Diatexite
Hill: from Metatexite to Granite
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| Diatexite Hill in the Broken Hill Block of the Paeloproterozoic Curnamona Province, NSW, records the progressive melting of the Hores Gneiss from a metatexite to a granite in continuous outcrop over 100 m across strike. The system is geochemically closed except for the influx of water during melting. During solidification of the granite, fluids retrogress the anhydrous minerals (e.g. garnet), and the chemistry of the granite coincides with that of the protolith. Slides show increased melt fraction and disaggregation of the Hores Gneiss from metatexite to diatexite to granite. CLICK ON THUMBNAILS FOR HIGH RESOLUTION PHOTOS. |
Metatexite
| A) Original Hores Gneiss with leucosomes sub-parallel to original S1 foliation linked to leucosomes parallel to F2 axial planes. | B) Stromatic migmatite with leucosomes parallel to S1 and folded by F2 forming angular, close folds. |
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| C) Stromatic migmatite block recording a gently folded S1 (roughly N-S), transposed by diatexite parallel to S2 (roughly E-W). | D) Leucosome focused on shear zone. |
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Diatexite
| E) Diatexite | F) Diatexite |
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Granite
| G) Heterogeneous granite with large quartz fragments and peritectic garnet grains retrogressed to biotite and euhedral magmatic K-feldspar grains. | H) Heterogeneous granite with large quartz fragments and peritectic garnet grains retrogressed to biotite, and euhedral magmatic K-feldspar grains. |
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I) Granite with ghost S1 layering |
J) Granite with broken-up pieces of early intruded and crystalized pegmatite (pre-melting) |
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| K) Granite with broken-up pieces of early intruded and crystalized pegmatite (pre-melting). | L) Granite with a rounded block of refractory material. |
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