In eastern Sardinia, the first Jurassic sedimentary cycle (Bajocian-Kimmeridgian) develops in response to the opening of the Alpine Tethys Ocean. Starting during the Bajocian (Middle Jurassic), over a horst-and-graben system initially drowning to the northeast, at first siliciclastic sediments take place, related to continental to transitional environments. In time, they are gradually followed by marine carbonate, assigned to inner to outer ramp deposits. Afterwards, the latter, in their turn, become shallow; they are newly covered with an inner ramp lithofacies. The Kimmeridgian-Tithonian unconformity ends the cycle. Therefore, this sedimentary cycle as a whole can be interpreted as a transgressive-regressive megasequence linked to tectono-eustatic factors. All the pertaining stratigraphic units have been included within the 'Baunei Group', newly described. A comparison with the neighbouring areas, with particular regards to the Jurassic series of the Corsica, has been made, attempting to improve the reconstruction of this part of the Tethyan Ocean Western margin.
Late to post-Variscan sedimentary basins of Sardinia were influenced during Pennsylvanian to Permian times by two main tectono-sedimentary cycles: a Pennsylvanian to Cisuralian cycle represented mainly by dark limnic deposits, overlain by a Guadalupian to a possibly Lopingian cycle, mostly characterized by red-bed deposits. Lacustrine waterbodies developed in some sedimentary basins that were filled with siliciclastic to frequently early silicified carbonate deposits, depending on the climate and environmental conditions, landscape morphology and tectonic regime. The limnic successions of the lower tectono-sedimentary cycle were deposited in permanent, tens of metres deep lakes in deep, narrow tectonic strike-slip basins under a temperate to warm-humid climate. They started as lakes with terrigenous sedimentary input and developed minor carbonate deposits mainly at the end of their story. Conversely, the red-bed successions of the upper cycle were deposited in ephemeral, shallow playa lakes related to wider basins in an extensive alluvial plain under a hot and arid climate. Here, the siliciclastic sediments are intercalated with thin carbonate beds that are typical of a high evaporation rate. The evolution of the lake type could be related not only to a major climatic shift, but also to the changing morphotectonic conditions of the Variscan chain influencing the local microclimate. Comparisons with coeval successions in the Provence Basin, the Massif Central Aumance basin (France) and the Saar–Nahe Basin (Germany) show both similarities and differences between the basins.
In Eastern Sardinia during the early Middle Jurassic, Alpine Tethys opening triggered the rise of a temporary tectonic high. The high collapsed\ud
rapidly, was fragmented into separate blocks, and subsequently covered by continental, transitional, and finally shallow marine deposits\ud
forming a narrow depositional system comprising the Genna Selole Fm. Present-day exposures in the southern part of the palaeo-high allow\ud
the sedimentological evolution of the transgressive cover sequence to be ascertained. Initial terrestrial deposits comprise alluvial fan deposits\ud
located at the mouths of palaeovalleys. These pass into braid-deltas and in the coastal areas located between adjacent valleys mouths,\ud
palustrine and coastal plain tidally-influenced environments developed. These environments interfingered laterally and passed seaward into\ud
a transitional, siliciclastic to carbonate tidal environment. With the collapse of the tectonic high, the continental to transitional environments\ud
were transgressed with deposition of marine carbonates. A comparison with similar coeval deposits of the W-Mediterranean domain has been\ud
undertaken
The classical Middle to Upper Triassic carbonate sections at Monte Santa\ud
Giusta and Punta del Lavatoio, North-west Sardinia (Italy), referred to the\ud
Muschelkalk and Keuper lithofacies group, are revisited and their trace fossil\ud
content is investigated for the first time. A combined ichnological and\ud
sedimentological study reveals insights into the depositional environments,\ud
regional context, palaeogeography and sequence stratigraphy. The results\ud
indicate deposition on a homoclinal carbonate ramp with broad facies belts.\ud
All recognized trace fossils are also known from time-equivalent deposits of\ud
Germany and thus indicate a close affinity between the North-west Sardinian\ud
Triassic and the Germanic Basin. Only a few trace fossils are particularly\ud
abundant and these indicate opportunistic colonization by their producers,\ud
which is probably related to restricted endobenthic conditions due to reduced\ud
oxygen and/or increased salinity. The trace fossil association can be grouped\ud
into a softground suite belonging to the Cruziana ichnofacies, and a firmground\ud
suite of the Glossifungites ichnofacies. This discrimination enables an\ud
interpretation of the northern Monte Santa Giusta section as a carbonate\ud
ramp with extensive tidal flats and abundant carbonate accumulation in a\ud
relatively proximal position, whereas the southern Punta del Lavatoio section\ud
exhibits broad lagoonal environments with reduced sedimentation in a deeper\ud
and more Tethys-influenced area. The Sardinian sections are ichnologically\ud
similar to the Anisian–Ladinian succession known from the Tatra Mountains,\ud
but differ from it by having a slightly higher ichnodiversity, which again can be\ud
attributed to a less restricted lagoonal environment. This study demonstrates\ud
the importance of integrating trace fossil analysis in sedimentological and\ud
palaeontological investigations of carbonate systems
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.