Structural Features of the Deep Structure of the Southeastern Yana-Kolyma Fold System From Complex Geophysical Data

Abstract

Ore deposits of the Magadan region are now in the focus of comprehensive studies as information on their deep structure is needed for both subsoil prospecting and regional development planning. This article presents the research results for the southeastern flank of the Yana-Kolyma orogenic belt. This area located at the junction with the Okhotsk-Koryak orogenic belt was investigated using the northeastern segment of the regional geophysical profile 3-DV. We analyzed the frequency-energy sections of the crust along the profile, 3D crustal density model of the entire study area, and magnetic, geoelectric and gravimagnetic characteristics of the crust. Complex data interpretation allowed tracing the crustal fault zones, areas wherein the crust material was strongly reworked, and zones of quasi-horizontal stratification. Considering the revealed features of the physical parameters of the crust material, we conclude that the currently accepted boundaries of individual tectonic blocks in the study area need to be adjusted. The northern boundary of the Balygychan uplift should be mapped along the Pautov fault. The Srednekansky branch of the Inyali-Debinsky synclinorium should be considered a transitional block that belongs to the Sugoi synclinorium, and its name should be changed to the Orotukan block.

Overview of early cretaceous gold mineralization in the orogenic belt of the eastern margin of the Siberian craton: geological and genetic features

“…The structural analysis shows their localization in connection with late sinistral strike-slip fault movements along these faults (Fridovsky et al, 2014). It should be noted that, according to geophysical data (Transects -Profiles 2-DV and 3-DV, and regional profiles), these faults can be traced in the YaKOB for the full thickness (42-48 km) of the Earth crust (Gayday et al, 2020). Besides, the spatial association of this mineralization with the occurrences of alkaline basaltoids and lamprophyres deep dikes, whose K-Ar dates (Indolev et al, 1980) coincide with Au-Sb ores, also attracts attention, and the only U-Pb SHRIMP date (126.0 ± 2.0 Ma) (Shpikerman et al, 2016) clearly corresponds to this stage.…”

“…Similarly van der Meer Douwe et al (2018) show that there is a slab that flattens out at a depth of about 600 km (according to one model) and about 400 km (according to another model), but the first tomographic model (U UP 07) notices the slab bifurcation and sort of superimposition of the young slab on the broken remains of the old UMA at depths of 1000-1400 km, while according to the second model, it is at depths of 500-800 km (upper + lower mantle model = SL2013+S40RTS). Documentation of slab remains under the areas of the Early Cretaceous gold-stibnite and gold orogenic-like deposits, the presence of crustal faults and areas of deformation of the Moho layer along the YaKOB strike (Gayday et al, 2020), mantle marks of associated Early Cretaceous magmatic bodies, specific nature of mineral composition and geochemical profile of ores suggest an active mantle influence on the origin of the deposits under discussion. The mantle wedge model implies the interaction of the mantle matter with the stagnant slab during its dehydration and the release of gold-bearing fluid flows.…”