Ground penetrating radar surveying and sediment coring analysis of a post-glacial lake, Eastern Newfoundland

• Main Author: Chen, Jianguang
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2018
• Subjects: Glacial Lake; Grassy Pond; Newfoundland
• Online Access: https://research.library.mun.ca/13338/; https://research.library.mun.ca/13338/1/thesis.pdf

Ground penetrating radar (GPR) is a relatively newly developed high-frequency electromagnetic technique that has been widely used in the shallow subsurface investigation for the last few decades. Recently, a GPR survey of a small organic-rich post-glacial lake (Grassy Pond) in Eastern Newfoundland shows significant continuous laminations within the lake sediments in the GPR profiles. Since there have been very few GPR stratigraphy studies of lacustrine sediments, the main focus of this project is on the correlation between the sediment stratigraphy and the GPR sub-bottom profiles. Secondary interests are: to estimate the carbon content of a typical small inland lake to help assess how such bodies have contributed to the carbon budget since the last glaciation; and to investigate chemical variability within the sediments. The work in this project includes GPR surveying, sediment coring, and sediment physical, geochemical and chronostratigraphic data acquisition, calibration and correlation. First of all, 50 and 100 MHz GPR surveys were completed on Grassy Pond when the lake surface was frozen in the winter. Bathymetric and depth-to-bedrock maps were created from the GPR profiles. Based on these two maps, a sediment distribution map was also created and this was used to choose sediment coring locations. Four sediment cores were collected by using a rod-driven piston corer, and additional GPR profiles were collected over these core locations. The cores were then scanned by a Multi-Sensor Core Logger (MSCL) to determine the physical properties. After that, the cores were sub-sampled and geochemically analyzed by ICP-OES. Selected sediment samples were also analyzed for C and N contents and isotopes, and radiocarbon dated. Lastly, the linkage was made between the geophysical and geochemical data, and a simple GPR forward model was created based on the sediment physical properties to enhance the data interpretation and correlation. The results show that the lake sediments of Grassy Pond are highly-organic and ...