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UDC (553.98.041:004.032.26):528.71 GEOLOGICAL AND GEOPHYSICAL PROGNOSIS OF A FERROMANGANESIAN ORE SOURCE OF THE BOTOMA-LYUTENGA FIELD IN THE BASEMENT OF THE YAKUTIAN LITHOSPHERIC BLOCK
G. N. Cherkasov, E. Yu. Goshko, S. S. Dolgushin, O. G. Sadur, A. S. Salnikov
The tectonic map of the North Asian craton basement shows two Archean terrains separated by the Aldanian and Yakutian orogenic belts, which were a mobile basin in the Proterozoic. The Never-Yakutsk- Khandyga - Agydalakh 3-DV deep seismic profile runs along the junction of the orogenic belts. The frequencyenergy section analysis («StreamSDS» software system) has shown that the mobile basin was formed in the Moho discontinuity gap. During Proterozoic and Neogene it was filled with carbonate-terrigenous-igneous material with some involvement of mantle fluids. On the south-western edge of the orogenic belt the 3-DV profi le intersects the Southern Aldan iron-ore region with its Tayozhinsky and Dyos-Savgelsky ore clusters. The north-eastern edge of the orogenic belt hosts the Early Mesozoic Botoma-Lyutenga Fe-Mn ore field situated symmetrically about the Southern-Aldan region. The genesis of the ore field can be considered from different points of view: the ores can be sedimentary, hydrothermal, or re-deposited weathering crust products. The authors consider the Botoma-Lyutenga ore field just to be superimposed on the primary iron-ore deposit and assume that the ores from the former originate from the latter. The primary deposit ores are hosted by the basement rocks and are syngenetic to the ores of the Southern-Aldan region. Thickness of the subore Vendian-Cambrian strata under the Botoma-Lyutenga field down to the Archean basement is variously estimated from 150 to 1,300 m. Ore genesis analogous to the Botoma-Lyutenga ores was examined at the Neogene-Quaternary Tya Fe-Mn ore show. The Tya and Botoma-Lyutenga ores are identical in mineralogy, chemical composition, and mode of occurrence at the surface. An assumption about the primary deposit in the basement that may be the source of ore components during the Botoma-Lyutenga ore field formation can be supported by the magnetic model of the field cross-section.
Key words: Aldanian orogenic belt, Yakutian orogenic belt, ferromagnesian ores, the Botoma-Lyutenga ore field, magnetic model of cross-section, jaspilite, terrains, faults.
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