DIGITAL STRUCTURAL-LITHOLOGICAL MODELS OF APTIAN–LOWER ALBIAN AND MIDDLE EOCENE CONTINENTAL PLACERS OF ILMENITE ON THE TERRITORY OF KORSUN-NOVOMYRHORODSKYI PLUTON

Abstract

Korsun-Novomyrhorodskyi pluton is the complex multiphase structure in the central part of the Ukrainian shield; it has a wide range of basic and acid rocks of anorthosite-rapakivigranite formation. The granitoid massifs – Korsun-Shevchenkivskyi in the northern part of the pluton and Shpolyanslyi in the southern one – are divided by latitu-dinal Smilyanska fractured zone. Several independent massifs are composed of basic rocks – anorthosites, gabbro and norite-anorthosites, gabbro-norites and their intermedi-ate differences. Basic rocks are characterized by increased ilmenite-bearingness: the contents of TiO2, depending on the type of rock ranges from 0.6 to 4.5 %. In consequence of relief peneplanation and intense chemical weathering under conditions of humid climate in the Late Jurassic–Early Cretaceous, a thick crust of weathering have been formed on the crystalline basement rocks with commercial content of ilmenite. There are several promising ilmenite placers: Birzulivskyi, Valuevskyi, Lypyanskyi etc. On the basis of digital structural-lithological modelling of placer deposits we have constructed appropriate models of the most promising placers, which cover a set of maps: (1) maps of the relief of bottom and surface of the productive deposits, (2) maps of the total capacity of Aptian–Lower Albian continental sediments, (3) maps of the il-menite-bearing lithotypes capacity, (4) maps of the spatial distribution of ilmenite con-tent in placers. It turned out that the commercial content of ilmenite is in the crust of weathering of basic crystalline rocks, Aptian-Lower Albian continental sediments (the product of re-deposition of eluvial formations) and Upper-Albian marine-coastal units (the product of erosion of the crust of weathering and rewashing of Aptian-Lower Albian continental deposits). On the basis of the revealed facts (the considerable amount of ilmenite, its high quality, various spatial-paragenetic combination as in indigenous sources and at differ-ent stratigraphic levels of the sedimentary cover), we can conclude that the investigated objects are attractive for investment.