Rapale Gneiss Charnockites

Here it is, Lee-Anne! Look happy because this quarry represents the next nine months of your life! You will be living and breathing Rapale charnockites from now on!! Heh heh. Hazing aside, you can no doubt see why Lee-Anne is so excited. Look at the orderly distribution of charnockitized fractures and K-rich melt veins! Look at the big clear quartzy blobs in those melt veins that could be chock full of fluid inclusions!

The charnockite is confined to zones on order 10cm-1m thick, corresponding to a surprisingly regular conduit network. You can see from the mafic dike here that the blocks of gneiss were rotated along the charnockite/melt seams, acting as semi-rigid blocks although the edges are somewhat sheared.


Some of the blocks contain folded dikes! But when did they fold? Was it during the regional metamorphism and folding (pan-African Age) or did the charnockitisation have anything to do with it? Looks to me like the former. Jodie helped me measure sets of these folds from the charnockite quarry and a nearby quarry which escaped charnockitisation to check for consistency. In these gneisses where there is no compositional banding, these are the only strain marker!


Tres Amigas before the deluge: