INVESTIGADORES
ORFEO Oscar
congresos y reuniones científicas
Título:
The alluvial architecture of a fine-grained meandering river: the Río Bermejo, Argentina
Autor/es:
SAMBROOK SMITH, G.; BEST, J.; ORFEO, O.; ZINGER, J.
Lugar:
Leeds
Reunión:
Congreso; International Conference on Fluvial Sedimentology; 2013
Institución organizadora:
University of Leeds
Resumen:
The results demonstrate that the PES has the ability to provide high resolution (decimeter) datasets from finegrained rivers that are equivalent to the more commonly used GPR, which works in coarser grained environments. Analysis of the data reveals that the deposits of the Rio Bermejo are characterized by a lower unit comprising long, low-angle surfaces associated with active point bar evolution (Fig. 1), and large-scale scour surfaces resulting from channel migration. These sediments are truncated and overlain by vertical accretion deposits, with sets associated with small bars, dunes and climbing ripples, and cut and fill structures resulting from cross-bar channels. This overall style of alluvial architecture is very different from other modern silt-bed-rivers in the literature that tend to emphasise the presence of oblique accretion. The Rio Bermejo differs from these other rivers because it is much more active, with very high rates of bank erosion and channel migration. Modern examples of this type of highly active fine-grained river have been rarely reported in the literature, although ancient examples are more prevalent. For example, the Lower Permian (Wolfcampian) Abo Formation of south-central New Mexico displays very similar alluvial architectures as the Rio Bermejo, which thus represents a useful analogue for the identification and interpretation of these ancient deposits. More broadly, it is concluded herein that the PES has the potential to transform our understanding of fine-grained rivers in as significant a way as GPR has for coarser-grained rivers. The PES is capable of imaging the detailed large scale alluvial architecture, which is simply not possible with cores or shallow trenches. In such a way, the full complexity of the sedimentology of this under-reported channel type may be revealed.
