Evolution of the accumulation of titan-zircon placers of the Earth history

Abstract

Introduction: a large number of publications are devoted to the study of titan-zircon placers. In these works, the geology, material composition, genesis of placers, as well as their role as a source of strategic types of mineral raw materials are examined in detail. At the same time, the evolution of the accumulation of titan-zircon placers, with rare exceptions, remained unexplored. Filling this gap is proposed in this article.

Methodology: when writing the work, numerous literary and own sources were used, containing information on titan-zircon placers. The main methods of research were comparative lithological, stratigraphic, formation, facies, as well as factor analysis.

Results and discussion: in the history of the Earth, the accumulation of placers occurred constantly. A study of the distribution of their reserves on a stratigraphic scale showed that from the late Archean to the present, the formation of the placers in question occurred constantly. But the vast majority of industrial placers have been known since the Middle Devonian. The following stages of concentration of titan-zircon minerals are distinguished: 1 − Pre-Middle Devonian, 2 − Middle Devonian-Early Carboniferous, 3 − Late Triassic-Middle Jurassic, 4 − Cretaceous, 5 − Cenozoic. The first stage includes the "history" of the formation of titan-zircon accumulations, when at different stratigraphic levels for a long time there was an accumulation of mainly non-industrial concentrations of the metals in question. A feature of the placers of the second stage is the noticeable influence of the endogenous factor on their formation. This is expressed in the appearance in the demolition sources of significant volumes of igneous rocks with accessions, the flow of explosive ore material into sedimentation basins. The imposition of metamorphism processes on placers, as it was on Timan, led to a change and redistribution of titan minerals. The third stage, unlike the previous one, is characterized by a close connection between placers and the large-scale Late Triassic-Early Jurassic era of powerful coring. This led to the appearance of the first eluvial deposits of the metals in question and placers of their near transport. But the main reserves of titan and zircon were still concentrated in long-range transport deposits. At the fourth stage, after the Cimmerian orogeny, CVs were formed in the Late Jurassic-Early Cretaceous and planation of territories, during the erosion of which in the Barremian-Aptian time, titan-zircon placers of near transport began to form in monomineral quartz sands. Extensive transgressions with deepening of marine basins in the Late Cretaceous determined the formation of placers of long-range transport in glauconite-quartz sands. The last stage is characterized by the largest formation of titan-zircon placers in the history of the Earth, especially Oligocene-Miocene and modern ones. This is caused by a number of favorable factors. Among them are the widespread development of CVs, especially in warm climate zones, a sharp increase in the length of coastlines, frequent changes in hydrodynamic regimes as a result of transgressions and regressions, relief contrast, which contributes to the removal of large volumes of terrigenous material with heavy minerals into sedimentation basins.

Conclusions: in general, the evolution of placer formation is cyclically directed. The focus is expressed in an increase in the reserves of titan and zircon metals over time, especially in the Cenozoic, and cyclical – in the presence of stages of a combination of factors favorable for placer formation.