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Geological Society, London, Special Publications; 2001; v. 183; p. 149-161;
DOI: 10.1144/GSL.SP.2001.183.01.08
© 2001 Geological Society of London

K-T boundary spherules from Blake Nose (ODP Leg 171B) as a record of the Chicxulub ejecta deposits

F. Martínez-Ruiz1, M. Ortega-Huertas2, I. Palomo-Delgado2 & J. Smit3

1 Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Facultad de Ciencias, Avda. Fuentenueva, s/n. 18002 Granada, Spain fmruiz{at}goliat.ugr.es
2 Departamento de Mineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva, s/n. 18002 Granada, Spain
3 Department of Sedimentary Geology, Vrije Universiteit, 1081 HV Amsterdam, Netherlands

The Cretaceous-Tertiary (K-T) boundary interval recovered by the ODP Leg 171 at Site 1049 (Blake Nose, NW Atlantic) contains a thick (9–17 cm) spherule bed marking the boundary. The spherules are mainly perfect spheres with a lesser proportion of oval spherules. They usually range from 100 to 1000 µm. This bed represent the diagenetically altered impact ejecta from Chicxulub and further supports this structure as the site of the K-T impact. Mineralogical and geochemical investigations indicate that impact-generated glass was altered to smectite. Transmission electron microscopy observations revealed in some spherules that smectite is forming from a Si-rich or Ca-rich material, which could suggest a precursor similar to Haitian glasses. The variable thickness and the presence of some Cretaceous planktonic foraminifera and clasts of Cretaceous chalk suggest reworking of the ejecta material. However, the spherule bed confirms that a large volume of the Chicxulub ejecta material reached the Blake Nose Plateau.





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 Clay MineralsHome page
M. ORTEGA-HUERTAS, F. MARTINEZ-RUIZ, I. PALOMO, and H. CHAMLEY
Review of the mineralogy of the Cretaceous-Tertiary boundary clay: evidence supporting a major extraterrestrial catastrophic event
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[Abstract] [Full Text] [PDF]