Geochemistry of Late Proterozoic volcanic rocks from Tassendjanet area (N.W. Hoggar,Algeria) |
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| Authors: | M Chikhaoui C Dupuy J Dostal |
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| Institution: | (1) Department des Sciences de la Terre, Faculte des Sciences, 2, rue Didouche Mourad, Alger, Algeria;(2) Centre Géologique et Geophysique, U.S.T.L., Montpellier, France;(3) Department of Geology, Saint Mary's University, Halifax, Nova Scotia, Canada |
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| Abstract: | The Late Proterozoic calc-alkaline andesitic rocks of the Tassendjanet volcanic complex, north-western Hoggar, Algeria resemble the continental margin rocks and also are closely comparable to the Archaean andesites. Most Tassendjanet rocks were affected to various extents by low grade hydrous metamorphism which led to an increase of Na, P, Fe, Ti, and V and a decrease of Mg, Ca, Sr, Cr, and Ni. Although K, Rb, Ba, and Li are enriched in the majority of altered rocks, these elements are strongly depleted in the albitized Na-rich volcanics. REE are enriched in albitized andesites but their fractionation patterns remain unchanged. The trace element data are consistent with the derivation of the Tassendjanet andesites by partial melting of an upper mantle source enriched in LILE and presumably overlying the subduction zone. |
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