Search results for "Cretaceou"
showing 4 items of 184 documents
Concreções calcárias da formação Santana, bacia do Araripe: uma proposta de classificação.
2007
18 pages; The calcareous concretions of the Santana Formation have been known since 1800 thanks to the work of João da Silva Feijó (1800). Their study was promoted internationally by the report of von Spix and von Martius (1823-1831), and their richness in fossil fishes led Silva Santos to name them “ichthyoliths” in 1950. Here we propose a classification for the various types of calcareous concretions that occurred in the Santana Formation (Late Cretaceous, Araripe Basin). We consider their geographic distribution and we propose a terminological uniformization for the descriptions of that material. This will serve future statistical, geographical, geochemical and taphonomical studies that,…
Preliminary study on the unusual properties in the habitat of Ranunculetum baudotii in Central Europe
2011
Abstract The study examines the patches of the saltwater association Ranunculetum baudotii in a new, atypical site; i.e., located more than 400 km away from the Baltic coastal line. They were found in a karst spring, and were the first locality of the community identified in Poland. The water and sediments within the patches were analyzed chemically in the laboratory, but, conductivity, water temperature and O2 content were measured in the field. The spring was determined to be a relatively stable aquatic habitat, with a typical chemical composition of subterranean water (a prevalence of hydro-carbonate, calcium and magnesium ions), and rich, e.g., in nitrogen and phosphorus, and disturbed …
Formation of microbial organic carbonates during the Late Jurassic from the Northern Tethys (Amu Darya Basin, Uzbekistan): implications for Jurassic …
2020
23 pages; International audience; The Late Jurassic was a period of major global carbon cycle perturbations with episodes of anoxia leading to regional accumulation of organic matter in sediments worldwide. The Tubiegatan section (SW Gissar Mountains, Uzbekistan) located in the Northern Tethys, shows atypical organic-rich limestone and marl deposits (up to 6% of total organic carbon) marked by pronounced negative excursions of δ13Ccarb (amplitude of ca. 12‰) and δ13Corg (amplitude of ca. 4‰) recorded during the Middle Oxfordian (Transversarium Zone). A transdisciplinary approach including sedimentology, palynofacies characterization, mineralogy, organic and inorganic geochemistry was carrie…
The late Late Albian (Mortoniceras fallax Zone) cephalopod fauna from the Bracquegnies formation at Strépy-Thieu (Hainaut, southern Belgium).
2016
Excavations in 1989-1990 for the construction of a boat lift near the villages of Strépy and Thieu, east of Mons (province of Hainaut, southern Belgium), exposed a 40-metre section of the Bracquegnies Formation (Haine Green Sandstone Group; the ‘Meule de Bracquegnies’ of previous authors). Several hundred well-preserved, silicified cephalopods were collected from between 15 and 35 metres above the base of the sequence temporarily exposed there. The fauna is: Eutrephoceras clementianum (d’Orbigny, 1840), Puzosia (Puzosia) mayoriana (d’Orbigny, 1841), Callihoplites tetragonus (Seeley, 1865), Discohoplites valbonnensis valbonnensis (Hébert & Munier-Chalmas, 1875), Cantabrigites cantabrigense S…