The promise of the Spacefaring Age - the era of human activities in space - is that it will link human expertise to the unlimited resources of space. When that linkage is established, the people of Earth will be supplied with an abundance of energy and material resources from space; the solar system will be explored in depth; human settlements will be established on multiple planets and moons; and voyages to the stars will be undertaken. The present “closed Earth” mindset - of limits to human potential related to the depletion of Earth’s resources and the vital need to preserve Earth’s environment - will be replaced by a much grander “open space’’ vision of broad-scale human advancements based upon access to unlimited resources and the opening of endless frontiers. <...>

This paper presents new petrological and geochronological data for the ~3.09-2.92 Ga Murchison Greenstone Belt (MGB), located in South Africa’s Kaapvaal Craton, and discusses their geotectonic implications. The MGB is made of three tectono-metamorphic units: the Silwana Amphibolites, the Murchison Unit and the La France Formation. They underwent contrasting clockwise pressure temperature-deformation (P-T-D) histories, and are separated from each other by relatively narrow, high strain shear zones, with a sinistral, transpressive top-to-the-south movement, consistent with the deformation patterns observed throughout the belt.

The origin of granite has for long fascinated geologists though serious debate on the topic may be said to date from a famous meeting of the Geological Society of France in 1847. My own introduction to the subject began exactly one hundred years later when, in an interview with Professor H.H. Read, I entered his study as an amateur fossil collector and left it as a committed granite petrologist - after just ten minutes!

The British sector of the Caledonide-Appalachian fold belt, which bridges the Iapetus plate closure zone, has a range of plutonic, volcanic and volcaniclastic lithologies with characteristic space-time variations. The map of Caledonian igneous rocks in the British Isles (Plate 1) is compiled from many sources, some of which predate the use of methods of classification which are based largely on chemical data. In such cases, whilst extensive re-mapping continues, the compilers have had to resort to the collection and analysis of representative samples from the areas in question, the collection sites being based on existing maps. Thus, whilst the references to the mapped areas indicate specific publications, the chemical data on which the coding is based are commonly derived from compilations such as Stillman & Williams (1979) and Stillman & Francis (1979) for volcanic rocks and Sutherland & Pankhurst (1982), Le Bas (1982), Hall (1972) and Brown et al. (1981) for plutonic rocks.