Les caractères magmatiques du volcanisme plio-quaternaire des Andes dans le Sud du Pérou |
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| Authors: | C Lefèvre |
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| Institution: | (1) R. C. P. 132, Laboratoire de Pétrologie, U.S.T.L., Montpellier, France |
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| Abstract: | Chemical data on late cenozoic lavas (83 new analyses) from southern of Peru indicate a zonal arrangement of lavas types according to their distance from the trench. The nearest belong to a calc-alkaline suite and the farthest are shoshonites rocks. The calc-alkaline rocks show progressive increase in K2O content and in K2O/Na2O ratio in northeastern direction. The shoshonitic rocks are more potassic and titaniferous, and the K2O/Na2O ratio is approximatively constant. The potash content of the two series correlate with the depth of the inclined seismic zone beneath the volcanoes, but this correlation is less well established than in island arcs. |
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