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Malyonkina, S.Y., Ivanov, A.V.

Paleogene columnar stromatolites from the “Kamyshinskie ushi” location (Lower Volga Region)

The article discusses the results of our preliminary studies of Paleocene columnar stromatolites from the “Kamyshinskie Ushi” location, near the northwestern periphery of the town of Kamyshin. The morphology, composition and features of the buildings were studied. They can be attributed to the morphological type of columnar non-branching stromatolites; fan-shaped branching stromatolites are less common; their mineral composition differs little from the host rocks and consists mainly of quartz grains cemented by silicon oxide. Dark layers are much more saturated with ore inclusions. The concentration of chromium, molybdenum, wolfram, vanadium, cobalt and nickel in dark varieties increases noticeably, which confirms their stromatolite origin. The deposition settings of their formation remain controversial.

Kokovkin, A.A.

On the influence of Holocene tectonics on the formation of the river network of the Alpine-Himalayan and Pacific mobile belts of Eurasia

This article continues the series of publications on the indicators of Holocene activation. Using the examples of the Volga and Amur rivers with their tributaries and the Razdolnaya River, the interaction of the river network with the Holocene orogenic system of the Alpine–Himalayan and Pacific mobile belts of Eurasia was studied. The river network is conformal to their orogenic system. Examples of the control of river valleys by shear systems of active faults are given. The influence of the rivers on the formation of erosional relief was studied. It is shown that loose sediments of the Mesozoic-Cenozoic rifts thrown up in the Holocene are actively destroyed by the river network, with a shear of up to many hundreds of meters. The rises on the riftogen framing and their internal rises, composed of strong pre-Mesozoic rocks, are weakly eroded. Many of them have a contrasting, nonequilibrium relief. The study was conducted within the framework of the pulsatingly expanding Earth model developed by the author.

Ivanov, A.V.

COASTAL ECOSYSTEM OF THE APTIAN SEA BASIN IN THE REGIONOF THE YELSHAN-KURDYUM UPLIFT (SARATOV VOLGA REGION)

The article presents the results of studies of a number of sections of Lower Cretaceous (Aptian) deposits in the Saratov Right Bank region (settlements Krasnyi Oktyabr’, Doktorovka, Kurdyum and Shirokoe), confined to the Yelshano-Kurdyum uplift. Oryctocenosis combines autochthonous (ichnofossils), subautochthonous (bivalves and gastropods) and allochthonous (ammonites, wood fragments) elements. Sedimentological and mineralogical indicators (ripple marks, desiccation cracks, wedge-shaped structures, cross-bedding, glauconite, and calcite veinlets), as well as fossil remains and features of their taphonomy, allow us to diagnose the coastal ecosystem of the epicontinental sea basin. In the ecosystem format, we see a variety of physico-geographical situations: areas of the bottom which are periodically actively bioturbated and hydrodynamically transformed into mature hardground; zones of active hydrodynamics with the formation of cross-bedding; and zones of subaerial surfaces with the possible development of stick soils. Reconstruction of the paleoecosystem is complicated by the presence of a number of natural facts that have not been unambiguously interpreted, images of which are given in the article. The studied sections are of interest from the standpoint of geoheritage. Selected natural facts are actively involved in the development of a number of geoscientific university museums.