А. N. Zavaritskli's book "Physicochemical Principles of the Petrography of Igneous Rocks" which was published in 1926, was the first systematic textbook on this subject to appear in world literature. It was written in conjunction with a course of lectures delivered by the author over a period of many years (both before and after its publication) at the Leningrad Mining Institute, developing the trend initiated by E. S. Fedorov.

Ordovician volcanic, volcaniclastic and intrusive rocks of calc-alkaline affinity in the Eastern Subprovince of the Lachlan Orogen were formed in the intraoceanic Macquarie Volcanic Arc. The Macquarie Arc was developed in response to west-dipping subduction along part of the boundary between eastern Gondwana and the proto-Pacific Plate and was situated on the Gondwana Plate, some 1000 km east of Precambrian continental crust. The intervening area was occupied by a back arc basin that developed on oceanic crust as the proto-PacificPlate rolled back eastwards after the Middle Cambrian Delamerian Orogeny. Subsequent extension, strike-slip translation and thin-skinned tectonics have structurally dissected the single arc into four north to NNE trending structural belts of Ordovician calc-alkaline rocks that are separated largely by younger rift basins and in part by coeval craton-derived turbidites.

The Almalyk porphyry Cu-Au system of eastern Uzbekistan encompasses the giant ore deposits at Kal'makyr (2.5 Gt @ 0.38% Cu, 0.5 g/t Au) and Dalnee (2.8 Gt @ 0.36% Cu, 0.35 g/t Au). The Sarycheku orebody (200 Mt @ 0.5% Cu, 0.1 g/t Au) is part of the Saukbulak porphyry Cu-Au system, some 18 km to the south. Both systems are associated with the second, Middle- to Late-Carboniferous, pulse of magmatic activity within the Devono-Carboniferous Valerianov-Bertau-Kurama volcano-plutonic belt that is the main element of the Middle Tien Shan terrane in Central Asia. Previous K-Ar dating of the ore-related porphyry intrusive and the mineralisation has returned ages in the range of 310 to 290 Ma, whereas recent U-Pb zircon dating reported for the intrusive sequence in the Almalyk district partially overlaps in the range of 320 to 305 Ma, with ore-related porphyries 315 to 319 Ma.

Mineralisation at both Kal'makyr and Dalnee is predominantly in the form of stockworks with lesser disseminations, and is associated with Late Carboniferous quartz monzonite porphyry plugs intruding earlier dioritic and monzonitic intrusive rocks of the same magmatic complex. The orebodies take the form of a cap like shell developed above and draped over the flanks of the related quartz monzonite porphyry stock. The dominant hosts to ore are the monzonite and diorite wall rocks, with the quartz monzonite porphyry only containing ore in its outer margins, surrounding and/or overlying a barren core. The focus of stockwork development is fracturing related to both the intrusive contact of the porphyry stock and to crosscutting faulting. Alteration comprises an early K-silicate phase followed by albite-actinolite and peripheral epidote-chlorite-carbonate-pyrite propylites, overprinted by an abundant phyllic episode which is closely related to the final distribution of the ore. Associated mineralisation commenced with barren quartz-hematite veining, followed by quartz-magnetite, quartz-pyrite-molybdenite-chalcopyrite with the bulk of the contained gold, quartz-carbonate-polysulphide with lesser gold, then by zeolite-anhydrite, and finally carbonate and barite veining. Subsequent oxidation and uplift developed a layer of oxide ore, a limited leached cap and supergene sulphide enrichment, largely in zones of fault related fracturing.

Many facets of Earth's evolution are intriguing, yet most of our attention is drawn to the more recent phases, as from the Cambrian epoch (c. < 540 Ma). The Precambrian Era, from 4.5 to 0.54 Ga, covers almost 90% of this planet's history but our knowledge of this segment of time remains elusive, save for selective aspects. Even though extensive research has been conducted on some topics, a significant diversity of opinions amongst researchers is evident and generally concerns the origin, the mechanism or the process inherent to a specific criterion. For example, did the atmosphere change with time?