Geological, Geodynamic, Morphostructural and Landscape Transformations in Amur Region, the Far East of Russia, at the Late Cretaceous–Early Paleogene Boundary

Geological and landscape transformations in Amur Region at the Late Cretaceous–Paleogene boundary were associated with movements of the Indian Plate with respect to the Eurasian Plate, which resulted in a setting of one-way compression in a northern direction under fluctuating acceleration and deceleration conditions. The influence of these changes on the structures of the Zeya–Bureya Basin was analyzed for the 85 to 64 Ma interval ranging from the Campanian to the Danian. Along the periphery of the basin, around 70 Ma, they caused a number of Maastrichtian sedimentation zones to contract with the formation of “crisis” structures, i.e., piedmont depressions and grabens dominated by coarse-grained gravel–cobble alluvial and mixed clayey–clastic proluvial sediments, which, under active sheet flood conditions, were transported by streams together with bones and body fragments of dinosaurs from the Bureya uplift to regions of their deposition and subsequent burial. In the central Zeya–Bureya basin, with the acceleration of the Indian Plate movements (60–50 Ma), crisis processes were associated with the dissection of lacustrine–alluvial plains, as well as the formation of ridges and swampy depressions, catastrophic floods, and forest and peat fires, which on the whole led to abrupt landscape degradation. The above crisis episodes in various geological and geodynamic settings were supplemented by specific events: volcanism, degassing, and possibly seismic events, which aggravated the negative situation in the Late Cretaceous to Early Paleogene stage.