Stratigraphy of Cambrian deposits in northeastern part of Gorny Altai
Cambrian deposits of the northeastern part of Gorny Altai received the reliable palaeontologic description. They were formed within the Palaeoasian Ocean. The cut of the Cambrian begins with the Baratalskaya series. In the Baratalskaya series divided into the lower bottom silicon-carbon-bearing and the upper dolomitic parts Late Vendian-Early Cambrian calcareous algae are found: Glomovertella sp., Obruchevella sp., Girvanella problematica Nich. Et Eth., G. sibirica Mast., Proaulopora glabra Krasn., Gemma sp. Epifiton, sp., Renalcis sp., Girvanella, etc. It is necessary to consider the Kayanchinskaya and Eskonginskaya suites as parts of the Baratalskaya series. The Baratalskaya series is compared with the Kaimskaya suite formed by deep-water siliceous sediments and oceanic basalts of feet of palaeovolcanic islands. The Sarasinskaya suite is on the Baratalskaya series. It was formed during the most part of the Lower Cambrian. The lower part of the Sarasinskaya suite is classified to the Ust-Kundatsky horizon. In the monotonous carbonate part of the suite four fauna complexes are allocated: 1) layers of Retecoscinus retetabulus. allocated by L.N. Repina, E.V. Romanenko, 2) layers of Resimopsis (P.S. Kranopeeva's Sarasinsky horizon), 3) layers of Sajanaspis. (the Kameshkovsky horizon), 4) layers of Polliellina-Laticephalus (the Sanashtygolsky horizon). The lower part of the Sarasinskaya suite is compared to the volcanogenic Manzherokskaya (basalts of oceanic islands) and Sarysazskaya (andesites and basalts) suites. The upper Sarasinskaya suite is compared with the Shashkunarskaya suite and the lower parts of mainly carbonate Siyskaya suite and the terrigenous-carbonate by Tyrganskaya and Ubinskaya suites. The carbonate Cheposhskaya Suite tops the lower Cambrian section. The middle Cambrian begins with the Ust-Seminskaya suite, which is compared with the volcanogenic Uskuchskaya suite. The terrigenous shallow marine Soviet suite is of Late Amginsky age. Breakings in the bases of the Cambrian suites of Gorny Altai have a local character and are connected with the washout of volcanic islands and small elevations. The complexes of trilobites, archaeocyathids, brachiopods, algae, and microphytolites are in sections of the Lower, Middle and Upper Cambrian deposits except the Areninsky and Khristinovsky biostratigraphy horizon. It is supposed that the considerable breaking in sedimentation is connected with the vertical movements preceding the transformation of the territory of the eastern regions of Gorny Altai into the suburb of the Siberian continent, periodically flooded by sea.