Палеогеотермальний режим літогенезу та гіпогенного рудоутворення в межах балтійсько-дністровської перикратонної зони прогинів в рифеї-фанерозої

Derevska K. I. "Palaeothermal conditions of Riphean to Phanerozoic lithogenesis and ore formation within the Baltic-Dniester peri-cratonic belt". - Manuscript.

Doctor Science's Thesis in speciality 04.00.21 - lithology - Institute of Geological Sciences of the National Academy of Sciences of Ukraine, Kyiv, 2008.

This thesis is devoted to the sedimentary strata lithogenetic alterations and ore formation in the sedimentary basins (SB) of passive continental margin. Specifically author researched these processes within the Western margin ot the East-European Craton (EEC). The study involved system approach realized with the set of analyses, such as petrographic analysis (lithological stages defining), GFI study (thermal analysis, cryometry, gases chromatography) and stable isotope composition study.

Comprehensive study carried out allow to define the Riphean to Phanerozoic sedimentary rocks are altered with post-diagenesis (eometamorphic) processes nonuniformly. Its alteration degree is defined from medium to deep. Lithogenetic zonality of sedimentary strata is analysed in SB of various structural zones within the EEC Western margin.

The thesis contains definition of hydrothermal metasomatic host rock alterations as well as origin and features of ore mineralization in the Baltic-Dniester peri-cratonic belt. Fluid conditions of mineral formation process and genetic peculiarities of gas-fluid inclusions in neogenetic minerals both are characterized for all of SB within the EEC Western margin. Thermobaric and isotope-geochemical peculiarities of ore formation with the fluid-dynamical ore generating systems are defined for Baltic-Dniester peri-cratonic belt.

Mineralogical and petrographic peculiarities of volcanogenic rocks are described for both Vendian ones in the Rafalivka ore field and for Middle Riphean ones within the Dniester area. The principal agents of volcanogenic rocks post-magmatic alterations are defined. A few stages of this process (autometasomatic - parahydrothermal - hydrothermal) are categorized for Volynian volcanogenic series.

Thermobaric conditions of various grade lithogenetical host rock alterations and hypogene ore formation are correlated for ore mineralization of single barite-fluorite sulfide ore formation (wall rock alterations, ore bodies morphology, mineral zonality, sequence of mineral formation are studied). Palaeothermal conditions of ore formation process are restored for SB of various geological features within the EEC Western margin.

Palaeothermal conditions and the factors of its changes are restored for all stages of passive continental margin's Riphean to Phanerozoic geological history. Three principal thermal events related to the Caledonian, Variscan and Cimmerian cycles are displayed in the grades of sedimentary rocks eometamorphic alterations, its zonality and in the neogenetic minerals in the SB of EEC Western margin.

A new methodology proposed in this thesis allow to separate sedimentary rocks lithogenetical alterations from superposed hydrothermal-metasomatic ones, to define the mineral associations and its subsequent development, to clear the sources of ore matter and water of ore-forming solutions as well as flow direction for latter, to calculate the energy of both lithogenetic alteration and ore forming processes. Generally, this methodology allow to direct the mineral deposits prospecting.

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Палеогеотермальний режим літогенезу та гіпогенного рудоутворення в межах балтійсько-дністровської перикратонної зони прогинів в рифеї-фанерозої

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