The formation of porphyroblasts by replacement and displacement of pre-existing S surfaces is examined in the light of textural evidence displayed by sediments hornfelsed by the Bushveld Igneous Complex. Helicitic biotite, staurolite, and cordierite all show replacement and displacement textures, the former being more common. The evidence indicates that porphyroblasts arc capable of creating lo...

Spinel + plagioclase symplectites in pelitic metamorphic rocks have been reported from many localities. We report detail an occurrence of this texture Tenmondai Rock, Lützow-Holm Complex, East Antarctica. This is produced by the following reaction; garnet sillimanite = spinel plagioclase. can be described as two net-transfer reactions; 5Grs Alm 12Als 3Hc 15An, and Prp 3Spl 15An. propose new geo...

FEW analytical data exist for staurolite, in comparison with other metamorphic minerals such as garnet. However, using the microprobe, Hollister and Bence (1967) working with relatively inclusion-free specimens from the Kwoiek Area, British Columbia, established compositional zoning across staurolite in addition to compositional irregularities across sectoral twin boundaries. The staurolites st...

Monazite-(Ce) and xenotime-(Y) were found in the metacherts (pumpellyite–actinolite-facies conditions: 3 ≤ P ≤ 4 kbars and 300 ≤ T ≤ 350°C) of the Monte Figogna Unit, Sestri–Voltaggio Zone, Liguria, in Italy, as scattered submillimetric grains in pelitic beds and as euhedral crystals in both millimeter-thick quartz veins and open fissures. Their composition is comparable to those of known occur...

Intrusion of the Kalaybar nepheline syenite into the Cretaceous pelitic and calcareous sediments has produced a thermal aureole up to 1km thick. Six mineralogical zones are developed in the pelitic rocks with minerals such as cordierite, K feldspar, sillimanite and corundum. Chemically suitable rocks are partially melted in response to the heat from the pluton. Five mineralogical zones are deve...