Hostname: page-component-cd9895bd7-p9bg8 Total loading time: 0 Render date: 2024-12-22T22:12:21.245Z Has data issue: false hasContentIssue false
  • English
  • Français

Origin and Clay-Mineral Genesis of the Cretaceous/Tertiary Boundary Unit, Western Interior of North America

Published online by Cambridge University Press:  28 February 2024

R. M. Pollastro  and
B. F. Bohor
R. M. Pollastro
Affiliation:
U.S. Geological Survey, Denver, Colorado 80225
B. F. Bohor
Affiliation:
U.S. Geological Survey, Denver, Colorado 80225
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

A 3-cm-thick, two-layered clay unit that records mineralogic and textural evidence of a catastrophic event that occurred at a time now marked as the end of the Cretaceous Period was preserved in ancient peat-forming environments of the Western Interior Basin of North America. The two layers of this unit consist of altered distal ejecta and are easily distinguished by their distinctive texture and impact components from other clay beds, mainly tonsteins and detrital shales, occurring within the sequence of rocks enclosing the Cretaceous/Tertiary (K/T) boundary interval.

The lower claystone layer of the K/T boundary unit represents melted silicic target rock that has altered mainly to kaolin minerals. Impact components and signatures of this lower layer include a relict imbricate fabric of glass fragments, shards, bubbles, hollow spherules (altered microtektites), small amounts of shocked mineral grains, and a subdued iridium anomaly. These components and textures, combined with the layer's restricted areal distribution, indicate that this layer, called the “melt ejecta layer,” is the distal part of an ejecta blanket deposit. We interpret the melt ejecta layer to be an altered deposit of mostly impact-derived, shock-melted, silicic target material that traveled through the atmosphere within a detached ejecta curtain and on other ballistic trajectories.

The upper laminated layer of the K/T boundary unit consists mostly of altered vitric dust and abundant shocked minerals whose size and amounts decrease away from the putative crater site in the Caribbean area. High-nickel magnesioferrite crystals, high iridium content, geochemical signature, and worldwide distribution all suggest this upper layer originated from a cloud of vaporized bolide and entrained target-rock materials ejected above the atmosphere. The components of this layer, called the “fireball layer,” settled slowly by gravitational processes from an Earth-girdling vapor cloud and were deposited immediately on top of the already-emplaced melt ejecta layer.

The clay minerals that formed in the two layers are largely a function of composition and the highly unstable, shock-modified state of the fallout materials altered in acidic, organic-rich waters of ancient peat swamps. The fireball layer is mostly altered to smectitic clay from a mafic glass condensed from the vaporized chondritic bolide, along with some kaolinite formed from blebs of melted silicic target material entrained in the vapor plume cloud during ejection. In contrast, the melt ejecta layer is mainly kaolinitic, derived from silicic glass formed from melted target rocks. In this layer, the glass rapidly altered to mostly disordered, micrometer-sized “cabbage-like” or submicrometer-sized embryonic forms of spherical halloysite, probably from an allophane precursor. These crystallization characteristics of the melt ejecta layer are much different than those which formed coarse vermicular aggregates and platy kaolinite crystals in tonsteins from outside the K/T boundary interval throughout the Western Interior. The contrast in the incipient formation of dominantly kaolinitic clay minerals in the basal melt ejecta layer and of smectitic clay minerals in the overlying fireball layer reflect silicic versus mafic starting materials, respectively, and also supports the proposed two-phased meteorite impact ejection and dispersal model.

During subsequent burial and diagenesis of the K/T boundary unit, the metastable halloysite and smectite aggraded to kaolinite and mixed-layer illite/smectite, respectively. Both the ordering of kaolinite and illitization of smectite varies locally as a function of the degree of diagenetic grade or maturity, probably in response to local variations in temperature due to maximum burial depth (burial diagenesis).

