Литосфера (Apr 2015)
Sedimentogenesis and geodynamics in the Cretaceous-Paleogene boundary at the epoch of continental peneplanation. Article 2. Platforms and mobile belts
Abstract
The article presents data on landscapes, geodynamic regime, and sedimentation at the Cretaceous-Paleogene epoch, which was characterized by planation of most territories on all continents. It is shown that crustal extensional environments have dominated both on platforms and mobile belts (which had nearly simultaneously the Laramide orogenic phase). These conditions caused relief planation (with the development of weathering crusts and products of their rewashing) as well as basaltic volcanism and rifting in platforms and in certain parts of mobile belts. The latter processes were most active within mobile belts and in oceanic areas. Found that in the mobile belts of characterized era where environment stretching has dominated is also evident processes of compression of the crust, which played a secondary role. These processes formed orogens, induced folding and thrusting, and were commonly accompanied by intermediate and acid volcanism. Intermountain molasse and coal-bearing formations simultaneously accumulated in terrestrial environments. The predominance of the aforesaid features, which are typical of crustal compressional settings, provides a basis for identifying orogenic epochs of tectogenesis. In this sense, their antipode - epochs of relief peneplanation - is commonly referred to regime of tectonic quiescence. However, the example of the boundary Cretaceous-Paleogene epoch indicates that the sharp intensification extension and particularly intense - in the mobile continental margins and oceanic areas, allows classifying them as a special category of tectonically active epochs with the dominance of destructive type of tectogenesis. The principal features of such epochs are peneplanation, development of extensive weathering crusts, origin of scattered grabens or their belts, intensified rifting, and basaltic volcanism, and hydrothermal activity.
