抄録
The geomagnetic variation anomaly on Ellesmere Island has been attributed to an elongated conductor located deep in the crust or in the upper mantle and striking northeast across the northern portion of the island. Recently observations have been made on the ice of the Lincoln Sea lying to the north of Ellesmere and Greenland, and the anomaly has been found to extend beyond the coast for a distance of 100km or more beneath the continental shelf. Fitting the data with a uniform current model suggests that the anomalous conductor is about 100km wide, 10km thick, and located in the crust at depths between 10 and 20km.
The anomaly lies at the northeastern end of the Innuitian Province. It follows approximately the axis of the Franklinian Geosyncline (Ordovician to mid-Silurian) and parallels the structural trend of the lower paleozoic strata which were folded during the Ellesmerian Orogeny of Devonian-Mississippian times. There is no geophysical evidence suggesting a contemporary or recent origin for the anomaly. The high conductivity zone seems more likely to be caused by hydration and structural changes deep in the crust; the geological evidence suggests that it may be a relic of ancient tectonic activity.