Keywords

ClaystoneEjectaGlass alterationHalloysiteKaoliniteK/T boundary unitMeteorite impactSEMXRD
Type
Research Article
Information
Clays and Clay Minerals , Volume 41 , Issue 1 , February 1993 , pp. 7 - 25
Copyright
Copyright © 1993, The Clay Minerals Society

References

Alvarez, L. W., Alvarez, W., Asaro, F. and Michel, H. V., 1980 Extraterrestrial cause of the Cretaceous-Tertiary extinction Science 208 1095 – 1108 10.1126/science.208.4448.1095.CrossRefGoogle ScholarPubMed
Alvarez, W., Smit, J., Lowrie, W., Asaro, F., Margolis, S. V., Claeys, P., Kastner, M. and 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 10.1130/0091-7613(1992)020<0697:PIDATC>2.3.CO;2.2.3.CO;2>CrossRefGoogle ScholarPubMed
Bailey, S. W., 1990 Halloysite—A critical assessment Proc. 9th Int. Clay Conf., Strasbourg, 1989 86 89 – 98.Google Scholar
Bates, T. F., 1959 Morphology and crystal chemistry of 1:1 layer lattice silicates Am. Mineral 44 78 – 114.Google Scholar
Bohor, B. F., 1988 K-T boundary claystone is a distal ejecta deposit Meteoritics 23 258 – 259.Google Scholar
Bohor, B. F., 1988 Ejecta components and thickness of K-T boundary clays and claystones EOS (Trans. Amer. Geophys. Union 69 1291.Google Scholar
Bohor, B. F., 1990 Shocked quartz and more: Impact signatures in Cretaceous/Tertiary boundary clays Global Catastrophes in Earth History 247 335 – 342.Google Scholar
Bohor, B. F., 1990 Shock-induced microdeformations in quartz and other mineralogical indications of an impact event at the Cretaceous/Tertiary boundary Tectonophysics 171 359 – 372 10.1016/0040-1951(90)90110-T.CrossRefGoogle Scholar
Bohor, B. F. and Betterton, W. J., 1988 Are the hollow spherules in the K-T boundary claystones altered micro-tektites? Meteoritics 23 259.Google Scholar
Bohor, B. F. and Betterton, W. J., 1991 K/T spherules are altered microtektites Meteoritics 26 320.Google Scholar
Bohor, B. F. and Betterton, W. J., 1991 Maximum shocked grain size dimensions from K/T ejecta, Western Interior Meteoritics 26 321.Google Scholar
Bohor, B. F. and Betterton, W. J., 1992 Ejection and dispersal mechanism of the K/T impact Lunar Planet. Sci 23 135 – 136.Google Scholar
Bohor, B. F. and Foord, E. E., 1987 Magnesioferrite from a nonmarine K-T boundary clay in Wyoming Lunar Planet Sci 18 101 – 102.Google Scholar
Bohor, B. F. and Izett, G. A., 1986 Worldwide size distribution of shocked quartz at the K/T boundary—evidence for a North American impact site Lunar Planet. Sci 17 68 – 69.Google Scholar
Bohor, B. F., Foord, E. E. and Betterton, W. J., 1989 Trace minerals in K-T boundary clays Meteoritics 24 253.Google Scholar
Bohor, B. F., Glass, B. P. and Betterton, W. J., 1993 Spherules from Haiti, Wyoming and Ivory Coast: Origin and diagenesis Lunar Planet. Sci 24 145 – 146.Google Scholar
Bohor, B. F., Foord, E. E., Modreski, P. J. and Triplehorn, D. M., 1984 Mineralogie evidence for an impact event at the Cretaceous-Tertiary boundary Science 224 867 – 869 10.1126/science.224.4651.867.CrossRefGoogle Scholar
Bohor, B. F., Pollastro, R. M. and Phillips, R. E., 1978 Mineralogical evidence for the volcanic origin of kaolinitic partings (tonsteins) in Upper Cretaceous and Tertiary coals of the Rocky Mountain region Abstracts and Program, 27 th Ann. Clay Minerals Conf. Indiana The Clay Minerals Society, Bloomington 47.Google Scholar
