Diamond Exploration Potential of the Northern East European Platform

Abstract

Abstract:In this study, we assess the diamond exploration potential of the northern East European Platform based on aeromagnetic survey results and the morphologic and geochemical analysis of 1513 grains of kimberlite indicator minerals (KIMs), such as purple pyrope garnet, olivine, and Cr-diopside. These minerals were recovered from samples collected from modern river and stream sediments in four areas located in the north-eastern (within the Arkhangelsk Diamondiferous Province) and south-western (hundreds of kilometers outside of the Arkhangelsk Diamondiferous Province) parts of the Arkhangelsk region in the European part of Russia. All the studied areas are located within ancient cratons, including the Kola, Karelian, and Shenkursk cratons. Based on the major element compositions of the KIMs and thermobarometric calculations, this study confirms that the lithospheric mantle beneath the studied areas is suitable for the formation and preservation of diamonds. The high percentage of KIMs with primary magmatic grain surface morphologies is evidence of the presence of local kimberlite sources within all of the studied areas. The significant amount of diamond-associated KIMs indicates that the potential sources are diamondiferous. Hence, the results suggest that the studied areas can be recommended for further diamond prospecting activity with a high probability of discovering new diamondiferous kimberlites.

Diamond-Bearing Root Beneath the Northern East European Platform (Arkhangelsk Region, Russia): Evidence from Cr-Pyrope Trace-Element Geochemistry

“…For equilibration temperatures of garnets, the Ni thermometer [9] was applied. Approximate pressure estimates were obtained from the extrapolation of pyrope T Ni data to the Cr-diopside-derived geotherms of 35-40 mW/m 2 [2].…”

“…During three years of field seasons, a total of 2938 samples was collected from modern river and stream sediments. A detailed description of the samples can be found elsewhere [2]. A total of 145 pyrope grains recovered from heavy mineral concentrates of alluvial samples were provided for this study.…”

“…Since the discovery of the V. Grib kimberlite pipe in 1996, no new kimberlites have been identified within the province. However, recent results [2] show that several areas, both within the ADP and outside it, have high potentials to host local diamondiferous kimberlite sources. In this study, we present geochemical data for 145 Cr-pyrope grains recovered from heavy mineral concentrates of samples collected from modern river and stream sediments in the southern part of the Arkhangelsk region.…”

“…This region is of particular collected from modern river and stream sediments in the southern part of the Arkhangelsk region. This region is of particular interest due to its location within the ancient Shenkursk craton, the presence of a significant number of kimberlite indicator minerals (KIMs) [2], and the lack of any known nearby magmatic bodies, including kimberlites. The geochemical composition of the Crpyropes is used for evaluation of the lithospheric mantle composition and assessment of its suitability for the formation and preservation of diamonds.…”

“…The results confirm that the lithospheric mantle beneath the study area is suitable for the formation and preservation of diamonds. The significant percentage of diamond-associated pyropes (15%) emphasizes the likelihood of high diamond contents in kimberlites to be discovered within the study area.Minerals 2019, 9, 261 2 of 15 interest due to its location within the ancient Shenkursk craton, the presence of a significant number of kimberlite indicator minerals (KIMs) [2], and the lack of any known nearby magmatic bodies, including kimberlites. The geochemical composition of the Cr-pyropes is used for evaluation of the lithospheric mantle composition and assessment of its suitability for the formation and preservation of diamonds.…”