04 Oct What is an impactite?
The term ‘impactite’ is a “collective term for all rocks affected by one or more hypervelocity impact(s) resulting from collision(s) of planetary bodies.” (D. Stöffler and R. A. F. Grieve, 2007)
In other words: Impactites are formed when a meteorite strikes the surface of the Earth and the impact forms a crater. The rocks of the area are blasted from the site and fall as debris. Some of the rock will be melted to one extent or another. Some melted to solid high quality glass some poorer fused into lump called Impactites and some of the rocks of the region may only be ribboned with glass.
Means that an impactite IS NOT a meteorite. An impactite is the Earths rock modified by the energy liberated when a meteorite strikes the surface.
Impact melt rocks are subdivided into three subgroups, according to the content of clasts. These three subtypes may be subclassified according to the degree of crystallinity into glassy, hypocrystalline, and holocrystalline varieties. The first two subtypes include ‘impact glass’ as well as ‘tektites’;
We found impactites in the Peruvian desert in a location near Chimbote town, which look very similar if not exactly like impactites from the Henbury crater field in Australia.
Henbury craters in the Australian desert
The Henbury craters are located 145 kilometres south-west of Alice Springs and the area contains 12 craters that were formed 4700 years ago when the Henbury Meteor, weighing several tonnes and accelerating to over 40,000 kilometres per hour, disintegrated into several pieces before impact. Scattered fragments of the meteor can be seen at the Museum of Central Australia. Each of the 12 craters is quite different, some barely noticeable. The largest crater is 180m wide and 15m deep.
Henbury impactites were created by the meteorites impact on the Australian deserts sand stone:
A few weeks ago we did find a number of impactites in the Peruvian desert near Chimbote that look exactly like the Henbury impactites. We are still in process of determining the exact position of the ancient crater and so far we could not find any meteorite parts.
- Stöffler and R. A. F. Grieve, 2007: “Impactites”, Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: Web version 01.02.07