Three dimensional finite element modeling of inloop transient electromagnetic measurements on a lake

摘要

Lake sediments are mainly archives on paleoclimatic fluctuations, geomagnetic field variations and volcanic activities.Therefore, the thickness of them is very important for paleoclimatic studies. To determine the thickness of sediments beneath the lakes a floating TEM field-setup with a transmitter size of 18x18m2 was developed which enables inloop TEM measurements on the surface of lakes. Due to its modular design it can be handled by two operators and is easy to transport.Lake Holzmaar in Eifel/Germany is a maar lake and its lacustrine sediments provide paleoclimatic proxy data. An extensive inloop TEM survey was carried out on the surface of this lake to determine the thickness of its sediments. The TEM data collected can be explained well by means of three dimensional Finite Element Modeling, resulting 55m sediment thickness beneath the 20m water of the lake.