Matches in SemOpenAlex for { <https://semopenalex.org/work/W2413095810> ?p ?o ?g. }
Showing items 1 to 74 of
74
with 100 items per page.
- W2413095810 endingPage "160" @default.
- W2413095810 startingPage "1" @default.
- W2413095810 abstract "The Lower to Middle Ordovician Dawan Formation and the base of the overlying Guniutan Formation have been sampled for palynomorphs at Daping (Yichang area, South China) with the aim to discuss the environmental history of the lower Yushanian to lower Zhejiangian Stages (Arenig) from South China. Two samples from the Huanghuachang section (the same area) were also examined for comparison. Fifty-three samples from Daping proved to be palyniferous, while 17 of 70 were barren or nearly so. The resultant taxonomic database comprises 129 acritarch taxa, belonging to 41 genera and two species of prasinophycean algae. The morphology and the systematic status of most taxa are discussed in detail and their geographic and stratigraphic distribution are documented. Two new acritarch species (Dasydorus microcephalus, and Tenuirica? gradata) and four new varieties [Cymatiogalea granulata VAVRDOVA 1966 var. changjiangensis, Pacbyspbaeridium rhabdocladium (Lu 1987 emend. TONGIORGI et al. 1995) RIBECAI et TONGIORGI 1999 var. striatellum, Petemospbaeridium dissimile GORKA 1969 var. contractum, and Stelliferidium striatulum (VAVRDOVA 1966) emend. DEUNFF et al. 1974 var. radiatum] are instituted; Stelomorpha crassula (VARDOVA 1990b) is proposed as a new combination. A compositional analysis of samples from Daping, embracing the middle Oepikodus evae through the lower Lenodus variabilis conodont zonal interval, is based on relative percentages of acritarchs belonging to nine morphological classes (Veryhachid-, Diacromorph-, Sphaeromorph-, Micrhystrid-, Polygonid-, Peteinosphaerid-, Baltisphaerid-, Galeata, and Others). SIMPSON'S (unbiased) Dominance Index is then extrapolated from 45 of the more productive samples of the Dawan Formation. To understand the compositional fluctuations through the Daping section, an interpretative model is elaborated, by analogy with WALL et al.'s (1977) study of the distribution of dinoflagellate cysts in the sediments of modern seas, integrated with reported correlations between trophic levels and phytoplankton diversity. According to the integrated model, two principal concurrent ecological trends influence the distribution of phytoplankton diversity; the first lies in the inshore to offshore transect, while the second corresponds to a climatic (temperature) variation through time. The model predicts that phytoplankton diversity increases (and dominance decreases) from mesotrophic-eutrophic, cold (regressive), proximal habitats, towards warmer (transgressive), distal, oligotrophic environments. With this approach, a large dominance peak situated in the upper Paroistodus originalis conodont Zone is considered indicative of an important regression separating Middle and Upper Members of the Dawan Formation. The multivariate Correspondence Analysis proved very useful to investigate the acritarch biofacies, which characterize the various habitats on the platform during both regressive and transgressive events. This analysis enables identification of four main biofacies, each referable to a particular environment, as follows: Biofacies I (Galeata Biofacies), from cool waters of eutrophic, upwelling influenced, coastal habitats; Biofacies II (Baltisphaerid-Petemosphaerid Biofacies), from temperate waters of inshore, mesotrophic habitats; Biofacies III (Veryhachid-Diacromorph-Polygonid Blofacies) from temperate waters of offshore, moderately to highly oligotrophic environments; and, Biofacies IV (Barakella, Picostella, Striatotbeca Biofacies), from temperate, oceanic, highly oligotrophic habitats. Biofacies I corresponds to regression, while Blofacies II-IV correspond to a range of environments during transgressive episodes. Although acritarch biofacies are conceptually unrelated to inferred palaeogeographic settings, the more distal habitats (Biofacies III and IV), influenced by oceanic waters, would be expected to show more Mediterranean than acritarch characteristics. Conversely, attributes would be embodied by acritarch assemblages from proximal or internal situations (Biofacies II), having more restricted circulation of warmer inshore or estuarine waters. Consequently, the more substantial transgressions could be signalled by the occurrence of Mediterranean-type assemblages, while the essentially unaffected, more internal contemporaneous habitats could retain attributes. A more reliable indicator of sea-level fluctuation is the Diversity Index. The acritarch diversity curve measured at Daping can be correlated with the global sea-level curve reported for the Arenig, as follows: a) a large transgressive peak extends from the topmost Oepikodus evae to the entire Baltoniodus? triangularis-B. navis Zone, b) a negative trend comprises the lower two-thirds of the R originalis Zone, c) a transgressive tendency covers the upper third of the P originalis Zone and the lower Microzarkodina parva-Baltoniodus norrlandicus Zone, with a maximum in the upper part of the latter, followed by d) a short-term regressive trend, with a minimum in the middle Lenodus antivariabilis Zone, and by e) an apparent further positive trend in the upper L. antivariabilis Zone. The evolutionary consequences of these events are discussed, taking into account the importance of the different biofacies for the adaptative changes of the phytoplankton across repeated extinction (regressive) events. Abandonment of the current palaeophytogeogeographic terminology (Mediterranean Province, Baltic Province) is proposed, in favour of different terms (Mediterranean palynoflora, Baltic palynoflora) that are more closely related to both the environmental/ecological factors and the evolutionary adaptations of the phytoplankton in response to such factors." @default.
