HR: 0830h
AN: GP21A-0036    [PDF]
TI: Interpretation of the new CHAMP crustal field anomaly maps using a GIS technique
AU: Hemant, K
EM: hemant@gfz-potsdam.de
AF: GeoForschungsZentrum, Potsdam, Telegrafenberg, Potsdam, 14473 Germany
AU: * Maus, S
EM: smaus@gfz-potsdam.de
AF: GeoForschungsZentrum, Potsdam, Telegrafenberg, Potsdam, 14473 Germany
AU: Haak, V
EM: vhaak@gfz-potsdam.de
AF: GeoForschungsZentrum, Potsdam, Telegrafenberg, Potsdam, 14473 Germany
AB: Reliable global crustal field anomaly maps produced from magnetic data of the first three years of the CHAMP satellite mission now allow for quantitative geological studies of crustal structure and composition. Here, we have developed a GIS based forward modeling technique to infer crustal structure overlain by younger cover. Modeling takes the geologic and tectonic maps of the world as the input and, depending upon the known rock types in each region, an average susceptibility value is computed for every geological unit. Next, the vertically integrated susceptibility (VIS) is generated by multiplying the average susceptibility with the seismic crustal thickness, as given by global models of 3SMAC and CRUST2.1. Starting with this initial VIS model, the vertical field anomaly is computed at an altitude of 400 km and compared with the corresponding CHAMP vertical field anomaly map. Significant geological inferences are made from the agreement and the discrepancies between our initial map and the observed anomaly map. In a subsequent modeling step the poorly known boundaries of buried crustal units are modified until the recomputed map fits the observed magnetic map. By this simple procedure a remarkably good fit to the magnetic anomaly map is be achieved. We conclude that the lateral extent of Archean units in the lower crust can thus be inferred from satellite magnetic anomaly maps.
DE: 1517 Magnetic anomaly modeling
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting