| Summary: | RESULTS OF PETROGRAPHIC STUDIES ON ICELANDIC VOLCANIC ROCKS AND THE MODERN CONCEPT OF STRUCTURE OF THE EARTH CRUST AND MANTLE Summary The importance of petrological studies on volcanic phenomena in Iceland for the developments in geotectonic ideas is emphasized and geology, volcanism and petrology of lavas known from Iceland are briefly discussed. Two models were proposed in order to explain origin of acid magmas in Iceland and their cooccurrence with tholeiitic ones: 1) model of secondary, partional melting of water-saturated basalts, and 2) model of partial melting of plagiogranite layer in the basement. The nature of volcanic phenomena in Iceland, anomafous for the Mid-Atlantic Ridge, is emphasized and hypotheses explaining this phenomenon are presented. The Authors emphasize the presence of "basalt pillow" beneath axial part of the oceanic ridge and discuss the Earth crust and mantle models based on geochemical data. Attention is especially paid to the Schilling's model of mantle plum.
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