Magnesioferrite spinel in Cretaceous/Tertiary boundary sediments of the Pacific basin: Remnants of hot, early ejecta from the Chicxulub impact?

Analyses of shocked quartz at the global K-P boundary indicate an origin from a single, high-angle, oblique impact at Chicxulub

“…The K-P layer also contains highly shocked terrestrial minerals (quartz, feldspar and zircon) that originated from rocks at the impact site, as well as impact-derived Ni-rich spinel [2][3][4][5][6][7][8]. After the Chicxulub impact crater was discovered [9] numerous studies of this crater and the K-P boundary led to widespread agreement that Chicxulub was the site of a K-P boundary impact, with a few notable exceptions [10][11].…”

First petrographic results on impactites from the Yaxcopoil‐1 borehole, Chicxulub structure, Mexico

“…Recent publications that question this association (Keller et al 2003a(Keller et al , 2004 are based on very limited data that are quite questionable. Crucial evidence in support of a collision with an extraterrestrial projectile at that time includes the widespread deposition of glass spherules around the Caribbean and beyond (e.g., Sigurdsson et al 1991;Smit et al 1992;Premo and Izett 1992;Koeberl and Sigurdsson 1992;Koeberl 1993;Oskarsson et al 1996;Chaussidon et al 1996;Hough et al 1998;Smit 1999), the global distribution of shock metamorphic quartz (Bohor 1990;Owen et al 1990;Alvarez et al 1995;Bostwick and Kyte 1996;Goto et al 2002), anomalous PGE concentrations with chondritic character (Alvarez et al 1980;Kyte et al 1980;Smit and Hertogen 1980;Orth et al 1981;Schmitz 1988;Evans et al 1995), Nirich spinels (Cisowski 1990;Kyte and Bostwick 1995;Gayraud et al 1996), the presence of fullerenes (Heymann et al 1994(Heymann et al , 1996Buseck 2002), evidence for a global occurrence of wildfires (Argyle et al 1986;Wolbach et al 1985Wolbach et al , 1990Kring and Durda 2001), and nano-to microdiamonds found worldwide in the K/T boundary clay layer (Gilmour et al 1992;Hough et al 1997). The major mass extinction event at the K/T boundary has been widely linked to this cosmic catastrophe (e.g., Alvarez et al 1980;…”

The crystal structures of synthetic Re‐ and PGE‐bearing magnesioferrite Spinels: Implications for impacts, accretion and the mantle

“…In particular, magnesiot•rrite is tYund in the cosmic spherules present in Cretaceous-Tertiar3• boundary. samples (e.g., Smit and Kyte, 1984: Kyte and Smit, 1986, Kyte and Bostwick, 1995 and is known to be a significant component of mantle and magmatic spinels (e.g., Haggerty, 1992) and spinels in meteorite lbsion crusts (Genge and Grady, 1999). Some experimental work suggests that PGE can be accommodated in the spinel structure (e.g., Table 1).…”