В сборнике освещены основные вопросы литолого-страти- графического анализа докембрийских образований территории СССР, сделана первая попытка обобщить большой конкретный материал по геологии метаморфизованных осадочноэффузивных отложений докембрия и выяснить основные закономерности метаморфического рудообразования.
Представленные доклады охватывают широкий круг вопросов древнейшего осадконакопления и последующего преобразования осадков в условиях гранитизации и ультраметаморфизма в различные по составу сланцы, гнейсы и граниты. Даны важнейшие направления по методике изучения вещественного состава древних кор выветривания и условий их образования. Рассмотрена также методика картирования глубокометаморфизованных осадочно-эффузивных толщ докембрия.
Сборник рассчитан на широкий круг геологов, работающих в области геологии и полезных ископаемых докембрийских щитов.

General Statement. The aim of this book is to discuss the processes that operate during the deformation and metamorphismof rocks in the crust and upper lithosphere of the Earth with the goal of understanding how these processes control or influence the structures that we observe in the field.

It is very common to find that in mineral synthesis experiments the crystals that form first have disordered cations, even when the synthesis conditions are well within the stability field of the ordered state. Some examples are the crystallization of albite from glass starting material (MacKenzie, 1957) or a flux (Woensdregt, 1983), cordierite from glass (Schreyer and Schairer, 1961; Putnis, 1980a), and plagioclase from glass (Eberhard, 1967; Kroll and Muller, 1980).

Igneous rocks formed at relatively high temperatures of approximately 650° to 1200°C and sediments deposited at the earth's surface represent extreme ends of the temperature range realized in the processes of rock formation.

METAMORPHISM is the mineralogical and structural (textural) adjustment of (dominantly) solid rocks to physical and chemical conditions which differ from those under which the rocks originated. Weathering and similar processes are conventionally excluded. The type of metamorphism depends on the relative values of temperature ( T ) , confining pressure (/*con)> pressure or chemical activity or fugacity of water (expressed generally as PHJO)* deformation or directed pressures (P^ir) and their variation with time {t). There is only a limited degree of interdependence of these controls and the metamorphic history of a rock is an expression of their mutual interaction with time (Fyfe, Turner and Verhoogen, 1958; Pitcher and Flinn, 1965). <...>

The study of rocks in thin section using a petrographic microscope is an essential part of any undergraduate course in geology. This is the fourth volume in a series of photographic atlases of minerals and rocks in thin section. As in previous volumes the main purpose of the book is to provide the student with a handbook for use in practical classes to enable him or her to become familiar with the more common mineral associations and textures to be found in metamorphic rocks. In addition, some more unusual rocks which have given rise to particular significant ideas about metamorphism are also illustrated; the aim of this atlas is however to complement, not replace, a theoretical course in metamorphism.

The process of rock metamorphism changes the mineralogical and chemical composition, as well as the structure of rocks. Metamorphism is typically associated with elevated temperature and pressure; thus it affects rocks within the earth's crust and mantle. The process is driven by changing physical and or chemical conditions in response to large-scale geological dynamics.

Metamorphism is the sum of all transformations which cause a rearrangement of the elements of a rock at the atomic scale, leading to a recrystallization in the solid state (with or without a fluid phase), as a result of variations in temperature, pressure or of composition.

There are three categories of rocks- igneous, sedimentary and metamorphic. Igneous rocks have been formed by solidification of hot silicate melts known as magmas, which may be erupted at the Earth's surface as lavas from volcanoes. Sedimentary rocks form by a variety of processes at low temperatures near the surface, including the bottom of the seas and oceans. Metamorphic rocks, the third category, were originally either igneous or sedimentary, but their character has been changed by processes operating below the surface of the Earth. The constituent minerals of the rocks may be changed, or the shapes, sizes and mutual spatial relationships of the crystals may change. There are a variety of processes involved, and they are collectively described by the term metamorphism. <...>