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TitleMagnetic mineralogy of the Yaxcopoil-1 core, Chicxulub
AuthorPilkington, M; Ames, D EORCID logo; Hildebrand, A R
SourceThe Chicxulub Scientific Drilling Project; Meteoritics and Planetary Science vol. 39, no. 6, 2004 p. 831-841, Open Access logo Open Access
LinksAbstract - Résumé
LinksThe Chicxulub Scientific Drilling Project
Alt SeriesGeological Survey of Canada, Contribution Series 2003222
Mediapaper; on-line; digital
File formatpdf
AreaChicxulub; Mexico
Lat/Long WENS -90.5000 -88.5000 22.0000 20.2500
Subjectsextraterrestrial geology; geochemistry; geophysics; metallic minerals; mineralogy; magnetic properties; magnetic susceptibility; magnetite; remanent magnetism; magnetic anomalies; magnetic surveys; magnetic surveys, airborne; magnetism; alteration; mafic rocks; amphibole; pyroxene
Illustrationsmagnetic profiles; magnetic cross-sections; tables; photomicrographs
Released2004 06 01
AbstractCore from the Yaxcopoil-1 (Yax-1) hole, drilled as a result of the Chicxulub Scientific Drilling Project (CSDP), has been analyzed to investigate the relationship between opaque mineralogy and rock magnetic properties. Twenty one samples of suevite recovered from the depth range 818-894 m are generally paramagnetic, with an average susceptibility of 2000 × 10-6 SI and have weak remanent agnetization intensities (average 0.1 A/m). The predominant magnetic phase is secondary magnetite formed as a result of low temperature (<150 °C) alteration. It occurs in a variety of forms, including vesicle infillings associated with quartz and clay minerals and fine aggregates between plagioclase/diopside laths in the melt. Exceptional magnetic properties are found in a basement clast (metamorphosed quartz gabbro), which has a susceptibility of >45000 × 10-6 SI and a remanent magnetization of 77.5 A/m. Magnetic mafic basement clasts are a common component in the Yax-1 impactite sequence. The high susceptibility and remanence in the mafic basement clasts are caused by the replacement of amphiboles and pyroxenes by an assemblage with fine <1 um magnetite,
ilmenite, K-feldspar, and stilpnomelane. Replacement of the mafic minerals by the magnetic alteration assemblage occurred before impact. Similar alteration mechanisms, if operative within the melt sheet, could explain the presence of the high amplitude magnetic anomalies observed at Chicxulub.

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