Metallogenic Evolution of Northeast Asia Related to the Cretaceous Turn of Geological Evolution

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Metallogenic Evolution of Northeast Asia Related to the Cretaceous Turn of Geological Evolution

Victor P. Nechaev, Frederick L. Sutherland and Eugenia V. Nechaeva

Abstract: This study tests the hypothesis of Cretaceous Turn of Geological Evolution (CTGE). It uses the large dataset on mineral deposits of NE Asia compiled by the US Geological Survey in collaboration with Russian, Mongolian, Korean, and Japanese geological institutions. As predicted, the Triassic–Early Jurassic and Late Cretaceous–Paleogene geodynamic activities in NE Asia were simple, producing a relatively small amount of mineral deposits (94 and 132, respectively). In contrast, the greatly increased geodynamic activity around CTGE produced a huge amount of mineral deposits (288). The Jurassic–Early Cretaceous superplume-related melts were injected into accretionary wedges that formed along the Pacific–Eurasian margins, whereas adakitic and granitic magmas derived from the shallow slab and lower crust were intruded into the huge intracontinental region. The characteristic mineral deposits are represented by the unique Jurassic–Early Cretaceous plume-related Ti-Fe-V (+P + Cr-PGE + Au + diamond) ores. Other CTGE representatives are the porphyry Cu-Mo and Au (+Ag)-vein deposits, which formation, however, continued into the Late Cretaceous–Paleogene epoch. These deposits were generated by the slab- and crust-derived adakitic and granitic melts formed under influence of the expiring superplume and intensifying subduction. The Late Cretaceous–Paleogene epoch is indicated by a decreasing metallogenic activity in general, and an increasing role of subduction-related deposits in particular.