Provenance shift in Cambrian mid-Baltica: detrital zircon chronology of Ediacaran–Cambrian sandstones in Estonia; pp. 251–256

Abstract

In order to clarify the tectono-sedimentary history of Paleozoic Baltica, age spectra of detrital zircon grains from the Ediacaran (Kotlin Regional Stage) and Lower Cambrian sandstones (lowermost Lontova and Lükati formations) in western Estonia in central Baltica were analyzed by LA-ICPMS. The abundant occurrence of Archean to Mesoproterozoic (2800-1000 Ma) zircon grains was confirmed in all samples. The new data provided the following information on the provenance of siliciclastic material as well as a major change in the sedimentary regime of the Paleo-Baltic basin during the Early Cambrian:(1) the Ediacaran-Lower Cambrian Paleo-Baltic basin received abundant terrigenous clastics from the core of Baltica underlain by the Archean-Mesoproterozoic crystalline crust, (2) the exposed surface area of the 1600 Ma Rapakivi granites apparently was more extensive during the Ediacaran-Early Cambrian than at present, (3) a major re-organization of the basin geometry occurred in the middle Early Cambrian (ca 530-515 Ma) in central Baltica, inducing a change in the sediment supply system, (4) in contrast to the total absence of Neoproterozoic detrital zircon grains before the middle Early Cambrian, their sudden appearance at this time, together with consistent occurrence at least until the mid-Devonian, suggests a significant uplift event located in southeast Baltica and/or in a more easterly land domain (e.g., in Sarmatia), (5) possible sources for the Neoproterozoic zircon grains include the peripheral mobile belts with pan-African signatures around Baltica, e.g., the so-called Gondwanan fragments along the Tornquist margin to the southwest and the Timanian belt along the northeastern margin.

Detrital zircon record of the Mesoproterozoic to Lower Cambrian sequences of NW Russia: implications for the paleogeography of the Baltic interior

“…Moreover, our distribution of detrital zircon ages is comparable to those reported from strata of the Kotlin Regional Stage (Late Ediacaran) to the west of the study area in central Estonia (Isozaki et al 2014) (Fig. 5).…”

“…Dated samples from the Starorussa and Vasileostrovskaya formations are generally dominated by detrital zircons that are much older than the depositional ages of the formations. Therefore, in combination with data from central Estonia (Isozaki et al 2014), our data suggest that clastic detritus deposited across much of the Late Ediacaran sedimentary basin, which occupies present-day NW Russia and Estonia, was mainly sourced from the southwestern part of the Baltic Shield (in modern coordinates).…”

“…However, whilst there are numerous provenance studies of Mesoproterozoic-Paleozoic successions of the Scandinavian Caledonides, which predominantly represented a marginal part of Baltica during the latest Precambrian-earliest Paleozoic (e.g., Andresen et al 2014;Gee et al 2014Gee et al , 2015Slama & Pedersen 2015;Slama 2016;Zhang et al 2015 and references therein), there are only few provenance studies of the clastic succession of the interior part of Baltica, occupied by the East European Platform. Previous work includes U-Pb dating of detrital zircons from the Upper Mesoproterozoic succession of the Pasha-Ladoga basin (Kuptsova et al 2011), a U-Pb detrital zircon study of Middle Cambrian-Devonian strata carried out by Miller et al (2011), and the dating of several samples from Ediacaran-Devonian strata from central Estonia (Isozaki et al 2014;Poldvere et al 2014). The only detrital zircon studies focused on the Leningrad region of the East European Platform in NW Russia are represented by recent preliminary studies published by Ivleva et al (2016), Ivleva et al (2018).…”

Rare late Neoproterozoic detritus in SW Scandinavia as a response to distant tectonic processes

“…Considering the first possibility, there is growing evidence for the continent‐scale transport of Neoproterozoic Timanian detritus across Baltica during the Cambrian and Ordovician (Andresen et al ., ; Slama and Pedersen, ). The derivation of Neoproterozoic detritus from other terranes with preserved Cadomian magmatic activity has also been suggested (Isozaki et al ., ). Some of these may be represented by blocks dispersed along the southern or south‐eastern margins of Baltica (Belka et al ., ; Winchester et al ., ; Nawrocki et al ., ).…”

“…the docking of microplates bearing Neoproterozoic magmatic rocks at the Baltica margin) did not occur before c . 521 Ma (Cambrian Stage 2) (Orlov et al ., ; Isozaki et al ., ; Slama and Pedersen, ). Their contribution to the Neoproterozoic sediments of Baltica is therefore unlikely.…”