Atlas of the textural patterns of basic and ultrabasic rocks and their genetic significance / Атлас текстур основных и ультраосновных горных пород и их генетическое значение

The recent progress in geodynamics has revolutionised our concept regarding the genesis of ultrabasic and basic rocks. In contrast to the explanation that the ultrabasics are differentiation products of a basaltic magma, mantle diapirism or oceanic crust-upper mantle obductions are put forward as explanations for the origin of ultrabasic complexes and rock types.

Parallel with the progress in geodynamics, progress in the petrofabric analysis of rocks has established the ultrametamorphic origin of rock types that were previously regarded to be magmatic (plutonic). Petrofabric analysis based on comparative microstructural studies provided a compounding amount of information in support of the ultrametamorphic origin of granites (see F.K. Drescher-Kaden, 1948, 1969, and S.S. Augustithis, 1973).

In a comparable and commensurable way present petrofabric analyses show evidence of an ultrametamorphic origin of a number of basic and ultrabasic rocks referred to as paragabbros and para norites, which were previously considered to be magmatic-plutonic.

However, realising that in addition to the mantle derivatives, and to the ultrametamorphic rock types, rock products of consolidation from melts exist, the present Atlas has as an aim to study and also present the magmatogenic textural patterns found in volcanic and subvolcanic basic and ultrabasic rocks, such as ophitic and spinifex textural patterns and the rocks in which they occur. A most extensive petrofabric analysis of magmatogenic textural patterns of basic rocks is presentedс in the "Atlas of the textural patterns of basalts and their genetic significance" (Augustithis, 1978).

There is therefore a limitation in the present Atlas as far as the presentation of basaltic textures is concerned. <...>