Digital Mapping of Post-Glacial Deep Water Depositional Systems, Carboniferous, Northwest Argentina

Philip Thompson¹, Mason Dykstra², Benjamin Kneller¹, Vanessa Kertznus¹, Magdalena Szuman¹, and Juan Pablo Milana^3
1 University of Aberdeen, Aberdeen, United Kingdom
² University of California, Santa Barbara, CA
³ Universidad de La Serena, La Serena, Chile

We present an approach to three-dimensional mapping using a hand-held reflector-less laser range-finder on areas of exceptional outcrop. An essential component of our technique is the mapping of geological boundaries directly in the field, calibrated to detailed sedimentological logs, and the construction of 3D surfaces within a Geographical Information System framework. Visualization is aided by the construction of digital elevation models using the same technology, and the integration of digital photos.

We present data from two systems. One of these includes exceptional exposure of a >100 meter thick debris flow, with overlying turbidites that are locally ponded in the relief atop the mass transport deposit, and the succeeding condensed section; the debris flow includes blocks and rafts of shallow marine sandstones in a matrix of pebbly silty mudstone (a remobilized dropstone deposit). The second system consists of sheet-like turbidite sands that form part of the fill of a steep-walled paleo-fjord, which constitutes an analog for ponded slope turbidite systems; we have used our 3D models to reconstruct the paleo-topography, and combined this with a detailed assessment of the sedimentology to elucidate the interactions between the turbidity currents and the fjord walls.