Neoproterozoic microfossils from the margin of the East European Platform and the search for a biostratigraphic model of lower Ediacaran rocks

Abstract

A ca. 600 m thick siliciclastic succession in northern Russia contains abundant and diverse microfossils that document early to middle Ediacaran deposition along the northeastern margin of the East European Platform. The Vychegda Formation is poorly exposed but is well documented by a core drilled in the Timan trough region (Kel'tminskaya-1 borehole). Vychegda siliciclastics lie unconformably above Tonian to lower Cryogenian strata and below equivalents of the late Ediacaran Redkino succession that is widely distributed across the platform. The basal ten meters of the formation preserve acritarchs and fragments of problematic macrofossils known elsewhere only from pre-Sturtian successions. In contrast, the upper, nearly 400 m of the succession contains abundant and diverse large acanthomorphic acritarchs attributable to the Ediacaran Complex Acanthomorph Palynoflora (ECAP). This distinctive set of taxa is known elsewhere only from lower, but not lowermost, Ediacaran rocks. In between lies an additional assemblage of relatively simple filaments and stratigraphically long ranging Manuscript Click here to view linked References 2 sphaeromorphic acritarchs interpreted as early Ediacaran in age. Bearing in mind that knowledge of late Cryogenian (post-Strurtian/pre-Marinoan) microfossils is sparse, the Vychegda record is consistent with data from Australia and China which suggest that diverse ECAP microfossil assemblages appeared well into the Ediacaran Period.Accumulating paleontological observations underscore both the promise and the challenges for biostratigraphic characterization of the early Ediacaran Period.

Controls on the evolution of Ediacaran metazoan ecosystems: A redox perspective

“…Whilst no direct fossil identification beyond microfossil evidence is possible from drill core samples, the stratigraphic succession from which the Kel'tminskaya‐1 core was extracted is known to host a richly fossiliferous example of the White Sea assemblage, which may have existed approximately contemporaneous with the mid‐upper Doushantuo Formation, Drook Formation and June Beds (Boag et al., ). Large ornamented microfossil assemblages composed of acanthamorphic acritarchs have made useful biostratigraphic indicators within the Vychegda Formation (Vorob'eva, Sergeev, & Knoll, ), whilst Ediacara biota including the probable motile early molluscan organism Kimberella are documented from the overlying Redkino Formation (Fedonkin et al., ; Gehling et al., ; Martin et al., ). The equivalent Ust’‐Pinega Formation on the Onega River also hosts soft‐bodied Swartpuntia, Vendoconularia triradiata and Ventogyrus (Ivantsov & Fedonkin, ; Fedonkin and Ivantsov, ).…”

Ediacaran Acanthomorphic Acritarchs and Other Microfossils from Chert Nodules of the Upper Doushantuo Formation in the Yangtze Gorges Area, South China

“…Several specimens published as Tanarium conoideum (Vorob'eva et al, 2009a(Vorob'eva et al, , 2009bMoczydłowska and Nagovitsin, 2012) probably should be excluded from this species because their processes are too short. Additional discussion of these specimens can be found in Xiao et al (2014).…”

Microfossils and Biofacies of the Vendian Fossil Biota in the Southern Siberian Platform

“…Близкий по составу биофации Vanavarataenia комплекс котлинского и ровенского горизонтов венда содержит остатки ветвящихся талломов со спорангиями, морфологически неотличимых от Vanavarataenia insolata [Бурзин, 1993;Burzin, 1996]. Ассоциация нижней части редкинского горизонта вычегодского прогиба [Подковыров и др., 2011], где, по всей видимости, в это время был максимально интенсивный водообмен с открытым морем, содержит богатую биоту доушаньто-пертататакского типа [Vorob'eva et al, 2009], которую с уверенностью можно сопоставить с биотами Сибирской платформы, отнесенными к биофации Appendisphaera. Среди раннередкинских ассоциаций Московской синеклизы и южных областей бассейна в обстановках, более удаленных от пролива, соединяющего внутренний редкинский бассейн с морем, указываются таксономически разнообразные ассоциации (включающие ряд проблематичных форм) [Бурзин, 1993;Burzin, 1996], очень напоминающие выделенную нами Переходную биофацию.…”

“…Сибирской платформе [Moczydlowska, 1993;Голубкова и др., 2010;Sergeev et al, 2011;Moczydlowska, Nagovitsin, 2012] и найденная затем в Китае [Zhang et al, 1998], а также на Восточно-Европейской платформе [Воробьева и др., 2006;Vorob'eva et al, 2009]. Отличительной особенностью этой ассоциации является таксономическое разнообразие крупных микрофоссилий с различными, в том числе морфологически сложными выростами.…”