Boreal Peat GPR & ERI
GPR and ERI Profiles of a Boreal Peatland Penetrating to 6 m and 10 m Depth, Respectively.
Fig. 1. GPR profile collected over 530 m of peatland with a 100-MHz antenna and lithostratigraphy from core C2. Core stratigraphy is peat (yellow) over a silt layer over lake sediment over glaciomarine mud (orange). Green dots are probe depths at refusal. High amplitude GPR events occur at the cored peat-lake sediment contact and the lake-marine sediment contact. The EM signal is attenuated in the top of the glaciomarine mud at a depth of ~ 6m. *
Fig. 2. Low-resolution (5 m electrode spacing) ERI image along the portion of the GPR profile in Fig. 1 marked 0-260. Note scale is in conductivity units. White dots represent the base of the peat; black dots represent the base of the lake sediment according to GPR. Black horizontal bar gives the location of Fig. 3. ERI shows three units: uniform upper resistive layer over a conductive unit of varying thickness over a resistive layer. The top of the conductive layer appears to occur within the peat; the bottom is considered the base of the glaciomarine sediment. Thus, ERI best reflects sub-peat, confining layer stratigraphy. *
Fig. 3. High-resolution (1.5 m electrode spacing) ERI image along the portion of the ERI profile in Fig. 2 with black bar. Note scale is in conductivity units. White dots represent the base of the peat, black dots represent the base of the lake sediment according to GPR. ERI shows downward increase in conductivity indicative of changes in peat matrix.*
* Slater, L. D., and Reeve, A., 2002, Investigating peatland stratigraphy and hydrogeology using integrated electrical geophysics: Geophysics, v. 67, no. 2, p. 365-378.