EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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2 resultados
Resultados da Pesquisa
Item Marine or freshwater? : accessing the paleoenvironmental parameters of the Caldas Bed, a key marker bed in the Crato Formation (Araripe Basin, NE Brazil).(2021) Varejão, Filipe Giovanini; Silva, Victor Ribeiro; Assine, Mario Luis; Warren, Lucas Veríssimo; Matos, Suzana Aparecida; Rodrigues, Mariza Gomes; Fürsich, Franz Theodor; Simões, Marcello GuimarãesThe Aptian Crato Formation is world renowned for its well-preserved fossils in microbially-induced laminated limestones, which are regarded as one of the main Cretaceous Konservat-Lagerstätte of the geological record. Detailed stratigraphic investigation and mapping of the up to 90-m-thick Crato Formation at the eastern border of the Araripe Plateau allowed recognition of a regionally persistent fossil-bearing muddy interval, herein defined as the Caldas Bed. At its type locality, it is defined as an up to 2-m-thick coarsening-upward succession of grey/green mudstone and interbedded sandy siltstone and claystone. The 0.85- to 2-m-thick interval was recognized in several localities along the outcrop belt, and it is bounded by sharp, lower (Konservat-Lagerstätte limestone) and upper (sandstone and heterolithic facies) contacts. Despite pre vious literature data suggesting the presence of marine mollusks, the bed contains freshwater bivalves, small gastropods, spinicaudatans, plant remains, trace fossils, and rare ostracods. The Caldas Bed records benthic paleocommunities representing a short-term isochronous regional freshening event, marked by abrupt changes in sedimentation pattern, bathymetry, salinity, oxygenation and water chemistry.Item New freshwater mussels (Bivalvia, Unionida) with potential trigonioidid and hyriid affinities from the Early Cretaceous of Brazil.(2020) Silva, Victor Ribeiro da; Varejão, Filipe Giovanini; Matos, Suzana Aparecida; Rodrigues, Mariza Gomes; Fürsich, Franz Theodor; Skawina, Aleksandra; Schneider, Simon; Warren, Lucas Veríssimo; Assine, Mario Luis; Simões, Marcello GuimaraesTwo new taxa of freshwater mussels (Bivalvia: Unionida) from the Aptian Crato Formation of the Araripe Basin, NE Brazil, are described. The fossil bivalves are confined to 30- to 130-cm-thick bioturbated mudstones overlying the fossil-rich laminated limestones of the Crato Formation Konservat- Lagersta ̈tte. Individuals are often preserved with closed or splayed articulated valves, some of them potentially in life position, forming an autochthonous to parautochthonous assemblage. Monginellopsis bellaradiata nov. gen., nov. sp. shares key characters with the Trigonioidoidea: (i) the anterior pedal retractor muscle scar is clearly separated from the anterior adductor muscle scar; (ii) the shell has fold- like radial ribs on the posterior half; (iii) a right valve anterior tooth has a striated facet. Araripenaia elliptica nov. gen., nov. sp. is the most abundant and widely distributed unionid of the Crato Formation. Its ornament of anterior inverted V-shaped riblets, and central and posterior radial and sub-radial riblets resembles modern and fossil Hyriidae from the Americas, but also Trigonioidoidea from Eurasia. Its dentition of two smooth anterior pseudocardinals and two smooth posterior laterals in each valve provides no further clues for systematic assignment; muscle scars are not preserved. Assignment to the Hyriidae would make Araripenaia the oldest member of this family known from South America. Moreover, this bivalve assemblage of trigonioidoidids, hyriids, and previously reported silesunionoids suggests palaeobiogeographic links to other areas in both Gondwana and Laurasia.