The distribution of andalusite, kyanite and sillimanite in an important part of the NE Dalradian is mapped. Sillimanite represents a late episode overprinted on the regional Andalusite and Kyanite Zones. The spatial distribution of sillimanite confirms that the heat source for the sillimanite-grade metamorphism in this area was the Newer (or Younger) Basic magma. The sillimanitic aureole of the Newer Basic intrusives is divisible into a Sillimanite Zone and a higher-grade Sillimanite—potash feldspar Zone. Relict andalusite is common in the Sillimanite Zone. Coarse muscovite replacing other minerals is primary in both zones, and should not be confused with late retrograde effects. Electron-probe analytical data on the Sillimanite–potash feldspar zone paragenesis of muscovite are presented. In this, its type area, the so-called ‘Boyne Line’ does not exist; the concept of such a tectonic dislocation arose through misinterpretation of the metamorphic effects.

It is suggested that post-(Hercynian)orogenic tensional forces may have initiated a major rift valley system in the Palaeozoic rocks of southern Britain. Large graben structures may underlie the Bristol Channel, the Severn Basin and the Weald Jurassic trough. Smaller graben structures are present in Devon and are associated with extrusive, potassium-rich lavas. The bounding faults of the larger postulated grabens may have been active during early Mesozoic times and may have fundamentally controlled sedimentation in local sags. A model is proposed which ascribes the development of fault-bounded Permo-Triassic basins and Jurassic axes of uplift to fracturing in the Palaeozoic basement.

Kaolinite is the major mineral in the saprolite of a fossil laterite, found intercalated amid basalt flows from the Lower Cretaceous in the Negev desert. The kaolinite was produced by pseudomorphic alteration of plagioclase. Haematite is a secondary product and accumulated in a ferruginous soil horizon. In the saprolite Sr, Mn and Cu were strongly depleted, Zn and Ni were slightly depleted, whereas Co and Cr accumulated. In the ferruginous horizon, Sr, Mn, Cu and Zn were severely depleted, while Cr and Ni accumulated. The lateritic formation is evidence for the possible existence of tropical or intertropical conditions during the Lower Cretaceous in the Negev.

Ultramafic and mafic nodules are abundant inclusions in Cainozoic alkali basalts at 7 localities in the Auckland Province. Nodule types show a gradation from dunites and pyroxenites through periodotites to eucrites. Bulk chemical variations in the nodules show a wide range in MgO/ΣFeO with a tendency for Al2O3, ΣFeO, CaO and Na2O + K2O to increase as this ratio decreases. These chemical trends, together with published data on the nodules mineralogy and fabric, are consistent with their being interpreted as fragments of the upper mantle.

In the Moinian rocks of Scotland, epidote-bearing calc-silicates, distinct from the commoner garnet-zoisite-bearing calc-silicates, occur at several widely scattered locations. The major element geochemistry of the two types of calc-silicate is very similar, and their somewhat different petrology and trace element geochemistry may be explained by the preservation of grains of detrital epidote and heavy minerals in the epidotic calc-silicates. These grains were concentrated in the original sediment and remained stable under greenschist and epidote-amphibolite metamorphic facies conditions. While the garnet-zoisite bearing calc-silicates may be derived from calcareous marls, the epidotic calc-silicate bands are probably derived from epidotic grits similar to those recorded in the Torridonian.

Quartz-plagioclase veins in staurolite schists often have margins depleted in the vein minerals. In some cases vein formation has simply involved recrystallization of groundmass grains into large vein grains in a closed system. The driving force for this process is reduction of strain energy and surface free energy. It is suggested that the veins initiate when grain boundaries have been opened up by hydraulic fracturing during medium grade metamorphism. The segregation process can be explained by a model of local equilibrium between grains and a continuous pore fluid similar to that commonly applied to metasomatic reactions; however, no phase change occurs.

Strain distribution inside an elliptical shaped boudin under normal compressive stress is calculated by photo-elastic methods following Frocht (1966). The strain magnitude varies horizontally within the boudin and the value increases gradually from the central part of the body to the margin. The magnitude is nearly constant along the vertical central part of the boudin. Around the margin, inside the body, it shows an average value of the vertical and horizontal stress magnitudes. No actual change in the direction of shearing stress in different parts within the boudin is noted, hence no directional change of strain. Petrofabric diagrams of different parts of natural boudins showing the quartz (0001) plots, indicate no variation in the pattern of orientation in different parts of the body. However, the elongation ratio of quartz grains shows a correspondent increase with the increment of stress magnitude as noted in the experiments.