Lithological Markers and Bio-indicators of Deep-water Environments During Paleozoic Siliceous Sedimentation (Gorny Altai Segment of the Paleo-Asian Ocean)

Upper Cambrian-Lower Ordovician volcanic-siliceous-terrigenous strata of the Zasurʹya Group belonging to the Gorny Altai segment of the Paleo-Asian Ocean are considered in this paper. The Gorny Altai segment developed over a long period, of not less than 25–30 million years. The Zasurʹya Group consists of the Listvenny, Talitsa and Marcheta Formations, in ascending stratigraphic order. The Listvenny Formation is represented by basalts, cherts and terrigenous rocks, whereas the Talitsa Formation mainly consists of terrigenous rocks. The Marcheta Formation is characterised by terrigenous rocks, tuffs, cherts and jasperoids. Geochemical features of basalts and tuffs from the Zasurʹya Group indicate they are oceanic island alkali basalts and E-MORB basalts. Lithologic markers of environments of sedimentation within the Gorny Altai segment of the Paleo-Asian Ocean are described, and bio-indicators of the environments of siliceous sedimentation are evaluated. The results indicate that the Zasurʹya Group was deposited in a deep-water oceanic environment.