- W2413095810 created "2016-06-24" @default.
- W2413095810 creator A5022844148 @default.
- W2413095810 creator A5089580599 @default.
- W2413095810 creator A5090935366 @default.
- W2413095810 date "2003-10-29" @default.
- W2413095810 modified "2023-09-27" @default.
- W2413095810 title "Lower Yushanian to lower Zhejiangian palynology of the Yangtze Gorges area (Daping and Huanghuachang sections), Hubei Province, South China" @default.
- W2413095810 doi "https://doi.org/10.1127/palb/266/2003/1" @default.
- W2413095810 hasPublicationYear "2003" @default.
- W2413095810 type Work @default.
- W2413095810 sameAs 2413095810 @default.
- W2413095810 citedByCount "33" @default.
- W2413095810 countsByYear W24130958102012 @default.
- W2413095810 countsByYear W24130958102013 @default.
- W2413095810 countsByYear W24130958102014 @default.
- W2413095810 countsByYear W24130958102015 @default.
- W2413095810 countsByYear W24130958102017 @default.
- W2413095810 countsByYear W24130958102019 @default.
- W2413095810 countsByYear W24130958102021 @default.
- W2413095810 countsByYear W24130958102023 @default.
- W2413095810 crossrefType "journal-article" @default.
- W2413095810 hasAuthorship W2413095810A5022844148 @default.
- W2413095810 hasAuthorship W2413095810A5089580599 @default.
- W2413095810 hasAuthorship W2413095810A5090935366 @default.
- W2413095810 hasConcept C100970517 @default.
- W2413095810 hasConcept C120359367 @default.
- W2413095810 hasConcept C127313418 @default.
- W2413095810 hasConcept C151730666 @default.
- W2413095810 hasConcept C162501224 @default.
- W2413095810 hasConcept C166957645 @default.
- W2413095810 hasConcept C187320778 @default.
- W2413095810 hasConcept C18903297 @default.
- W2413095810 hasConcept C191935318 @default.
- W2413095810 hasConcept C205649164 @default.
- W2413095810 hasConcept C2780618852 @default.
- W2413095810 hasConcept C3018003528 @default.
- W2413095810 hasConcept C3018430610 @default.
- W2413095810 hasConcept C86803240 @default.
- W2413095810 hasConceptScore W2413095810C100970517 @default.
- W2413095810 hasConceptScore W2413095810C120359367 @default.
- W2413095810 hasConceptScore W2413095810C127313418 @default.
- W2413095810 hasConceptScore W2413095810C151730666 @default.
- W2413095810 hasConceptScore W2413095810C162501224 @default.
- W2413095810 hasConceptScore W2413095810C166957645 @default.
- W2413095810 hasConceptScore W2413095810C187320778 @default.
- W2413095810 hasConceptScore W2413095810C18903297 @default.
- W2413095810 hasConceptScore W2413095810C191935318 @default.
- W2413095810 hasConceptScore W2413095810C205649164 @default.
- W2413095810 hasConceptScore W2413095810C2780618852 @default.
- W2413095810 hasConceptScore W2413095810C3018003528 @default.
- W2413095810 hasConceptScore W2413095810C3018430610 @default.
- W2413095810 hasConceptScore W2413095810C86803240 @default.
- W2413095810 hasIssue "1-6" @default.
- W2413095810 hasLocation W24130958101 @default.
- W2413095810 hasOpenAccess W2413095810 @default.
- W2413095810 hasPrimaryLocation W24130958101 @default.
- W2413095810 hasRelatedWork W1973831813 @default.
- W2413095810 hasRelatedWork W2082402042 @default.
- W2413095810 hasRelatedWork W2093776561 @default.
- W2413095810 hasRelatedWork W2328146096 @default.
- W2413095810 hasRelatedWork W2413095810 @default.
- W2413095810 hasRelatedWork W3118751091 @default.
- W2413095810 hasRelatedWork W4206762528 @default.
- W2413095810 hasRelatedWork W4229847984 @default.
- W2413095810 hasRelatedWork W4249742163 @default.
- W2413095810 hasRelatedWork W607160123 @default.
- W2413095810 hasVolume "266" @default.
- W2413095810 isParatext "false" @default.
- W2413095810 isRetracted "false" @default.
- W2413095810 magId "2413095810" @default.
- W2413095810 workType "article" @default.