Sedimentology of Hirnantian glaciomarine deposits in the Balkan Terrane, western Bulgaria: Fixing a piece of the north peri-Gondwana jigsaw puzzle

Chatalov, Athanas

doi:10.1016/j.sedgeo.2017.01.004

Cited by 13 publications

(12 citation statements)

References 147 publications

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“…The Tazekka glacigenic deposits essentially derived from the cannibalization of the "great Lower Paleozoic quartz-rich sandstone sheet", itself initially having recycled the Pan-African molasse and flysch basins (Avigad et al, 2017), rather than recording a pulse of fresh, far-travelled, first-cycle clastic sediments issuing from basement rocks. This finding is in line with conclusions of Chatalov (2017) and Gärtner et al (2017), also dealing with the north Gondwana area but is in contrast with common views about the limited maturity of syn-glaciation deposits (Nesbitt and Young, 1982;Yan et al, 2010;Bahlburg and Dobrzinski, 2011;Huang et al 2014). More interestingly, end-Ordovician glacigenic deposits in South Africa show a significantly lower CIA than that of the underlying preglacial succession (Young et al, 2004), which is in contrast to the north-Gondwanan examples from this study, even regarding the diamictite samples (Fig.…”

Section: Discussionsupporting

confidence: 88%

“…However, latest Ediacaran-early Cambrian zircon grains throughout the Tifarouine Fm., absent from NF01 and 15DL12, suggest that the Tazekka watershed was not restricted to the Meseta. This is corroborated by the great thickness of the glacigenic succession (>350 m), largely exceeding that of other coeval peri-Gondwanan records that are generally no more than a few tens of metres in thickness (Chatalov, 2017 and references therein).…”

Section: Deciphering Sediment Sourcesmentioning

confidence: 71%

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The impact of the end-Ordovician glaciation on sediment routing systems: A case study from the Meseta (northern Morocco)

et al. 2018

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Assessment of sediment redistribution by end-Ordovician ice sheets is crucial for the reconstruction of Lower Paleozoic source-to-sink patterns. Focussing on the ice-distal, deepwater Tazekka depocenter (Moroccan Meseta), we thus performed a provenance study that combined whole-rock geochemistry, petrography and insights from highresolution detrital zircon ages. The results show that the glacigenic sediments are compositionally-mineralogically and geochemically-more mature than preglacial strata. This observation points to a preferential cannibalization of the "great Lower Paleozoic quartz-rich sandstone sheet", with a limited input of first-cycle, far-travelled clastic sediments. Differentiation of glacial units is not straightforward, yet the glaciation acme is typified by a highly mature sedimentary source and an age spectrum lacking Mesoproterozoic zircon grains, both features strongly indicating derivation from the Cambrian-Lower Ordovician cover of the Tuareg Shield. More regional sources are expressed during the earlier glaciation stages, during which lowstand remobilisations unrelated to subglacial erosion are also suspected. Subordinate but notable late Tonian (∼ 0.8 Ga) and latest Stenian to early Tonian (∼1 Ga) zircon populations are also evidenced in Morocco, which may have implications for future paleogeographic reconstructions.

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Section: Discussionsupporting

confidence: 88%

Section: Deciphering Sediment Sourcesmentioning

confidence: 71%

The impact of the end-Ordovician glaciation on sediment routing systems: A case study from the Meseta (northern Morocco)

et al. 2018

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“…Similar deposits corresponding to the Ordovician–Silurian (O‐S) boundary have been recognized on many continents from Gondwana, such as Africa, Europe, and Asia (Arnaud & Etienne, ; Benedetto et al, ; Chatalov, ; Hambrey, ; El‐ghali, ; Young, Minter, & Theron, ) related to the O/S boundary. However, until now, there has been no mention of this deposit association from the Central Precordillera.…”

Section: Discussionmentioning

confidence: 64%

Stratigraphy and facies analysis of the La Chilca Formation, Central Precordillera: Insights on the postglacial Ordovician–Silurian boundary and Early Silurian deposits from Argentina

