Episodic sedimentation on a peri-Tethyan ridge through the Middle–Late Jurassic transition (Villány Mountains, southern Hungary)

Vörös, Attila (2012) Episodic sedimentation on a peri-Tethyan ridge through the Middle–Late Jurassic transition (Villány Mountains, southern Hungary). Facies, 58 (3). pp. 415-443. ISSN 0172-9179

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Abstract

The Villa´ny area, as a central part of the Tisza microcontinent/terrane along the European margin of Tethys, was characterized by intense subsidence in the Early and Middle Triassic, followed by a long interruption of subsidence in the Late Triassic to Middle Jurassic. During the Middle–Late Jurassic transition, marine sedimentation started with three distinct sedimentary episodes dated as Late Bathonian, Early Callovian, and Middle–Late Callovian, respectively. The succession is terminated by a thick limestone of Middle Oxfordian age. The sedimentary features, microfacies, and macroinvertebrate associations of these four stratigraphic units are documented and illustrated. The Middle to Late Jurassic sedimentary episodes of the Villa´ny succession record an interplay of local and global factors and paleogeographical changes. At the beginning, local tectonic movements governed the main features of sedimentation, though the role of eustasy was also essential. From the mid-Callovian onwards, global climatic, biotic, and paleoceanographical changes controlled the nature and formation of the local carbonate sediments. The Callovian stromatolites are attributed to the activity of sulphate-reducing bacteria in a deep sublittoral, current-swept environment. Upwelling of eutrophic Tethyan waters is recorded by the prevalence of the Bositra filament microfacies in the Callovian. The long submarine hiatus at around the Callovian–Oxfordian transition mirrors a serious restriction of the carbonate budget, due to sudden cooling and a change in the oceanic current system (opening of a circumglobal Tethyan Passage), and to a higher amount of dissolved CO2. In the Middle Oxfordian, the carbonate production considerably increased in accordance with the sudden global warming.

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