An attempt to determine the microwave paleointensity on historic Paricutín volcano lava flows, Central Mexico

Abstract

We report a preliminary rock-magnetic and microwave paleointensity study of historic lava flows between 1943 and 1948 of Paricutín volcano. These lava flows show well-preserved, well-exposed, fresh and extensive outcrops. Most samples are characterized by simple uni-vectorial plots. The isothermal remanent magnetization curves show saturation at low to moderate fields, suggesting titanomagnetite series. From hysteresis experiments magnetic carriers are likely iron-rich titanomagnetites with single-domain or pseudo-single-domain behavior. Microwave paleointensity technique was applied to three selected samples using Kono and Ueno's (1977) method; i.e., the direction of applied laboratory field was perpendicular to the direction of remanent magnetization. The samples yielded paleointensity values of 11.38, 26.37 and 51.6 micro Tesla, which are significantly different from expected values. The observed scatter is likely to be caused by the small fraction of natural remanent magnetization used for paleointensity determination, or from not using a cooling rate correction for natural samples.