Abstract
The basal quartzite (grit) of the Gedinne that overlies unconformably the Salmian of Ordovician age was found to contain a pebble of the typical garnetiferous Mn-rich coticules occurring in the Salmian. However, the metamorphic mineral assemblage Mn-rich garnet-chlorite-muscovite present in the pebble was also formed in the pelitic matrix of the quartzite itself and must, therefore, be due to a post-Gedinnian, Hercynian event of metamorphism. The garnets of the pebble and the matrix are of identical composition and free from chemical zoning, but they are richer in Fe than the spessartine of in situ coticules. This seems to indicate that the pebble did not contain any garnet at the time of its deposition thus ruling out any noteworthy degree of pre-Gedinne, i. e. Caledonian metamorphism. The temperature of the Hercynian metamorphism was about 400‡–450‡ C and represents the highest degree of metamorphism found in rocks exposed in the central and northern parts of the Rhenish Mass.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
