Abstract: Ground Penetrating Radar: High Resolution Imaging of Braided River and Sandur Valley-fills

MEYERS, RICHARD A.

The present body of knowledge on the internal stratigraphy, sedimentary structures and geometry of valley-fills in gravel braided rivers, sandurs and strand plains is based on limited field evidence. The main problem encountered by researchers investigating active modern gravel fluvial depositional environments is the lack of an inexpensive, portable, non-destructive to the environment and high resolution geophysical technique for subsurface investigations. Drilling has been used in the past, but it is expensive, time consuming and provides only point sources of data and limited structural data of the gravel body. This limitation has forced past studies to concentrate on process monitoring and surface sedimentology, describing only the top few metres of these depositional environments. In addition, exposures do not often permit the study of variability between sections of a single braid bar, scour depression or braid plain.

The overall objective is to characterize the cross-sectional nature and three-dimensional architecture of valley-fills, primarily using radar stratigraphy and radar facies analysis. A pulseEKKO IV radar system with 12.5, 25, 50, 100 and 200 MHz antennae will be used to investigate over 30 braided river and sandur sites. Most importantly, the properties of the sedimentary deposits, areal variations in the sediments (both vertically and horizontally) and the geometry of the deposits will be investigated. The goal is to determine the internal primary sedimentary structures of braided river and sandur valley-fills and test the presently accepted litho-facies models for these environments.

AAPG Search and Discovery Article #90940©1997 AAPG Foundation Grants-in-Aid