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Data on the composition, inner structure, and age of volcanic and siliceous-terrigenous complexes and granitoids occurring in association with them in the Caledonian Lake zone in Central Asia are discussed in the context of major relations and trends in the growth of the Caledonian continental crust in the Central Asian Foldbelt (CAFB). The folded structures of the Lake zone host basalt, basalt-andesite, and andesite complexes of volcanic rocks that were formed in distinct geodynamic environments. The volcanic rocks of the basalt complex are noted for high concentrations of TiO and alkalis, occur in association with fine-grained siliceous siltstone and siliceous-carbonate rocks, are thus close to oceanic-island complexes, and were likely formed in relation to a mantle hotspot activity far away from erosion regions supplying terrigenous material. The rocks of the basalt-andesite and andesite complexes have lower TiO concentrations and moderate concentrations of alkalis and contain rock-forming amphibole. These rocks are accompanied by rudaceous terrigenous sediments, which suggests their origin in island-arc environments, including arcs with a significantly dissected topography. These complexes are accompanied by siliceous-terrigenous sedimentary sequences whose inner structure is close to those of sediments in accretionary wedges. The folded Caledonides of the Lake zone passed through the following evolutionary phases. The island arcs started to develop at 570 Ma, their evolution was associated with the emplacement of layered gabbroids and tonalitetrondhjemite massifs, and continued until the onset of accretion at 515-480 Ma. The accretion was accompanied by the emplacement of large massifs of the tonalite-granodiorite-plagiogranite series. The postaccretionary evolutionary phase at 470-440 Ma of the Caledonides was marked by intrusive subalkaline and alkaline magmatism. The Caledonides are characterized by within-plate magmatic activity throughout their whole evolutionary history, a fact explained by the accretion of Vendian-Cambrian oceanic structures (island arcs, oceanic islands, and back-arc basins) above a mantle hotspot. Indicators of within-plate magmatic activity are subalkaline high-Ti basalts, alkaline-ultrabasic complexes with carbonatites and massifs of subalkaline and alkaline gabbroids, nepheline syenites, alkaline granites, subalkaline granites, and granosyenites. The mantle hotspot likely continued to affect the character of the lithospheric magmatism even after the Caledonian folded terrane was formed. [ABSTRACT FROM AUTHOR]

The article reports on the study which reveals the first data on the age of early Paleozoic Granitoids from the Malyi Khingan Terrane of the Central Asian Fold Belt in Russia. It notes that the combination of many continental massifs and small fold belts of different ages is the determiner of the principal structure of the Central Asian fold belt. It cites Bureya (Turan) and Malyi Khingan (Jiamusi), which represent the main element of Bureya-Jiamusi superterrane, as the most typical examples of the massifs. Accordingly, granitoids largely represents the Early Paleozoic igneous rocks of the Bureya-Jiamusi superterrane.

The article presents a study on two-feldspar of K-feldspar (sodium—potassium) mineralization on primary mineral leucosomes which are separated from anatectic migmatite formation timing. The study analyzed monazite-bearing post-tectonic dyke of granitoid in the Priozersk subzone in Ladoga region of Russia where isotopic methods were used to estimate formation time of typical quartz—K-feldspar margin. The results show that the K-feldspar crystals found at the subzone have morphological features analogous to migmatite leucosomes. Moreover, the uranium—lead (U-Pb) dating of zircon and monazite in leucosomes demonstrate the stages of anatectic melt crystallization of K-feldspar mineralization. It depicts that the evolution of leucosomes migmatite in the region was founded.

The results of investigations of the electronic energy structure and physicochemical properties of nanostructured systems by optical and photoelectron spectroscopy using synchrotron radiation are briefly reviewed. The quantum-size effect in thin metal films and surface lateral superlattices are analyzed. The effect of structural defects on the chemical state of metal clusters on the surface of oxides in catalytically active systems is discussed. The results of the study of the specific features of chemical bonding in solid-state nanostructures within the quasi-molecular approach are presented. The possibility of using biological structures (proteins) as matrices for the formation of ensembles of nanoclusters is considered. [ABSTRACT FROM AUTHOR]