The major difference in the pattern of distribution of the biofacies probably reflects the faunal development in rather different climatic conditions, suggesting that the Yangtze block is supposedly positioned rather distant from Baltica, but still close enough to share genera inhabiting the outer shelf.ĪUTOCHTHONOUS BIOFACIES IN THE PLIOCENE LORETO BASIN, BAJA CALIFORNIA SUR, MEXICOįull Text Available The present paper examines the molluscan and/or echinoid assemblages recovered from two lithostratigraphic units (Piedras Rodadas Sandstone and Arroyo de Arce Norte Sandstone outcropping in the Pliocene Loreto Basin, Baja California Sur, Mexico. By contrast, the shelf part of the South China Plate shows a development of fifteen biofacies distinguished on the genus level, and the number of species for each biofacies is notably small. In the South Urals there was a development in the Darriwilian of a Cheirurid biofacies following the Ceratopyge biofacies. Over most of the Ural border north of the South Urals there was a further development of first a Ceratopyge biofacies, then an eastern Asaphid biofacies, together with more siliciclastic input to the lithofacies and with fewer asaphids than in Baltoscandia. A slightly younger, sparse fauna is known from Paj-Khoj. A poorer fauna is known from the Polar Urals. In the South Urals immigration started in the earliest Tremadocian with fairly rich deep-water faunas. For the rest of the time (Floian to mid-Darriwilian, Baltoscandia had fairly monotonous lithologies and faunas, constituting a single Asaphid biofacies with lateral variations expressed as differences largely in the relative abundance of species. In Baltoscandia the Olenid biofacies lingered on until it was replaced by the late Tremadocian Ceratopyge biofacies. Trilobites and biofacies in the Early–Middle Ordovician of Baltica and a brief comparison with the Yangtze Plateĭirectory of Open Access Journals (Sweden)įull Text Available Baltica except for Baltoscandia was subject to an early Tremadocian immigration of trilobites similar to that on other plates. The foraminiferal biofacies contribute with detailed information to sedimentary facies previously characterized in the study area by the reconstruction of paleoenvironment succession. Marine ingressions are recorded and those biofacies show the pleistocenic coastal hydrodinamic in the deltaic complex. cananeiaensis is associated with paralic environments. cananeiaensis, Gavelinopsis praegeri, and Hanzawaia nitidula, represents the estuary complex with middle or outer shelf influence biofacies QL represents hypersaline waters dominated by lagoonal miliolids and biofacies HP characterized by Haynesina germanica and P. and Pararotalia cananeiaensis represents an inner shelf environment biofacies QP dominated by shelf miliolids species biofacies PGH, dominated by P. The biofacies ABP dominated by Ammonia parkinsoniana and Bolivina spp. From the bottom to the top of the core, the biofacies succession represents the environmental changes in the coastal area associated to sea-level oscillations. Several biofacies were identified along the core depending on the species dominance. The coastal dynamic was recognized from five biofacies based on clusters, the Planktonic/Benthic (P/B) ratios and indicator species distribution in the core. An abundant assemblage was found in the upper portion of the well core, inferred to be pleistocenic deposits. The paleoecology and distribution of benthic foraminiferal assemblages were analyzed in the core 2-MU-1-RJ well, drilled in the ParaÃba do Sul Deltaic Complex, Rio de Janeiro (Brazil). Gasparini, Sarah Pereira Vilela, Claudia Gutterres Paleoenvironmental evolution based on benthic foraminifera biofacies of the ParaÃba do Sul Deltaic Complex, eastern Brazil
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