Литосфера (Jan 2015)
Sedimentogenesis and geodynamics in the Cretaceous-Paleogene boundary at the epoch of continental peneplanation. Article 1. Central and Eastern Eurasia
Abstract
In Central and Northeast Eurasia, we describe the sedimentation and tectonic regime of a subglobal epoch of land peneplanation, which at the latest Cretaceous and at the earliest Paleogene covered all continents. It is usually associated with the regime of tectonic quiescence. However our researches determined that the time of vertical tectonic movement stabilization was accompanied by a sharp strengthening of crustal extension processes. In Central Eurasia, on the land platform (partly covered by sea), these processes led to relief planation, formation of weathering crust and products of its rewashing, activation of hydrothermal process, and in some cases (rather not often and locally) - to the appearance of predominantly basaltic volcanism spots. Synchronously mountainous landscape with areas of plain relief developed on the eastern mobile Pacific and Arctic margins of Eurasia, which are covered by Laramide tectogenesis. However, this areas are characterized by widespread crustal extension, whose intensity sharply increased (as compared with platform regions). This led to the formation of grabens and their extended belts, to mass inception of rifts, activation of basaltic volcanism. Sediments contain abundant clastic deposits, which make up intermountain molasses and fan formations which fill up the grabens among plain relief. It is shown that the mobile margin of the continent is characterized by processes of crustal compression, accompanied by orogenesis and folded deformations. However, compared with extension processes they played a minor role.
