A New typification scheme of postsedimentation transformations of terrigenous deposits of continents and their margins with allowance for geodynamic factors

Abstract

Previous studies of postsedimentation and deep rock transformations (the diagenetic, catagenetic, and anchimetamorphic stages) by the author and other Russian lithologists are revised by evaluating the different types of zoning of authigenic mineral formation within terrigenous complexes of different ages in definite structural-tectonic units of continents and their margins. It was emphasized that an intrarock aqueous fluid phase played a dual role in authigenic mineral formation: (1) it served as a medium for internal redistribution of sedimentogenic components or (2) as a carrier of external material. Indicator features of its own newly formed (A1) and allogenic (A2) authigenic minerals are given. It was shown that the background subsidence lithogenesis (SL) of the sedimentary sequence provides the formation of A1 varieties in the sequence, whereas the prevalence of A2 marks the superimposed or secondary alterations (SAs) of sedimentary rock. A combination of SL and SA features is demonstrated for different structures: syneclises and anteclises of cratons, rifts, fore troughs, orogens, and others. The SL and SA formation is determined by definite numerous exogenic and endogenic factors, which are often obliterated but integrated by geodynamic settings and geological evolution of sedimentary complexes. According to this conclusion, a new typification scheme of post-sedimentation transformations was proposed on the paleogeodynamic basis.