Abstract

Sedimentation in different tectonic environments influences the distribution of sedimentary facies. Two specific contrasting type cases illustrating this principal were studied in connection with Lower Devonian sequences in Novaya Zemlya and in West Taimyr.

The Lower Devonian sediments in southwestern Novaya Zemlya were deposited under geosynclinal conditions. Sedimentation took place against a background of active and multidirectional tectonic movements. Three sequences in this succession are distinguished related to the main events of the development of strata in the deepening marine basin. Chemically precipitated magnesian-carbonate and essentially chemical calcareous muds are followed by fragmental-organic limestones, lime-sands and small bioherms. These rocks have distinctive facies features. Multiple facies recurrence in the succession are a consequence of sedimentation under conditions of migrating accumulative mesoform floors and subaqueus channels.

In West Taimyr the accumulation of deposits occurred under relatively quiet conditions intermediate between those of geosynclines and platforms. Four lithological-faunal complexes are distinguished comprising a clearly transgressive cycle. The sequence consists of dolomite-gypsum deposits of lagoons which grade through limestone-dolomite rocks into limestones of extensive shallow, open-marine environments. Tectonic oscillations are reflected in the occurrence of argillite and shale beds. The stabilization of subaqueous sedimentary facies with respect to areal differentiation suggests that tectonic movements become slower.