Perovskites as an Exploration Tool

English Abstract:

Perovskite-group minerals are common accessory constituents of such economically important rocks as kimberlites, lamproites, carbonatites and agpaitic feldspathoid syenites. These minerals accumulate in clastic sediments and can be potentially used as an exploration tool. Because perovskites incorporate a wide range of trace elements specific to their parental magmas and crystallization conditions (including many of the isotopes routinely used in geochronology), mass-spectrometry analysis can be used to track the sources of clastic perovskites and search for unrecognized mineral deposits. In the present work, we conducted a detailed comparative analysis of trace-element distributions in loparite [(Na,REE,Ca,Sr,Th)(Ti,Nb,Ta)O₃] and perovskite [(Ca,Na,REE,Sr)(Ti,Nb,Fe)O₃] from several well-known occurrences of kimberlite, carbonatite, alkaline silicate and contact-metamorphic rocks. We identified a number of trace-element characteristics that can be used to discriminate among different source rocks, and applied these criteria to detrital perovskite and loparite from clastic sediments of Jurassic age in the eastern part of the East European craton (Veslyana basin, Perm Krai, Russia). We also used U-Pb dating techniques to constrain the age of the Veslyana samples. Based on these data, the examined perovskite is derived from a Devonian carbonatitic source probably related to Mid-Paleozoic rifting of the margin of the East European platform. The loparite is derived from relatively primitive agpaitic syenites of Ediacaran age, which can be linked to widespread alkaline magmatism in the East European craton and elsewhere, heralding the final stage of Rodinia breakup.