Physical Sciences and Mathematics Commons^™

Timing Of Magnetite Formation In Basaltic Glass: Insights From Synthetic Analogs And Relevance For Geomagnetic Paleointensity Analyses, Julie A. Bowles, Jeffrey S. Gee, Katherine Burgess, Reid F. Cooper

Geosciences Faculty Articles

Absolute paleointensity estimates from submarine basaltic glass (SBG) typically are of high technical quality and accurately reflect the ambient field when known. SBG contains fine-grained, low-Ti magnetite, in contrast to the high-Ti magnetite in crystalline basalt, which has lead to uncertainty over the origin of the magnetite and its remanence in SBG. Because a thermal remanence is required for accurate paleointensity estimates, the timing and temperature of magnetite formation is crucial. To assess these factors, we generated a suite of synthetic glasses with variable oxygen fugacity, cooling rate, and FeO* content. Magnetic properties varied most strongly with crystallinity; less crystalline …