Metamorphic Geology of Leornian

Units: A12 and A13

image MS-10

full-size image

Similar relationship to that shown in MS-03 but with some interesting differences. The gneiss in the foreground has a porphyroblastic texture: large white feldspar crystals are set in a finer matrix. These may represent feldspar megacrysts from an originally magmatic, broadly granitic rock. Note that felsic material invades the margin of the amphibolite unit. This may indicate that the "granitic" material was mobilised (by partial melting) during injection of the basic magmatic sheet and that this resulted in back-veining of the sheet. Alternatively, the mobilisation could have occurred during subsequent metamorphism.


Grid reference: 932 214

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This page is maintained by Roger Suthren

Last Modified: 21 October, 2008