Paleoenvironmental reconstruction of a Neogene diatomite deposit from La Pampa Province (Argentina)

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Geobios Pub Date : 2025-02-01 DOI:10.1016/j.geobios.2024.02.009

Rocío Fayó , Marcela Alcira Espinosa , Camilo Andrés Vélez-Agudelo

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引用次数: 0

Abstract

Diatomite deposits constitute siliceous biogenic sedimentary rocks primarily composed of diatoms. In Argentina, there is a scarcity of paleoenvironmental reconstructions for these deposits. This study focuses on the analysis of the diatom content in a Plio-Pleistocene diatomite from La Pampa Province. The aim is to identify diatom diversity and reconstruct the evolution of paleoenvironments. The studied section of 4.40 m is located at the CP site (38°08′40.5’’S; 67°09′23.2’’W, El Sauzal Formation). The profile is a laminated white diatomite with three levels of volcanic ash. Seven samples 50 cm-equidistant were extracted and oxidized with H₂O₂ for diatom analysis. 500 valves/slide were counted in order to calculate relative abundances. Diatom zones were defined using CONISS. The analysis revealed 72 morphospecies, with 28 of them exhibiting abundances >4%. The diatom flora is predominantly composed of small fragilarioid diatoms accompanied by Discostella, Aulacoseira, Epithemia, Rhopalodia, and Cymbella species, indicating a lacustrine origin. At the base, a paleolake with a relatively alkaline pH, low nitrogen concentrations and high phosphates (volcanic ash) favored the growth of a diverse diatom community. Towards the top, the dominance of fragilarioids, the decrease in freshwater planktonic taxa and the presence of gypsum suggest a shallower environment with increased salinity during the drier periods of the Plio-Pleistocene.

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来源期刊

Geobios 地学-古生物学

CiteScore

3.30

自引率

6.20%

发文量

审稿时长

6-12 weeks

期刊介绍： Geobios publishes bimonthly in English original peer-reviewed articles of international interest in any area of paleontology, paleobiology, paleoecology, paleobiogeography, (bio)stratigraphy and biogeochemistry. All taxonomic groups are treated, including microfossils, invertebrates, plants, vertebrates and ichnofossils. Geobios welcomes descriptive papers based on original material (e.g. large Systematic Paleontology works), as well as more analytically and/or methodologically oriented papers, provided they offer strong and significant biochronological/biostratigraphical, paleobiogeographical, paleobiological and/or phylogenetic new insights and perspectices. A high priority level is given to synchronic and/or diachronic studies based on multi- or inter-disciplinary approaches mixing various fields of Earth and Life Sciences. Works based on extant data are also considered, provided they offer significant insights into geological-time studies.