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Depositional environments, facies and diagenesis of the Upper Jurassic–Lower Cretaceous carbonate deposits of the Buila-Vânturariþa Massif, Southern Carpathians (Romania)

Pleş G., Bucur I. I., Săsăran E.

Annales Societatis Geologorum Poloniae

2016

Vol. 86, No. 2

165--183

The Buila-Vânturariţa Massif consists of massive Upper Jurassic reef limestones (Kimmeridgian–Tithonian) and Lower Cretaceous (Berriasian–Valanginian, and Barremian–?Lower Aptian) deposits. Besides corals and stromatoporoids, a wide range of micro-encrusters and microbialites has contributed to their development. In this study, the authors describe briefly and interpret the main facies associations and present the microfossil assemblages that are important for age determination. The distribution of facies associations, corroborated with the micropalaeontological content and early diagenetic features, indicate different depositional environments. The carbonate successions show the evolution of the Late Jurassic–Early Cretaceous depositional environments from slope and reef-front to internal-platform sedimentary settings, including peritidal environments in the lowermost Cretaceous. Early diagenesis, represented by synsedimentary cementation in the form of micritization (including cement crusts in the reef microframework), followed by dissolution, cementation and dolomitization in a meteoric regime, and void-filling late cementation during the burial stage.

Stratigraphy and microfacies of the Jurassic and lowermost Cretaceous of the Veliky Kamenets section (Pieniny Klippen Belt, Carpathians, Western Ukraine)

Rehakova D., Matyja B., Wierzbowski A., Schlogl J., Krobicki M., Barski M.

Volumina Jurassica

2011

Vol. 9, no. 1

61-104

The Veliky Kamenets section in the eastern part of the Pieniny Klippen Belt in the Ukrainian Carpathians shows a well exposed, 83 m thick succession composed of Jurassic and lowermost Cretaceous (Berriasian) deposits. The terrigenous part of the section includes: gravels with a sandy matrix (unit 1A), massive grey-green sandstones (unit 1B) and shales with intercalations of siltstones/sandstones and oyster/gastropod lumachelles (unit 2). Organic-walled dinoflagellates document the Toarcian-Aalenian age of the siliciclastic deposits of unit 2. The carbonate part of the succession embraces: stromatactis mud-mounds interfingering with crinoidal limestones (unit 3A), lower nodular limestones (unit 3B), cherty limestones (unit 3C), upper nodular limestones (unit 3D), pink pelitic limestones (unit 3E), limestones with a volcanogenic bed (unit 5) and limestone breccia limestones (unit 6). This succession has yielded abundant ammonites from the Bathonian, Oxfordian and Kimmeridgian (with a stratigraphical hiatus covering the Callovian and Lower Oxfordian), as well as calcareous dinoflagellates (from the Upper Oxfordian towards the top of the succession), and calpionellids (in the Tithonian and Berriasian). Detailed stratigraphical study of the succession based both on ammonites and microfossils has resulted in the recognition of biostratigraphical units and their correlation with the chronostratigraphical scale.The microfacies recognized in the pelagic part of the succession include: the “filament” (Bositra) microfacies (Bathonian), the planktonic foraminifer microfacies (Oxfordian), the Saccocoma microfacies (Kimmeridgian to Upper Tithonian), and the calpionellid microfacies (Upper Tithonian–Berriasian). The volcanogenic rocks (lava flows and volcanic ash) appear in the topmost part of the succession (units 4 to 6) and this volcanic event is very precisely located in the Elliptica-Simplex chrons of the Middle and Late Berriasian.

Malm-Berriasian formations of northern Tunisia: updated biostratigraphy, regional correlations and western Tethys geodynamic context

Boughdiri M., Sallouhi H., Cordey F., Maalaoui K., Soussi M.

Volumina Jurassica

2006

Vol. 4, no. 1

148-149

Upper Jurassic – lowermost Cretaceous formations in northern Tunisia include the Zaress Fm. of the Tunisian “Dorsale” (Ammonitico Rosso facies: Middle Callovian-Oxfordian) and the corresponding beds from Fahs and Jédidi fms (radiolarian-bearing series: Upper Bajocian-Oxfordian) of the nearby surrounding exposures and the “Tunisian Trough”, respectively. These heteropic facies are overlain by the marl/limestone alternations of the Beni Kleb Fm. (Kimmeridgian – Middle Berriasian). Recent integrated biostratigraphic investigations (ammonites, radiolarians, calpionellids) undertaken in different palaeogeographical domains of northern Tunisia allowed a precise dating of the Malm -Berriasian fms. Revised lithostratigraphy and regional correlations lead to the recognition of an updated facies repartition in central and northern Tunisia. Within the North Maghrebian Range, main palaeogeographical segments can be outlined considering facies affinities: the North-South Axis successions of Central Tunisia show close affinities with those described from the Middle and Central AurŻs Range (eastern Algeria). The Tunisian “Dorsale” series are to be compared with corresponding beds of northern AurŻs, Hodna Mounts and the South Tellian Border (Tiaret area), in Algeria, and with the Prérif and Mésorif Upper Jurassic facies, in Morocco. Deeper facies of the Tunisian Dorsale surrounding outcrops and the “Tunisian Trough” are closer to successions described in ancient literature from the Babors and the West Numidian Range of Algeria. All these equivalent successions from the external segments of the Maghrebian Range are quite distinctive from the Internal Rif and Kabylias “Dorsales calcaires” series. Both facies types have evolved in clearly different palaeogeographical realms related with the tectonic evolution of north- and south-western Tethys margins since the Triassic – Early Jurassic times.