Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Geology Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Geology; November 1998; v. 26; no. 11; p. 979-982
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Retallack, G. J.
Right arrow Articles by Kyte, F. T.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Search for evidence of impact at the Permian-Triassic boundary in Antarctica and Australia

Gregory J. Retallack, Abbas Seyedolali, Evelyn S. Krull, William T. Holser, Clifford P. Ambers, and Frank T. Kyte

University of Oregon, Department of Geological Sciences, Eugene, OR, United States

Life on Earth was almost destroyed some 250 m.y. ago in the most profound of all known mass extinction events. We investigated the possible role of impact by an extraterrestrial bolide through chemical and mineralogical characterization of boundary breccias, search for shocked quartz, and analysis for iridium in Permian-Triassic boundary sections at Graphite Peak and Mount Crean, Antarctica, and Wybung Head, Australia. Thin claystone breccias at the isotopically and paleobotanically defined boundary at all three locations are interpreted as redeposited soil rather than impact ejecta. The breccias at all three locations also yielded shocked quartz, but it is an order of magnitude less abundant (0.2 vol%) and smaller (only as much as 176 mu m diameter) than shocked quartz at some Cretaceous-Tertiary boundary sites. Faint iridium "anomalies" were detected (up to 134 pg.g (super -1) ). These values are an order of magnitude less than iridium anomalies at some Cretaceous-Tertiary boundary sites. Furthermore, peak iridium values are as much as 1 m below the isotopically and paleobotanically defined boundary. The idea that impact caused the extinctions thus remains to be demonstrated convincingly.

This record provided courtesy of AGI/GeoRef.




This article has been cited by other articles:


Home page
 GeologyHome page
S. Xie, R. D. Pancost, J. Huang, P. B. Wignall, J. Yu, X. Tang, L. Chen, X. Huang, and X. Lai
Changes in the global carbon cycle occurred as two episodes during the Permian Triassic crisis
Geology, December 1, 2007; 35(12): 1083 - 1086.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
J. M. Thery, D. Vachard, and E. Dransart
Late Permian limestones and the Permain-Triassic boundary:new biostratigraphic, palaeobiogeographical and geochemical data in Caucasus and eastern Europe
Geological Society, London, Special Publications, January 1, 2007; 275(1): 255 - 274.
[Abstract] [PDF]

Home page
 Geol Soc Am BullHome page
J. W. Collinson, W. R. Hammer, R. A. Askin, and D. H. Elliot
Permian-Triassic boundary in the central Transantarctic Mountains, Antarctica
GSA Bulletin, May 1, 2006; 118(5-6): 747 - 763.
[Abstract] [Full Text] [PDF]

Home page
 Journal of Sedimentary ResearchHome page
G.J. Retallack
Earliest Triassic Claystone Breccias and Soil-Erosion Crisis
Journal of Sedimentary Research, July 1, 2005; 75(4): 679 - 695.
[Abstract] [Full Text] [PDF]

Home page
 GeologyHome page
Geochemistry of the end-Permian extinction event in Austria and Italy: No evidence for an extraterrestrial component
Geology, December 1, 2004; 32(12): 1053 - 1056.


Home page
 ScienceHome page
L. Becker, R. J. Poreda, A. R. Basu, K. O. Pope, T. M. Harrison, C. Nicholson, and R. Iasky
Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia
Science, June 4, 2004; 304(5676): 1469 - 1476.
[Abstract] [Full Text] [PDF]

Home page
 ScienceHome page
A. R. Basu, M. I. Petaev, R. J. Poreda, S. B. Jacobsen, and L. Becker
Chondritic Meteorite Fragments Associated with the Permian-Triassic Boundary in Antarctica
Science, November 21, 2003; 302(5649): 1388 - 1392.
[Abstract] [Full Text] [PDF]

Home page
 Geol Soc Am BullHome page
G. J. Retallack, R. M.H. Smith, and P. D. Ward
Vertebrate extinction across Permian-Triassic boundary in Karoo Basin, South Africa
GSA Bulletin, September 1, 2003; 115(9): 1133 - 1152.
[Abstract] [Full Text] [PDF]

Home page
 PALAIOSHome page
Permian-Triassic Boundary Sections from Shallow-Marine Carbonate Platforms of the Nanpanjiang Basin, South China: Implications for Oceanic Conditions Associated with the End-Permian Extinction and Its Aftermath
Palaios, April 1, 2003; 18(2): 138 - 152.


Home page
 PALAIOSHome page
Tetrapod and Large Burrows of Uncertain Origin in Triassic High Paleolatitude Floodplain Deposits, Antarctica
Palaios, June 1, 2001; 16(3): 218 - 232.


Home page
 ScienceHome page
L. Becker, R. J. Poreda, A. G. Hunt, T. E. Bunch, and M. Rampino
Impact Event at the Permian-Triassic Boundary: Evidence from Extraterrestrial Noble Gases in Fullerenes
Science, February 23, 2001; 291(5508): 1530 - 1533.
[Abstract] [Full Text] [PDF]

Home page
 Geol Soc Am BullHome page
E. S. Krull and G. J. Retallack
{delta}13C depth profiles from paleosols across the Permian-Triassic boundary: Evidence for methane release
GSA Bulletin, September 1, 2000; 112(9): 1459 - 1472.
[Abstract] [Full Text] [PDF]

Home page
 GeologyHome page
K. G. MacLeod, R. M. H. Smith, P. L. Koch, and P. D. Ward
Timing of mammal-like reptile extinctions across the Permian-Triassic boundary in South Africa
Geology, March 1, 2000; 28(3): 227 - 230.
[Abstract] [Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by Geological Society of America