Diatom-inferred palaeoenvironmental changes of a Pliocene lake disturbed by volcanic activity |
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| Authors: | G Vilaclara G Martinez-Mekler E Cuna E Ugalde |
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| Institution: | 1.Limnología Tropical, UIICSE, División de Investigación y Posgrado, FES-Iztacala,Universidad Nacional Autónoma de México,Tlalnepantla,México;2.Instituto de Ciencias Físicas,Universidad Nacional Autónoma de México,Cuernavaca,México;3.Centro de Ciencias de la Complejidad,Universidad Nacional Autónoma de México,Coyoacán, México City,México;4.Posgrado de Ciencias del Mar y Limnología,Universidad Nacional Autónoma de México,Coyoacán, México City,México;5.Instituto de Física,Universidad Autónoma de San Luis Potosí,San Luis Potosí,México |
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| Abstract: | Lake development in geologically active basins is a complex phenomenon as shown by the bed of the Pliocene Tlaxcala paleolake
disturbed by volcanic eruptions in central Mexico. A 5-m layered freshwater diatomite outcrop section shows volcanic ashes
throughout a bottom Stephanodiscus zone up to a more recent Aulacoseira zone. A 0.5-m transition region begins with an abrupt decrease in volcanic inputs and ends with a shift to Aulacoseira solida (Eulenstein) Krammer. Sediment analysis points to a shallow eutrophic lake in the bottom zone undergoing a transition to
higher water volume leading to a threshold depth for the species shift. The lake was apparently deeper and mesotrophic thereafter.
A common interpretation is to attribute such a volume change to a moisture increase. However, evidence of geological activity,
mainly volcanism and faulting, suggests that it could have also been rooted in geomorphological changes of the lake basin. |
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