SEDIMENT DISPERSAL AND BOTTOM-CURRENT INFLUENCE IN A CARBONATE RAMP SYSTEM: AMS AND STRATIGRAPHIC EVIDENCE FROM THE VACA MUERTA FORMATION

This study integrates sedimentological, sequence-stratigraphic, and geophysical analyses to identify sediment dispersal patterns within the foreset area of a prograding clinoform. Three stratigraphic sections of the Vaca Muerta Formation, distributed along a 15 km transect, were examined, allowing the identification of six facies and two facies associations (FA1, FA2). The interval corresponds to a third-order composite sequence composed of three fourth-order high-frequency sequences (HFS). HFS-1, assigned to the lower member of the Vaca Muerta Formation, is integrated by FA1, and it represents a mixed carbonate-siliciclastic ramp system. HFS-2 and HFS-3, which includes FA2 and the Los Catutos Member, represent sedimentation in a carbonate outer ramp setting. Anisotropy of Magnetic Susceptibility analyses allowed recognition of primary, post-depositional, and inverse fabrics. Primary fabrics include fall-out and flow-aligned petrofabrics; post-depositional fabrics are related to bioturbation and dolomitization processes; inverse fabrics respond to the presence of ferroan calcite. Paleocurrent data indicate SE-to-NW-directed flows for the turbiditic deposits, consistent with the direction of clinoform progradation, as well as SW-NE to W-E oriented bottom-currents for the rest of the succession, interpreted as shore-parallel bottom currents. These results underscore the usefulness of the AMS technique as a tool for resolving depositional dynamics in distal marine environments.