DIFFERENTIAL PRESERVATION OF FRESHWATER DIATOMS AND MOLLUSKS IN LATE HOLOCENE SEDIMENTS: PALEOENVIRONMENTAL IMPLICATIONS

HASSAN, GABRIELA S.; TIETZE, ELEONOR; CRISTINI, PAULA A.; DE FRANCESCO, CLAUDIO G.

Mendoza

Congreso; 4th International Paleontological Congress; 2014

IANIGLA, CCT-CONICET Mendoza

One of the limitations of paleoenvironmental reconstructions based on multiple bioindicators is the lack of knowledge on the differential preservation of hard parts, which may lead to biases in the interpretations. This is particularly important when biological proxies differ in their intrinsic properties, as skeletal mineralogy or size. We explored and compared the preservational patterns of siliceous (diatoms) and carbonatic (mollusks) indicators during the Late Holocene (last ca. 4000 cal. years B.P.) in two lacustrine sedimentary successions from Argentina (Nahuel Rucá and Hinojales San Leoncio). Fragmentation and fine-scale surface alteration indices were calculated on two target species: the diatom Cyclotella meneghiniana and the snail Heleobia parchappii. The taphonomic curves obtained were smoothed along depth with a locally weighted regression (LOESS), and statistically compared using Spearman correlations. Additionally, past environmental conditions were inferred from the autoecology of the dominant taxa. Diatoms and mollusks displayed similar tendencies in fragmentation (r=0.31, p