Paleomagnetism

SP Crater has been dated by several methods, but the results, with ages between 5.5 and 73 ka, conflict rather than agree.  Paleosecular variation is one technique that may help us evaluate the date.  Because Earth’s north magnetic pole changes with time, and because the Late Holocene time period is characterized by rapid secular variations, we can compare the magnetic direction locked in the rock with the record of this variation to see if the 5.5 ka date is possible.  We can also check for the time span between the emplacement of two lava flows from the eruption.  Third, we can determine whether spatter cones were rafted from the vent and rotated on a vertical axis during transport. 

Colton Crater (also called Crater 160) is a scoria cone that exploded when magma encountered water.  Paleomagnetism can be used to determine whether spatter layers were rotated after cooling, and may also be useful in determining the temperatures of emplacement of the pyroclasts.  This will help us understand the history and timing of eruptive events in this rather complex scoria cone. 

Both projects will involve field work to better define the problems and to drill oriented cores from the rock.  Lab work will involve cutting the samples and analyzing them at NAU and possibly at other laboratories.  Physics classes through electricity and magnetism (usually toward the end of the first year of physics) will be helpful.

Contact Michael Ort for more information.