Evolution of sedimentary environments in Podolya basin (Ukraine) at the moment of appearence of Ediacaran biota

• Main Author: Soldatenko, Yevheniia
• Other Authors: Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC), Université de Poitiers, Université nationale des mines (Dnipropetrovsk, Ukraine), Abderrazzak El Albani, Marina Ruzina
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2018
• Subjects: Geology; Earth sciences; Sedimentology; Biota; Neoproterozoic; Precambrian; Ediacara; Earth history; Géologie; Sédimentologie; Néoprotérozoïque; Précambrien; Histoire de la Terre; [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology; [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy; White Sea
• Online Access: https://tel.archives-ouvertes.fr/tel-02064630; https://tel.archives-ouvertes.fr/tel-02064630/document; https://tel.archives-ouvertes.fr/tel-02064630/file/2018-Soldatenko-Yevheniia-These.pdf

On the East European Platform (EEP), Neoproterozoic siliciclastic sediments have revealed a typical animal fauna of Ediacaran in the Podolya basin. The geological data are typical of marine tidal domain and suggest that this fauna lived under a water depth that did not exceed the euphotic zone. After this period, the basin, located on the edge of the Ukrainian Shield, has remained safe from tectonic events and its subsidence was low, which explain that these deposits are unmetamorphosed and unaffected by processes of burial diagenesis. These conditions allowed both the preservation of animal fossils and argillaceous minerals. Thus, four levels rich in IS mixed-layers could be identified as bentonites, altered pyroclastic products. Zircons of the youngest bentonite, which caps the fossiliferous levels, have been dated (238U/206Pb ratio) to 556±1 Ma, so Podolya's ediacaran macrobiota is of older age. Moreover, the variations of the kaolinite content in sedimentary pile indicates the neighboring mainland of the Baltica micro-continent (current EEP), source of the detritism, has been subjected to temperate-warm-temperate climate cycle. According to the paleomagnetic data, this shows that Baltica migrated from high to low latitudes and followed a retrograde motion. The kaolinite-poor fossil stratas can be correlated with high latitude position of Baltica, close to the northern border of Rodinia and of Avalon micro-continent. Our results make it possible to better situate the Ediacarian fossils of Ukraine in relation to the global biochronostratigraphic scale, but also to better understand the spatial and temporal relationships of Podolya’s ediacaran biota compared to other faunas located in the vicinity of Baltica at this time. The new data and primitive morphologies of Podolya's fossils – usually compared to the only fossils of White Sea (Russia) might explain why Ediacaran biota from Podolya Basin has more phylogenic resemblance to some Avalon’s macrofossils. Sur la Plate-forme Est Européenne (PEE), des sédiments ...