Petrology and Geochemistry of Target Rocks, Breccias, and Impact Melt Rocks from the Ilyinets Crater, Ukraine
The Ilyinets impact structure has a present-day diameter of about 3 to 3.5 km and is situated in the western part of the Ukrainian shield at 49 degrees 07'N and 29 degrees 06'E. The crater formed in Precambrian basement, and most of it is presently covered by Quaternary sediments. The structure is deeply eroded, but various types of impact breccias and melts are exposed in its southern section. Several drill cores have been obtained from within the crater, indicating that it is a complex structure with a central uplift that is surrounded by an annular deposit of breccias and melt rocks. In the annulus, brecciated basement rocks are overlain by up to 80 m of allochthonous polymict breccia, which is overlain (and partly intercalated) by suevitic breccia with a thickness of up to 130 m. Impact melt rocks occur within and on top of the suevites, in some cases in the form of devitrified bomb-shaped impact glasses. The age of the Ilyinets structures has been determined to be about 400 Ma. We have studied the petrographic and geochemical characteristics of 8, mostly shocked, target rock samples (granites, gneisses, and one amphibolite) obtained from drill cores within the structure, as well as 13 impact breccias and melt rock samples from cores and surface exposures.
Lunar and Planetary Science Conference
- Pub Date:
- March 1996
- CRATERS: ILYINETS;
- CRATERS: IMPACT;
- MELT BOMBS;