Geodynamic Emplacement Setting of Late Jurassic Dikes of the Yana-Kolyma Gold Belt, NE Folded Framing of the Siberian Craton: Geochemical, Petrologic, and U-Pb Zircon Data

We present the results of geostructural, mineralogic-petrographic, geochemical, and U-Pb geochronological investigations of mafic, intermediate, and felsic igneous rocks from dikes in the Yana-Kolyma gold belt of the Verkhoyansk-Kolyma folded area (northeastern Asia). The dikes of the Vyun deposit and the Shumniy occurrence intruding Mesozoic terrigenous rocks of the Kular-Nera and Polousniy-Debin terranes were examined in detail. The dikes had diverse mineralogical and petrographic compositions including trachybasalts, andesites, trachyandesites, dacites, and granodiorites. The rocks showed significant similarities in distributions of REE, and their concentrations of most HFSEs were close to the intermediate ones between ocean islands basalts and enriched middle ocean ridge basalts. We propose that the subduction that was ongoing during the collision of the Kolyma-Omolon superterrane with Siberia led to melting in the asthenospheric wedge and in the lithosphere, which formed a mixed source for the dike systems from both an enriched and a depleted mantle source. The U-Pb SHRIMP-II dates obtained for the dikes corresponded to the Late Jurassic interval of 151-145 Ma. We present a geodynamic model for the northeastern margin of the Siberian Craton for the Tithonian age of the Late Jurassic.