Fig 7 - uploaded by N.V. Sennikov
Content may be subject to copyright.
Inferred Late Ordovician-early Silurian position of the Altai block, updated after Sennikov et al. (2006).
Source publication
The paper presents data on the classification, structure, and biota of reef complexes from the Late Ordovician-early Silurian Altai Basin. The early Paleozoic history of the Altai Basin included the early-middle Katian, late Katian, early Hirnantian, late Telychian, and middle-late Sheinwoodian events of large-scale reef formation which produced fr...
Contexts in source publication
Context 1
... to numerous reconstructions ( Rasmussen and Harper, 2011;Golonka and Gawęda, 2012;Boucot et al., 2013;Torsvik and Cocks, 2017), orogens of southern Siberia, including Gorny Altai, flanked the Siberian craton and were turned 180° relative to the present position in the early Paleozoic (Fig. 7). See the example late Katian and late Telychian reef complexes of Altai with reef, fore-reef and backreef facies in Fig. 6 (Panels А and С). If the late Katian and Telychian reef systems had been oriented as they are at present, no effect of warm near-surface currents (directed from east to west due to the Earth's rotation) would have ...
Context 2
... 6, Panels B and D). Thus, the reconstructed position of the Altai Late Ordovician and early Silurian seas along the eastern coast of the continental block was favorable for reef formation. The inputs of warm rich tropical currents maintained the proliferation of reef builders in the past and have controlled the location of the present large reefs (Fig. ...
Citations
... Many sections sampled in the composite Charysh-Inya and Anui-Chuya--Charysh-Chuya facies zones of Gorny Altai (Khankhara and Tekhten' formations) record various deposition settings of a warm shelf basin: reefs in the Muta, Khankhara, and other sections (Sennikov et al., 2019a(Sennikov et al., , 2023; interreef zones in the Azratkan, Ebogon, and other sections (Sennikov et al., 2014(Sennikov et al., , 2019a; backreef facies in the Chineta, Tekhten', and other sections (Sennikov et al., 2019a). Additionally, deepsea continental rise facies was found as siliciclastic sediments in the Suetka, Tachalov, and other sections (Sennikov et al., 2011). ...
New and revised previous data based on detailed description of sections have provided better constraints on fauna taxonomy, lithology, and stratigraphy, as well as on biostratigraphic ages of sediments. The lithology and stratigraphy of several key Upper Ordovician sections in the northern Gorny Altai area show that the local units of Sandbian and Katian Savelieva and Bulukhta formations can be used as reference for the regional Ordovician division. It is suggested to include a newly distinguished Bulukhta facies zone, an area of Late Ordovician coarse clastic deposition, into the mapped Ordovician deposits of Gorny Altai. According to paleogeographic reconstructions, the deposition occurred in a large sea gulf surrounded with elevated landmasses exposed to erosion.
The article presents the study results of carbonaceous rocks and taxonomic diversity of the Upper Ordovician calcareous algae of the Tachalov section left half, located on the left side of the same-name creek in the central district of the Charysh-Inya structure-facies zone of Gorny Altai. Six microfacies are distinguished in rocks: algal-bacterial boundstones, crinoid mudstones, crinoid-algal wackestones, polybioclastic wackestones, crinoid-algal packstone-wackestones and crinoid-algal packstones. Calcareous algae of the following genera were recorded in limestones: Proaulopora Volgdin, 1934 (Ms), Girvanella Nicholson et Etheridge, 1878, Vermiporella Stolley, 1893, Apidium Stolley, 1896, Ortonella Garwood, 1914, Contexta Gnilovskaja, 1972, Halysis Høeg, 1932, Rothpletzella Wood, 1948. It is found, that during the formation of biohermal buildups in more active hydrodynamics, different groups of calcareous algae react either by increasing species diversity (like green algae) or by increasing the number of organisms of the same species (like red algae).
