俄罗斯阿尔丹地块南部辉长-斜长岩杂岩体的构造-物质组分特点及其演化

Ｋａｌａｒｓｋｙ岩体是沿阿尔丹南部边缘分布的规模巨大的ＤｊｕｇｄｊｕｒＫａｌａｒｓｋｙ辉长－斜长岩岩带的一部分。本文研究了代表典型地球早期（前寒武纪）发展史、在行星水准上发育的这个特殊杂岩体的构造－物质组分、形成的阶段性及其继后构造演化。辉长－斜长岩杂岩体产于前寒武纪克拉通化地块交接处及其褶皱的流动性较高的框架中。该杂岩体由两个岩浆岩共生组合组成：硅铝质（斜长岩及辉长－斜长岩）及镁铁质（基性－超基性岩）。体积上前者明显小于后者。这两个岩石共生组合的锶同位素比值都特别低，说明其原始岩浆的地幔属性，是在一个相对宁静的背景中在早期分异出来的产物。辉长－斜长岩杂岩体的演化明显分３个阶段：早期是圈闭结晶岩并将其极度加热的阶段，是庞大的具对称构造的地块的形成阶段；中期是地块的最终固结阶段，在此期间发生了褶皱变形，是高压变质作用的初期阶段；晚期是发生刚性变形，形成辉长－斜长杂岩岩体的岩浆岩岩墙群、链状构造及雁行构造，并发生最大高压变质作用的阶段。文中对与辉长－斜长岩杂岩体共生的似榴辉岩也进行了探讨。

STRUCTURAL MATERIAL PECULIARITIES AND EVOLUTION OF GABBRO ANORTHOSITE COMPLEXES OF THE ALDEN MASSIF, SOUTH RUSSIA

The Kalarsky massif is a constituent part of the extensive Djugdjur Kalarsky gabbro anorthosite belt, confined to the southern periphery of the Aldan massif. It exemplifies the structural material composition, stage recurrence of the formation, and subsequent tectonic evolution of specific complexes, developing on a planetary level and typical of the early (Precambrian) history of the Earth. Gabbro anorthosite complexes originate at the junction of cratonitized Precambrian blocks and their fold framing of relatively high mobility. Their composition is marked by two associations: salic (anorthosites and gabbro anorthosites) and mafic (basite hyperbasites). The salic association of magmatic rocks is notably less voluminous than the mafic one. The extremely low strontium isotope ratios of any component of these associations evidence in favour of mantle nature of the primary melt that was differentiated at earlier stages in a relatively tranquil setting. The evolution of gabbro anorthosite complexes is distinguished by three stages. The early stage concurs with extension and maximum heating of the enclosing crystalline rocks, and with the formation of symmetrically structured enormous massifs. The middle stage witnesses final consolidation of the massifs, their participation in fold deformations, which coincide with the initial stages of high P metamorphism. Rigid deformations (late stage) are related to the reconstruction of the structural plan, the formation of extensive clusters, chains and echelons of magmatic rocks of gabbro anorthosite complexes, and to maximum high P metamorphism. Eclogite like rocks that paragenetically related to the formation of gabbro anorthosite complexes are examined.