Search results for "Lower Cambrian"
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The Early-Cambrian Boho volcano of the El Graara massif, Morocco: Petrology, geodynamic setting and coeval sedimentation
2006
15 pages; International audience; A major volcanic episode is recorded across the Neoproterozoic-Cambrian transition in the Moroccan Anti-Atlas. Several volcanic cones are still preserved in the El Graara massif, laterally correlatable with volcanic flows dated as Early Cambrian (U/Pb date of 534 ± 10 Ma). Volcanic ashes and flows are interbedded with the uppermost part of the Adoudou dolostones, whereas the best-preserved volcano (the Boho Jbel) is onlapped by the overlying Lie-de-vin strata. Available petro-geochemical data from the Boho volcano suggest an alkaline magmatism probably derived from low-grade melting of a garnet–lherzolite mantle source, followed by fractional crystallizatio…
Lower and Middle Cambrian brachiopods from the Iberian Chains and Sierra Morena (Spain)
2021
Brachiopods from the Lower and Middle Cambrian of the Iberian Chains and Sierra Morena are described. The following taxa occur in the Iberian Chains: "Lingulella" sp., Redlichella cf. bohemica (Barrande), Dictyonina radioplicata sp. n., Micromitra sp., Trematobolus simplex (Vogel), Trematobolus borobiensis sp. n. and Jamesella sp. The taxa "Lingulella" sp. and Sibiria? sp. are reported from the Lower Cambrian of Sierra Morena. Brachiopods constitute several distinct associations: the relatively shallow water Trematobolus assemblage near the Lower-Middle Cambrian boundary interval is followed by the deeper DictyoninaRedlichella assemblage. The alternation of these assemblages permit us to i…
Stranded jellyfish in the lowermost Cambrian (Corduban) of Spain
2021
Ninety discoid structures of big size occurring on a bedding plane of Nemakit-Daldynian to Tommotian sandstones (i.e. Corduban in the Spanish scale of Cambrian stages) from south-western Spain are described. Cross-cutting relationships between discoid structures and associated trace fossils, as well as evidence for penecontemporaneous deformation of sediment laminae below the discoids, permit to interprete these structures as impressions of ancient, soft-bodied marine organisms. Taphonomic, biometric, and morphological studies suggest that they are outer moulds of both sides, subumbrellar and exumbrellar, of ancient jellyfish of hydrozoan coelenterates, whose canals resemble the modern genu…