Taphonomic analysis of an autochthonous fossil concentration in Jurassic lacustrine deposits of Patagonia, Argentina
| Autor: | Sergio Martínez, Oscar Florencio Gallego, Nora Graciela Cabaleri, Iracema A. Zacarías, Diego G. Silva Nieto, Mateo D. Monferran, Claudia Armella |
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| Rok vydání: | 2019 |
| Předmět: |
010506 paleontology
education.field_of_study Taphonomy biology Aragonite Population Paleontology engineering.material 010502 geochemistry & geophysics Oceanography biology.organism_classification 01 natural sciences Diagenesis Brachyphyllum Ostracod Facies Paleoecology engineering education Ecology Evolution Behavior and Systematics Geology 0105 earth and related environmental sciences Earth-Surface Processes |
| Zdroj: | Palaeogeography, Palaeoclimatology, Palaeoecology. 514:265-281 |
| ISSN: | 0031-0182 |
| DOI: | 10.1016/j.palaeo.2018.10.020 |
| Popis: | A new fossiliferous level from the Las Chacritas Member (Bajocian-Callovian) of the Canadon Asfalto Formation, which crops out in the Canadon Asfalto Basin (Extraandean-Chubut) Argentina was analyzed. The study of this assemblage was made on the basis of paleoecological, sedimentological and taphonomic criteria. This polytypic assemblage is composed mainly of bivalves, spinicaudatans, gastropods, and ostracods, associated with plant remains (such as Brachyphyllum sp., Charophytes, conifers, seeds, and indeterminate remains). The tabular bed of oncolitic packstone facies corresponds to a shallow marginal lacustrine environment of intense organic productivity. Taphonomic and paleoecological features, such as closed articulated valves, random orientation, and size-frequency histograms indicate that the fauna is autochthonous. The short life cycle with a quick turnover of the population, suggests that the time averaging would only comprise a few years. In addition, the analysis of Energy dispersive X-ray spectrometry supports early diagenesis affecting the remains and favoring the dissolution of aragonite/calcite, as well as the silicification of shells. Therefore, this fossil assemblage can be classified as a sedimentological concentration, which could have been originated by seasonal cyclicity in an environment subject to water level fluctuations. |
| Databáze: | OpenAIRE |
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