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dc.contributor.authorVillasante-Marcos, Víctor-
dc.contributor.authorMartínez Ruíz, Francisca C.-
dc.contributor.authorOsete, María Luisa-
dc.contributor.authorUrrutia-Fucugauchi, Jaime-
dc.identifier.citationMeteoritics & Planetary Science 42(9): 1467-1698 (2007)en_US
dc.description23 pages, 18 figures.en_US
dc.description.abstractRock magnetic properties across several K-T boundary sections have been investigated reveal any possible magnetic signature associated with the remains of the impact event at the end the Cretaceous. Studied ections’ locations vary in distance to the Chicxulub structure from distal (Agost and Caravaca, Spain), through closer (ODP Hole 1049A, Blake Nose, North Atlantic), proximal (El Mimbral and La Lajilla, Mexico). A clear magnetic signature is associated with fireball layer in the most distal sections, consisting of a sharp increase in susceptibility and saturation isothermal remanent magnetization (SIRM), and a decrease in remanence coercivity. Magnetic properties in these sections point to a distinctive ferrimagnetic phase, probably corresponding to reported Mg- and Ni-rich, highly oxidized spinels of meteoritic origin. At closer and proximal sections magnetic properties are different. Although there is an increase in susceptibility and SIRM associated with a rusty layer placed on top of the siliciclastic deposit in proximal sections, and with a similar limonitic layer on top of the spherule bed that defines the boundary at Blake Nose, magnetic properties indicate a mixture of iron oxyhydroxides dominated by fine-grained goethite. Based on previous geochemical studies at Blake Nose and new geochemical and PGE abundance measurements performed in this work at El Mimbral, this goethite-rich layer can be interpreted as effect of diagenetic remobilization and precipitation of Fe. There is not enough evidence to assert that this Fe concentration layer at proximal sections is directly related to deposition of fine meteoritic material. Magnetic, geochemical, and iridium data reject it as a primary meteoritic phase.en_US
dc.description.sponsorshipThe authors of this paper are grateful to the staff of the Paleomagnetic Laboratory of ETH, Zürich (Switzerland) for their help during some experiments; to Danis Nourgaliev and Pavel Iassonov, Kazan University, for the measurement of Agost Fe-O spherules thermomagnetic curve; to J. C. Gómez-Sal and colleagues, Universidad de Cantabria, for their facilities and help during low-temperature measurements; to Belén Soutullo, Universidad Complutense de Madrid, for the X-ray diffraction measurements; to the Ocean Drilling Program for samples from Leg 171B, Hole 1049A; to Guillermo Villasante for his help during fieldwork in southern Spain; to Lucía Lozano for her support in Mexico; to Pedro Arredondo (Instituto de Geología, Universidad Nacional Autónoma de México) for his invaluable help during fieldwork in northeastern Mexico; and finally to Eric Robin and Frank Kyte for their constructive reviews.en_US
dc.format.extent10752 bytes-
dc.publisherUniversity of Arizona-
dc.titleMagnetic characterization of Cretaceous-Tertiary boundary sedimentsen_US
dc.description.peerreviewedPeer revieweden_US
item.fulltextNo Fulltext-
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