0000000001025510
AUTHOR
M Rigo
Sedimentology and biostratigraphy of a peritidal succession across the Triassic/Jurassic boundary: Monte Sparagio, north western Sicily
A 490 m thick section of shallowing upward peritidal cycles spanning the Triassic-Jurassic boundary is exposed along the northern slope of Mount Sparagio in the San Vito Lo Capo Peninsula (Western Sicily). A detailed microfacies analysis allowed defining the aspects of cyclic sedimentation of this section and especially the stratigraphic occurrence patterns of benthic foraminifera and algae across the T/J boundary. The lower part of cycles commonly shows medium to low energy subtidal facies, typical of the inner lagoon of the carbonate platform. Subtidal facies such as coral bafflestone in some cycles suggest more open lagoonal conditions (patch reefs), while some higher energy layers such …
Triassic/Jurassic boundary in peritidal carbonates from western Tethys
A carbonate platform from the western margin of the Ionian Tethys has been investigated for biotic and geochemical variations across the Triassic/Jurassic boundary (TJB). The section of Mount Sparagio (north-western Sicily) exposes a peritidal succession of Rhaetian-Hettangian age with a thickness of about 400 m. The peritidal sediments are organized in metre-scale shallowing upward cycles formed by subtidal, intertidal and supratidal facies. Along the section, the subtidal facies vary from bioturbated mud/wackestones with rare mollusc shells, to Megalodont-rich wacke/packstones to, more rarely, coral bafflestones, most likely as response to variations of the accommodation space and water e…
Shallow ocean oxygen decline during the end-Triassic mass extinction
The end-Triassic mass extinction (ETME) was associated with intensified deep-water anoxia in epicontinental seas and mid-depth waters, yet the absolute oxygenation state in the shallow ocean is uncharacterized. Here we report carbonate-associated iodine data from the peritidal Mount Sparagio section (Southern Italy) that documents the ETME (~ 200 Ma) in the western Tethys. We find a sharp drop in carbonate I/(Ca + Mg) ratios across the extinction horizon and persisting into the Early Jurassic. This records local dissolved oxygen and iodate decline in the near-surface ocean of low-latitude Tethys due to the development of depleted oxygen concentrations. Consequently, during the ETME even sha…
Acidification processes in a peritidal carbonate succession across the Triassic/Jurassic boundary (Sicily)
For the first time, a correlation between biostratigraphic events and δ13C curve was attempted along an UpperTriassic-Lower Jurassic peritidal limestone succession cropping out in westernmost Sicily. The peritidal carbonates are organized in shallowing upward cycles characterized by subtidal skeletal mudstone to grainstone, intertidal microbial mats and supratidal paleosoils. About 300 meters of this succession covering the Triassic-Jurassic interval were studied in details. On the base of the macro- and microfossil assemblages from the subtidal facies, four informal units have been recognized along the studied section. Unit R1 (at the base, 111 m thick) is dominated by large megalodonts, r…