Abstract Magma-wall-rock interaction contributes gases to evolving magmatic systems, and removes volatiles into the country rock. These processes happen at depth, far away from direct observation. Micro-analysis of particles collected from volcanic plumes can provide information about these processes. For Popocatépetl volcano, scanning electron microscope (SEM) and field emission gun SEM (FESEM/EDS) analysis of contact-metamorphosed particles from fallout ash reveal the presence of wollastonite, hercynite and glass of non-volcanic, contact-metamorphic origin. Condensates from the passively degassing plume show a wide variety of chemical elements and are rich in phosphorus, indicating a possible non-magmatic source for this element.

Abstract The Alps and Western Carpathians constitute that part of the Alpine-Mediterranean orogenic belt which advances furthest to the north into Central Europe. They were formed by a series of Jurassic to Tertiary subduction and collision events affecting several Mesozoic ocean basins, continental margins, and continental fragments. The Western Alps form a pronounced, westward-convex arc around which the strike of the tectonic units changes by almost 180° ( Fig. 18.1 ). The Western Carpathians are a northward-convex arc of similar size but with minor curvature. The two arcs are connected by an almost straight, WSW-ENE striking portion including the Eastern Alps Stresses produced by tectonic processes in the Alps also influenced the tectonics of large parts of central and northern Europe, leading, for example, to basin inversion and strike-slip faulting. In this chapter, we will discuss the present-day structure of the different tectonic units in the Alps and Western Carpathians in relation to their palaeotectonic history in order to illustrate the plate tectonic evolution using geological data. Many tectonic problems of the Alps and Western Carpathians are still unsolved, although dramatic progress has been made, especially over the last c. 20 years. Therefore, some of the interpretations presented below are still controversial and do not always express the opinion of all three authors. Given that the main theme of this book is Central Europe, the Southern and Western Alps are discussed in less detail than those parts of the Alps which belong to Central Europe: the Central Alps, the Eastern Alps and the Western Carpathians.