Sources of Magnetic Anomalies over a Sedimentary Basin: Preliminary Results from the Coastal Plain of the Arctic National Wildlife Refuge, Alaska*
Jeffrey D. Phillips, Richard W. Saltus, Richard L. Reynolds, 1998. "Sources of Magnetic Anomalies over a Sedimentary Basin: Preliminary Results from the Coastal Plain of the Arctic National Wildlife Refuge, Alaska", Geologic Applications of Gravity and Magnetics: Case Histories, Richard I. Gibson, Patrick S. Millegan
Download citation file:
As part of tectonic studies by the Energy Program of the U.S. Geological Survey, we have modeled aeromagnetic anomalies over the coastal plain of the Arctic National Wildlife Refuge (ANWR), Alaska. Preliminary models indicate that the lineated, moderate-intensity anomalies produced by shallow sources within the coastal plain are best fit by a series of stratigraphic layers with both normal and reversed remanent magnetization. The layers follow seismically determined stratigraphic and structural boundaries from near the surface to depths of 1 to 2 km. The modeled total magnetic intensities range up to .115 A/m for the reversely magnetized units and up to .069 A/m for the normally magnetized units. Based on these models, we suspect that the magnetic anomalies are primarily the result of detrital remanent magnetization that formed as the sediments were deposited. Another plausible explanation involves chemical remanence, acquired rapidly with respect to geomagnetic polarity reversals, as the marine turbidite sediments accumulated, thus producing a stratigraphically ordered polarity sequence. The high total magnetizations and reversed polarities leave open the additional possibility that thick sequences of originally reversed magnetization were overprinted by normal remanence through some stratigraphically controlled mechanism.