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This is the second part of a two-volumespecial issueof Open Geoscience (formerly Central European Journalof Geosciences) that aims to be instrumental in providingan update of Mafic-Ultramafic Rocks and Alkaline-Carbonatitic Magmatism and Associated HydrothermalMineralization. Together, these two volumes provide a detailedand comprehensive coverage of the subjects thatare relevant to the research work of P.Comin-Chiaramonti(Italy) and LiaN. Kogarko (Russia) towhomPart-I and Part-II have been respectively dedicated.To a significant extent, the development of advanced samplingtechnologies related to alkaline and carbonatiticmagmatism by Lia N. Kogarko, has allowed geoscientiststo measure and sample the deep crust of the planet notonly for the exploration for the mineral deposits, but alsoto answer basic scientific questions about the origin andevolution of alkaline rocks (kimberlites, lamproites and relatedrocks associated with carbonatites). The papers presentedin this Part-II of the special issue cover the petrologyand geochemistry of the rocks collected from the surfaceand penetrated by drilling. Lia Kogarko proposed anew theory for the evolution of alkaline magmatism in thegeological history of the Earth – that the appearance of alkalinemagmatism at the Archaean-Proterozoic boundary(~2.5 – 2.7 Ga), and its growing intensity, was related tochanges in the geodynamic regime of the Earth and oxidationof the mantle due to mantle-crust interaction.

Emerald from the deposits at Poona shows micrometre-scale chemical, optical, and cathodoluminescence zonation. This zonation, combined with fluid inclusion and isotope studies, indicates early emerald precipitation from a single-phase saline fluid of approximately 12 weight percent NaCl equivalent, over the temperature range of 335-525 °C and pressures ranging from 70 to 400 MPa. The large range in pressure and temperature likely reflects some post entrapment changes and re-equilibration of oxygen isotopes. Secondary emerald-hosted fluid inclusions indicate subsequent emerald precipitation from higher salinity fluids. Likewise, the δ18O-δD of channel fluids extracted from Poona emerald is consistent with multiple origins yielding both igneous and metamorphic signatures. The combined multiple generations of emerald precipitation, different fluid compositions, and the presence of both metamorphic and igneous fluids trapped in emerald, likely indicate a protracted history of emerald precipitation at Poona conforming to both an igneous and a metamorphic origin at various times during regional lower amphibolite to greenschist facies metamorphism over the period ~2710-2660 Ma. [ABSTRACT FROM AUTHOR]