Gabbroic rock

Anorthositic deposits - nearly all of the known commercially important rock deposits of titanium minerals are associated with anorthositic or gabbroic rocks. There are three main types (a) ilmenite-magnetite (titanoferous magnetite), (b) ilmenite-haematite, and (c) ilmenite-rutile. 

Table 5.32 Compositions (in weight %) of natural pyroxenes (samples 1-5 from Deer et al., 1983 samples 6 and 7 from Bonatti et al., 1986) (1) enstatite from a pyroxenite (2) ferrosilite from a thermometamorphic iron band (3) hedembergite (4) chromian augite from a gabbroic rock of the Bushveld complex (5) aegirine from a riebeckite-albite granitoid (6) diopside from a mantle peridotite (7) enstatite from a mantle peridotite. ...

Criss et al. (1987) and Gregory et al. (1989) developed a theoretical framework that describes the kinetics of oxygen isotope exchange between minerals and coexisting fluids. Figure 2.17 shows characteristic patterns in 8-5 plots for some hy-drothermally altered granitic and gabbroic rocks. The arrays displayed on... 

Fig. 2.17 6 0 (feldspar) vs 5 0 (quartz) and vs 8 0 (pyroxene) plots of disequilibrium mineral pair arrays in granitic and gabbroic rocks. The arrays indicate open-system conditions from circulation of hydrothermal fluids (after Gregory et al. 1989)... 

Hafnium is dispersed in the Earth s crust to the extent of three parts per million, and is invariably found in minerals of zirconium up to a few percent compared with zirconium. Hafnium vapor has been identified in the Sun s atmosphere. Commercial sources of hafnium-bearing zirconium minerals are found in beach sands and river gravel in the United States (principally Florida), Australia, Brazil, western Africa, and India. Hafnium is concentrated in the upper horizons in a weathering profile of gabbroic rocks (Serpa, Portugal) ranging between 1.0 and... 

Gouveia MA, Prudencio MI, Morgado I, Mag-ALHAES MT and Cabral JMP (1992) Distribution of Sc, Cr, Co, Hf, Ta and Thin a weathering profile of gabbroic rocks (Serpa, Portugal). J Radioanal Nud Chem 161 245-252. 

Fig. 16.25 The Melbourne volcanic province of northern Victoria Land forms an arc that extends from Mt. Melbourne in the south to the Vulcan Hills, Mt. Overlord, The Pleiades, and the Malta Plateau in the north. In addition, the Melbourne volcanic province contains numerous small volcanic vents where lava and volcanic ash of basaltic composition have been extruded. The Meander intrusive suite consists of gabbroic rocks whose presence was inferred by an aeromagnetic survey by Bosum et al. (1991) and Behrendt et al. (1991a, b) (Adapted from Kyle (1990f) and from Fig. 2 of Nathan and Schulte (1968))...

Experimental and microstructural studies of granitic rocks demonstrate that feldpars are stronger than quartz [286]. By contrast, plagioclase feldspar becomes a weak and interconnected phase controlling the rheology of more mafic gabbroic rocks [263], which are common in the lower continental crust and oceanic crust. 

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