Book ; Online: Analyses of shocked quartz from the K-P boundary, supplementary data to: Morgan, Joanna; Lana, Cristiano; Kearsley, Anton; Coles, Barry; Belcher, Claire; Montanari, Sandro; D?az-Mart?nez, Enrique; Barbosa, Antonio; Neumann, Virginio (2006): Analyses of shocked quartz at the global K-P boundary indicate an origin from a single, high-angle, oblique impact at Chicxulub. Earth and Planetary Science Letters, 251(3-4), 264-279
2006
Abstract: The precise cause and timing of the Cretaceous-Paleocene (K-P) mass extinction 65 Ma ago remains a matter of debate. Many advocate that the extinction was caused by a meteorite impact at Chicxulub, Mexico, and a number of potential kill-mechanisms have ... ...
| Abstract | The precise cause and timing of the Cretaceous-Paleocene (K-P) mass extinction 65 Ma ago remains a matter of debate. Many advocate that the extinction was caused by a meteorite impact at Chicxulub, Mexico, and a number of potential kill-mechanisms have been proposed for this. Although we now have good constraints on the size of this impact and chemistry of the target rocks, estimates of its environmental consequences are hindered by a lack of knowledge about the obliquity of this impact. An oblique impact is likely to have been far more catastrophic than a sub-vertical one, because greater volumes of volatiles would have been released into the atmosphere. The principal purpose of this study was to characterize shocked quartz within distal K-P ejecta, to investigate whether the quartz distribution carried a signature of the direction and angle of impact. Our analyses show that the total number, maximum and average size of shocked quartz grains all decrease gradually with paleodistance from Chicxulub. We do not find particularly high abundances in Pacific sites relative to Atlantic and European sites, as has been previously reported, and the size-distribution around Chicxulub is relatively symmetric. Ejecta samples at any one site display features that are indicative of a wide range of shock pressures, but the mean degree of shock increases with paleodistance. These shock- and size-distributions are both consistent with the K-P layer having been formed by a single impact at Chicxulub. One site in the South Atlantic contains quartz indicating an anomalously high average shock degree, that may be indicative of an oblique impact with an uprange direction to the southeast +/- 45?. The apparent continuous coverage of proximal ejecta in this quadrant of the crater, however, suggests a relatively high impact angle of >45?. We conclude that some of the more extreme predictions of the environmental consequences of a low-angle impact at Chicxulub are probably not applicable. |
|---|---|
| Language | English |
| Dates of publication | 2006-9999 |
| Size | Online-Ressource |
| Publisher | PANGAEA - Data Publisher for Earth & Environmental Science |
| Publishing place | Bremen/Bremerhaven |
| Document type | Book ; Online |
| Note | This dataset is supplement to doi:10.1016/j.epsl.2006.09.009 |
| DOI | 10.1594/PANGAEA.723777 |
| Database | Library catalogue of the German National Library of Science and Technology (TIB), Hannover |
Full text online
More links
Kategorien
Inter-library loan at ZB MED
Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.