Potassic igneous rocks and associated gold-copper mineralization / Калиевые магматические горные породы и их связь с золото-медной минерализацией

Potassic igneous rocks were originally recognized in the late 19th century by Iddings (1895), who described some orthoclase-bearing basalts from the Yellowstone Park, Wyoming, and coined the term “shoshonite”. In the last century, petrologists generated many names for potassic igneous rocks which were either based on their mineralogy or, more commonly, based on the locality of their occurrence. The practice was to name a new rock after a place where it occurred —the type locality. These different names for essentially similar rocks from different localities led to great confusion (Sørensen 1974; De Wit 1989; Rock 1991; Peccerillo 1992; Soloviev 2014a).
The first attempts to explain the petrogenesis of potassic magmatism date back to the beginning of the 20th century when Daly (1910) explained potassic melts as products of the assimilation of carbonate sediments by uprising basaltic magmas. Rittmann (1933) adopted this hypothesis in order to explain the potassic magmatism of the Vesuvius volcano and the Mediterranean Series, as potassic igneous rocks were named at that time (Peccerillo 1992), with the assimilation of carbonates by evolved trachytic magmas. This model was widely  ccepted until the 1960s, although it was unable to explain the potassic magmatism in the East African Rift (e.g. Foley et al. 2011), where carbonates are absent. However, Savelli (1967) was able to demonstrate that potassic magmas have much higher abundances of large-ion lithophile elements (LILE) and mantle-compatible elements, such as Cr, Ni, and V, than do both carbonates and basalts. Therefore, the assimilation model appeared rather unlikely and alternative explanations were developed. One of these was the zone-refining model proposed by Harris (1957). This model was adapted from the steel industry, where the process of zone-refining was used to purify metal bars. Harris (1957) suggested that a mantle plume would rise adiabatically by melting the roof rocks at its top and by crystallizing minerals at its base. This process would allow the rising melt to incorporate all the mantleincompatible impurities such as LILE and light rare-earth elements (LREE). As a result, the migrating melt would become progressively enriched in these elements and gain a potassic composition. Another model to explain potassic magmatism was based on observations from trace-element modeling (Kay and Gast 1973), which implied that the enrichments in LILE and LREE in potassic igneous rocks were an effect of very low degrees of partial melting (i.e. melt increments of <1 vol%) of a garnet-peridotite in the upper mantle. <...>