2018

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The La Chilca Formation is exposed at the Poblete Norte and Ancha sections, Talacasto, Central Precordillera. Detailed facies analysis on field outcrops suggests a tide-dominated tidal plain model on the Silurian siliciclastic ramp, integrated by supratidal to subtidal plain deposits. The lower part of the La Chilca Formation (upper supratidal plain) is herein attributed to reworked glaciomarine deposits that occurred during interglacial Hirnantian age, under conditions of sea rise and the action of tidal amplification. The intertidal-supratidal depositional environments are represented by tidal channels, scour and fill, tidal dunes, and hummocky cross-stratified sandstones. The estimated tidal conditions for the tidal plain were mesotidal to macrotidal, under action of combined flows, attributed to the interaction of tidal currents and orbital low-velocity waves. The identification of microbially induced sedimentary structures (MISS) in these deposits, such as petee polygonal structures, pitted texture, imploded sand volcanoes, Astropolithon sp., Manchuriophycus sp., domal build-ups, biofilms, elephant skin, and trace fossils such as Chondrites sp., Zoophycos sp., Undichnia sp., Planolites sp., Monomorphichnus sp., and gastropod traces, may have played a protection and stabilization role on the clastic sediment surfaces against erosion of the La Chilca Formation deposits. The prolific growth of microbial mat on the intertidal to supratidal zone occurs explicitly at the turning points of transgression-regression cycles in shallow-water environments under stable base-level conditions. The middle-upper section of the La Chilca Formation shows non-cyclic rhythmites that are replaced by the cyclic rhythmites, suggesting an open tidal plain subject to an orbital/climatic rather than a tectonic control of cyclicity (Milankovitch cycles). The aggradation in this section indicates a shallowing towards the top of the formation. The La Chilca Formation records two third-order transgressive events and a shallowing event. The transgressive events are found in the base and top of the formation and are marked by the presence of Fe-oolites, while the shallowing event is determined by the presence of MISS.

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“…The occurrence of isolated mudstone/marl clasts and large quartz grains scattered in the muddy/sandy groundmassespecially those revealing small-scale soft sediment deformation below themmay suggest that the sandstones and mudstones of the Zalesie Formation, like similar diamictites in the East European Platform, were deposited by icebergs migrating from Gondwana to the SW margin of Baltica (see Porębski et al 2019). It is noteworthy that in terms of grain composition, texture and thickness, the Zalesie Formation is similar to the peri-Gondwanan glaciomarine diamictites of the Sirman Formation in Bulgaria (Chatalov, 2017). Therefore, icebergs appear to be an alternative explanation for the occurrence of the Middle Ordovician Frankea specimen in the Hirnantian acritarch assemblage, in contrast to its redeposition from the Baltica/Avalonia collision zone postulated by Trela & Szczepanik (2009).…”

Section: W Trelamentioning

confidence: 95%

Eustatic and local tectonic impact on the Late Ordovician – early Silurian facies evolution on the SW margin of peri-Baltica (the southern Holy Cross Mountains, Poland)

Trela

2021

Geol. Mag.

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This paper provides insight into the Late Ordovician to earliest Silurian evolution of sedimentary environments in the southern Holy Cross Mountains (SE Poland), which at that time were a part of the SW periphery of Baltica. The facies layout in this area was influenced by the basement block faulting, which differentiated the basin bathymetry into submarine horst and grabens, controlling facies distribution. However, the local tectonism was insufficient to fully mask the global eustatic events. Therefore, it is possible to correlate some facies changes in the Upper Ordovician and lower Llandovery sedimentary record of the southern Holy Cross Mountains with eustatic and palaeoceanographic changes reported worldwide. The most noticeable influence of eustasy on the sedimentary record in the studied area occurs at the Ordovician/Silurian boundary. It is manifested by Hirnantian regressive coarse-grained clastic sediments overlain by a post-glacial anoxic/dysoxic interval represented by the Rhuddanian transgressive black cherts and shales. It is noteworthy that the pre- and post-Hirnantian sedimentary environments in the southern Holy Cross Mountains were affected by upwelling induced by the SE trade winds.

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Sedimentology of Hirnantian glaciomarine deposits in the Balkan Terrane, western Bulgaria: Fixing a piece of the north peri-Gondwana jigsaw puzzle

Cited by 13 publications

References 147 publications

The impact of the end-Ordovician glaciation on sediment routing systems: A case study from the Meseta (northern Morocco)

The impact of the end-Ordovician glaciation on sediment routing systems: A case study from the Meseta (northern Morocco)

Stratigraphy and facies analysis of the La Chilca Formation, Central Precordillera: Insights on the postglacial Ordovician–Silurian boundary and Early Silurian deposits from Argentina

Eustatic and local tectonic impact on the Late Ordovician – early Silurian facies evolution on the SW margin of peri-Baltica (the southern Holy Cross Mountains, Poland)

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