Hostname: page-component-78c5997874-94fs2 Total loading time: 0 Render date: 2024-11-17T23:16:59.833Z Has data issue: false hasContentIssue false
  • English
  • Français

Review of the mineralogy of the Cretaceous-Tertiary boundary clay: evidence supporting a major extraterrestrial catastrophic event

Published online by Cambridge University Press:  09 July 2018

M. Ortega-Huertas ,
F. Martí Nez-Ruiz ,
I . Palomo  and
H. Chamley
M. Ortega-Huertas*
Affiliation:
Departamento deMineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, 18002 Granada, Spain
F. Martí Nez-Ruiz
Affiliation:
Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, 18002 Granada, Spain
I . Palomo
Affiliation:
Departamento deMineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, 18002 Granada, Spain
H. Chamley
Affiliation:
Sédimentologie et Géodynamique, SN5, Université de Lille I, 59655 Villeneuve d'Ascq cedex, France
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The proposed impact event at the end of the Cretaceous resulted in mass extinctions and subsequently significant variations in the geochemical and mineralogical composition of the sediments marking the K/T boundary. The impact-generated material derived from target rocks produced the ejecta layer deposits around Chicxulub crater, which were subsequently diagenetically altered to mainly smectite in marine sections and to kaolinite in continental sections. The fireball layer represents the cosmic dust dispersed and deposited globally and contains smectite derived from the alteration of microkrystites and the finest fraction. The lowermost Danian clay layer, recognized in marine sections, resulted from the sudden decrease in ocean productivity and represents a reduced sedimentation deposit. Its clay mineral associations depend on local environmental conditions and diagenetic processes. Overall, the diagenetic alteration of the boundary materials resulted in a significant modification of original signatures. The composition of the clay mineral phases can, however, still be evidence of the nature of the precursor materials providing evidence for an extraterrestrial impact event.

Keywords

ChicxulubK/Tclay mineralsejecta layerfireball layerclay boundary layerimpact glassesmicrokrystitesdiagenesisDSDPODP
Type
Research Article
Information
Clay Minerals , Volume 37 , Issue 3 , September 2002 , pp. 395 - 411
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2002

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adatte, T., Keller, G. & Stinnesbeck, W. (2002) Late Cretaceous to early Paleocene climate and sea-level fluctuations: the Tunisian record. Palaeogeography, Palaeoclimatology, Palaeoecology, 178, 165–196.CrossRefGoogle Scholar
Alvarez, L.W., Alvarez, W., Asaro, F. & Michel, H.V. (1980) Extraterrestrial cause for the Cretaceous/ Tertiary extinction. Science, 208, 1095–1108.Google Scholar
Alvarez, W., Smit, J., Lowrie, W., Asaro, F., Margolis, S.V., Claeys, P., Kastner, M. & Hildebrand, A.R. (1992) Proximal impact deposits at the Cretaceous- Tertiary boundary in the Gulf of Mexico: a restudy of DSDP Leg 77 Sites 536 and 540. Geology, 20, 697–700.Google Scholar
Alvarez, W., Claeys, P. & Kieffer, S. (1995) Emplacement of Cretaceous-Tertiary boundary shocked quartz from Chicxulub crater. Science, 269, 930–935.Google Scholar
Aróstegui, J., Zuluaga, M.C., Velasco, F., Ortega-Huertas, M. & Nieto, F. (1991) Diagenesis of the Central Basque-Cantabrian Basin (Iberian Peninsula) based on illite-smectite distribution. Clay Minerals, 26, 535–548.CrossRefGoogle Scholar
Bauluz, B., Peacor, D.R. & Elliott, W.C. (2000) Coexisting altered glass and Fe-Ni oxides at the Cretace ous-Tertiary bounda ry, Stevns Klint (Denmark): direct evidence of meteorite impact. Earth and Planetary Science Letters, 182, 127–136.Google Scholar