Bohor, B. F., Triplehorn, D. M., Nichols, D. J. and Millard, H. T. Jr., 1987 Dinosaurs, spherules and the “magic” layer: A new K/T boundary clay site in Wyoming Geology 15 896 – 899 10.1130/0091-7613(1987)15<896:DSATML>2.0.CO;2.2.0.CO;2>CrossRefGoogle Scholar
Boslough, M. B., 1991 Shock modification and chemistry and planetary geologic processes Ann. Rev. Earth Planet. Sci 19 101 – 130 10.1146/annurev.ea.19.050191.000533.CrossRefGoogle Scholar
Boslough, M. B. and Cygan, R. T., 1988 Shock-enhanced dissolution of silicate minerals and chemical weathering on planetary surfaces Proc. Lunar Planet. Sci 18 443 – 453.Google Scholar
Brindley, G. W., 1980 Order-disorder in clay mineral structures Crystal Structure of Clay Minerals and their X-ray Identification 5 125 – 195.CrossRefGoogle Scholar
Churchman, G. J., Whitton, J. S., Claridge, G G C and Theng, B. K. G., 1984 Intercalation method using for-mamide for differentiating halloysite from kaolinite Clays & Clay Minerals 32 241 – 248 10.1346/CCMN.1984.0320401.CrossRefGoogle Scholar
Fastovsky, D. E., McSweeney, K. and Norton, L. S., 1989 Pedogenic development at the Cretaceous-Tertiary boundary, Garfield County, Montana J. Sed. Petrol 59 758 – 767.Google Scholar
Fisher, R. V. and Schmincke, H. U., 1984 Pyroclastic Rocks New York Springer-Verlag 10.1007/978-3-642-74864-6.CrossRefGoogle Scholar
French, B. M. and Short, N. M., 1968 Shock Meta-morphism of Natural Materials Maryland Mono Book Corp., Greenbelt.Google Scholar
Grieve, R A F Dence, M. R., Robertson, P. B., Roddy, D. J., Pepin, R. O. and Merrill, R. B., 1977 Cratering processes as interpreted from occurrence of impact melts Impact and Explosion Cratering New York Pergamon 791 – 814.Google Scholar
Hinckley, D. N., 1963 Variability in crystallinity values among the kaolin deposits of the coastal plain of Georgia and South Carolina Clays & Clay Minerals 11 229 – 235 10.1346/CCMN.1962.0110122.CrossRefGoogle Scholar
Hoffman, J. and Hower, J., 1979 Clay mineral assemblages as low grade metamorphic geothermometers: Application to the thrust faulted disturbed belt of Montana Aspects of Diagenesis 26 55 – 79 10.2110/pec.79.26.0055.CrossRefGoogle Scholar
Hughes, R. E. and Bohor, B. F., 1970 Random clay powders prepared by spray drying Amer. Mineral 55 90 – 105.Google Scholar
Izett, G. A., (1990) The Cretaceous-Tertiary (K-T) boundary interval, Raton Basin, Colorado and New Mexico, and its content of shock-metamorphosed minerals: Evidence relevant to the K-T boundary impact-extinction theory: Geol. Soc. Amer. Spec. Paper 249.Google Scholar
Jones, E. M. and Kodis, J. W., 1982 Atmospheric effects of large body impacts: The first few minutes Geological Implications of Impacts of Large Asteroids and Comets on the Earth 190 175 – 186 10.1130/SPE190-p175.CrossRefGoogle Scholar
Kastner, M., Asaro, F., Michel, H. V., Alvarez, W. and Alvarez, L. W., 1984 Did the clay minerals at the Cretaceous-Tertiary boundary form from glass? Evidence from Denmark and DSDP hole 465A J. Non-crystal. Solids 67 463 – 464 10.1016/0022-3093(84)90170-4.CrossRefGoogle Scholar
Kyte, F. T., 1990 Comment on “Origin of microlayering in worldwide distributed Ir-rich marine Cretaceous/Tertiary boundary clays” Geology 18 87 – 88 10.1130/0091-7613(1990)018<0087:CAROOO>2.3.CO;2.2.3.CO;2>CrossRefGoogle Scholar
