An integrative physical, mineralogical, and ichnological approach to characterize underfilled lake-basins

MANCUSO, ADRIANA CECILIA; KRAPOVICKAS, VERÓNICA; BENAVENTE, CECILIA ANDREA; MARSICANO, CLAUDIA

SEDIMENTOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020 vol. 67 p. 3088 - 3118

0037-0746

Lakes are particularly sensitive to environmentalfluctuations, which are recorded in their facies and depositional histories. Ephemerallakes reveal their sensitivity to paleoenvironmental changes in theoverprinting of the sedimentary features in every single bed. Detailed studiesabout the tetrapod-track taphonomic modes and ichnological taphonomic pathways canbe used as sensitive indicators of environmental conditions of thetrack-bearing beds during deposition and imprinting. The Anisian Cerro de lasCabras succession (Cuyana Basin, Argentina) provides an excellent opportunityto characterize tetrapod footprint preservation and ichnofauna taphonomicpathways in an underfilled paleolake. A preservation model of the ichnologicalrecord for underfilled lake systems is proposed and evaluated the role ofichnology record in the sequencestratigraphy analysis, [A1] [A2] based on the integration of tetrapod track modes, taphonomicpathways of playa-lake ichnofauna, mineralogy, and physical data. Soft-groundsuites dominate[A3] invertebrates producing delicate grazing traces,arthropod locomotion traces (Suite 1) overprinted by horizontal-verticaldwelling burrows (Suite 2), and tetrapod tracks preserve in taphonomic modes 2and 3. Firm-ground suite (Suite 3) comprises tetrapod tracks with the bestpreservation styles (modes 1 and 2) and, less abundant, dwelling and feedingtraces (Suite 2). Clay mineralogy (dominated by illite with subordinatedsmectite) suggests low plasticity of the layers in agreement with low-reliefdeformation structures observed in tetrapod track taphonomic modes. Thewell-preserved track tetrapod features documented in the Cerro de las Cabrassuccession, together with the absence of pedogenic disturbance, tramplingobliterating the footprints, and/or evidence of strong disturbance by wind, desiccation, and/or precipitation supportsshort periods of exposure of the imprinted surface. The observed aggradationaltrend suggests an equilibrium between rates of accommodation creation andsediment supply, and the basin-center did not experience prolonged starvedconditions.