HR: 16:30h
AN: H54A-02    [Abstracts]
TI: Environmental Magnetic Analysis of Sediment Samples From the Lower Trinity River, Texas, USA
AU: * Slattery, M
EM: m.slattery@tcu.edu
AF: Texas Christian University, Institute for Environmental Studies, PO Box 298830, Fort Worth, TX 76129 United States
AU: Walden, J
EM: jw9@st-andrews.ac.uk
AF: University of St. Andrews, Department of Geography and Geology, St. Andrews, KY169ST United Kingdom
AU: Phillips, J
EM: jdp@uky.edu
AF: University of Kentucky, Department of Geography, Lexington, KY 40506 United States
AB: This paper presents the results of an environmental magnetic study of potential source materials to the sediment system of the lower Trinity River system, Texas, USA. Environmental magnetic analysis was performed on a total of 138 individual samples representing examples of potential source materials, including surface soils, drainage ditches, channel banks, exposed channel bedforms, and a small number of bedrock exposures. The purpose was to characterise the degree of variability of these potential sources to the Trinity system and, on the basis of the results obtained, to evaluate the potential for using environmental magnetic analysis to establish sediment-source linkages within the system and its sub-catchments. A range of magnetic properties were measured and the parameters calculated include some sensitive to both concentrations of magnetic minerals and different types of magnetic behaviour. The results demonstrate considerable variability in the magnetic properties of the various source samples analysed (and, by inference, their iron mineral composition). On this basis, some sub-catchments do appear to show distinct magnetic properties and, as a result, it may well be possible to identify their potential contribution to sediment supplied to the main river system immediately downstream. However, the potential source samples for other sub-catchments show either (i) similar properties to each other or (ii) high levels of compositional variability within the sub-catchment. On this basis, we suggests that any future attempts to use compositional properties to establish sediment-source linkages within the Trinity River system, or efforts to quantify the relative contributions of the various sub-catchments to the overall sediment budget of the system, should be preceded by a further evaluation programme. Ideally, this should involve two sub-catchments of different magnetic characteristics - one with high concentration of magnetic minerals and another with low/intermediate concentrations. In each case, this should involve a suspended sediment sampling programme both upstream and downstream of the sub-catchment tributary with a view to characterising the compositions of the sediments and evaluating the reliability of a sediment source mixing model based on environmental magnetic properties might be in ascribing the contribution to the main channel sediment transport system made by the respective sub-catchments.
DE: 1512 Environmental magnetism
DE: 1815 Erosion
DE: 1825 Geomorphology: fluvial (1625)
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: Fall Meeting 2005