INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Fish taphonomy in lacustrine environment: Cacheuta Formation (Middle Triassic, Mendoza)
MANCUSO, ADRIANA CECILIA
San Rafael, Mendoza, Argentina
Jornada; XXIV Jornadas Argentinas de Paleontología de Vertebrados; 2009
Important water bodies were housed in extensional basins, during Triassic, in Center-Western Argentina. The broadest lacustrine sequence in Cuyana Basin is known as Cacheuta Formation, and supplies wide fish diversity. This work evaluates the Cacheuta fish remains within environmental context, as their preservation and growth is closely linked to it. In addition, they will be contrasted to the reduced Los Rastros fish record, and to the classic models of fish preservation. The features of Cacheuta fish reveal their taphonomic history: the remains found in open lake facies arrived to bottom, either after suffering flotation-decay (scales and bones isolated and dispersed, without spatial pattern, well sorted), or intact without suffering flotation-decay, predation or scavenging (articulated fish, without preferred orientation, concordant to stratification, dispersed, poorly sorted). The remains found in underflows (scales and bones associated but dispersed, forming clumps and stringer, concordant to stratification, loosely-packed, well sorted) and turbiditic flows (scales and bones associated but dispersed, forming clumps with bioclast cutting the stratification, densely-packed, loosely sorted, abrasion and breakage in bioclast) arrived to delta associated facies, after suffering flotation-decay and rework by different flows that imprinted their particular features. In contrast to Los Rastros Lake, Cacheuta Lake preserved abundant fish remains, both in lake and delta facies. In both cases, flotation-decay process mainly lead to fish disarticulation. Only in Cacheuta Lake articulated fish occur in open lake facies. Accordingly, and unlike to the allochthonous Los Rastros fish record, the Cacheuta fish remains represent an abundant autochthonous lacustrine community of primarily pelagic and nektonic organisms.