Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Amor, K. Articles by Parnell, J. Search for Related Content GeoRef GeoRef Citation

A Precambrian proximal ejecta blanket from Scotland

¹ Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK
² Department of Geology and Petroleum Geology, Meston Building, King's College, Aberdeen AB24 3UE, UK

Ejecta blankets around impact craters are rarely preserved on Earth. Although impact craters are ubiquitous on solid bodies throughout the solar system, on Earth they are rapidly effaced, and few records exist of the processes that occur during emplacement of ejecta. The Stac Fada Member of the Precambrian Stoer Group in Scotland has previously been described as volcanic in origin. However, shocked quartz and biotite provide evidence for high-pressure shock metamorphism, while chromium isotope values and elevated abundances of platinum group metals and siderophile elements indicate addition of meteoritic material. Thus, the unit is reinterpreted here as having an impact origin. The ejecta blanket reaches >20 m in thickness and contains abundant dark green, vesicular, devitrified glass fragments. Field observations suggest that the deposit was emplaced as a single fluidized flow that formed as a result of an impact into water-saturated sedimentary strata. The continental geological setting and presence of groundwater make this deposit an analogue for Martian fluidized ejecta blankets.

Key Words: ejecta • impactites • shock metamorphism • PGE • suevite • Torridonian

This article has been cited by other articles:

				S. C. Sherlock, R. A. Strachan, and K. A. Jones High spatial resolution 40Ar/39Ar dating of pseudotachylites: geochronological evidence for multiple phases of faulting within basement gneisses of the Outer Hebrides (UK) Journal of the Geological Society, December 1, 2009; 166(6): 1049 - 1059. [Abstract] [Full Text] [PDF]

				R. A. BATCHELOR, A. R. PRAVE, G. J. H. OLIVER, and A. S. RAEBURN Petrogenesis of albite-rich mid- to late Proterozoic tephra-fall deposits ('brown beds') Geological Magazine, November 1, 2008; 145(6): 858 - 867. [Abstract] [Full Text] [PDF]