Melosh, H. J., 1989 Impact Cratering—A Geologic Process New York Oxford University Press.Google Scholar
Minato, H., Utada, M. and Heller, L., 1969 Mode of occurrence and mineralogy of halloysite from Iki, Japan Proc. Internat. Clay Conf, Tokyo, Japan Jerusalem Israel Univ. Press 393 – 402.Google Scholar
Montanari, A., 1991 Authigenesis of impact spheroids in the K/T boundary clay from Italy: New constraints for high-resolution stratigraphy of terminal Cretaceous events J. Sed. Petrol 61 315 – 339.Google Scholar
Moore, D. M. and Reynolds, R. C. Jr., 1989 X-ray Diffraction and the Identification and Analysis of Clay Minerals New York Oxford University Press.Google Scholar
Nagasawa, K. and Noro, H., 1987 An electron spin resonance study of halloysites Clay Science 6 261 – 268.Google Scholar
Nagasawa, K. and Noro, H., 1987 Mineralogical properties of halloysites of weathering origin Chemical Geol 6 145 – 149 10.1016/0009-2541(87)90120-3.CrossRefGoogle Scholar
Nichols, D. J., Jarzen, D. M., Orth, C. J. and Oliver, P. Q., 1986 Palynological and iridium anomalies at the Cretaceous-Tertiary boundary, south-central Saskatchewan Science 231 714 – 717 10.1126/science.231.4739.714.CrossRefGoogle ScholarPubMed
Noro, H., 1986 Hexagonal platy halloysite in an altered tuff bed, Komaki City, Aichi Prefecture, central Japan Clay Miner 21 401 – 415 10.1180/claymin.1986.021.3.11.CrossRefGoogle Scholar
Ostertag, R. and Stöffler, D., 1982 Thermal annealing of experimentally shocked feldspar crystals J. Geophys. Res 63 A457 – 463 10.1029/JB087iS01p0A457.Google Scholar
Palme, H., 1982 Identification of projectiles of large terrestrial impact craters and some implications for the interpretation of Ir-rich Cretaceous/Tertiary boundary layers Geological Implications of Impacts of Large Asteroids and Comets on the Earth 190 223 – 234 10.1130/SPE190-p223.CrossRefGoogle Scholar
Pillmore, C. L. and Flores, R. M., 1987 Stratigraphy and depositional environments of the Cretaceous-Tertiary boundary clay and associated rocks, Raton basin, New Mexico and Colorado The Cretaceous-Tertiary Boundary in the San Juan and Raton Basins, New Mexico and Colorado 209 111 – 129 10.1130/SPE209-p111.CrossRefGoogle Scholar
Pollastro, R. M., 1981 Authigenic kaolinite and associated pyrite in chalk of the Cretaceous Niobrara Formation, eastern Colorado J. Sed. Petrol 51 553 – 562.Google Scholar
Pollastro, R. M., Nuccio, V. F. and Barker, C. E., 1990 The illite/smectite geothermome-ter—Concepts, methodology, and application to basin history and hydrocarbon generation Applications of Thermal Maturity Studies to Energy Exploration 1 – 18.Google Scholar
Pollastro, R. M. and Bohor, B. F., 1991 Origin and genesis of clay minerals at the Cretaceous/Tertiary boundary interval, U.S. Western Interior Program and Abstracts, 28th Ann. Meeting, Clay Minerals Society, Houston, Texas 129.Google Scholar
Pollastro, R. M. and 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 J. Sed. Petrol 54 456 – 466.Google Scholar
Pollastro, R. M. and Scholle, P. A., 1986 Diagenetic relationships in a hydrocarbon-productive chalk—the Cretaceous Niobrara Formation Studies in Diagenesis 1578 219 – 236.Google Scholar
