Coexisting altered glass and Fe-Ni oxides at the Cretaceous-Tertiary boundary, Stevns Klint (Denmark); direct evidence of meteorite impact

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doi: 10.1016/S0012-821X(00)00245-4
Authors:Bauluz, Bianca; Peacor, Donald R.; Elliott, W. Crawford
Author Affiliations:Primary:
Universidad de Zaragoza, Saragossa, Spain
Other:
University of Michigan, United States
Georgia State University, United States
Volume Title:Earth and Planetary Science Letters
Source:Earth and Planetary Science Letters, 182(2), p.127-136. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X
Publication Date:2000
Note:In English. 48 refs.; illus., incl. 3 tables
Summary:The Cretaceous-Tertiary (K-T) boundary at Stevns Klint, Denmark, is noteworthy for its large Ir anomaly that is taken as evidence of extraterrestrial components, but the origin of the smectite in this marl has been variously interpreted to have a detrital, meteorite impact, or volcanic origin. We have carried out scanning electron microscopy and transmission electron microscopy (TEM)/analytical electron microscopy observations of the impact and contiguous layers within the K-T marl at Stevns Klint. TEM images show abundant smectite, much of which occurs with layers curving around and grading into cores of nanometer-scale glass shards. The smectite composition is unusual in having both significant octahedral Al and Mg. The glass and smectite major element compositions are similar and unique relative to glasses of terrestrial and extraterrestrial origin with the exception for one kind of glass at the K-T boundary in Haiti. Abundant 10-20-nm diameter iron oxides having as much as 10% Ni and minor Zn are intergrown with smectite. We interpret these domains to be altered meteorite fragments, which formed when impact glass was transformed to smectite. The direct association of unique glass and meteorite fragments is unambiguous evidence for meteorite impact. These data may imply fall-out of globally distributed impact-derived particles over an extended time period. The relations imply that TEM observations may be a powerful tool in detecting other impact events in the geological record. Abstract Copyright (2000) Elsevier, B.V.
Sections:Meteorites and tektites
Subjects:Alteration; Cenozoic; Clastic rocks; Clay mineralogy; Clay minerals; Cretaceous; Experimental studies; Glass materials; Impacts; Iron; Iron oxides; Lower Paleocene; Marl; Mesozoic; Metals; Nickel; Oxides; Paleocene; Paleogene; Sedimentary rocks; Sheet silicates; Silicates; Smectite; Stratigraphic boundary; TEM data; Tertiary; Upper Cretaceous; Zinc; Denmark; Europe; Scandinavia; Stevns Klint; Western Europe; K-T boundary; Nickel oxides
Coordinates:N551300 N552500 E0122500 E0120600
Abstract Numbers:01M/1972
Record ID:2001004520
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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