Bensalem, H. (2002) The Cretaceous-Tertiary transition in Tunisia: general overview. Palaeogeography, Palaeoclimatology, Palaeoecology, 178, 139–143.CrossRefGoogle Scholar
Bohor, B.F. (1990) Shock-induced microdeformation in quartz and other mineralogical indications of an impact event at the Cretaceous/Tertiary boundary. Tectonophysics, 171, 359–372.CrossRefGoogle Scholar
Bohor, B.F. & Betterton, W.J. (1990) K/T boundary spherules: Clarifying the concept (abstract). Lunar and Planetary Science Conference, 21, 108–109.Google Scholar
Bohor, B.F. & Foord, E.E. (1987) Magnesioferrite from a nonmarine K-T boundary clay in Wyoming. Lunar and Planetary Science, 18, 101–102.Google Scholar
Bohor, B.F. & Glass, B.P. (1995) Origin and diagenesis of K/T impact spherules from Haiti to Wyoming and beyond. Meteoritics, 30, 182–198.CrossRefGoogle Scholar
Caillère, S., Hénin, S. & Rautureau, M. (1982) Miné ralogie des Argiles. 2. Classification et Nomenclature, Massonet Cie, Paris. 189 pp.Google Scholar
Chamley, H. (1989) Clay Sedimentology. Springer- Verlag, Berlin, pp. 521–524.CrossRefGoogle Scholar
Chamley, H., Coulon, H., Debrabant, P. & Holtzapffel, T. (1985) Cretaceous interactions between volcanism and sedimentation in the east Mariana Basin, from mineralogical, micromorphological, and geochemical investigations (Site 585, Deep Sea Drilling Project). Initial Reports of the Deep Sea Drilling Project, 89, 414–429.Google Scholar
Claeys, P., Smit, J., Montanari, A. & Alvarez, W. (1998) The Chicxulub impact crater and the Cretaceous- Tertiary boundary in the Gulf of Mexico region. Bulletin de la Societé géologique de France, 169, 20–27.Google Scholar
Courtillot, V.E. & Cisowski, S. (1987) The Cretaceous- Tertiary boundary event: external or internal causes. Lunar and Planetary Science, 18, 103–104.Google Scholar
Courtillot, V.E., Besse, J., Vandamme, D., Montigny, R., Jaeger, J.J. & Cappetta, H. (1986) Deccan flood basalts at the Cretaceous-Tertiary boundary. Earth and Planetary Science Letters, 80, 361–374.Google Scholar
Courtillot, V.E., Férand, G., Malusky, N., Vandamme, D., Mureau, M.G. & Besse, J. (1988) The Deccan flood basalts and the Cretaceous-Te rtiary boundary. Nature, 333, 843–846.Google Scholar
Debrabant, P., Fourcade, E., Chamley, H., Rocchia, R., Robin, E., Bellier, J.P., Gardin, S. & Thiébault, F. (1999) Les argiles de la transition Crétacé-Tertiaire au Guatemala, témoins d’un impact d’astéroide. Bulletin de la Société géologique de France, 170, 643–660.Google Scholar
Elliott, W.C. (1993) Origin of the Mg-smectite at the Cretaceous/Tertiary (K/T) boundary at Stevns Klint, Denmark. Clays and Clay Minerals, 41, 442–452.Google Scholar
Elliott, W.C., Aronson, J.L., Millard, H.T. & Gierlowski-Kordesch, E. (1989) The origin of the clay minerals at the Cretaceous/Tertiary boundary in Denmark. Geological Society of America Bulletin, 101, 702–710.2.3.CO;2>CrossRefGoogle Scholar
Fourcade, E., Alonzo, M., Barrillas, M., Bellier, J.P., Bonneau, M., Cosillo, A., Cros, P., Debrabant, P., Gardin, S., Masure, E., Philip, J., Renard, M., Rocchia, R. & Romero, J. (1997) La limite Crétacé/Tertiaire dans le Sud-Ouest du Pétén (Guatemala). Comptes Rendus de l’Académie des Sciences, Paris, 325, 57–64.Google Scholar
Glass, B.P. & Burns, C.A. (1987) Microkrystites: A new term for impact produced glassy spherules containing primary crystallites. Proceedi ngs of the 18thLunar and Planetary Science Conference, Houston, Texas, Lunar and Planetary Institute, pp. 308–310.Google Scholar
Hildebrand, A.R. & Boynton, W.V. (1987) The K/T impact excavated oceanic mantle: Evidence from REE abundances. Proceedings of the 17th Lunar and Planetary Science Conference, Houston, Texas, Lunar and Planetary Institute, pp. 427–428.Google Scholar
Hildebrand, A.R., Penfield, G.T., Kring, D.A., Pilkington, M., Camargo, A.Z., Jacobsen, S.B. & Boynton, W.V. (1991) Chicxulub crater: a possible Cretaceous/ Tertiary boundary impact crater on the Yucatán Peninsula, Mexico. Geology, 19, 867–871.2.3.CO;2>CrossRefGoogle Scholar
Hsü, K.J. & McKenzie, J.A. (1985) A ‘strangelove’ ocean in the earliest Tertiary. American Geophysical Union–Geophysical Monograph, 32, 487–892.Google Scholar
Hsü, K.J. & McKenzie, J.A. (1990) Carbon-isotope anomalies at era boundaries; global catastrophes and their ultimate cause. Geological Society of America Special Paper, 247, 61–69.CrossRefGoogle Scholar
Hsü, K.J., He, Q., McKenzie, J.A., Weissert, H., Perch-Nielsen, K., Oberhänsli, H., Kelts, K., LaBrecque, J., Tauxe, L., Krähenbühl, U., Percival, S.F., Wright, R., Karpoff, A.M., Petersen, N., Tucker, P., Poore, R.Z., Gombos, A.M., Pisciotto, K., Carman, M.F. & Schreiber, E. (1982) Mass mortality and its environmental and evolutionary consequences. Science, 216, 249–256.Google Scholar
Izett, G.A. (1987) Authigenic ‘spherules’ in the K/T boundary sediments at Caravaca, Spain, and Raton Basin, Colorado and New Mexico, may not be to carbonaceous chondrites. Geological Society of America Bulletin, 99, 78–86.Google Scholar
Izett, G.A. (1990) The Cretaceous/Tertiary boundary interval, Raton Basin, Colorado and New Mexico. Geological Society of America Special Paper, 249, 1–100.Google Scholar
Izett, G.A., Dalrymple, G.B. & Snee, L.W. (1991) 40Ar / 39Ar Age of Cretaceous-Tertiary boundary Tektites from Haiti. Science, 252, 1539–1542.CrossRefGoogle ScholarPubMed
Javoy, M. & Courtillot, V.E. (1989) Intense acidic volcanism at the Cretaceous-Tertiary boundary. Earth and Planetary Science Letters, 94, 409–416.CrossRefGoogle Scholar
Kaiho, K., Kahiwara, Y., Tazaki, K., Ueshima, M., Takeda, N., Kawahata, H., Arinobu, T., Ishiwatari, R., Hirai, A. & Lamolda, M.A. (1999) Oceanic primary productivity and dissolved oxygen levels at the Cretaceous/ Tertiary boundary: Their decrease, subsequent warming, and recovery. Paleoceanography, 14, 511–524.Google Scholar
Kastner, M., Asaro, F., Michel, H.V., Alvarez, W. & Alvarez, L.W. (1984) The precursor of the Cretaceous-Tertiary boundary clays at Stevns Klint and DSDP Hole 465A. Science, 226, 137–143.Google Scholar
Kettrup, B., Deutsch, A., Ostermann, M. & Agrinier, P. (2000) Chicxulub impactites: Geochemical clues to the precursor rocks. Meteoritics and Planetary Science, 35, 1229–1238.Google Scholar
Klaus, A., Norris, R.D., Kroon, D. & Smit, J. (2000) Impact-induced mass wasting at the K-T boundary: Blake Nose, western North Atlantic. Geology, 28, 319–322.Google Scholar
Klaver, G.T., van Kempen, T.M.G., Bianchi, F.R. & van der Gaast, S. (1987) Green spherules as indicators of the Cretaceous/Tertiary boundary in Deep Sea Drilling Project Hole 603 B. Pp. 1039–1056 in. Initial Reports of the Deep Sea Drilling Project, 93, U.S. Government Printing Office, Washington, D.C.Google Scholar
Koeberl, C. (1990) The geochemistry of tektites: An overview. Tectonophysics, 171, 405–422.Google Scholar
Koeberl, C. & Sigurdsson, H. (1992) Geochemistry of impact glasses from the K-T boundary in Haiti: relation to smectites and a new type of glass. Geochimica et Cosmochimica Acta, 56, 2113–2129.Google Scholar
Kring, D.A. & Boynton, W.V. (1991) Altered spherules of impact melt and associated relic glass from the K/T boundary sediments in Haiti. Geochimica et Cosmochimica Acta, 55, 1737–1742.CrossRefGoogle Scholar
Kyte, F.T. & Smit, J. (1986) Regional variation in spinel compositions: An important key to the Cretaceous- Tertiary event. Geology, 14, 485–487.Google Scholar
Kyte, F.T., Zhou, Z. & Wasson, J.T. (1980) Siderophileenriched sediments from the Cretaceous-Tertiary boundary. Nature, 288, 651–656.Google Scholar
Kyte, F.T., Smit, J. & Wasson, J.T. (1985) Siderophile interelement variations in the Cretaceous-Tertiary boundary sediments from Caravaca, Spain. Earth and Planetary Science Letters, 73, 183–195.CrossRefGoogle Scholar
Lerbekmo, J.F., Sweet, A.R. & St. Louis, R.M. (1987) The relationship between the iridium anomaly and palynological floral events at three Cretaceous- Tertiary boundary localities in western Canada. Geologic al Society of America Bulletin, 99, 325–330.Google Scholar
Lindinger, M. (1988) The Cretaceous-Tertiary boundaries of El Kef and Caravaca: sedimentological, geochemical and clay mineralogical aspects. PhD thesis, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland.Google Scholar
López Galindo, A. (1986) Mineralogía de series cretácicas de la Zona Subbética. Algunas consideraciones paleogeográficas derivadas de la composicio ´n química de las esmectitas. Estudios Geológicos, 42, 231–238.Google Scholar
Margolis, S.V., Mount, J.F., Doehne, E., Showers, W. & Ward, P. (1987) The Cretaceous/Tertiary boundary carbon and oxygen isotope stratigraphy, diagenesis, and paleoce anography at Zumaya , Spain. Paleoceanography, 2, 361–367.Google Scholar
Martin, E.E. & MacDougall, J.D. (1991) Seawater Sr isotopes at the Cretaceous/ Tertiary boundary. Earth and Planetary Science Letters, 104, 166–180.Google Scholar
Martínez-Ruiz, F. (1994) Geoquímica y mineralogía del tránsito Cretácico-Terciario en las Cordilleras Béticas y en la Cuenca Vasco-Cantábrica. PhD thesis, Universidad de Granada, Spain.Google Scholar
Martínez-Ruiz, F., Ortega-Huertas, M., Palomo, I. & Barbieri, M. (1992) The geochemistry and mineralogy of the Cretaceous-Tertiary boundary at Agost (southeast Spain). Chemical Geology, 95, 265–281.Google Scholar
Martínez-Ruiz, F., Ortega-Huertas, M., Palomo, I. & Acquafredda, P. (1997) Quench textures in altered spherules from the Cretaceous-Tertiary boundary layer at Agost and Caravaca, SE Spain. Sedimentary Geology, 113, 137–147.Google Scholar
Martínez-Ruiz, F., Ortega-Huertas, M. & Palomo, I. (1999) Positive Eu anomaly development during diagenesis of the K/T boundary ejecta layer in the Agost section (SE Spain): implications for traceelement remobilization. Terra Nova, 11, 290–296.Google Scholar
Martínez-Ruiz, F., Ortega-Huertas, M., Palomo, I. & Smit, J. (2001a) K-T boundary spherules from Blake Nose (ODP Leg 171B) as a record of the Chicxulub ejecta deposits. Geological Society Special Publication, 183, 149–161, Geological Society, London.Google Scholar
Martínez-Ruiz, F., Ortega-Huertas, M., Kroon, D., Smit, J., Palomo, I. & Rocchia, R. (2001b) Geochemistry of the Cretaceous-Tertiary boundary at Blake Nose (ODP Leg 171B). Geological Society Special Publication, 183, 131–148, Geological Society, London.Google Scholar
Martínez-Ruiz, F., Ortega-Huertas, M. & Palomo, I. (2001c) Climate, tectonics and meteoritic impact expressed by clay mineral sedimentation across the Cretaceous -Tertiary boundary at Blake Nose, Northwestern Atlantic. Clay Minerals, 36, 49–60.Google Scholar
Martínez-Ruiz, F., Ortega-Huertas, M., Palomo, I. & Smit, J. (2002) Cretaceous-Tertiary boundary at Blake Nose (Ocean Drilling Program Leg 171B): A record of the Chicxulub impact ejecta. Geological Society of America Special Paper, 356, 189–199.Google Scholar
Mata, P., Peacor, D.R., Soria, A.R., Liesa, C. & Meléndez, A. (2001) The spherule facies at the Cretaceous-Tertiary (K/T) boundary in the El Tecolote (Northeastern Mexico): A TEM study. Pp. 77–78 in: Impact Markers in the Stratigraphic Record (6th ESF-Impact Workshop), Granada, Spain.Google Scholar
Mathey, B. (1988) Paleogeographical evolution of the Basco-Cantabria n domain during the Upper Cret aceous. Revista Sociedad Espan˜ o la Paleontología, n. extraord., 142–147.Google Scholar
Montanari, A. (1991) Authigenesis of impact spheroids in the K/T boundary clay from Italy: new constraints for high-re solutio n stratigraphy of terminal Cretace ous events. Journa l of Sedimentary Petrology, 671, 315–339.Google Scholar
Montanari, A., Hay, R.L., Alvarez, W., Asaro, F., Michel, H.V., Alvarez, L.W. & Smit, J. (1983) Spheroids at the Cretaceous-Tertiary boundary are altered impact droplets of basaltic composition. Geology, 11, 668–671.Google Scholar
Nieto, F., Ortega-Huertas, M., Peacor, D.R. & Aróstegui, J. (1996) Evolution of illite-smectit e from early diagenesis through incipient metamorphism in sediments of the Basque-Cantabrian basin. Clays and Clay Minerals, 44, 304–323.Google Scholar
Norris, R.D., Kroon, D., Klaus, A. et al. (1998) Proceedings of the Ocean Drilling Program, Initial Reports, 171B. Ocean Drilling Program, College Station, Texas, USA.Google Scholar
Officer, C.B. & Drake, C.L. (1985) Terminal Cretaceous environmental events. Science, 227, 1161–1167.Google Scholar
Officer, C.B., Hallam, A., Drake, C.L. & Devine, J.D. (1987) Late Cretaceous and paroxysmal Cretaceous/ Tertiary extinctions. Nature, 326, 143–149.CrossRefGoogle Scholar
Olsson, R.K., Miller, K.G., Browning, J.V., Habib, D. & Sugarman, P.J. (1997) Ejecta layer at the Cretaceous- Tertiary boundary, Bass River, New Jersey (Ocean Drilling Program Leg 174AX). Geology, 25, 759–762.Google Scholar
Ortega-Huertas, M., Martínez-Ruiz, F., Palomo, I. & Chamley, H. (1995) Comparative mineralogical and geochemica l clay sedimentat ion in the Betic Cordilleras and Basque-Cantabrian Basin areas at the Cretaceous-Tert iary boundary. Sedimentary Geology, 94, 209–227.CrossRefGoogle Scholar
Ortega-Huertas, M., Palomo, I., Martínez-Ruiz, F. & González, I. (1998) Geological factors controlling clay mineral patterns across the Cretaceous-Tertiary boundary in Mediterranean and Atlantic sections. Clay Minerals, 33, 483–500.CrossRefGoogle Scholar
Pardo, A., Adatte, T., Keller, G. & Oberhänsli, H. (1999) Palaeoenvironmental changes across the Cretaceous- Tertiary boundary at Koshak, Kazakhstan, based on plankt ic foraminifera and clay mineralogy. Palaeogeography , Palaeoclimatology , Palaeoecology, 154, 247–273.Google Scholar
Perch-Nielsen, K., McKenzie, J.A. & He, Q. (1982) Biostratigraphy and isotope stratigraphy and the ‘catastrophic’ extinction of calcareous nannoplankton at the Cretaceous/ Tertiary boundary. Geological Society of America Special Paper, 190, 353–372.Google Scholar
Pierazzo, E. & Melosh, J.H. (1999) Hydrocode modeling of Chicxulub as an oblique impact event. Earth and Planetary Science Letters, 165, 163–176.Google Scholar
Pollastro, R.M. & Pillmore, C.L. (1987) Mineralogy and petrology of the Cretaceous-Tertiary boundary clay bed and adjacent clay-rich rocks, Raton Basin, New Mexico and Colorado. Journal of Sedimentary Petrology, 57, 456–466.Google Scholar
Pollastro, R.M. & Bohor, B.F. (1993) Origin and claymineral genesis of the Cretaceous/Tertiary boundary unit, western interior of North America. Clays and Clay Minerals, 41, 7–25.Google Scholar
Pope, K.O., Ocampo, A.C., Kinsland, G.L. & Smith, R. (1996) Surface expression of the Chicxulub crater. Geology, 24, 527–530.Google Scholar
Pope, K.O., Ocampo, A.C., Fischer, A.G., Alvarez, W., Fouke, B.W., Webster, C.L., Vega, F.J., Smit, J., Fritsche, A.E. & Claeys, P. (1999) Chicxulub impact ejecta from Albion Island, Belize. Earth and Planetary Science Letters, 170, 351–364.Google Scholar
Rampino, M.R. & Reynolds, R.C. (1983) Clay mineralogy of the Cretaceous-Tertiary Boundary Clay. Science, 219, 495–498.Google Scholar
Robert, C. & Chamley, H. (1990) Palaeoenvironmental significance of clay mineral associations at the Cretaceous-T ertiary passage. Palaeogeography , Palaeoclimatology, Palaeoecology, 79, 205–219.CrossRefGoogle Scholar
Robin, E., Boclet, D., Bonté, P., Froget, L., Jéhanno, C. & Rocchia, R. (1991) The stratigraphic distribution of Ni-rich spinels in Cretaceous-Tertiary boundary rocks at El Kef (Tunisia), Caravaca (Spain) and Hole 761C (Leg 122). Earth and Planetary Science Letters, 107, 715–721.Google Scholar
Schmitz, B. (1985) Metal precipitation in the Cretaceous/ Tertiary boundary clay at Stevns Klint, Denmark. Geochimica et Cosmochimica Acta, 49, 2361–2370.CrossRefGoogle Scholar
Schultz, P.H. & D’Hondt, S. (1996) Cretaceous-Tertiary (Chicxulub) impact angle and its consequences. Geology, 24, 963–967.Google Scholar
Sharpton, V.L., Burke, K., Camargo, A., Hall, S.A., Lee, D.S., Marin, L.E., Suarez, G., Quezada, J.M., Spudis, P.D. & Urrutia, J. (1993) Chicxulub multiring impact basin: size and other characteristics derived from gravity analysis. Science, 261, 1564–1567.Google Scholar
Sigurdsson, H., D’Hont, S., Arthur, M.A., Bralower, T.J., Zachos, J.C., van Fossen, M. & Channell, E.T. (1991) Glass from the Cretaceous/Tertiary boundary in Haiti. Nature, 349, 482–487.Google Scholar
Smit, J. (1999) The global stratigra phy of the Cretaceous-Tert iary boundar y impact ejecta. Annual Reviews of Earth and Planetary Sciences, 27, 75–113.Google Scholar
Smit, J. & Hertogen, J. (1980) An extraterrestrial event at the Cretaceous-Tertiary boundary. Nature, 285, 198–200.Google Scholar
Smit, J. & Klaver, G. (1981) Sanidine spherules at the Cretaceous-Tertiary boundary indicate a large impact event. Nature, 292, 47–49.Google Scholar
Smit, J. & ten Kate, W.G.H.Z. (1982) Trace element patterns at the Cretaceous-Tertiary boundary: Consequences of a large impact. Cretaceous Research, 3, 307–332.Google Scholar
Smit, J., Alvarez, W., Montanari, A., Swinburne, N., Van Kempen, T.M., Klaver, G. & Lustenhouwer, W.J. (1992) ‘Tekti tes’ and microte ktite s at the Cretaceous-Tertiary boundary: two strewn fields, one crater. Proceedings of Lunar and Planetary Science, 22, 87–100.Google Scholar
Soria, A.R., Liesa, C., Mata, M.P., Arz, J.A., Alegret, L., Arenillas, I. & Meléndez, A. (2001) Slumping and a sandbar deposit at the Cretaceous-Tertiary boundary in the El Tecolote section (Northeastern Mexico): An impact-induced sediment gravity flow. Geology, 29, 231–234.Google Scholar
Stanley, S.M. (1986) Earth and Life through Time. W.H. Freeman and Co., New York, a pp.Google Scholar
Stüben, D., Kramar, U., Berner, Z., Stinnesbeck, W., Kelleg, G. & Adatte, T. (2002) Trace elements, stable isotopes, and clay mineralogy of the Eles II K– T boundary section in Tunisia: indications for sea level fluctuation sandprimary productivity. Palaeogeography , Palaeoclimatology , Palaeoecology, 178, 321–345.CrossRefGoogle Scholar
Taylor, S.R. & McLennan, S.M. (1988) The significance of the rare earths in geochemistry and cosmochemistry. Pp. 485–578 in. Handbook on the Physics and Chemistry of Rare Earths, 11, Elsevier, Amsterdam.Google Scholar
Triplehorn, D.M. & Bohor, B.F. (1993) Goyazite kaolinitic altered tuff beds of Cretaceous age near Den, Colorado. Clays and Clay Minerals, 31, 299–304.Google Scholar
Zachos, J.C., Arthur, M.A. & Dean, W.E. (1989) Geochemical evidence for suppression of pelagic marine productivity at the Cretaceous/Tertiary boundary. Nature, 337, 61–64.Google Scholar