HR: 0830h
AN: GP31B-0753    [PDF]
TI: The Hysteresis Properties of Multidomain Magnetite and Titanomagnetite/-maghemite in Mid Ocean Ridge Basalts
AU: * Wang, D
EM: wangdm@umich.edu
AF: Department of Geological Sciences, University of Michigan, 425 E. University Ave., Ann Arbor, MI 48109-1063
AU: Van der Voo, R
EM: voo@umich.edu
AF: Department of Geological Sciences, University of Michigan, 425 E. University Ave., Ann Arbor, MI 48109-1063
AB: Hysteresis measurements have been carried out on a suite of ocean-floor basalts with ages ranging from Quaternary to Cretaceous. Approximately linear, yet separate, relationships between coercivity (Bc) and the ratio of saturation remanence /saturation magnetization (Mrs/ Ms) are observed for massive doleritic basalts with low-Ti magnetite and for pillow basalts with multi-domain titanomagnetites (with x = 0.6). Even when the MORB has undergone low-temperature oxidation resulting in titanomaghemite, the parameters are still distinguishable, although offset from the trend for unoxidized multidomain titanomagnetite. The parameters for these iron-oxides with different titanium content reveal contrasting trends that can be explained by the different saturation magnetizations of the mineral types. This plot provides a previously underutilized and non-destructive method to detect the occurrence of low-titanium magnetite in igneous rocks, notably MORB.
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting