic nerve remains clinically relevant to the modern otolaryngologist and as such a detailed understanding of its anatomy is crucial.展开更多
文摘Rocks of the late Neoproterozoic Askaoun pluton (558 ± 2 Ma) located in the Ouzellarh-Sirwa promontory (Anti-Atlas) include magmatic microgranular enclaves (MMEs) ranging from rounded to ovoid in shape, dark and fine grained and generally 5 to 10 cm in size, some reaching a size of 50 cm. They are composed of microdiorite, quartz microdiorite and micromonzodiorite, whereas the felsic host rocks comprise mainly quartz-diorite and amphibole-biotite granodiorite based on mineralogical compositions. The mineral assemblage is similar to those described in their hosting granitoids but with different proportions. In this study composition of minerals is used to describe the nature of the magma and estimate the pressure, temperature and oxygen fugacity at which Askaoun pluton is emplaced. Based on chemistry of biotite Askaoun pluton formed from calc-alkaline magma. Compositions of plagioclase (An5 - An29);hornblende (Mg ≠= 0.59 - 0.65) and biotite (Mg ≠= 0.49 - 0.55) of MMEs are slightly distinct or similar to those of host rocks (An7-40;hbl Mg ≠= 0.64 - 0.69;Bi Mg ≠= 0.49 - 0.50) which suggest partial to complete equilibration during mafic-felsic magma interaction. The coexisting hornblende and plagioclase (hornblende-plagioclase thermometry), Al content in hornblende (aluminum-in-hornblende barometry) and the assemblage titanite-magnetite-quartz were used to constrain the P, T and fO2 during the crystallization of the parent magmas. The Askaoun pluton was emplaced at temperature ca. 504°C - 633°C and at pressure ca. 0.9 - 4.66 ± 0.6 Kbars (average depth = 6.5 km) from a highly oxidized magma (log fO2 = ?24.8 to ?19.2).
文摘The tympanic （Jacobson’s） nerve is a useful anatomi-cal structure in the middle ear with both practical and physiological functions extending beyond its origin. The paper reviews its clinical anatomy in adults and its surgical signifcance. English language articles from 5 major databases and Google scholar search engine were used to identify papers outlining the anatomy of the tympanic nerve, associated pathology and surgical relevance. In the majority of cases the tympanic nerve arises from the inferior ganglion of the glossopharyn-geal nerve traversing through the tympanic canaliculus into the middle ear. On the promontory it coalesces with sympathetic fbres from the carotid chain forming the tympanic plexus which has individual variability. Functionally, as well as giving off parasympathetic fbres to the parotid gland via the lesser petrosal nerve, it is a useful anatomical landmark for cochlear implantation. The surgical importance of the tympanic nerve is not only restricted to middle ear surgery; it also extends to salivary gland disorders. The tympanic nerve remains clinically relevant to the modern otolaryngologist and as such a detailed understanding of its anatomy is crucial.
