Comparative analysis of Aptian–Albian rocks of the Kema and Kiselevka–Manoma terranes: Geochemistry, geochronology, and paleomagnetism

Abstract: The results of comprehensive (geological, geochemical, geochronological, and petro- and paleomagnetic) study of the Aptian–Albian rocks of the Kema Terrane and the northeastern Udyl segment of the Kiselevka–Manoma Terrane are presented. The obtained results suggest that the studied volcanogenic–terrigenous complexes of rocks formed in a suprasubduction zone at about the same time (early Albian, 110 Ma ago) at close latitudes but in different island arcs unequally distant from the continent: the complexes of the Kema Terrane at a latitude of 36° ± 6° N in the island arc close to the continent as evidenced by the petro–geochemical characteristics of the volcanites and the presence of ancient zircons in the sediments; and the rocks of the Udyl segment of the Kiselevka–Manoma Terrane at a latitude of 33° ± 5° N in an intraoceanic island arc separated from the volcanic arc of the Kema terrane by an interarc basin, which was wide and deep enough to avoid the influence of the continental source areas in the sediment accumulation zone of the Kiselevka–Manoma Terrane. Based on the conclusions, the geodynamic reconstruction is developed for the formation and history of motions of the studied rock complexes during the oceanic plate movement, their displacement along the transform margin, as well as post-accretionary movements at various distances to the current position with the following coordinates: Udyl 52° N, 140° E; Kema 45°–46° N, 136°–137° E.