INCORPORATING TAPHONOMY INTO COMMUNITY-BASED PALEOENVIRONMENTAL RECONSTRUCTIONS: CAN DIATOM PRESERVATION DISCRIMINATE BETWEEN SHALLOW LAKE SUB-ENVIRONMENTS?

HASSAN, GABRIELA S.; ROJAS, LUCIANA A.; DE FRANCESCO, CLAUDIO G.

PALAIOS

SEPM-SOC SEDIMENTARY GEOLOGY

Lugar: Lawrence; Año: 2018 vol. 33 p. 376 - 392

0883-1351

The value oftaphonomic signatures as a source of paleoenvironmental information has beenrecognized at local and regional environmental scales. In environmentallyheterogeneous shallow lakes, the habitat complexity provides an opportunity toevaluate the potential use of taphonomy to uncover environmental differencesbetween within-lake sub-environments. In this contribution, the composition andpreservation of diatom assemblages from five sub-environments (free-floatingand attached macrophytes, water column, open waters and littoral sediments) wereanalyzed in a Pampean shallow lake (Nahuel Rucá, Argentina). Sub-environmentsdiffered in depth, macrophyte coverage, and water composition, being thesedifferences reflected both by the composition and preservation of diatomassemblages. Diversity, fragmentation, and dissolution were higher inplanktonic and open-waters sedimentary assemblages, whereas fragmentationdominated in littoral sediments. Epiphytic assemblages were the least diverse andshowed the best preservation. Compositional and taphonomic indices weresignificantly correlated, suggesting common environmental controls on thespecies composition and preservation at local scales. The joint analysis ofcompositional and taphonomic variations in the recent sedimentary record ofNahuel Rucá demonstrated the usefulness of taphonomic analyses to uncover subtlepaleoenvironmental variations, which could be overlooked if only traditionalcompositional analyses are performed. We concluded that both taphonomicanalyses and a holistic consideration of ecologically meaningful taxa should beconsidered in order to improve paleoenvironmental reconstructions inenvironmentally heterogeneous shallow lakes.