Impact Materials

During 1991-1992 12 research cores were drilled into the Manson Impact Structure. As a result the researchers found 6 main types of impact materials unique to the impact.

Six primary impact materials were encountered:


6 types of impact materials


  • Crystalline Basement Blocks -  Large blocks of crystalline basement materials lifted up over 5 km with the crater's central peak.


  • Crystalline Clast Breccia with Sandy Matrix - Blocks of brecciated crystalline rocks in a matrix of disaggregated crystalline rock and mineral fragments.


  • Crystalline Clast Breccia with Melt Rock Matrix - Blocks of brecciated crystalline rocks and mineral grains (dominantly quartz) in a melt rock matrix.


  • Keweenawan Clast Breccia - Clasts of brecciated dark gray to black Keweenawan (Middle Proterozoic) shales, siltstones, and sandstones mixed with light gray-green, devitrified melt rock.


  • Phanerozoic Clast Breccia -  A matrix-dominated breccia composed primarily of clasts of Cretaceous marine shale clasts with lesser numbers of Paleozoic carbonate clasts, rare clasts of Proterozoic Keweenawan clastic rocks, and very rare clasts of crystalline rock and melt rocks in a medium gray calcareous sandy shale matrix.


  • Impact Ejecta - An overturned flap of latest ejecta on the terrace terrane.


This information was obtained from the Abstract: IMPACT MATERIALS RECOVERED BY RESEARCH CORE DRILLING IN THE MANSON IMPACT STRUCTRE by R.R. Anderson, B.J. Witzke, and J.B. Hartung