Skip to Main Content
Book Chapter

Shock Metamorphism

January 01, 2005

The distribution and origin of impact diamonds in the ejecta blanket of the Ries crater, Germany, was investigated. Impact diamonds are present in the fallout suevite, whereas the cataclastic crystalline breccias, lithic impact breccia (Bunte Breccia) and clast-rich impact melt rock do not contain diamonds. No regional concentrations of impact diamonds in the fallout suevite could be detected. The average concentration of diamonds is ∼0.1–0.2 ppm. The carriers of impact diamonds are specific suevite components, such as graphite-bearing crystalline rock fragments of shock stage III, and most likely small fragments thereof in melt fragments and suevite matrix. Impact diamonds occur as pseudohexagonal, transparent, and birefringent plates, which reach sizes up to 300 µm. Their color is commonly greenish, but can also be black, gray, yellow, or colorless. Most of the impact diamonds have a fibrous or spongy internal structure and extensional microfractures, which lead to a characteristic porosity. This is the result of a volume decrease due to the phase transformation of graphite to diamond. The Raman characteristics of these impact diamonds are discussed in detail. The strong morphologic similarity of impact diamonds to the precursor graphite from the crystalline target rocks indicate a solid state martensitic phase transformation which occurs at shock pressures of 45–55 GPa.

You do not currently have access to this article.
Don't already have an account? Register

Figures & Tables


GSA Special Papers

Large Meteorite Impacts III

Thomas Kenkmann
Thomas Kenkmann
Search for other works by this author on:
Friedrich Hörz
Friedrich Hörz
Search for other works by this author on:
Alex Deutsch
Alex Deutsch
Search for other works by this author on:
Geological Society of America
ISBN print:
Publication date:
January 01, 2005




A comprehensive resource of eBooks for researchers in the Earth Sciences

This Feature Is Available To Subscribers Only

Sign In or Create an Account

This PDF is available to Subscribers Only

View Article Abstract & Purchase Options

For full access to this pdf, sign in to an existing account, or purchase an annual subscription.

Subscribe Now