Abstract:
The work deals with the mechanism of diatreme formation that is greatly controlled by formation of “magmatic corks” when magma rises to the surface. It explains: 1) manifestation of explosive effects that influence the peculiarities of rocks composing diatremes; 2) difference in peculiarities of rocks of different phases of intrusion in the same diatremes; 3) difference in the composition of different pipes and the occurence of xenoliths of country rocks not only at the edges of the diatremes but in their central parts as well; 4) existence of “blind pipes”. The assumption on the origin of pipes of different types of the same field from a singe vertical non-homogeneous magmatic hot-bed has been put forward. Difference in the rock composition and the degree of productivity of diatremes inside each field depends on the character of vertical non-homogeneity of the hot-bed that is related with lateral variability of sediments attracted into the subduction zone.