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Vol 51, No 6 (2016)

Article

The Latnenskoe refractory clay deposit (Central Russia)

Bortnikov N.S., Savko A.D., Novikov V.M., Boeva N.M., Soboleva S.V., Zhegallo E.A., Dmitriev D.I., Krainov A.V., Zhukhlistov A.P., Bushueva E.B.

Abstract

This paper reports the results of our recent studies and generalizes previously known data on the geology, mineralogy, geochemistry, and genesis of the Russia’s largest Latnenskoe refractory clay deposit. It is shown that conditions of its localization were defined by regional and local factors. The regional factors controlled the distribution of the clay raw material in the region, while the local factors were responsible for the genesis and composition of refractory clays of the Latnenskoe deposit. Our studies showed that the formation of refractory clays is not only related to terrigenous but also to authigenic processes of sedimentation. The terrigenous component of clays was formed by the erosion of kaolin weathering crusts of the Voronezh anteclise crystalline basement and Paleozoic sedimentary hydromica–kaolinite rocks. Authigenic processes were significantly contributed by organic matter, which determined the environmental pH and Eh parameters. It is established that the mineral matter of clays of the deposit is represented by three morphological modifications (crystalline, amorphous, and biomorphic), which were formed subsequently and (or) simultaneously and could be transformed into each other. Application of a complex of modern precision methods allowed us to reveal a previously unknown biomorphic modification of kaolinite, the major rock-forming mineral, as well as mixed-layer kaolinite-smectite in the clays. It is shown that the distribution of major and trace elements and the sulfur isotope composition in different technological types of clay depend mainly on the facies conditions of their formation. Technological properties of clay raw material are considered.

Lithology and Mineral Resources. 2016;51(6):425-438
pages 425-438 views

Hydrothermal alterations of the chemical composition in grain size fractions of sediments in the Guaymas Basin, Gulf of California

Kurnosov V.B., Konovalov Y.I.

Abstract

The paper presents data on the contents of macro- and microelements (rare earth elements included) determined in grain size fractions of the Upper Pleistocene hydrothermally altered and unaltered sediments from the Guaymas Basin (Gulf of California). Sediments subjected to high-temperature hydrothermal alteration were recovered by DSDP Hole 477A. In the finely dispersed fractions, which are mainly composed of clay minerals, alteration of the chemical composition was provoked by the hydrothermal transformation of terrigenous clay minerals. The concentration of microelements in these fractions takes place primarily at the cost of the hydrothermal finely dispersed ore minerals. Alteration of the chemical composition of the coarse-grained fractions is related to the replacement of clastogenic minerals by the secondary varieties and the formation of new minerals (including ore minerals and native metals) from the solutions. Hydrothermal alterations of the chemical composition of bulk samples depend on the degree of chemical element concentration in fractions and their content in samples.

Lithology and Mineral Resources. 2016;51(6):439-466
pages 439-466 views

Noble metal specialization of Lower and Middle Riphean terrigenous rocks in the South Urals

Kovalev S.G., Maslov A.V., Gareev E.Z.

Abstract

Results of the study of noble metal specialization of Lower and Middle Riphean terrigenous rocks in the Bashkir Anticlinorium (South Urals) are reported. The study revealed their genetic differences in the relatively unaltered, i.e., “background” terrigenous rocks in type sections of the Burzyan and Yurmatau groups and in sedimentary rocks of the same stratigraphic levels from tectonic zones subjected to local dynamothermal metamorphism of the greenschist facies and intruded by mafic rocks. It has been established that Ru serves as a geochemical marker of the impact of magmatic processes on sedimentary rocks and the redistribution of noble metals during metamorphism and local metasomatism. A generalized model is proposed for the formation of noble metal geochemical specialization of Lower and Middle Riphean terrigenous rocks in the South Urals.

Lithology and Mineral Resources. 2016;51(6):467-483
pages 467-483 views

Structure and stages in development of the cataplatform cover in the Central Russian‒Belomorian province

Chamov N.P.

Abstract

The results of correlation between seismic sequences (based on the CMP data) and lithostratigraphic units (based on drilling data) of the preplate sedimentary section are discussed. By the structure and interrelations of seismic sequences, as well composition and facies features of lithological varieties, three successive stages in the formation of the cataplatform cover of the province are recognizable: (1) main stage of the graben formation in the Central Russian and White Sea‒Pinega regions; (2) terminal stage of the graben formation‒initial stage of postrift subsidence in all regions; (3) the formation of a ‘protosyneclise” (non-riftogenic depression) in the Orsha region. The model for explaining the formation of the Orsha depression is proposed.

Lithology and Mineral Resources. 2016;51(6):484-499
pages 484-499 views

Geochemical features, depositional settings, and provenances of Lower Paleozoic rocks in the Mamyn terrane, Central Asian Fold Belt

Smirnova Y.N., Sorokin A.A., Popeko L.I.

Abstract

New data on geochemical features of the Lower Paleozoic terrigenous rocks in the Mamyn terrane (eastern Central Asian Fold Belt) and U–Pb geochronological studies of the detrital zircon from these rocks are presented. The obtained results suggest the following conclusions. 1. At present, the Kosmataya sequence includes different age Lower Cambrian terrigenous–carbonate and Lower Ordovician terrigenous rocks or represents Lower Ordovician olistostromes including limestone blocks with the Lower Cambrian fauna. Lower Ordovician terrigenous rocks were formed in an island arc or active continental margin, mainly, owing to the erosion of Cambrian–Early Ordovician plutons and volcanics that are widespread in structures of the Mamyn terrane and weakly reworked by the chemical weathering. 2. The Silurian Mamyn Formation was developed at a passive continental margin. The main sources of clastic material for this formation were the same Cambrian–Early Ordovician igneous rocks as for the Cambrian sequence, with the participation of Early Silurian and Vendian igneous complexes. The obtained data significantly refine concepts about the geological structure of the Mamyn terrane, which is a member of the Argun Superterrane, one of the largest tectonic structures in the eastern Central Asian Fold Belt.

Lithology and Mineral Resources. 2016;51(6):500-517
pages 500-517 views