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Feldspathoidal rocks from the Cainozoic volcanic province of Ethiopia

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Zusammenfassung

Das Vorkommen von Feldspatoidgestein im Vulkangebiet des Känozoikums von Äthiopien wird besprochen. Ijolit und Melanephelinit werden zum erstenmal von diesem Gebiet beschrieben.

Die enge Verbindung zwischen Gräben überquerenden, transversalen Verwerfungen und der Lage des peralkalischen Gesteins, einschließlich der feldspatoidischen Varietäten, wird betont. Kein Feldspatoidgestein ist innerhalb des äthiopischen Grabensystems bekannt; sein Vorkommen ist auf das Innere der Plateaus von Äthiopien und Somalien beschränkt.

Abstract

A review of the occurrence of feldspathoidal rocks in the Cainozoic volcanic province of Ethiopia is given. Ijolite and melanephelinite are described for the first time from this province.

The close relationship between cross-rift transcurrent faults and situation of peralkaline rocks, including the feldspathoidal varieties, is emphasized. No feldspathoidal rocks are known from within the Ethopian rift system, being restricted to the interiors of the Ethiopian and Somalian plateaux.

Résumé

La présence de roches feldspathoidiques dans la région volcanique cainozoique de l'Éthiopie est considérée. L'ijolite et la mélanéphélinite de cette région sont décrites pour la première fois.

L'étroite relation entre failles transversales croisant un graben et la disposition de roches peralcalines, en particulier des variétés feldspathoidiques, est soulignée. Aucun spécimen de roche feldspathoidique n'est connu provenant de l'intérieur du graben éthiopien, ces roches ne se trouvant que dans les plateaux de l'Éthiopie et de la Somalie.

Краткое содержание

Дан обзор расположен ия фельдшпатоидных п ород в Кайнозое вулканичес кой области Эфиопии. Впер вые описывается иоло ит и меланефелинит. Подчеркивается непо средственное соотно шение между разломами в грабенах и местополо жением щелочных поро д, в том числе и фельдшпатоидных. В сборосовом грабене Эфиопии нет никаких фельдшпатоидных пор од, они встречаются толь ко на плоскогорьях Эф иопии и Сомали.

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Author notes

  1. M. J. Le Bas

    Present address: Department of Geology, The University of Leicester, LE1 7RH, Leicester, England

  2. P. A. Mohr

    Present address: Smithsonian Inst. Astrophysical Obs., 60 Garden Street, 02138, Cambridge, Mass., USA

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    1. M. J. Le Bas
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    2. P. A. Mohr
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    Le Bas, M.J., Mohr, P.A. Feldspathoidal rocks from the Cainozoic volcanic province of Ethiopia. Geol Rundsch 58, 273–280 (1968). https://doi.org/10.1007/BF01820608

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