Magnetization of Extraterrestrial Allende material may relate to terrestrial descend
Gunther Kletetschka
Earth and Planetary Science Letters
Volume 487, 1 April 2018, Pages 1–8
Available online 3 February 2018
“Highlights
• Magnetic component of Allende connects to the descend through the terrestrial atmosphere.
• Allende was magnetized due to preexisting porosity collapse within geomagnetic field.
• Porosity of Allende created conditions for accumulation of anisotropic energy during descend.
• Anisotropic energy resulted in Allende’s acquisition of inverse thermoremanent magnetization.
• Magnetic evidence supports the absence of igneous differentiation for parent asteroid of Allende.”
“The origin of magnetization in Allende may have significant implications for our understanding of core formation/differentiation/dynamo processes in chondrite parent bodies. The magnetic Allende data may contain information that could constrain the magnetic history of Allende. The measurements on Allende chondrules reveal an existence of magnetization component that was likely acquired during the meteorite transit to terrestrial conditions. Both the pyrrhotite carrying magnetic remanence intensity and direction of the chondrules change erratically when subjecting the Allende meteorite’s chondrules to temperatures near 77 K and back to room temperature. Chondrules with more intense original magnetization are denser and contain larger inverse thermoremanent magnetization (ITRM). Temperature dependent monitoring of ITRM revealed that magnetization was acquired at temperature near 270 K. Such temperature is consistent with the condition when, in addition to temperature increase, the atmospheric uniaxial pressure applied during the meteorite entry on the porous material was responsible for meteorite break up in the atmosphere. During this process, collapse of the pore space in the matrix and some chondrules would generate crystalline anisotropy energy accumulation within pyrrhotite grains in form of parasitic magnetic transition.”
