Heterogeneity Of The Sources Of Clastic Material Of Terrigenic Rocks Of The Tauhin Accretion Complex (Sikhote-Alin) At Early Stages Of Its Formation

The paper presents data from geochemical and isotopic studies of the sandstones of the upper structural level of the Taukhinsky accretionary complex (Ustinovsky subterrane) of South Sikhote-Alin, exposed in two discrete areas of its distribution: southern and northern area.The studies showed a sharp difference in geochemical characteristics and, as a consequence, the sources of the turbidite clastic material of two areas. Sandstones of the northern range are characterized by high silicic acid, low levels of femic components and moderate alkalis. They are poorly depleted in comparison with PAAS incompatible elements and have Paleoproterozoic (approximate to 2 billion years) model Nd ages. According to the compositional features, the turbidites of the southern area correspond to lithogenic rocks - erosion products of recycled orogens with a noticeable admixture of acidic petrogenic material.Sandstones of the southern area have lower silica contents, are relatively enriched with femic components and calcium, have lower concentrations of incompatible elements, and young (0.94 billion years) model Nd ages. In terms of material characteristics, they correspond to petrogenic rocks - products of volcanic arcs erosion of medium acid composition.The difference in the sources of clastic material for the two areas is also indicated by distinct discrete trends in the evolution of the rare-element composition of rocks with a change in their siliceous content. From which it can be concluded that the differences in the material composition are due to the different compositions of the feeding provinces, and not to different fractions of the same spectrum of rocks in the source of clastic material.The synthesis of new data and the results of previous studies prove that the early stage of the formation of the Taukhinsky accretion complex was not accompanied by synchronous volcanic activity. Terrigenous rocks had local sources of clastic material, different for the rocks of the northern and southern areas.