Prinn, G. G. and Fegley, B Jr., 1987 Bolide impacts, acid rain, and biospheric traumas at the Cretaceous-Tertiary boundary Earth Planet. Sci. Lett 83 1 – 15 10.1016/0012-821X(87)90046-X.CrossRefGoogle Scholar
Rampino, M. R. and Reynolds, R. C. Jr., 1983 Clay mineralogy of the Cretaceous-Tertiary boundary clay Science 219 495 10.1126/science.219.4584.495.CrossRefGoogle ScholarPubMed
Reynolds, R. C. Jr., Brindley, G. E. and Brown, G., 1980 Interstratified clay minerals Crystal Structures of Clay Minerals and Their X-ray Identification London Mineral. Soc. 249 – 303.CrossRefGoogle Scholar
Reynolds, R. C. Jr. and Hower, J., 1970 The nature of interlayering in mixed layer illite/montmorillonite Clays & Clay Minerals 18 25 – 36 10.1346/CCMN.1970.0180104.CrossRefGoogle Scholar
Schmincke, H. U., Viereck, L. G., Griffin, G. J. and Prichard, R. G., 1982 Volcaniclastic rocks of the Reydarfjordur drillhole, DSDP Leg 46 Initial Reports Deep Sea Drilling Project 46 341 – 355.Google Scholar
Schultz, L. G., 1978 Mixed-layer clay in the Pierre Shale and equivalent rocks, northern Great Plains region U.S. Geol. Surv. Prof. Paper 1064–a 1 – 28.Google Scholar
Sigurdsson, H., D’Hondt, S., Arthur, M. A., Bralower, T. J., Zachos, J. C., van Fossen, M. and Channell, J. E. T., 1991 Glass from the Cretaceous/Tertiary boundary in Haiti Nature 349 482 – 487 10.1038/349482a0.CrossRefGoogle Scholar
Smith, S. T., Snyder, R. L. and Brownell, W. E., 1979 Minimization of preferred orientation in powders by spray drying Advances in X-ray Analysis 22 77 – 87.CrossRefGoogle Scholar
Spears, D. A. and Kanaris-Sotiriou, R., 1979 A geochem-ical and mineralogical investigation of some British and other European tonsteins Sedimentology 26 407 – 425 10.1111/j.1365-3091.1979.tb00917.x.CrossRefGoogle Scholar
Sudo, T. and Yotsumoto, H., 1977 The formation of halloysite tubes from spherulitic halloysite Clays & Clay Minerals 25 155 – 159 10.1346/CCMN.1977.0250213.CrossRefGoogle Scholar
Sudo, T., Shimoda, S., Yotsumoto, H., and Aita, S., (1981) Electron Micrographs of Clay Minerals: Develop. in Sedimentol. 31: Elsevier Publishing, New York.Google Scholar
Surdam, R. C. and Boles, J. R., 1979 Diagenesis of volcanic sandstones Aspects of Diagenesis 27 227 – 242 10.2110/pec.79.26.0227.CrossRefGoogle Scholar
Tazaki, K., 1982 Analytical electron microscopic studies of halloysite formation processes—Morphology and composition of halloysite Proc. Int. Clay Conf, 1981 Italy, Develop. in Sediment 35 573 – 584.Google Scholar
Tomura, S., Shibasaki, Y., Mizuta, H. and Kitamura, M., 1985 Growth conditions and genesis of spherical and platy kaolinite Clays & Clay Minerals 33 200 – 206 10.1346/CCMN.1985.0330305.CrossRefGoogle Scholar
Triplehorn, D. M. and Bohor, B. F., 1983 Goyazite in kaolinitic altered tuff beds of Cretaceous age near Denver, Colorado Clays & Clay Minerals 31 299 – 304 10.1346/CCMN.1983.0310408.CrossRefGoogle Scholar
Wada, K., 1990 Minerals and mineral formation in soils derived from volcanic ash in the tropics Proc. 9th Internat. Clay Conf 2 69 – 78.Google Scholar
Wada, K. and Kakuto, Y., 1985 Embryonic halloysites in Ecuadorian soils derived from volcanic ash Soil Sci. Soc. Amer. J 49 1309 – 1318 10.2136/sssaj1985.03615995004900050047x.CrossRefGoogle Scholar
Waldrop, M. M., 1988 After the fall Science 239 977 10.1126/science.239.4843.977.CrossRefGoogle ScholarPubMed