Abstract: | Based on original data on the East European and Siberian platforms and materials on the best studied foreign objects, a comparative
analysis of kimberlites and lamproites was conducted and the criteria of their differences were formulated. Among most significant
differences are the following: (1) the high-Mg potassic rocks (kimberlites and lamproites) show major-component variations,
which are significantly wider in lamproites as compared to kimberlites. Kimberlites differ from lamproites not only in the
content of SiO2, but also in alkalis, volatiles, and some trace elements. Kimberlites are characterized by CO2-dominated regime, whereas formation of lamproites was assisted by essentially H2O fluid; (2) Kimberlites are localized within ancient cratons, while within-plate lamproites are restricted to adjacent Proterozoic
belts. Kimberlites are produced in the low-heat flow regions, whereas lamproites occur in the high-heat flow regions; (3)
Kimberlites and lamproites were formed in different time; in particular, most productive kimberlitic magmatism was observed
in the EEP and SP in the Devonian; (4) Kimberlite and lamproite bodies have different morphology: lamproites compose small
subvolcanic bodies with lava flows, while kimberlites form volcanic pipes with no lavas; (5) Kimberlites contain highly silica-undersaturated
minerals, while ultrabasic lamproites—silica-undersaturated ones; priderite and wadeite, the characteristic accessory minerals
of lamproites, are not observed in kimberlites; (6) The primary melts of kimberlites and lamproites were derived from different
types of mantle. The moderate and low-Ti kimberlites were generated from BSE or EMI type mantle. Precisely these types of
kimberlites host diamond deposits, including economic grade objects in EEP. The lamproite sources were localized only in the
enriched mantle (EMI and EMII). At the same time, these rocks share some similarities, primarily, with respect to their genesis
and classification. Diamonds are common accessory minerals of kimberlites (low-Ti and some other types), but are observed
only in only lamproite variety—olivine lamproites. |