RHIZOID LIMESTONE FROM THE URZHUMIAN (MIDDLE PERMIAN) RED BEDS OF TETYUSHI VOLGA REGION, RUSSIA

Mouraviev, F.; Silantiev, V.; Gareev, B.; Batalin, G.
Abstract:
The separate layer of rhizoid limestone from Urzhumian red succession of Tetyushi Volga region was studied to clarify its depositional features. Field description, optical microscopy, bulk geochemistry, stable isotopes of carbon and oxygen analysis, scanning electron microscopy (SEM) were used. The limestone under study has a thickness of about 1 m, is penetrated by a network of thin root channels (rhizoid limestone), the upper part of the rhizoid limestone is overlain by thin-laminated leafy limestone (3-5 cm) (laminar limestone). Both limestones are crossed by desiccation cracks filled with dark gray massive limestone. Rhizoid limestone contains the lacustrine fauna of ostracods and bivalves, has a bioturbated micritic internal structure; the laminated limestone has a thin-layered microbially induced sedimentary structure (MISS) and ostracod shells; the massive limestone is characterized by a microbial-clotted structure (microbial limestone) and contains, along with the lake fauna, intraclasts of the host rhizoid limestone. Massive limestone filling the desiccation cracks shows a lighter isotopic composition and enrichment in biophilic elements (P2O5, SO3) compared to the host limestone. Microbial films with the development of coccoid and filamentous bacteriomorphs were identified in massive limestone using SEM. Thus, the rhizoid limestone is interpreted as a lacustrine carbonate sediment that underwent bioturbation by plant roots during the shallowing of lake. Laminar limestone is interpreted as palustrine (littoral) sediment. The complete drying of these sediments resulted in the formation of a network of cracks in them, which were filled with massive microbial limestone after the flooding of these sediments with lake waters. The lithostratigraphic significance of rhizoid limestones is discussed.
SGEM Research areas:
Year:
2021
Type of Publication:
In Proceedings
Keywords:
rhizoid limestone; Middle Permian; palustrine; lacustrine; microbial
Editor:
• Prof. DSc. Oleksandr Trofymchuk, UKRAINE • Prof. Dr. hab. oec. Baiba Rivza, LATVIA
Volume:
21
SGEM Book title:
21st International Multidisciplinary Scientific GeoConference SGEM 2021
Book number:
1.1
SGEM Series:
SGEM International Multidisciplinary Scientific GeoConference
Pages:
125-132
Publisher address:
51 Al. Malinov blvd, Sofia, 1712, Bulgaria
SGEM supporters:
SWS Scholarly Society; Acad Sci Czech Republ; Latvian Acad Sci; Polish Acad Sci; Serbian Acad Sci & Arts; Natl Acad Sci Ukraine; Natl Acad Sci Armenia; Sci Council Japan; European Acad Sci, Arts & Letters; Acad Fine Arts Zagreb Croatia; Croatian Acad Sci
Period:
16 - 22 August, 2021
ISBN:
978-619-7603-20-0
ISSN:
1314-2704
Conference:
21st International Multidisciplinary Scientific GeoConference SGEM 2021, 16 - 22 August, 2021
DOI:
10.5593/sgem2021/1.1/s01.016
Hits: 484